ABSTRACT. Introduction Joint-preserving tumor resection and patient-specific implant (PSI) reconstruction have the advantages of retaining the function and growth of native joints. Long-term complications of PSI in young active patients were a concern [1]. 3D planning and assistive tools like Navigation (NAVI) or 3D-printed guides (PSG) may facilitate the technically demanding surgical procedures [2,3] as it is challenging to translate the surgical plan with a negative surgical margin and match it to the PSI.

Methods We treated 20 paediatric and adolescent patients with lower extremity bone sarcoma who underwent joint-preserving tumor resection and extendable PSI (2006 and 2019). The mean age was 11 (5-17). Engineers designed PSI and PSG based on surgeons' defined surgical planning in MIMICS (version 16, Materialise, Belgium). After neoadjuvant chemotherapy, surgeries were assisted with 12 NAVI (Stryker), 4 PSG, or a combination (4 NAVIG) (Figure 1). Oncological results and limb functions were recorded. Patient overall disease survival and PSI survival with revision surgery as endpoint were calculated using Kaplan-Meier method (R Core Team (2023).

Results With a mean follow-up of 9.9 years (4.7 -17.7), three patients died from disease progression, and one patient defaulted follow-up. Using Kaplan-Meier, patient survival was 90% and 81.8% at five and ten years (Figure 2A). PSI survival was 94.1% and 86.9% at five and ten years (Figure 2B). One Henderson Type II aseptic loosening and two Type III structural failures required major implant components to be revised. MSTS score was 29.2 out of 30 (28-30). Surgical margins were all negative in bone except one soft tissue positive margin. All PSIs matched well to the retained articular bones intraoperatively and showed osseointegration at PSI junctions (except one) and continuous joint growth postoperatively.

Discussion With 3D planning and tools like NAVI and PSG, technically demanding joint-preserving surgeries could be accurately implemented as planned with excellent limb and joint function without compromising oncological results[4]. The computer-assisted approach might minimize soft tissue detachment by retaining the blood supply to the small articular bone segments. Osseointegration at the well-matched PSI junction suggested stable primary fixation and secondary healing of the PSI [5]. More cases and comparisons with conventional joint-sacrificing surgery were needed.

ABSTRACT. Here we investigate the impact of intra-operative balance and laxity on 2-year outcomes using two posterior cruciate ligament (PCL) sacrificing implant systems: ultra-congruent(UC) and posterior-stabilizing(PS) geometry. Four hundred twenty-five patients were enrolled in a prospective cohort and received robot assisted (OMNIBotics, Corin, UK) PCL sacrificing TKA with either a UC tibial insert(n=310) or PS components(n=115)(APEX Corin, UK) utilizing a tibia-first gap-balancing approach. Demographics were captured pre-operatively and KOOS pain questionnaires at 2-years post-op. Final joint laxity in midflexion and flexion were measured immediately prior to implantation. A Simulated Annealing optimization algorithm was used to identify optimal balance and laxity windows. Mann-Whitney-U tests were used to compare groups. Both cohorts report typical demographics. Similar laxity windows are observed between the 2 implant systems in midflexion. Medial flexion laxity however, reports different windows, in which the PS cohort reports a maximum laxity of 0 mm and no tightness boundary. The UC cohort reports a window of 5.5mm centered on a small amount of residual laxity. This difference drives optimal flexion balance in which the PS cohort favors relative lateral laxity compared to the UC cohort which reports a neutral balance window. The balance windows defined for UC and PS, respectively, are not associated with improved outcomes when applied in cross-over analysis to the opposite impant cohort(p>0.05). This is the first study to directly compare the impact of implant geometry on joint laxity and balance for optimizing patient outcomes and indicates that optimal soft tissue balance may be specific to implant design.

ABSTRACT. Technological advancements have led to an increase in use of computer assisted navigated and robotic Total Knee Arthroplasty (TKA) technology in recent years. However, there is little information on long-term outcome in terms of function and satisfaction as well effect of age on implant longevity. This single-centred retrospective study addresses these gaps by analysing data from 1677 consecutive primary navigated Columbus TKA cases, performed between 2005 and 2011. Patients were followed for 10 years, outcome collected at 6 weeks, 1, 5 and 10 years. Kaplan-Meier survival analysis carried out to determine likelihood of revision. Oxford Knee Score (OKS) and Satisfaction questionnaires taken to determine function and satisfaction. Kaplan-Meier reports a high probability of all cause survival of 0.96 as well as survival for aseptic cause (loosening, instability) 0.98 at 18 years. Kruskal Wallis test reports significance in function and satisfaction between age groups at each follow-up stage. At 10 years, OKS/ Satisfaction score shown to be of 34/48 (range 5-47)/ 75% for <=54.9 and 41/48 (range 1-48)/ 90-96% for >55 years groups. In summary, navigated TKA has shown excellent long-term survivorship (>90%) across all age groups, but the younger patients are most at risk, likely due to the higher residual symptoms. The authors conclude that navigated TKA should remain common practice; however, it is still likely beneficial that patients of working age <55 be monitored postoperatively more closely than patients >55 who remain functionally stable for 10 years in case active recommendation or treatment may prevent early revisions.

ABSTRACT. Smartphone apps are increasingly used to assess patient progress post-total knee arthroplasty (TKA). Activity levels during TKA recovery have not been optimized. Correlations between step-count and patient reported outcome measures (PROMs) were explored with sub-analyses investigating demographic effects. Smartphone step-count data from 862 TKA patients (Mean age: 66±9 years. 62% female. Mean BMI: 31±7kg/m2) were retrospectively reviewed. Mean daily step-count was calculated over five time windows: 60 days prior to surgery (pre-op), 42-49 days post-op (6 weeks), 91-98 days post-op (3 months), 183-197 days post-op (6 months), and 365-395 days (1 year). Spearman correlation coefficient and linear regression gauged the association between PROMs (KOOS-12 and UCLA) and step-count. Patients were separated into three step-count levels: low (<1500 steps/day), medium (1500-4000 steps/day), and high (>4000 steps/day). Demographic comparisons were performed using age >65 years, BMI >35 kg/m2, and sex. Welch’s unequal variances t-tests, or Wilcoxon rank-sum tests, both with Bonferroni corrections, were used where appropriate when comparing between groups. UCLA correlated with step-count at all time-windows (p<0.001). KOOS12 Function correlated with step-count preoperatively, and at 6 weeks (p<0.01). High versus low step-count individuals had improved UCLA scores at all time points (∆0.5-∆1, p<0.01) and improved KOOS12 Function scores preoperatively, at 6 weeks, and at 3 months (∆3.6-∆6.9, p<0.05). Males and young patients walked more at all time points (p<0.05). PROMs improved with higher step-count. Early post-operative step-count was significantly impacted by age and sex. Generic recovery profiles may not be appropriate across diverse populations.

ABSTRACT. This study explores the use of automated unsupervised evaluations via wearable devices, to assess the success of hip and knee replacements as a complement to traditional PROMs. A comprehensive analysis was conducted on data from 1144 TKA and THA patients utilizing a mobile application, with activity data collected through the Garmin Vivofit 4 wearable device. Key parameters, including daily Peak 6-Minute Consecutive Cadence (P6MC) and daily Peak 1-Minute Cadence (P1M), were computed pre and post surgeryand analyzed to assess the efficacy of these metrics in monitoring the recovery progress and the surgery outcomes. Cadence measurements, specifically P6MC and P1M, emerged as robust indicators. These metrics exhibited a superior level of responsiveness compared to traditional step-count measurements and showed good complementarity with PRO’s traditionally used in clinical practices. Moreover, the capture of these parameters being daily, unsupervised, and automated gives the potential of offering more granularity and better compliance than PROMs, providing new insights to assess quality of new surgical techniques. Moreover, the growing ubiquity of smartphones and wearables makes the use of such metrics usable in daily practice.

ABSTRACT. Postoperative monitoring has been gaining emphasis as a measure to optimize Total knee arthroplasty (TKA) patient care, in face of mounting demand for this procedure. The use of wearable and implantable devices continues to increase to monitor arthroplasty patients’ functional recovery. The identification of relevant functional metrics remains, however, a topic of discussion which we aim to assess in this paper. Various functional metrics were remotely collected from 89 unilateral primary TKA patients using a wearable system. Daily metrics including knee active time, load bearing time, range of motion, cadence, and step count were further summarized into weekly trends that were assessed and compared during the first 12 weeks post-surgery. All metrics tracked TKA patients’ functional improvements during the first 12 weeks postoperative, with higher rates of change observed during the first 6 weeks. Beyond 6 weeks, the average change rate over time is low but showed variation among patients up to 12 weeks postoperative. It is concluded that remote monitoring of wearable functional metrics provides a good assessment of TKA patients functional recovery at a higher temporal resolution than can be achieved through practice visits alone.

ABSTRACT. Background: Pelvic and sacral sarcomas are more likely to have positive surgical margin and recurrence. With the anatomical complexity and surgical difficulty of pelvic and sacral surgery, navigation-assisted surgery may benefit in bone resection to improve the surgical margin[2]. We wonder if navigated-assisted resection can provide a better adequate surgical margin than non-navigated resection of pelvic and sacral sarcomas.

Methods: Between 2009 and 2022, we performed 117 bone resections for pelvic and sacral sarcomas. There were 91 bone sarcomas, 32 of which were chordomas and 31 of which were chondrosarcomas, the two most common diagnosis. There were 26 soft-tissue sarcomas in which malignant peripheral nerve sheath tumor was the most common diagnosis in 9. Fifty-seven sarcomas (49%) were grade 3, 22 (19%) were grade 2 and 38 (32%) were grade 1. For pelvic, sacral, and combined pelvic and sacral resections, there were 57, 46, and 14 resections, respectively. Thirty-four resections (29%) were performed using navigation-assisted technique and 83 resections were performed without. There were no differences between the two groups in gender, age, location, and diagnosis. The mean maximum diameter of the tumor was significantly bigger in the navigation group than in the non-navigation group (p=0.01).

Results: The proportion of positive bony margin pathological specimens was lower in the navigation group (15%; 5 of 34) than in the non-navigation group (34%; 28 of 83) (p=0.004). However, there was no difference in the proportion of positive soft-tissue margins between the navigation (15%; 5 of 34) and non-navigation groups (11%; 9 of 83) (p=0.55). There was no significant difference in intraoperative blood loss or operative time between the two groups. The mean follow-up in the navigation group was 24 months (1-83) and 45 months (1-165) in the non-navigation group (95% CI; 4.3-34.2; p=0.01). Local recurrence occurred in 29.4% (10 of 34) of the navigation group and 26.5% (22 of 83) in the non-navigation group (p=0.82).

Discussion and conclusion: When compared to non-navigation surgery, navigation-assisted surgery can improve the accuracy of pelvic and sacral sarcoma bone resection resulting in a better negative bony surgical margin with no difference in intraoperative time. Our results are comparable to other studies and navigation-assisted surgery cannot improve the adequacy of the soft-tissue margin.

ABSTRACT. A Total ankle arthroplasty (TAA) procedure is a suite of numerous surgical steps, and even using Computer Assisted Surgery (CAS) systems, each of these steps may be associated with error such as mispositioning of the cutting block, play between the sawblade and the cutting slot due to the length and width of slot, or saw bending and skiving of the blade during the resection. For this reason, the error sources of the individual surgical steps were evaluated for a novel image-based CAS system for TAA. TAA was performed by a board-certified, fellowship-trained orthopedic surgeon on twelve artificial ankle joint specimens using a CAS system featuring a dedicated ankle application. Bone resections were individually virtually planned and performed by the surgeon using template software to choose appropriate implant position and size relative to the bony anatomy. The resected bones were scanned with structured light before and after the procedure and the resultant models overlaid for assessment of the error relative to the original plan. Mean and 95 % confidence intervals for positioning, execution and verification errors were less than 2mm and 2°. Design elements of the CAS system likely contribute to the low observed error. The surgeon receives visual confirmation of the plan and resection confirmation throughout the procedure which allows for real-time adjustments. In addition to the demonstrated ability to review the slot and cut positions during the procedure, there is future potential to remove the need for other checks for positioning guides which could reduce the burden on the user and reduce radiation exposure of the patient.

ABSTRACT. purpose: This study aimed to determine whether a CT-based robotic arm-assisted system helps surgeons perform more accurate cup placement, minimizes leg length, and offsets discrepancies than a CT-based navigation system. Methods: We studied 60 hips from 54 patients who underwent rTHA and 45 hips from 44 patients who underwent nTHA with the same target cup orientation. After propensity score matching, each group had 37 hips. Postoperative acetabular cup position and orientation were measured using the planning module of the CT-based navigation system. Postoperative leg length and offset discrepancies were evaluated using postoperative CT in patients who have unilateral hip osteoarthritis. Results: The absolute differences in radiographic inclination (RI) and radiographic anteversion (RA) from the target were significantly smaller in rTHA (RI: 39.6°±1.7°, RA: 15.3°±2.1°) than in nTHA (RI: 41.4°±2.9°, RA: 17.1°±3.4°) (p=0.005 for RI, p=0.002 for RA). The absolute distance of the target’s postoperative center of rotation was significantly smaller in the medio-lateral (ML) and supero-inferior (SI) directions in rTHA (ML: 1.1 mm±0.8 mm, SI: 1.3 mm±0.5 mm) compared with nTHA (ML: 1.9 mm±0.9 mm, SI: 1.6 mm±0.9 mm) (p=0.002 for ML, p=0.042 for SI). Absolute leg length and absolute discrepancies in the acetabular, femoral, and global offsets were significantly lower in the rTHA group (p=0.042, p=0.004, p=0.003, and p=0.010, respectively). In addition, the percentage of hips significantly differed with an absolute global offset discrepancy of <5 mm (p<0.001). Conclusion: rTHA was more accurate in cup orientation and position than nTHA, effectively reducing postoperative leg length and offset discrepancy.

ABSTRACT. The aim of this study is to assess the difference in the position of the femur relative to the tibia among different implant designs in total knee arthroplasty (TKA) and investigate its influence on postoperative clinical outcomes. In this study, varus knees underwent TKA using a navigation system was evaluated. The position of the femur relative to the tibia were calculated from each status obtained by a navigation system at maximum knee extension, 30°, 45°, 60°, 90° and maximum knee flexion before and after TKA. In addition, 2011 knee society score was investigated before and 1 year after surgery. The position of the femur relative the tibia after TKA at mid-flexion was statistically anterior than it before TKA in bi-cruciate stabilised (BCS)-TKA and posterior cruciate (PS)-TKA. The AP movement throughout range of motion after BCS-TKA was similar with that after PS-TKA. Moreover, the changes in the position of the femur after bi-cruciate stabilised TKA and posterior cruciate TKA at mid-flexion were negatively correlated with postoperative patient satisfaction.

ABSTRACT. The DePuy Synthes VELYS Robotic-Assisted Solution (VRAS), is one of the latest robotic-assisted technologies for total knee arthroplasty (TKA). Currently, there is limited evidence associated with the use of VRAS. This study is designed to evaluate the revision and readmission rates as well as the economic impact and operating room time associated with VRAS for TKA. The Premier Healthcare Database was used to identify patients undergoing VRAS or manual TKA between September 1, 2021, and February 28, 2023. Baseline covariate differences between the two cohorts were balanced using fine stratification methodology and analyzed using generalized linear models. The cohorts included 1,180 VRAS and 161,866 manual TKA cases with 866 VRAS and 128,643 manual cases having 90-day follow-up. The rate of all-cause and knee-related hospital follow up visits were significantly lower for VRAS compared to manual TKA patients by 19% and 45% respectively, at 90-day follow-up. The rate of knee-related inpatient readmission was also significantly lower (53%) for VRAS compared to manual TKA patients. There was no significant difference between total cost of care at 90-day follow-up between VRAS and manual TKA cases. In addition, discharge status and revision rates were similar between the cohorts. On average, the operating room time was higher for VRAS compared to manual TKA cases by 4 minutes. Based on early VRAS data and 90-day follow-up, the use for VRAS for TKA is associated with lower readmission rates while having similar total cost of care and operating time compared to manual TKA.

ABSTRACT. The contribution of individual ligaments to midflexion stability in normal knees has not been fully investigated. This study aimed to evaluate the anterior cruciate ligament (ACL), posterior cruciate ligament (PCL), and deep medial collateral ligament (dMCL) as stabilizers against anteroposterior stress. In this study, passive anteroposterior stress was applied to the knees at midflexion angles under image-free navigation monitoring. The ACL, PCL, and dMCL were detached from the intact knees as stepwise cutting sections. Removal of the ACL and PCL indicated that anteroposterior laxity was approximately twice as large as that of the intact knee. Subsequently, additional dMCL release significantly increased anteroposterior laxity by an additional 23 %. Our study revealed that preserving the dMCL provides midflexion anteroposterior stability in the midflexion range.

ABSTRACT. Background: New technologies introduction in the operating room induces a cost for the health system which can be assessed. This evaluation should focus on the stages dedicated to this innovation, not on the whole surgical workflow. The aim of this study was to evaluate the learning time for surgeons using a new intraoperative planning technique for total knee arthroplasty, coupled with instrumented knee laxity measurement.

Material and Methods: CUSUM analysis of the time spent planning their surgery intraoperatively were retrospectively performed on the first 50 cases of surgeons starting using a new device allowing to record knee joint laxities throughout the full arc of motion under quasi-constant distraction force coupled to a navigation system. The duration of the learning phase was analyzed per surgeon and globally and its Pearson correlation coefficient with the time required to achieve the first 50 surgical procedures was investigated.

Results: A total of 450 cases performed by 9 individual surgeons were considered, showing a mean by surgeon of 239±98 days to perform their 50 first cases. The CUSUM learning phase varied from 2 to 11 cases, with a mean of 6.4±2.8 cases. For all surgeons combined, the total intraoperative planning mean time in the learning phase was 82 seconds longer than in the proficiency phase (132 vs. 49 sec; p ¡ 0.0001). The correlation coefficient between the learning phase and completion time for the first 50 cases was 0.75 (p=0.0203, 95% CI 0.17 to 0.94).

Conclusion: While the previous studies have compared the overall operative time, we focused on analysing the intraoperative planning stage duration only, the step where the technology has been added. Our study shows that the average planning time is more than halved after a learning phase of 6.4 cases. Finally, the correlation coefficient analysis seems to show that the faster the 50 first cases are achieved, the shorter the learning curve.

ABSTRACT. Human Risk management poses a challenge for an open integration of medical devices in digital operating rooms according to the ISO IEEE 11073 SDC standard. A User Interface Profile has the potential to improve safety and usability, which defines the HMI characteristics of a medical device in an ensemble, aligning with ISO 14971 and IEC 62366-1 standards. We discuss applications in orthopedics, highlighting UI Profiles' potential to mitigate human-induced and process-related risks.

ABSTRACT. In this paper, we proposed an automatic cylinder-fitting based cut plane planning method, in particular for computer-assisted long bone tumor resection surgery. The proposed method first generated an expanded tumor region by a safe margin determined by tumor stage, then estimated orientations of the local medullary-cavity regions around the proximal and distal borders of expanded tumor, respectively, through fitting the local medullary-cavity region by a cylinder. Finally, the proposed method automatically planned one or two cut planes, perpendicular to local medullary cavity while tightly against the proximal or distal borders of extended tumor, for resecting long bone tumor. Efficacy of our method was evaluated on the surgical data obtained from ten patients undergoing long bone tumor resection surgery between January 2015 to January 2024. Results showed that our method was able to generate satisfactory cut planes for long bone tumor resection surgery, and it demonstrated comparable or even superior performance compared to the orthopedic surgeons (P=0.99). Overall, the results indicate that our method is of great potential to assist orthopedic surgeons to design optimal surgical plans for long bone tumor resection surgery.

ABSTRACT. This paper aims to address the issue from navigation perspective. Given the current state of tool tracking graphical interface in robotic spine surgery navigation systems are often highly simplified that it loses information of certain dimensions, or require assessing multi-views to interpret the tool alignment, this paper proposes a compact visual widget capable of showing the all 6-degrees-of-freedom (DOFs) in single view to improve tool alignment precision and surgeon’s cognitive load. Possibilities of using mobile display are also explored to improve hand-eye coordinated manipulation for the surgeons without the need to switch between looking at computer screens and surgical site.

ABSTRACT. Background: TKA with CR design is terchnically difficult, however become recently popular due to advantages of robotic assistance in terms of knee balance and alignment. The purpose of this study was to compare the success rate of CR implantation between modified mechanical alignment (mMA) and modified kinematic alignment (mKA) using MAKO robot.

Methods: 203 TKAs for osteoarthritis knees were divided 2 groups. The first 100 TKAs with modified MA and 2nd 103 TKAs with modified KA were performed from 2022 to 2023. mMA was defined by limiting the limb alignment & position of implant within 3° of mechanical axis. mKA was defined by limiting them within 5° of mechanical axis. PCL was resected when 5° or greater ER of TEA and/or 13mm or greater bony cut from posterior medial femoral condyle for knee balance. Knee balance was considered to be successful when the difference between the medial and lateral gap was within 1° or 2 mm.

Results: 37 TKAs of 100 mMA group (37%) and 6 TKAs of 103 mKA group (5.8%) required PCL resection for successful alignment and knee balance within definition. And when deformities was over 10° varus or flexion contractures PCL resection was required in 22 TKAs(55%) of 40 mMA group and 5 TKAs(9.6%) of 52 mKA group.

Conclusion: The mKA was better than mMA to achieve successful knee balance with CR design TKA. And mKA was even further better in case of deformities 10° or greater.

ABSTRACT. Robotic Ultrasound Systems are an emerging technology. Autonomous systems, which are not yet on the market, comprise detection of the scanning area, the ultrasound scan and image processing. However, contact gel application is performed manually. This work proposes a concept for an autonomous contact gel applicator to contribute to a full automation of robotic ultrasound scanning systems e.g. for 3D-imaging of the knee.

ABSTRACT. Robotic-assisted solutions have been developed to reduce surgical variability in total knee arthroplasty (TKA). This study assessed the clinical and economic outcomes associated with the use of the VELYS™ Robotic-Assisted Solution (VRAS) and reports on outcomes for other robotic surgery for primary TKA as a reference. Patients in the Premier Healthcare Database who received robotic-assisted primary TKA from September 1, 2021, to February 28, 2023, were included in the study. Readmission and revision rates at 90-day post TKA, operating room time, discharge status, and hospital costs were evaluated. This was designed as a single arm study and outcomes were analyzed using standard descriptive statistics. The study includes 955 VRAS TKA cases of which 690 had 90-day follow-up data. In the same period, there were 24,283 TKA cases performed with other robotic-assisted technologies with 19,226 having 90-day follow-up data. The all-cause and knee-related readmission rates were 1.47% and 0.59%, respectively for VRAS TKA cases at 90-day follow-up. As a reference, the readmission rates were 2.90% and 1.32% for other robotic-assisted solutions during the same period. The 90-day revision rate was 0.29% for VRAS TKA cases and 0.59% for the class of other robotic-assisted technologies. Average cost of care for inpatient readmission at 90-day follow-up was $15,273 and $14,820 for all-cause and knee-related costs, respectively. Average operating time was 141 mins for VRAS cases and 97% of VRAS cases were discharged to home. Early post-operative outcomes for readmission and revision rates associated with VRAS appear low considering other robotic-assisted solutions as a reference.

ABSTRACT. Placement of tibial tunnel in anterior cruciate ligament (ACL) reconstruction is crucial for the successful rate in ACL reconstruction. Angle of the tibial tunnel in respect to tibial plateau not only influence the tunnel length, but also graft impingement. In this study, we compared the accuracy between the angles of tibial tunnel and the tunnel length created with conventional surgical guide by surgeons, and that created by a handheld robot. Each 3D printed bone model was inserted by a guide pin targeting at 40o, 50o, and 60o. In the conventional method, the set-up was to mimic arthroscopic assisted ACL reconstruction, and three orthopedic surgeons of different clinical experience were recruited. In the robotic group, three sets of models were carried out as well, targeting at the same angle. In the conventional group, the mean error of angles placed by the young attending staff was 6.87o, and the mean tunnel length were 28.4mm. For the senior resident, the mean error was 14.3o, with the tunnel length of 30.9mm, 28.5mm, and 26.2mm. The mean error in junior resident was 10.85o, with the tunnel length were 17.4mm, 20.4mm, and 9.2mm. In the robotic group, the mean errors were 1.66o, 1.17o and 0.3o, with mean tunnel length of 33.1mm, 33.9mm, and 32mm for the three trials in respective to the targeting angles. Accurate placement of bone tunnels for cruciate ligament reconstruction requires substantial clinical experience and learning curve. Handheld robot can achieve a more accurate and consistent result.

ABSTRACT. Introduction:

The weight-bearing X-ray of the entire lower limb is mandatory to evaluate the mechanical axis (MA) while planning deformity correction in lower extremity. Computer assisted 3 D planning and making of 3 D printed guide (CA3DPG) needs data from 3 d CT scan of lower limbs. A significant limitation of current CT technology is that current technique forces image acquisition with the subject in a supine position. On the other hand longitudinal load methods used to obtain simulated weight bearing in a CT scanner are inaccurate, cumbersome and have limited availability. We use an an innovative method of simulating weight bearing lower extremity CT scan by superimposing supine 3 d CT data on weight bearing xray scanograms of lower extremities. The purpose of this study is to examine the difference in lower limb alignment in standard supine CT scan and simulated weight bearing CT scan in paediatric patients undergoing correction for genu valgum.

Material and methods:

18 children with genu valgum were included in study (age group 11 to 14 years). Simulated weight bearing CT model was created using Rhino 3D software. Mechanical TFA, mLDFA, a LDFA, mMPTA, a MPTA, JLCA were measured on the soft ware for supine 3 D CT model and simulated 3D CT model.

Results

The mean angles before and after simulation were as follows: TFA 3.25/ 10.24. mLDFA 81.25/ 83.53 aLDFA 78.33 79.85/JLCA 3.97 8.25/MPTA 85.38 85.45. The differences were statistically significant

Conclusion

There are significant differences in mechanical angle measurements for lower limb between standard supine 3 d model of lower limbs and simulated weight bearing 3 D model. The differences are greatest for JLCA and minimum for MPTA. Weight bearing model should be considered while doing computer assisted deformity correction planning.

ABSTRACT. One singularity of the total knee arthroplasty (TKA) compared to other joint replacements relates to the large panel of surgical workflow options depending on the order of the bone cuts as well as the definition of the landmarks. In this context, the objective of this study was to evaluate the impact of the surgical workflow on the bone cut parameters.

A retrospective review was performed on the intra-operative data from a cohort of 8 surgeons, who switched their surgical technique for TKA from a femur first measured resection (MR) workflow to a tibial first gap balancing (GB) workflow. This study compared seven femoral cut parameters, including four related to position and three related to orientation. The evaluation was performed at three distinct timepoints: the last 20 TKAs performed using the MR protocol (MR proficient group), the first 20 TKAs performed using the GB protocol (GB learning group), and the last 20 TKAs performed using the GB protocol (GB proficient group).

For the position parameters, 3 to 4 surgeons displayed statistically significant (p  0.05) variance differences across the three groups. Conversely, a higher number of surgeons, specifically 7 and 8 surgeons exhibited statistically significant variance across the three groups in relation to the flexion and axial rotation of the femoral component, respectively. Overall, a clear trend is observed in both position and orientation cut parameters, showing that most of the surgeons exhibited lower SD in the MR proficient group when compared to the GB groups (learning and proficient).

This study demonstrates that the surgical technique has an impact on the bone cut parameters and surgeons seeking to switch from MR to GB should be aware of these changes. The limited sample size in each group constitutes a limitation of this study. A larger sample size would yield more comprehensive insights.

ABSTRACT. Introduction

Distal radial fractures are one of the most frequent fractures throughout the body. Some of them, with joint involvement, can present a large number of fragments and fracture lines with great complexity, which increases the technical requirements during the surgical treatment of them. Next, we show our experience after performing five cases of complex intra-articular fractures of distal radius in which we use 3D bioreplication for surgical planning (B.R.E.Q).

Material and methodology

We present five cases of radial distal intraarticular fractures classified as OA / 2R3C3. All of them were treated by open reduction and osteosynthesis with plaque of the radius of the distal medulla assisted by arthroscopy. We complement the usual treatment plan with bioreplic 3D for surgical plan. We obtained DICOM images from the fracture TAC that were digitally treated with OSIRIX and processed with MeshMixer3.2 to obtain the print file in UltimakerCURA 3.0.4 later. and make a conventional impression with PLA. Two bioreplics were obtained for fracture, one for use in planning by the surgical team and another for intraoperative use.

Results

Using the 3D bioreplics for the surgical plan, we carried out the orientation of the surgical plan evaluating the different fragments, which allowed us to obtain a better perception of the fractures and a better communication between the members of the surgical team. The selection of the implant size was made after the test in the 3D bioreplicator. During the surgical procedure, 3D bioreplic allowed us to accurately communicate which fragment to manipulate at each moment and it served the surgeons as orientation for the instruments in the process of reduction of intraarticular fragments.

Conclusions

During treatment of intra-articular radial distal fractures, the presence of 3D bioreplics allows more precise planning, which also helps to solve possible intraoperative difficulties and the selection of more precise implants. Intraoperatively, 3D bioreplics helps precise and concrete communication between the surgical team, which translates into a lower rate of complications and a greater precision in intraoperative gestures, which, as it is logical to think, is reflected in a saving of surgical time.

ABSTRACT. We are developing the AI-based system which estimates the muscle mass and volume from anteroposterior plain radiograph of the pelvis. 97 patients (21 males and 76 females) who underwent X-ray imaging of the pelvis and whole-body DXA before total hip arthroplasty. Correlation of pelvic muscles mass and volume calculated by AI and limb muscles mass measured by whole-body DXA was evaluated. A high correlation was observed between the AI-estimated pelvic muscle mass and volume and the limb muscle mass measured by whole-body DXA. The AI-based system which estimates the muscle mass and volume from anteroposterior plain radiograph of the pelvis might be able to replace DXA-based sarcopenia screening.

ABSTRACT. Shameem Sampath and Mikail Aktas Ai Rehab LLC1, Atlanta, GA 30318, USA. admin@airehab.com

This study investigates trends in quadriceps inhibition after total knee arthroplasty (TKA). Eighteen patients for total knee arthroplasty (TKA) had perioperative physiotherapy with Slider, a Class 1 medical device that measures forces and knee motion. Slider monitors and uses gamification to encourage users to do knee exercises at home while displaying the results on their smartphones. The results are sent securely to their clinician with exception notification. Perioperative changes in the straight leg raise (SLR), inner range quadriceps (IRQ), and knee flexion lying (KFL) exercises were analysed. After starting Slider two patients declined surgery because their knee pain had decreased, two moved away, two were cancelled for medical reasons, and twelve had TKA. Two patients developed infections and abnormal trends in the results of the knee exercises were detected by the Slider algorithm before the patients’ clinic appointments. Graphs of the perioperative results of patients with no infections showed J-shaped (concave)curves for the SLR. While those for the patients with infections showed m-shaped (double-convex) curves. These objective findings are consistent with clinical experience of quadriceps inhibition occurring due to fluid accumulation following infection. In the infected patients, Slider’s algorithm enabled timely alerts to the patients’ clinics and early intervention. One had a successful washout, the other needed a revision. Larger studies on Slider are needed to provide statistically significant characterisation of anomalies to support clinical decisions.

ABSTRACT. Many patients exhibit joint level biomechanics and mobility deficits after knee arthroplasty, which have been linked to patient dissatisfaction. Advancements in robotic-assisted surgery offer the potential for surgery personalization to address these deficits, yet the link between surgical planning and joint mechanics remains unclear. This research aims to comprehensively model the relationships among patient variability in joint mechanics, anatomy/morphology, physical activity, implant characteristics and post-operative outcomes to inform personalization strategies to address these deficits in joint mechanics. This is a five-year longitudinal patient cohort study with integrated data at several time points perioperatively including longitudinally during the pre-operative wait period, and post-operatively to one year. We combine patient-specific information from multiple domains including demographics and anthropometrics; patient-reported outcomes; three-dimensional gait kinematics through AI-driven markerless motion capture integrated into the clinic hallway; free-living physical activity (PA) and gait outcomes with inertial sensors; joint anatomy, morphology and OA feature modeling through custom CT image processing; and intraoperative robotic data. Longitudinal pre-operative outcomes have been collected for a subset (n=57) to date. There were no significant longitudinal changes in gait kinematics or objective PA outcomes on a population level pre-operatively. However, a subset of patients exhibited significant gait worsening, and worsening was significantly correlated with more advanced OA-related gait deficits at baseline. Unique free-living gait metrics were identified that moderately correlated with in-clinic gait kinematics. PA outcomes were not significantly correlated to gait outcomes, and significantly worse PA outcomes (step count, %sedentary, %light and moderate to vigorous PA) were identified for female patients.

ABSTRACT. Given evidence that patients with a lower age at index surgery and higher BMI have an enhanced risk of aseptic revision. In this study, we used a previously developed methodology to estimate how large a comparative study would need to be to detect differences between navigated/robotic TKA and conventional TKA in both higher- and lower-risk patient populations, and how long the follow-up periods would need to be to be sufficiently powered to detect those differences. We modeled and simulated the likely outcomes of potential RCT study designs according to our previously published method. We generated three large sets of patients with distributions of patient-specific factors characteristic of patients at a reduced or enhanced risk of aseptic revision (relative to the typical risk assumed in our previous study). We then computed the corresponding Kaplan-Meier survival curves and applied a log-rank test to each study for statistical differences in revision rates at concurrent follow-up timepoints. The results from our simulation found survivorship differences favoring TA-TKA ranging from 2.8% to 3.9% at 15- and 20-years follow-up on the patient population at an enhanced risk of aseptic revision. Even for the patient population at the highest baseline risk of aseptic revision, comparative studies would still need to enroll at least 1750 patients in each arm of the study to have an 80% chance of showing this reduction in revision rates at 15 years of follow-up. Traditional RCT studies would require impractically large numbers of patients to be enrolled and excessively long follow-up times to demonstrate whether such a reduction actually exists.

ABSTRACT. OpenSim Moco enables Predictive and Tracking simulations, with both aiming to solve for the optimal kinematics and dynamics for a musculoskeletal model to complete a task. However, Tracking simulations may offer computational efficiency compared to Predictive simulations. This study demonstrated the effectiveness of Tracking simulations in achieving outcomes equivalent to Predictive simulations across models with diverse scapula geometries, using the Predictive solution of a mean model as a tracking reference. The software CORA quantified the correlation between the Tracking and Predictive simulation results through a calculated rating ranging from 0 (no match) and 1 (perfect match). This resulted in average ratings of 0.908±0.063 and 0.914±0.068 for lateral and forward-reaching tasks. These ratings highlight the capability of Tracking simulations to deviate from the tracked reference and find model-specific solutions. Tracking simulations achieved a speed-up factor of 5.90±2.31 and 7.64±3.35 for lateral and forward-reaching tasks, respectively, highlighting their computational advantages.

ABSTRACT. In this simulation study, we asked: Can such a matched case-control design enable us to estimate key functional relationships between multiple surgeon-controlled variables and aseptic revision risk in studies involving a number of patients that is practical to enrol? We simulated a matched case-control methodology that contrasted simulated TKA patients having functioning knee replacements with those who are candidates for aseptic revision surgery. Simulated functioning-TKA patients were matched 2:1 with candidates for revision surgery based on patient-specific factors. We modeled three surgeon-controlled factors (overall coronal alignment, tibial slope, and femoral component rotation), estimating surgical precision and relationship to aseptic revision risk based on previously reported literature. We then trained a Naïve Bayes classifier to predict functional relationships. Finally, we calculated the weighted mean absolute error by comparing the estimates of the simulated relationships used to generate the simulated TKA patient population. With as few as 300 revision candidates (900 total simulated patients), the weighted mean absolute error in predicting the functional relationships for coronal alignment, tibial slope, and femoral component rotation was 3.3 % ± 0.9%, 2.6 % ± 1.0%, and 5.4 % ± 0.8%, respectively. A matched case-control methodology may be an efficient approach to uncover multifactorial relationships between surgeon-controlled variables and risk of aseptic revision in TKA. Overall, a clearer understanding of these relationships could enable surgeons developing and practicing new techniques in TKA in addition to manufacturers of surgical guidance systems to base their design choices on the most significant factors aggravating risk of aseptic revision.

ABSTRACT. In many orthopedic surgeries, particularly those related to trauma, the surgeon uses a C-arm fluoroscopy machine which displays the x-ray images on a bedside monitor. The surgeon must manually map the information visible on the monitor to the surgical site, which frequently necessitates retaking x-ray images to ensure that the surgical tools are placed in the correct position relative to internal patient anatomy, which is visible only in the x-ray images. To reduce the number of x-ray images needed, we designed a Depth Camera Augmented Fluoroscopy (DeCAF) device that overlays the fluoroscopic images onto a live video of the patient’s surface anatomy to enable the surgeon to monitor changes in tool position without reacquiring x-ray images. In this study, we evaluated the performance of DeCAF in a simulated proximal tibial plate fixation procedure performed by an experienced orthopaedic trauma surgeon. We found that DeCAF had clinically acceptable overlay accuracies (1.6 ± 0.4 mm) and substantially eliminated the need to use X-ray images (down from 39.2 ± 5.1 to 0), without significantly changing the time required (498.8±57.2s for conventional approach vs 475.2±83.2s for DeCAF, p = 0.47). Screws placed using DeCAF were ~3mm deeper on average (p < 0.05), but were still placed at safe depths. These findings justify advancing DeCAF towards use in live operating room scenarios.

ABSTRACT. Background: Bone metastases significantly affect patients' quality of life, causing pain, immobility, and fracture risks. Accurate survival estimates are crucial for treatment decisions, particularly regarding surgery and implant selection. For extremity bone metastases, critical survival thresholds are often set at ninety days and one year. The SORG machine learning (ML) algorithms, initially developed for predicting 90-day and 1-year survival in the United States and Taiwan, exhibited reduced performance in a Dutch population, likely due to patient condition differences and improved overall survival in the Netherlands.

Objective: To develop a survival prediction model for 90-day and 1-year survival in patients with extremity metastases in a Dutch population.

Methods: A total of 292 patients with long-bone metastases between 2010 and 2022 were included at a tertiary referral Orthopaedic Oncology Center in the Netherlands. Patient data, including demographics, tumor characteristics, clinical variables, and laboratory values, were manually retrieved from electronic medical records. Model performance was assessed through discrimination using the area under the ROC-curve (AUC) and calibration curves.

Results: Of the 292 included patients, 190 underwent surgery (65%), while 102 were treated conservatively (35%). Among them, 143 were male (49%), and the median age was 64 years (IQR 56-70). The 90-day survival rate for surgical patients was 82%, and for conservatively treated patients, it was 76% (p = 0.31). The 365-day survival rate for surgical patients was 51%, and for conservatively treated patients, it was 48% (p = 0.97). The UMCG-MLA demonstrated reasonable discriminative ability, with an AUC of 0.70 for 90-day mortality and 0.75 for 1-year mortality. However, calibration analysis revealed overestimation of European patients’ 90-day mortality and underestimation of 1-year mortality.

Conclusion: The study found that MLA predictions are generalizable for surgical versus conservative treatment. The UMCG-MLA showed promise in predicting survival for patients with extremity metastatic disease. However, due to a relatively small sample size, predictions should be approached with caution. The model requires further training on a larger patient cohort to enhance predictive performance. Additionally, external validation in other Dutch hospitals is essential before implementing the model in daily clinical practice.

ABSTRACT. About 4 % of THA patients suffer from iliopsoas syndrome (IS). Modelling of the iliopsoas muscles is considered to be a reasonable aspect for identification of risk factors for IS. In this study we modelled the m. iliacus and the m. psoas major as separate muscles, consisting of 3 fascicles each. We analysed length and angular change of the fascicles from preoperative to postoperative state in a reference position on a database of 201 Japanese patients that underwent unilateral primary THA, with five of these patients being diagnosed with IS postoperatively. We did not find any correlation between length and angular changes and the appearance of IS. Further investigation is needed to find relevant risk factors for prediction of IS.

ABSTRACT. In order to improve the usability of surgical navigation systems, this paper presents the design, implementation and testing of a mobile wireless tracking camera cart for intraoperative use. The tracking data, i.e., tool poses, are made available on the operating room (OR) network by means of the manufacturer-independent communication standard ISO IEEE 11073 (“SDC”). In this way, the wireless tracking system (WTS) can act as a modular localization service for various medical devices such as robots and navigation software.

The concept and implementation of the battery-powered wireless tracking cart is shown. The paper furthermore evaluates how the use of a new software library improves latency and reliability in contrast to previous implementations. The results indicate that the new software library and the wireless data transfer do indeed meet the required latency of 50 milliseconds for hand-eye coordination tasks with a reliability of 99.395% even when the network is under OR-typical load. However, as the library does not offer any additional safety determinism, increased maximum latency times may occur in individual cases, making the device unsafe for intraoperative use.

ABSTRACT. INTRODUCTION: Image-based navigation systems for total knee arthroplasty (TKA) require intra-operative registration of anatomical landmarks to the pre-operative images. Unfortunately, this process is long, tedious, and involves multiple steps with an optical tracking probe to bony identify landmarks. We hypothesized that use of a handheld laser scanner can achieve an accurate and fast registration of cartilage surface.

METHODS: Magnetic resonance imaging (MRI) scans were obtained for six cadavers and images were segmented to produce 3-dimenstional (3D) models of the articulating surface of tibia and femur using commercial software (MIMICS, Materialise). A portable, hand-held laser scanner (E4D Technologies) was used to generate surface models of the same tibia and femur. An iterative closest point (ICP) algorithm was then used to align the handheld scans to the MRI scans. The accuracy of the registration fit was determined by the Root Mean Square (RMS) difference between the two surfaces.

RESULTS: There were a total of 72 scans. All 6 cadaveric knees were successfully registered to their MRI images with <1mm mean RMS error. The mean time for successful registration was 54 +/- 24 seconds. The inter- and intra-observer reliability were 0.92 and 0.87 respectively.

CONCLUSION: A handheld laser scanner can produce fast and accurate registration of the tibia and femur during a TKA. Registration was accurate within less than 1mm with multiple operators of different training. Further studies should assess in vivo accuracy of scanned bone topography and implant positioning compared to other technologies.

ABSTRACT. Aims

This study aimed to answer the following questions: do 3D-printed models lead to a more accurate and reliable recognition of complex elbow fracture patterns?; and do junior surgeons benefit more from 3D-printed models than senior surgeons?

Methods

A total of 15 orthopaedic trauma surgeons (seven juniors, eight seniors) evaluated 20 complex elbow fractures for their overall pattern (i.e., varus posterior medial rotational injury, terrible triad injury, radial head fracture with posterolateral dislocation, anterior or posterior olecranon fracture-dislocation) and their specific characteristics. First, fractures were assessed based on radiographs and 2D and 3D CT scans; and in a subsequent round, one month later, with additional 3D-printed models. Diagnostic accuracy (acc) and inter-surgeon reliability (κ) were determined for each assessment.

Results

With the use of 3D-printed models, the accuracy (acc2D/3D= 0.62 vs acc3Dprint= 0.69; p = 0.025) and reliability (κ2D/3D= 0.41 vs κ3Dprint= 0.59; p = ≤0.001) improved for the whole group on pattern recognition. Accuracy was comparable between junior and senior surgeons with the 3D-printed model (accjunior= 0.70 vs accsenior= 0.68; p = 0.904). Reliability was comparable between junior and senior surgeons without the 3D-printed model (κjunior= 0.39 vs κsenior= 0.43; p = 0.318), but greater improvement was seen for the juniors with 3D-printed models (κjunior= 0.65 vs κsenior= 0.54; p = 0.002).

Conclusion

3D-printed models enhanced accuracy and reliability in identifying complex elbow fracture patterns, yet prolonged printing times and non-reusable materials may restrict their clinical utility. However, they could serve as a reusable teaching tool for residents.

ABSTRACT. Background: During the last decade, the use of deep learning for computer-assisted guidance has dramatically grown, especially when including medical image processing. This practice requires to train and evaluate segmentation models by maximizing the control and knowledge of data. In this study we seek to demonstrate the relevance of data feature mastery on the prediction accuracy through the examples of scapula and humerus segmentation Material and Methods: Two datasets dedicated for scapula and humerus have been used for the training of models, built by experienced and qualified operators. The cases were meticulously chosen, according to their features, so that the models can be trained with features equally represented. Evaluation was made by comparing model predictions to the original ones with Dice coefficient, Hausdorff distance, and using a 3D meshes surface similarity-based metric. Results: Results shown significant accuracy decrease in presence of implant metal artefacts in the CT-scans. Scapula mesh evaluation demonstrated that for standard cases, 98.8% of the vertices carried negligible error against 94.6% in metal artefact cases. In evaluation of humerus meshes, 94.5% of standard cases vertices carried a negligible error against 86.7% in in metal artefact cases. Conclusion: Subgroup analysis accurately assessed segmentation model performance. It revealed that presence of metal implant artefacts significantly influenced accuracy for both scapula and humerus. Mastery of features enhances understanding of deep learning algorithms, emphasizing balanced feature representation for improved AI model performance.

ABSTRACT. Introduction In orthopaedic oncology, computer navigation and 3D-printed guides facilitate precise osteotomies only after surgical exposure[1,2]. Mixed Reality is an immersive technology merging real and virtual worlds, and users can interact with digital objects[3]. Through Head-Mounted Displays, surgeons directly visualize holographic models that overlay tumor patients in their physical environment before surgeries start. Clinical reports of MR application are limited, and no data in orthopaedic oncology.

Methods Between July 2021 and January 2024, we retrospectively reviewed 24 bone tumor patients undergoing surgeries. A holographic application was created using patients’ 2D medical images. In the conventional 2D method (Figure 1A), the surgeon studied 2D images and mentally overlaid the virtual 3D models onto the patients’ bodies. In the MR method (Figure 1B), the surgeons directly visualized 3D holograms on the patients’ bodies via HMD. Both methods were used to clinically assess the same patient. The surgeon completed 1) a Likert-Scale (LS) questionnaire to assess his opinions on the spatial awareness of the bone structures and the effectiveness of surgical planning and 2) The National Aeronautics and Space Administration-Task Load Index (NASA-TLX) score to evaluate the surgeons’ cognitive workload. The results of the two methods were compared using Wilcoxon Signed Rank Test.

Results The Likert-scale questionnaire revealed that the 3D holograms in the MR technology group were more effective than the Conventional 2D group. For the cognitive workload for preoperative clinical assessment, the MR technology group received significantly lower “mental”, “performance” and “frustration” scores; however, they received significantly higher “physical demand” and “effort” ratings than the Conventional group.

Discussion and Conclusion MR technology improved 3D visualization and spatial awareness of bone tumors in patients’ anatomies and may facilitate surgical planning before skin incisions in orthopaedic oncology surgery. The results concurred with the first case series of MR applications during orthopaedic surgery [4]. With less cognitive load and better ergonomics, surgeons can stay focused on the patients and surgical tasks while keeping their hands free and sterile to manipulate virtual objects [5]. Further studies can investigate whether MR technology guides and replicates surgical plans.

ABSTRACT. Aims: A comprehensive assessment of knee phenotypes is crucial for optimizing surgical realignment strategies in total knee arthroplasty (TKA). The purpose of this study was to investigate the relationship between the restoration of preoperative phenotypes, such as joint line orientation and alignment, and clinical outcomes following TKA.

Methods: We conducted a review of the records for 1052 primary osteoarthritic knees that underwent mechanically aligned (MA) TKAs between March 2016 and October 2021. Patient-reported outcome measures (PROMs) were assessed both before and 2 years after the surgery. The patients were then categorized based on to the Coronal Plane Alignment of the Knee (CPAK) classification system, which considers the arithmetic hip-knee-ankle (aHKA) angle as a measure of constitutional alignment, and joint line obliquity (JLO). The clinical results were compared between patients whose knee phenotype was maintained and those whose knee phenotype was not restored.

Results: More than half of the patients with osteoarthritic knees were found to have CPAK type I (varus aHKA, apex distal JLO; 59.4%) before undergoing TKA. The native phenotype was restored in 127 (12.1%) out of 1052 cases using MA techniques. These patients showed significantly better postoperative clinical results in terms of WOMAC function and Forgotten Joint Scores (FJS) compared to the non-restored group following MA TKA (p < 0.05). After adjusting the alignment by narrowly analysing the patients with maintained alignment between the preoperative and latest follow-up assessments, the significance persisted in the WOMAC function and FJS between the restored JLO and non-restored JLO groups (all p < 0.05). However, there was no significant association found between patients with or without a restoration of aHKA. In other words, the restoration of JLO was more clinically relevant to higher knee function compared to alignment.

Conclusion: Restoring the anatomical knee phenotype leads to improved postoperative PROMs, especially in terms of function, following TKA. Our findings highlight the clinical relevance of considering preoperative JLO for achieving more successful outcomes, rather than focusing solely on overall limb alignment.

ABSTRACT. Three-dimensional printing technology has been developed and applied in orthopedic surgery, including knee arthroplasty. To match individual knee morphology, surgeons can choose between standardized implants or customized 3D-printed ones. Despite technical advancements, the routine adoption of 3D-printed implants faces slow progress and various barriers. Our study explores surgeons' perspectives on 3D-printed prostheses by inviting them to freely express their thoughts by answering the question “What do you think about the manufacture of a prosthesis by 3D printing?

The questionnaire was completed by 90 surgeons, with an average experience exceeding 10 years (57.8% ± 10.2%). The majority worked in public hospitals (60% ± 10.1%) and performed zero to 100 prostheses annually (66.7% ± 9.7%). A large proportion do not use planning software (52.2% ± 9.7%), navigation systems, or robots (68.9% ± 9.6%). Respondents collectively agreed on the additional surgical time necessitated by technological innovation (74.4% ± 9.0%). Opinions on 3D printing were diverse, with 70%± 9.5% expressing positivity and 30%± 9.5% holding negative views. Motivations were categorized into seven domains, centered around "pre-surgery" and "post-surgery" concerns. Notably, results showed that a favorable disposition towards 3D printing was associated with the use of navigation systems or robots.

In conclusion, while no outright opposition to implementation was found, some surgeons expressed a preference for validated results and raised concerns about the entire supply chain, encompassing hospitals, insurance companies, and manufacturers. Despite the absence of opposition, the full adoption of 3D printing in joint replacement hinges on advancements across various areas of joint surgery.

ABSTRACT. Early identification and prediction of chronic pain in patients after total knee arthroplasty can significantly impact treatment strategies and improve patient satisfaction. This study introduces an innovative artificial intelligence model that predicts pain levels and pain evolution after TKA, empowering surgeons with insights for personalized patient care. The pain intensity was measured with a visual analog scale on a mobile application, from 1650 knee arthroplasty patients from one week before surgery and up to 12 weeks after surgery. A training set was first used to identify patterns in the data that could best approximate pain trajectories. Out-of-sample pain trajectories were predicted by estimating pattern weights and reconstructing the remaining timepoints. Confidence intervals were calculated to determine prediction accuracy. The model's accuracy was evaluated based on the percentage of predictions falling within 10 % of the true pain values. With an observation time of up to week 2, the model achieved 67% accuracy in forecasting pain levels for the next 4 weeks, and 61% accuracy for the next 10 weeks. By extending the observation time to week 4, the accuracy improved to 84% and 69% respectively. The artificial intelligence model showed promising results in predicting pain evolution. By utilizing this model, surgeon teams can manage patient expectations and tailor pain management strategies. The model's predictions facilitate efficient tele-monitoring, enabling remote patient monitoring of patient with less good evolution prediction, reducing the need for frequent clinic visits. Incorporating this technology into surgical practice can enhance surgical outcomes and patient satisfaction.

ABSTRACT. Background: Measuring the knee laxities when performing total knee arthroplasty (TKA) is part of the regular workflow and can be used as input for intra-operative planning. Gaps are traditionally measured by varus-valgus tests, but new instrumented methods have recently been proposed. This cadaveric study showed that the instrumented method is more reproducible than the manual one.

Material and Methods: Five operators, 3 senior surgeons and 2 juniors performed laxity measurements during navigated TKA on 8 knees. Each operator acquired the knee joint laxities throughout the full flexion, using the conventional method (varus-valgus stress tests) prior to any bone cutting, and then using an instrumented method with a distractor inserted between the tibial cut and the native femur. Each of the measure was repeated 6 times. Reproducibility of measurements was assessed by inter-operator and intra-operator ICC.

Results: The instrumented method had a significantly greater inter-operator ICC than the manual method for the lateral laxity (0.92 versus 0.25; p<0.0001) and the medial laxity (0.87 versus 0.60; p=0.02). For the manual method, the lateral laxity acquired under varus stress was less reproducible than the medial laxity acquired under valgus stress (0.25 versus 0.60; p=0.01), while the instrumented method showed no difference (0.92 versus 0.87; p=0.8) between the two compartments. For both manual and with the distractor, the seniors had better inter-operator ICCs than the juniors, although this was not significant (manually 0.55 versus 0.39; p=0.1, with the distractor 0.92 versus 0.90, p=0.3). The intra-operator ICC was significantly higher with the instrumented method than with the manual method for laxity assessment in all tests (0.78 versus 0.51; p<0.0001) and for the lateral compartment (0.84 versus 0.40; p<0.0001), but not for the medial compartment (0.71 versus 0.63; p=0.07).

Conclusion: The instrumented method enabled better reproducibility of the knee laxity acquisitions, limiting the influence of experience and the acquisition difficulty inherent in maintaining a varus force throughout flexion with the manual method. The application of a force controlled by the distractor, as well as its ease of use in the neutral position, may play a role in the reproducibility of gaps acquisitions.

ABSTRACT. Computer-assisted surgery relies on precise labelling of patient anatomy using 3D images. Major part of this process is nowadays performed by deep-learning (DL) algorithms. However, the evaluation of automated segmentations using conventional metrics have limitations, especially when assessing non-significant errors at the mesh level. To overcome this, we propose a novel metric focusing on significant surface disparities to enhance evaluation accuracy. SSPC metric consists of measuring cloud-to-mesh distances between two 3D objects in both directions and by setting one to several tolerance threshold and normalized by the total number of points. This metric was evaluated against a cohort of 103 shoulder reconstruction cases and compared to Dice coefficient, and Hausdorff distance. With a tolerance threshold set to T=0.5mm, SSPC met an agreement with experts of 87.4% of the cases. It overpassed Dice coefficient and Hausdorff distance reaching agreement of 76.7% and 62.1% respectively. This study demonstrated SSPC's superior ability over traditional metrics in identifying significant differences among 3D anatomical objects, as recognized by experts. Unlike conventional metrics, it selectively focuses on impactful differences, proving reliable comparison between two reconstruction systems. Further work is planned to explore integration of this metric into deep learning model training phase for accuracy improvement.

ABSTRACT. The presence of a tight lateral retinaculum can lead to the generation of a tilting moment and lateral force exerted on the patella. The degree of the strain contribution caused by a tight lateral retinaculum is sufficient to lead to the onset of patellar dislocation. Arthroscopic lateral retinacular release is one of the surgical techniques to improve patellofemoral (PF) biomechanics, prevent patellar dislocation and relieve tension in the PF joint. The release is done by making a sufficiently long incision on the lateral retinaculum. However, the outcome of surgery is still unpredictable. This paper aims to conduct a finite element analysis of patellofemoral contact during lateral retinacular release to quantify the stress released. A preliminary experiment on a cadaver was also performed for understanding the motion characteristics of the patellofemoral kinematics.

ABSTRACT. In vitro physiological knee joint simulators have been proven to be valuable tools for characterizing knee joint biomechanics, complementing in vivo measurements. However, many simulators only allow simulations of squatting motions. This is partly due to the lack of a tailored approach to efficiently identify the required simulator input parameters for accurate investigation of other frequently performed activities of daily living (ADL). Therefore, we aimed to develop a novel in vivo-based computational approach which uniquely integrates multiple constraints from a novel in vitro knee simulator to determine the required muscle forces during various ADLs. During a motion capture study, six healthy subjects performed squatting, sit-stand-sit and gait motions. Subject-scaled musculoskeletal models were adapted to include constraints of the knee joint simulator by including only quadriceps and hamstring muscle actuators, down-scaling ground reaction forces and applying constant hamstring force. Subsequently, muscle forces were computed for each motion using the Concurrent Optimization of Muscle Activations and Kinematics algorithm. Afterwards, the in silico-based squatting results were retrospectively compared with previously performed in vitro experiments using the knee joint simulator, which actively controlled the quadriceps and bilateral hamstrings to maintain a constant vertical ground reaction force of 110N during squatting. Resulting in silico computed and simulator-measured forces during squatting showed similar magnitudes and high correlations. This indicates robustness of the proposed in vivo-based computational approach. Accordingly, its application to stance phase of gait initiated quasi-static in vitro simulations of this additional motion, further demonstrating its feasibility.

ABSTRACT. Objective To investigate the clinical outcome of telerobot-assisted internal fixation in the treatment of thoracolumbar fractures. To Provide evidence for the clinical application of 5G-based telerobot-assisted spine surgery. Methods This study retrospectively analyzed 48 patients accepted internal fixation surgery by experts from Beijing Jishuitan Hospital remotely manipulating orthopedic robot of other hospitals from April 2021 to December 2021. Outcome of fixation, complications and success rate of communication were collected to evaluate the clinical outcome of telerobot-assisted surgery. Results A total of 48 telerobot-assisted internal fixation surgeries were successfully completed, with an average operation time of 93.23 ± 33.3 min. A total of 288 pedicle screws were placed, 254 (88.19%) were grade A, 26 (9.03%) were grade B, and 8 (2.78%) were grade C. The clinically acceptable rate of screw placement (Grade A + Grade B) was 97.22%. The postoperative height of the fractured vertebral body was greater than that preoperatively (63.15±13.69% vs. 86.93±8.41%, P＜0.001). There were no communication failures, robot failures, and no perioperative complications. Conclusion Telerobot-assisted internal fixation surgery for thoracolumbar fractures could achieve good fracture fixation. Telerobot-assisted thoracolumbar internal fixation surgery based on 5G network is safe and effective.

ABSTRACT. Robotic-Assistance (RA) in total knee arthroplasty (TKA) has gained popularity due to its ability to improve accuracy and facilitate patient specific techniques. However, the reported influence on clinical outcomes is inconsistent. This study assessed the influence of the recently introduced VELYS Robotic-Assisted Solution on the Knee Society Function Score (KSFS) at early follow up. A retrospective review of a prospective company sponsored registry was conducted to assess KSFS at first post-operative follow up for all ATTUNE primary TKAs. RA-TKAs were differentiated from MI-TKA. The mean KSFS was compared between groups. Pre-operative demographic information including sex, age, BMI and pre-operative KSFS scores were compared and an ANCOVA was used on post-operative KSFS scores to account for any differences. There were 553 RA-TKAs and 6,710 MI-TKAs with KSFS reported at first post-operative follow-up. The proportion of females was similar between the groups but the RA-TKA group was older (69.37 Vs. 66.37, p<0.0001), had slightly lower BMI (29.90 Vs. 30.79, p<0.0001) and had post-operative follow up at an earlier time point (87.43 Vs. 116 days, p<0.0001). The mean post-operative KSFS was significantly higher for the RA-TKA group than the MI-TKA group (79.59 Vs. 76.44, p=0.0001 and 78.15 Vs. 74.05 following ANCOVA adjustment). In this study, KSFS was improved for RA compared to MI at first follow-up. These findings suggest that RA combined with patient specific techniques can improve patient outcomes. Further investigation with longer-term follow-up is required.

ABSTRACT. Robotically controlled ligament balancing in total knee arthroplasty (TKA) allows for precise and reproducible measurements while manual assessment using conventional implant trials depends on surgeon and patient variability. This study aims to compare these two modalities with the goal of understanding which measurement technique is more reliable. 100 consecutive robotic-assisted TKA were retrospectively reviewed from six surgeons (600 total). Robotic and manual mediolateral (ML) balance was collected, normalized, and compared for each surgeon. For both robotic and manual assessments differences in ML balance and ∆ML (manual-robotic) balance were compared between right and left knees. All surgeons had poorly correlated (ICCs<0.46) and significantly different ML balance between manual and robotic from 45° to 90° flexion. Four surgeons manually measured more relative medial laxity, while two surgeons manually measured more lateral laxity compared to the robot. Five of six surgeons showed significant differences between operative leg side manual assessments throughout flexion (p<0.05). Two surgeons showed significant differences between right and left leg robotic assessments at 10° and 30° (p<0.05). Five surgeons had significant differences in ∆ML balance between operative leg sides (p<0.05). Surgeon-specific variations were evident in terms of relative medial or lateral laxity. Manual ML balance assessment is poorly correlated with robotic assessment, is significantly different and further from the surgical plan than robotic assessment, and less reproducible side to side. Individual surgeons exhibit unique patterns in how these measurements differ. This indicates that robotic balance assessment should be recommended to help standardize ligament laxity and balance measurements.

ABSTRACT. This study aimed to quantify the effect of posterior cruciate ligament (PCL) resection on medial and lateral joint gaps throughout the range of motion in a cohort of robotic-assisted total knee arthroplasties (TKA). 619 PCL-retained robotic-assisted TKAs performed with a digital joint tensioning device were retrospectively reviewed and matched 1:1 to PCL-sacrificed TKAs based on tibial slope, tibial resection thickness, knee alignment parameters, and patient demographics. Medial and lateral joint gaps in extension, mid-flexion, and flexion, as well as the posterior condylar offset (PCO) and femoral component rotation to achieve a balanced knee, were compared between PCL-retaining and PCL-resecting groups. The PCL-sacrificed cohort had a greater mean medial gap in mid-flexion (0.6mm greater, p<0.001) and flexion (1.5mm greater, p<0.001). The lateral joint gaps throughout the range of motion and the medial joint gap in extension were not different between groups (p>0.05). The increase in the medial joint gap in flexion creates sagittal imbalance which requires on average 1.3 mm increase in PCO and an average 1.2˚ decrease in femoral component external rotation to achieve a balanced knee. In this study of >1200 robotic-assisted TKAs, PCL sacrifice was associated with an increase in the medial joint gap in mid-flexion and flexion but not in extension. Lateral joint gaps were on average not affected by PCL release. This data is relevant to the successful performance of a balanced TKA as it indicates the need for more medial PCO and less femoral component external rotation in the PCL-sacrificed knee.

ABSTRACT. Introduction Predicting plantar pressure using personalized finite element (FE) biomechanical models of the patient’s anatomy holds significant promise for aiding in virtual surgical planning and predicting clinical outcomes. While sophisticated FE models have been described in literature, they come at high computational cost and therefore are not suitable for routine clinical care. Therefore, this paper presents an automatically generated FE biomechanical model of the foot, offering an efficient alternative for clinical applications. Methods The simplified foot model was based on the same CT image that was used by Kamal et al. The bones were segmented as a unified part. Subsequently, the bone and soft-tissue segmentations were used to automatically reconstruct an FEBio model. The soft tissue was modelled as homogenous and represented using the Ogden material and the bone as rigid and fully constrained. A ground force was applied based on the body weight. Results The FEBio model was successfully generated, and the computation of plantar pressure was completed in approximately 35 minutes on a personal laptop (using a 4mm edge length mesh). A ground reaction force of 657N was applied, yielding a plantar pressure distribution comparable to that of the sophisticated model. Conclusion Predicting plantar pressure using a simplified biomechanical FE foot model solely based on patient anatomy appears feasible for routine clinical application through our fully automatic workflow. The predicted pressure distribution was similar to that of a sophisticated FE model. However, further evaluation is needed to determine the accuracy in different patients and the clinical benefit.

ABSTRACT. In the realm of Computer Assisted Surgery (CAS), the accurate localization of anatomical features and surgical tools is crucial for enhancing surgical outcomes. Important efforts have been recently focused toward markerless navigation to reduce intraoperative intrusivity. Unfortunately, recent studies don't always satisfy the required accuracy and precision to be used clinically. This research investigates the application of deep learning models for pose estimation of synthetic anatomical features and surgery instruments to improve the localization accuracy. Based on the models from CosyPose and Coupled-Iterative-Refinement methods, we applied a three-step pose estimation process. Using 3D meshes and BlenderProc we generated a synthetic RGB-D dataset of scenes including tibias, femurs, shoulder's glenoids and surgical instruments (PSI) to train and test our model. Moreover, we compared our results to the Point Pair Features (PPF) method, a conventional pose estimation algorithm based on point cloud data. We found a significant enhancement regarding the accuracy with our model, achieving sub-millimetric and sub-degree accuracy, surpassing the PPF algorithm. We also provided qualitative examples of the estimated poses to visualize the accuracy of our model. While the proposed method shows promising results, challenges remain in particular passing from synthetic to real-world data. Future efforts will focus on collecting annotated real-world data.

ABSTRACT. Assessment of the loss in skeletal muscle mass (SMM) is often quantified by measuring the skeletal muscle index (SMI) through dual-energy x-ray absorptiometry (DXA). However, as SMI measurement is not always performed in the clinical setting, we aimed to develop and verify a system that predicts SMM loss from the CT images of the lower extremity that were acquired for the preoperative assessment of hip surgery. Sixty female patients with hip diseases who underwent CT and a whole-body DXA scan were retrospectively analyzed. Using an automated CT segmentation model of each muscle, muscles of the lower extremities were segmented and classified into three groups: gluteal muscles, muscles above the knee joint, and all lower extremity muscles. The relationship between the total muscle mass of the three groups and DXA-measured lean mass was assessed. Further, the SMI of the three groups was calculated, and their diagnostic performance in predicting sarcopenia (SMI < 5.4 kg/m^2) was evaluated using the receiver operating characteristic curve (ROC) analysis. Strong correlations were observed with lean mass and SMM of gluteal muscles (r = 0.82, p < 0.01), above the knee joint (r = 0.90, p < 0.01), and of all lower extremities (r = 0.94, p < 0.01). The area under the curves for each region were 0.93, 0.90, and 0.96, respectively. Our findings suggest that lower extremity CT scans with limited regions of interest may serve as a viable method for predicting whole-body SMM loss, indicating the possibility of diagnosing sarcopenia from such CT images.

ABSTRACT. Knee joint laxity or instability post total knee arthroplasty (TKA) is a common reason for patient dissatisfaction, and in some cases, can even result in the need for revision TKA. With the ultimate goal of developing an EOS-based knee joint laxity technique, the objective of this study was therefore to determine how repeatably EOS biplanar X-rays can measure 3D knee joint transforms on a radiographically realistic knee phantom between the femur and tibia in the presence of a TKA implant. To assess repeatability, we first scanned a femoral and a tibial anatomical model (Tactile KneeTM, Tactile Orthopaedics) using a clinical CT scanner and segmented the scans semi-automatically. The fully assembled TKA phantom was then placed within a jig that maintained a fixed and rigid connection between the femur and tibia. This model was then scanned 10 times with the EOS system, with approximately equally spaced perturbations ranging up to ±30⁰ around the superior/inferior axis, applied manually between scans. We then implemented a 2D-3D registration technique to assign Euler coordinate systems to both the femoral and tibial phantoms using JointTrack Auto. This process was completed for both the femoral and tibial TKA phantoms, and coordinate system assignment repeatability was calculated. The mean deviations from the mean for the medial-lateral, anterior-posterior, and superior-inferior translational axes were all submillimetric: 0.6 ± 0.7 mm, 0.4 ± 0.6 mm, and 0.7 ± 0.8 mm, respectively. The mean deviation from the mean around the medial-lateral, anterior-posterior, and superior-inferior rotational axes were all on the order of 1 degree or less: 1.0 ± 1.2⁰, 0.8 ± 1.1⁰, and 1.0 ± 1.2⁰, respectively.

ABSTRACT. This paper introduces and validates a 3D speckle tracking algorithm for assessing strains in knee collateral ligaments using ultrasound simulations. The study uses a numerical knee phantom based on a cadaveric post-total knee arthroplasty (TKA) knee with a posterior stabilized implant and with subject-specific material properties of knee collateral ligaments. The algorithm shows promise in capturing subtle deformations and strain patterns, with root mean square values of 0.10 mm and 0.72 mm for maximal and minimal principal strains, respectively. However, optimization and validation are currently limited to one specimen and loading scenario, necessitating further research for broader applicability. This work lays the foundation for advancing ultrasound-based biomechanical assessments, particularly in knee arthroplasty, with the potential for broader clinical impact on musculoskeletal health assessments.