ABSTRACT. Alignment techniques in total knee arthroplasty (TKA) continue to evolve and enable the possibility of planning the bone cut parameters in terms of position, rotation as well as laxity considerations. In this regard, the objective of this study was to evaluate the laxity targets set-up by surgeons at the time of the planning of the femoral cut parameters in TKA.

A retrospective review was performed on a proprietary cloud-based database utilizing an instrumented computer-assisted surgery system. 631 cases performed by 9 individual surgeons (minimum 30 cases each) were considered. Based on the potential impact of the conservation of the posterior cruciate ligament (PCL) or not, the cases were separated between posterior-stabilized (PS) and cruciate-retaining (CR) cases with 6 surgeons and 4 surgeons, respectively. One surgeon did participate in both the PS and CR groups. For each case, relative planned laxities were calculated for both medial and lateral compartments from 10° to 120° of flexion by using the 10° flexion planned medial laxity as the reference. Two Way ANOVA was used to compare the surgeon effect on the laxity definition, and Tukey multiple comparisons of means were used to compare pairwise laxity differences between surgeons. The significance level was set at 0.05.

The study found significant differences in relative laxities between the 9 surgeons regardless of PCL conservation and compartment side. Median values at each flexion angle and overall laxity signatures looked surgeon specific. Further statistical analysis using Tukey comparisons revealed significant mean laxity difference in most pairwise comparisons (76% of the cases).

The exact laxity required in TKA remains uncertain. Some surgeons aim for equal rectangular gaps in both flexion and extension and some target trapezoidal gaps with added laxity on the lateral compartment compared to medial. Despite using the same knee system and surgical technique, this study revealed surgeon-specific laxity goals. Recent studies highlight the impact of even minor laxity deviations (~2mm) on outcomes, emphasizing the need for further development of solutions to precisely define optimal laxity for a given TKA patient.

ABSTRACT. To address the increasing global demand for Total Knee Arthroplasty and reduce the need for revisions, several technologies combining 3D planning and artificial intelligence have emerged. These innovations aim to enhance customization, improve component positioning accuracy and precision. The integration of these advancements paves the way for the development of personalized and connected knee implant.

These groundbreaking advancements may necessitate changes in surgical practices. Hence, it is important to comprehend surgeons' intentions in integrating these technologies into their routine procedures. Our study aims to assess how surgeons' preferences will affect the acceptability of using this new implant and associated technologies within the entire care chain.

We employed a Discrete Choice Experiment, a predictive technique mirroring real-world healthcare decisions, to assess surgeons' trade-off evaluations and preferences.

A total of 90 experienced surgeons, performing a significant number of procedures annually (mostly over 51) answered. Analysis indicates an affinity for technology but limited interest in integrating digital advancements like preoperative software and robotics. However, they are receptive to practice improvements and considering the adoption of future sensors.

In conclusion, surgeons prefer customized prostheses via augmented reality, accepting extra cost. Embedded sensor technology is deemed premature by them;

ABSTRACT. New surgical techniques, such as robotics and augmented reality, promise to increase the quality and reduce the variability of the surgical procedure. But the effect of these new developments could be altered by the variability of the post operative care. Rehabilitation following total knee replacement (TKA) traditionally involves in-person therapy, presenting challenges in terms of protocol adherence, reproducibility, and cost. Digital rehabilitation holds promise in addressing these issues, but existing systems often lack personalization, neglecting factors such as patient pain, participation, and recovery speed. Moreover, most digital platforms lack essential human support. This study aimed to explore the engagement, safety, and clinical effectiveness of a personalized and adaptive app-based human-supported digital monitoring and rehabilitation program. Conducted as a prospective multi-center longitudinal cohort study, 127 patients were enrolled. A smart alert system managed undesired events, triggering physician interventions in case of suspected issues. The app collected data on dropout rates, complications, readmissions, Patient-Reported Outcome Measures (PROMS), and patient satisfaction. Results showed a 2% readmission rate, with smart alerts potentially preventing 85% of flagged issues through timely doctor interventions. Program adherence reached 77%, and 89% of patients endorsed the program's use. The integration of personalized, human-backed digital solutions emerged as a transformative approach to standardise and enhance the rehabilitation journey post-TKA, while showing potential cost savings.

ABSTRACT. The DePuy Synthes VELYS™ Robotic Assisted Solution (VRAS), is the latest entrant in the field of robotic technologies for total knee arthroplasty (TKA). MAKO by Stryker was one of the earliest TKA robots introduced to the market. This study is designed to evaluate the economic impact of VRAS and MAKO systems on TKA. The Premier Healthcare Database was analyzed for patients undergoing TKA using the VRAS or MAKO system between September 1, 2021, and February 28, 2023. Hospital cost at index and 30-, 60- and 90-day following procedures were evaluated. Cost breakdown at index hospitalization was also studied. All the outcomes were analyzed using standard descriptive statistics. The cohorts included 865 VRAS and 14,423 MAKO TKA cases with 90-day follow-up data. Average hospital cost at index for VRAS cases was $14,802. As a reference, MAKO hospital cost at index was $15,962. Average incremental cost of care for VRAS cases, 30-days following TKA was $97 for knee-related costs. Similarly, the incremental cost of care for MAKO cases during the same period was $168. A similar trend was observed for 30 to 60 and 60 to 90-days follow-up periods. Supply and operating room cost comprised more than 85% of total hospital cost at index. For VRAS, supply cost was $6,530 and operating room cost was $6,430. Similarly, for MAKO, supply cost was $6,664 and operating room cost was $6,917. Based on the early VRAS data and short follow-up, the use for VRAS for TKA is associated with lower hospital cost while referencing TKA performed with MAKO.

ABSTRACT. Methods We retrospectively collected 51 shoulder CT scans from 44 patients. Two senior and one junior orthopaedic shoulder surgeons created manual annotations of the glenoid best-fit circle and the maximum distance between the best-fit circle and the glenoid contour. Computed GBL annotations and measurements were obtained with our method. The GBL % ratio was computed from the resulting measurements. The inter-observer variability on the surgical decision of Bankart vs. Latrajet with the 13.5% % ratio cut-off threshold was determined as follows. Each surgeon chose for each scan the required surgery based on their manual annotations. The agreement/disagreement between the surgeons and the effect of replacing the threshold with an interval was then derived. The effect of the selection of the best-fit circle and of the largest radial distance between the glenoid contour and the best-fit circle was determined by presenting four options to the surgeons: the manual annotations of each surgeon and the computed annotation with their respective GBL deficiency %. Each surgeon then chose one of the annotations. Results In the 20 cases in which the GBL % ratio was < 5% or > 25%, all three surgeons agreed on the surgical procedure. For the remaining 31 cases, they disagreeded in 13 cases (42%). When the GBL cut-off of 13.5% was replaced by the interval 12.0-16.5%, the disagreement disappeared. In only ~30% of the cases, the surgeons chose their own annotation. The computed annotations were selected by all at least as often as those of the junior surgeon. Conclusion The established GBL % ratio cut-off of 13.5% may lead to significant discrepancies between surgeons regarding the type of surgery to be performed. Replacing it by the interval 12.0-16.5% may improve decision making by helping identify borderline cases for which there is no consensus. The computed GBL % ratio is within the observer variability and may thus be reliably used to save time and increase decision consistency.

ABSTRACT. Surgical robots can improve safety and surgical outcomes in neurosurgery and orthopedic surgery, but their clinical adoption remains limited. Among other reasons, the application scope of current robotic systems in surgery is limited due to safety hazards caused by over-dimensioned kinematics, thus contradicting international safety standards for cooperative robotic systems.

A modular dual robot system is presented, consisting of an off-the-shelf lightweight carrier robot for pre-positioning and an in-house developed, highly dynamic, application-specific miniaturized tooling robot. For the use case laminectomy, a formative usability study was performed with ten neurosurgeons on a spine phantom, comparing the dual robot system with manual milling. The tooling robot compensates for patient motion and robot elasticity, and an admittance control allows the user to move the burr within pre-planned virtual fixtures. These virtual fixtures include a safety margin that can be manually adjusted in 0.1 mm increments to compensate for inaccuracies in image acquisition, planning, and registration.

With the dual robot system, seven surgeons were able to successfully perform a planar laminectomy with a breach below 0.3 mm, corresponding to the thickness of the dura mater. Most surgeons rated the proposed dual robot system's safety, usability, and workload positively compared to manual milling. However, they also identified areas for improvement. The feedback indicates the necessity of changes to the user interface, extended virtual fixture planning possibilities, and more realistic study conditions, such as cadaver studies.

While further research is needed, the formative user study shows the potential of dual robot systems with application-specific tooling robots for high-risk applications like laminectomies. In the future, modular dual robot systems could support the widespread adoption of cooperative robotic assistance, helping to improve safety and surgical outcomes for various surgical treatments.

ABSTRACT. Introduction Surgical intervention is often indicated for complex multiplanar foot deformities (CMFDs). Addressing the 3D nature of these deformities proves challenging for achieving optimal foot alignment and reoperations are often necessary. Virtual surgical planning (VSP) can aid in the understanding of the multiplanar deformity and determine the osteotomies needed for correction. This study introduces a patient-specific guide (PSG) applied to a CMFD patient undergoing midfoot closing wedge osteotomy. Methods Based on a preoperative CT scan, a VSP was created based on correction of the lateral and axial Meary’s angle. Subsequently, a novel PSG design was developed that allows for intraoperative translational adjustments while guiding the osteotomy plane and the planned angular correction. First, a Jones tendon transfer was performed, two months later foot correction surgery was performed using the PSG. Postoperative CT-images were used to evaluate the outcome based on the VSP. Results Corrective foot surgery was performed successfully without complications. The VSP assisted the surgeon in understanding the deformity and necessary corrections. During surgery the PSG was used to guide the positioning of the triple arthrodesis. The fit was sufficient, albeit marginal for the distal reposition part. The analysis showed an improvement in the foot alignment and the clinical status improved to a stable gait with absence of pain. Conclusion. The intervention resulted in an improvement in foot shape, consequently enabling the patient to walk pain-free. Further improvement of the PSG was proposed to ensure an even better fit in future applications.

ABSTRACT. This study aimed to investigate how implant alignment philosophy in total knee arthroplasty (TKA) affects femoral trochlea groove restoration. Sixty-one imageless-robotic TKAs performed by a single orthopaedic surgeon were reviewed. In each case, the entire native trochlea was digitized to generate the native femoral anatomy, and implants were planned according to a functional alignment (FA) technique. Final implant position was recorded using the validated resection planes from the navigation system. Simulated femoral component positions were generated according to previously described alignment techniques; Mechanical alignment (MA), gap balancing (GB), kinematic alignment (KA), restricted KA (rKA), restricted inverse KA (riKA). Trochlear angle (TA), trochlear under/overstuffing, and mediolateral sulcus offset were compared between the six simulated alignment techniques as well as the final implanted technique. Further analyses investigated the effect of preoperative coronal alignment on trochlear position. The implanted and simulated techniques all resulted in greater TA valgus compared to the native groove (p<0.001). FA, KA, and rKA were closer to the native TA than GB, MA, and riKA (p<0.001). All alignment philosophies under-stuffed the native trochlea groove. KA and rKA under-stuffed less than all other techniques (p<0.001), and GB under-stuffed more than all other techniques (p<0.001). In extension, all techniques shifted the trochlear sulcus laterally, while in flexion, they medialized it. These effects were most prominent in GB and MA. Personalized alignment techniques such as KA and rKA that consider variations in individual anatomy best restore the native patellar groove compared to systematic alignment techniques when using a standardized femoral component.

ABSTRACT. Accurate positioning of shoulder implants is important as malposition can increase the risk of failure. Recently, patient specific instrumentation (PSI) guides, computer assisted navigation (C-NAV), and mixed-reality navigation (MR-NAV) which utilizes surgical visualization and holographic navigation, aim to improve component positioning. This study compared guide pin insertion accuracy using traditional 3D software planning (TSP), PSI, C-NAV, and MR-NAV. CT patient scans (n=20,68±12 years) with glenohumeral arthritis or rotator cuff tears were used. Scans were segmented and planned using preoperative software. Quadruplicate models of each glenoid were plastic 3D printed, resulting in a total of 80 plastic models (4 techniques X 20 cases). Four guide pin insertion methods were randomly performed by a fellowship trained surgeon as follows: (1) TSP employed 3D preoperative planning which permitted the surgeon to view and manipulate the plan during pin insertion. (2) PSI guides were created for each patient and affixed to the glenoid. (3) An in-house C-NAV system utilized an optical tracking system (accuracy = 0.1mm). (4) MR-NAV comprised of a Microsoft HoloLens II head mounted display. Following guide pin placement, the position and orientation of the guide pin relative to the glenoid was measured using a digitization system. Similar inclination accuracy occurred between PSI, C-NAV, and MR-NAV techniques (21, P>0.066). Furthermore, all three of these methods exhibited significantly less error in guide pin inclination compared to TSP (53, P<0.025). Similar accuracy in guide pin version was also observed between PSI (11), C-NAV (22), and MR-NAV (11) (P>0.515). Greater version error was observed with TSP (43) but was not significantly greater than the other techniques (P>0.063). The error in guide pin entry point was similar between all four methods utilized (TSP: 21mm, PSI: 21mm, C-NAV: 31mm, and MR-NAV: 21mm). This study showed that the accuracy of PSI, C-NAV, and MR-NAV are superior to TSP for glenoid pin insertion in-vitro. While some of the statistically significant differences observed in this study may not be clinically relevant, the maximum errors in inclination and version observed with the TSP could result in glenoid component malposition and corresponding glenoid component complications. Further investigation is needed to validate the accuracy of all guide pin insertion techniques in-vivo.