Source of the study: University of Auckland, Auckland, New Zealand. Unicompartmental knee arthroplasty (UKA) has benefits for patients with appropriate indications. However, UKA has a higher risk of revision, particularly for low-usage surgeons. The introduction of robotic-arm assisted systems may allow for improved outcomes but is also associated with a learning curve. We aimed to characterise the learning curve of a robotic-arm assisted system (MAKO) for UKA in terms of operative time, limb alignment, component sizing, and patient outcomes. Operative times, pre- and post-surgical limb alignments, and component sizing were prospectively recorded for consecutive cases of primary medial UKA between 2017 and 2021 (n=152, 5 surgeons). Patient outcomes were captured with the Oxford Knee Score (OKS), EuroQol-5D (EQ-5D), Forgotten Joint Score (FJS-12) and re-operation events up to two years post-UKA. A Cumulative Summation (CUSUM) method was used to estimate learning curves and to distinguish between learning and proficiency phases. Introduction of the system had a learning curve of 11 cases. There was increased operative time of 13 minutes between learning and proficiency phases (learning 98 mins vs. proficiency 85 mins; p<0.001), associated with navigation registration and bone preparation/cutting. A learning curve was also found with polyethylene insert sizing (p=0.03). No difference in patient outcomes between the two phases were detected for patient-reported outcome measures, implant survival (both phases 98%; NS) or re-operation (learning 100% vs. proficiency: 96%; NS). Implant survival and re-operation rates did not differ between low and high usage surgeons (cut-off of 12 UKAs per year). Introduction of the robotic-arm assisted system for UKA led to increased operative times for navigation registration and bone preparation, but no differences were detected in terms of component placement or patient outcomes regardless of usage. The short learning curve regardless of UKA usage indicated that robotic-arm assisted UKA may be particularly useful for low-usage surgeons

Introduction. Primary robotic-arm assisted total hip arthroplasty (THA) yields more accurate and reproducible acetabular cup placement, nonetheless, data is scarce in terms of outcomes. The purpose of the present study was to report on patient-reported outcomes (PROMs) in a large group of patients who underwent robotic-arm assisted THA. The authors hypothesized that (1) patients who underwent robotic-arm assisted primary THA would achieve favorable and significant improvement in PROMs, (2) an accurate and reproducible acetabular cup placement with respect to the defined SafeZones would be obtained, and (3) a low rate of THA dislocation would be observed. Methods. Prospectively collected data were retrospectively reviewed between April 2012 to May 2017. Primary THA using Mako Robotic-Arm [Mako Surgical Corp. (Stryker), Fort Lauderdale, FL, USA] with minimum two-year follow-up for the Harris Hip Score (HHS) and the Forgotten Joint Score-12 (FJS-12) were included. Exclusion criteria were: bodymass index (BMI) > 40 kg/m2, age < 21-year old, worker's compensation, or unwilling to participate. Visual analog scale (VAS) for pain and patient satisfaction were obtained. Intraoperative measurements for leg-length, global offset, acetabular inclination and version were documented. Results. 501 hips were included (57.29% females), follow-up was 43.99 ± 15.59 months. Average age was 58.70 ± 9.41 years, and the BMI was 28.41 ± 4.55 kg/m2. The group reported HHS of 90.87 ± 13.45, FJS-12 of 79.97 ± 25.87, VAS of 1.20 ± 2.06, and patient satisfaction of 8.85 ± 2.08. Intraoperative values for acetabular inclination and version were 40.0° ± 2.2 ° and 20.5° ± 2.4° respectively. Revision due to instability was 0.2%. Conclusions. Patients who received primary robotic-arm assisted THA reported excellent results at 44-month follow-up for multiple PROMs. Consistency in acetabular cup placement accuracy was achieved in regard to the Lewinnek and Callanan safe-zones

Outpatient total hip arthroplasty (THA) has remained controversial and challenging. Traditional hospital stays following total joint arthroplasty were substantial and resulted in increased rates of morbidity, significant pain, and severe restriction in mobility. Advancements in the surgical approach, anesthetic regimens, and the initiation of rapid rehabilitation protocols have had an impact on the length of recovery following elective THA. Still, very few studies have specifically outlined outpatient hip arthroplasty and, thus far, none have addressed the use of robotic-arm navigation in outpatient THA. This article describes in detail the technique used to perform outpatient THA with the use of robotic-arm assistance. We believe that outpatient THA using robotic-arm assistance in combination with tissue-preserving surgery, multi-modal pain and nausea management, early rehabilitation, and stringent patient selection yields a suitable alternative to inpatient joint replacement

Background. Manually instrumented knee arthroplasty is associated with variability in implant and limb alignment and ligament balance. When malalignment, patellar maltracking, soft tissue impingement or ligament instability result, this can lead to decreased patient satisfaction and early failure. Robotic technology was introduced to improve surgical planning and execution. Haptic robotic-arm assisted total knee arthroplasty (TKA) leverages three-dimensional planning, optical navigation, dynamic intraoperative assessment of soft tissue laxity, and guided bone preparation utilizing a power saw constrained within haptic boundaries by the robotic arm. This technology became clinically available for TKA in 2016. We report our early experience with adoption of this technique. Methods. A retrospective chart review compared data from the first 120 robotic-arm assisted TKAs performed December 2016 through July 2018 to the last 120 manually instrumented TKAs performed May 2015 to January 2017, prior to introduction of the robotic technique. Level of articular constraint selected, surgical time, complications, hemoglobin drop, length of stay and discharge disposition were collected from the hospital record. Knee Society Scores (KSS) and range of motion (were derived from office records of visits preoperatively and at 2-weeks, 7-weeks and 3-month post-op. Manipulations under anesthesia and any reoperations were recorded. Results. Less articular constraint was used to achieve balance in the robotic group, with a higher incidence of cruciate retaining retention (92% vs. 55%, p < 0.01) and a trend towards lower use of varus-valgus constrained articulations (5% vs. 11%, p = 0.068). Robotic surgery increased mean operative time by 22 minutes (p < 0.001). Operative time improved by 26 minutes from the first 10 robotic cases to the last 10 robotic cases. The robotic group had a lower hospital length of stay (2.7 vs. 3.4 days, p < 0.001). Discharge home was not significantly different between robotic and manual groups (89% vs. 83%, p = 0.2). Postoperative Knee Society scores were similar between groups at each postoperative time interval. Robotic-arm assisted TKA patients demonstrated lower mean flexion contracture at 2-weeks (1.8 vs. 3.3 degrees, p < 0.01), 7-weeks (1.0 vs. 1.8 degrees, p <0.01), and 3-months (0.6 vs 2.1 degrees, p = 0.02) post-surgery, but these differences were small. Mean flexion did not differ between groups at 3-month follow-up, but motion was achieved with a significantly lower rate of manipulation under anesthesia in the robotic group (4% vs 17%, p = 0.013). Conclusion. Preliminary findings demonstrate robotic-arm assisted TKA is safe and efficacious with outcomes comparable, if not superior, to that of manually instrumented TKA. Keywords. total knee arthroplasty, robotic arm-assisted total knee arthroplasty. For any figures or tables, please contact authors directly

Introduction. Robotic-arm assisted knee arthroplasty (rKA) has been associated with improved clinical, radiographic, and patient-reported outcomes. There is a paucity of literature, however, addressing its cost effectiveness. In the context of an integrated health system with an insurance plan and single source comprehensive data warehouse for electronic health records and claims data, we present an evaluation of healthcare costs and utilization associated with manual knee arthroplasty (mKA) versus rKA. We also examine the influence of rKA technology on surgeons’ practice patterns. Methods. Practice patterns of KA were assessed 18 months before and after introduction of robotic technology in April 2018. For patients also insured through the system's health plan, inpatient costs (actual costs recorded by health system), 90-day postoperative costs (allowed amounts paid by insurance plan), and 90-day postoperative utilization (length of stay, home health care visits, rehabilitation visits) were compared between mKA and rKA patients, stratified by total (TKA) or unicompartmental (UKA) surgery. Linear regression modeling was used to compare outcomes between the two pairs of groups (mKA vs. rKA, for both UKA and TKA). Log-link function and gamma error distribution was used for costs. All analyses were done using SAS statistical software, with p<0.05 considered statistically significant. Results. Overall KA volume increased 21%, from 532 cases in the pre-rKA period to 644 post-rKA introduction, with UKA surgeries increasing from 38 to 97 (155%). Of these KAs, 218 patients were insured through our system's health plan (38 rUKAs, 9 mUKAs, 91 rTKAs, and 80 mTKAs), allowing precise insurance claims analysis for postoperative utilization and cost. Patients with rKA had significantly lower mean home health costs (-90% difference for UKA, −79% difference for TKA, p<0.02) and home rehab costs (-64% difference for UKA, −73% difference for TKA, p≤0.007) than mKA patients. No significant differences were observed in outpatient rehab (visits or costs), total rehab costs, or length of stay. Mean total postoperative costs were significantly lower for rUKA than mUKA (-47% difference, p=0.02) but similar for TKA (p>0.05). There were no significant differences in total inpatient costs between MAKO and non-MAKO patients. Conclusion. Robotic-arm assisted KA can allow for increased UKA volume and potential for substantial cost savings over the total episode of care by reducing postoperative utilization and costs

Introduction. Robotics have been applied to total knee arthroplasty (TKA) to improve surgical precision in components’ placement, providing a physiologic ligament tensioning throughout knee range of motion. The purpose of the present study is to evaluate femoral and tibial components’ positioning in robotic-assisted TKA after fine-tuning according to soft tissue tensioning, aiming symmetric and balanced medial and lateral gaps in flexion/extension. Materials and Methods. Forty-three consecutive patients undergoing robotic-assisted TKA between November 2017 and November 2018 were included. Pre-operative radiographs were performed and measured according to Paley's. The tibial and femoral cuts were performed based on the individual intra-operative fine-tuning, checking for components’ size and placement, aiming symmetric medial and lateral gaps in flexion/extension. Cuts were adapted to radiographic epiphyseal anatomy and respecting ±2° boundaries from neutral coronal alignment. Robotic data were recorded, collecting information relative to medial and lateral gaps in flexion and extension. Results. Patients were divided based on the pre-operative coronal mechanical femoro-tibial angle (mFTA). Only knees with varus deformity (mFTA<178°), 29 cases, were taken into account. On average, the tibial component was placed at 1.2°±0.5 varus. Femoral component fine-tuning based on soft-tissues tensioning in extension and flexion determined the following alignments: 0.2°±1.2 varus on the coronal plane and 1.2°±2.2° external rotation with respect to the trans-epicondylar axis (TEA) as measured on the CT scan in the horizontal plane. The average gaps after femoral and tibial resections, resulted as follows: 19.5±0.8 mm on the medial side in extension, 20.0±0.9 mm on the lateral side in extension, 19.1±0.7 mm on the medial side in flexion and 19.5±0.7 mm on the lateral side in flexion. On average, the post-implant coronal alignment as reported by the robotic system resulted 2.0°±1.5 varus. Discussion. The proposed robotic-arm assisted TKA technique, aiming to preserve the integrity of the ligaments, provides balanced and symmetric gaps in flexion and extension and an anatomic femoral and tibial component's placement with post-implant coronal alignment within ±2° from neutral alignment

Introduction

Dislocation is a major cause of Total Hip Arthroplasty (THA) early failure and is highly influenced by surgical approach and component positioning. Robotic assisted arthroplasty has been developed to improve component positioning and therefore reduce post-operative complications.

The purpose of this study was to assess dislocation rate in robotic total hip arthroplasty performed with three different surgical approaches.

INTRODUCTION

we have previously reported that bone preparation is quite precise and accurate relative to a preoperative plan when using a robotic arm assisted technique for UKA. However, in that same study, we found a large variation between intended and final tibial implant position, presumably occuring during cement curing. In this study, we reviewed a subsequent cohort of patients in which the tibial and femoral components were cemented individually with ongoing evaluation of tibial component position during cement curing.

Background:

Numerous studies have reported the importance of acetabular component positioning in decreasing dislocation rates, the risk of liner fractures, and bearing surface wear in total hip arthroplasty (THA). The goal of improving acetabular component positioning has led to the development of computer-assisted surgical (CAS) techniques, and several studies have demonstrated improved results when compared to conventional, freehand methods. Recently, a computed tomography (CT)-based robotic surgery system has been developed (MAKO™ Robotic Arm Interactive Orthopaedic System, MAKO Surgical Corp., Fort Lauderdale, FLA, USA), with promising improvements in component alignment and surgical precision. The purpose of this study was to compare the accuracy in predicting the postoperative acetabular component position between the MAKO™ robotic navigation system and an imageless, CAS system (AchieveCAS, Smith and Nephew Inc., Memphis, TN, USA).

Introduction. Isolated lateral compartment osteoarthritis (OA) occurs in 5–10% of knees with OA [1, 2]. Lateral unicompartmental knee arthroplasty (LUKA) emerged as a treatment to this disease in the early 80s but challenging surgical technique has limited the prevalence of this treatment option [1–3]. A robotic-arm assisted surgical technique (MAKO Surgical Corp.) has emerged as a way to achieve precise implant positioning which can potentially improve surgical outcomes. Objectives. The purpose of this study was to evaluate short term outcomes for patients that received LUKA using a novel robotic-arm assisted surgical technique. Methods. Thirty-seven (37) patients (12 male, 25 female - mean age 63.7 years) with lateral OA received a robotic-arm assisted LUKA between July 2011 and September 2013 from 3 surgeons. All patients were evaluated by an independent surgeon not involved in the treatment of these patients at an average follow-up of 15.9 months (8–27). Range of motion and limb alignment was compared pre- and post-operatively. Results. Lateral UKA using robotic-arm assistance improved the post-operative range of motion an average of 4.8 ± 7.1º (p<0.0001) from a starting value of 136.5 ± 8.6º to a post-operative value of 141.6 ± 8.0º. In addition, patients began with a pre-operative deformity of 3.1 ± 3.2º of valgus and resulted in a post-operative alignment of 0.8 ± 1.9º of valgus corresponding to an average correction of 2.4 ± 2.3º less valgus (p<0.000001). The average operative time was 44.0 ± 10.8 minutes with 97% of the cases completed within 60 minutes. Conclusion. These results suggest that LUKA with robotic-arm assistance provides excellent post-operative alignment and demonstrate a reliable option for management of isolated lateral knee OA

Introduction. The purpose of this study is to compare total and rate of caloric energy expenditure between conventional and robotic-arm assisted total knee arthroplasty (TKA) between a high volume “veteran” surgeon (HV) and a lower volume, less experienced surgeon (LV). Methods. Two specialized arthroplasty surgeons wore a biometric-enabled shirt and energy expenditure outcomes were measured (total caloric expenditure, kilocalories per minute, heart rate variability, and surgical duration) during 35 conventional (CTKA) and 29 robotic primary total knee arthroplasty (RTKA) procedures. Results. Overall, the rate of caloric expenditure was similar between RTKA (5.60 ±2.50 kcal/min) and CTKA (4.79cal/min ±1.79, p=0.25). With 6.15 minute longer operative times, the total energy expenditure (TEE) for RTKA (239.31±96.79 kcal) was higher thanCTKA(181.54 ±80.90 kcal, p<0.001). The HV surgeon's TEE (p<0.001) and rate of energy expenditure (REE) (p<0.001) were significantly higher in RTKA (261.53cal; 6.499cal/min) versus CTKA (71.00cal; 3.759cal/min). However, the LV surgeon's TEE and REE for RTKA (207.83cal; 4.32cal/min) and CTKA (195.81cal; 4.92cal/min) were not significantly different (p>0.05). Both surgeons (HV; LV) had significantly longer surgical durations (p<0.001) in RTKA (40.41 ±4.94min; 48.91 ±8.45min) compared to CTKA surgeries (18.75±4.27min; 40.4 ±8.34min), respectively. Conclusion. While REE did not varybetween CTKA and RTKA for the LV surgeon, it did vary significantly for the HV surgeon. Additionally, RTKA took longer and increased TEE, but one less operating room assistant was needed. Surgeons with less experience in TKA may be less likely to notice a difference in energy expenditure when utilizing robotic-arm assisted technology. It is possible that more experience with using the robotic arm could create efficiencies over time that may also reduce TEE

Introduction. While manual total knee arthroplasty (MTKA) procedures have demonstrated excellent clinical success, occasionally intraoperative damage to soft tissues can occur. Robotic-arm assisted technology is designed to constrain a sawblade in a haptic zone to help ensure that only the desired bone cuts are made. The objective of this cadaver study was to quantify the extent of soft tissue damage sustained during TKA through a robotic-arm assisted (RATKA) haptically guided approach and conventional MTKA approach. Methods. Four surgeons each prepared six cadaveric legs for CR TKA: 3 MTKA and 3 RATKA, for a total of 12 RATKA and 12 MTKA knees. With the assistance of an arthroscope, two independent surgeons graded the damage of 14 knee structures: dMCL, sMCL, posterior oblique ligament (POL), semi-membranosus muscle tendon (SMT), gastrocnemius muscle medial head (GMM), PCL, ITB, lateral retinacular (LR), LCL, popliteus tendon, gastrocnemius muscle lateral head (GML), patellar ligament, quadriceps tendon (QT), and extensor mechanism (EM). Damage was defined as tissue fibers that were visibly torn, cut, frayed, or macerated. Percent damage was averaged between evaluators, and grades were assigned: Grade 1) complete soft tissue preservation to ≤5% damage; Grade 2) 6 to 25% damage; Grade 3) 26 to 75% damage; and Grade 4) 76 to 100% damage. A Wilcoxon Signed Rank Test was used for statistical comparisons. A p-value <0.05 was considered statistically significant. Results. Significantly less damage occurred to the PCL in the RATKA than the MTKA specimens (p=0.004). RATKA specimens had less damage to the dMCL (p=0.186), ITB (p=0.5), popliteus (p=0.137), and patellar ligament (p=0.5). The sMCL, POL, SMT, GMM, GML, LR, LCL, QT, and EM were grade 1 in all MTKA and RATKA specimens. No intentional soft tissue releases were performed in either group to balance the knee. Discussion/Conclusion. The results of this study indicate that RATKA may result in less soft-tissue damage than MTKA, especially to the posterior cruciate ligament. This finding can potentially be attributed to RATKA using a haptic boundary to constrain the sawblade, which can help prevent unwanted soft-tissue damage. However, since any damage was post-operatively assessed and in a cadaveric model, further investigations on soft-tissue damage from patients with clinical outcomes should be performed

Introduction. A careful evaluation of new technologies such as robotic-arm assisted total knee arthroplasty (RATKA) is important to understand the reduction in variability among users. While there is data reviewing the use of RATKA, the data is typically presented for experienced TKA surgeons. Therefore, the purpose of this cadaveric study was to compare the variability for several surgical factors between RATKA and manual TKA (MTKA) for surgeons undergoing orthopaedic fellowship training. Methods. Two operating surgeons undergoing orthopaedic fellowship training, each prepared six cadaveric legs for cruciate retaining TKA, with MTKA on one side (3 knees) and RATKA on the other (3 knees). These surgeons were instructed to execute a full RATKA or MTKA procedure through trialing and achieve a balanced knee. The number of recuts and final poly thickness was intra-operatively recorded. After completion of bone cuts, the operating surgeons were asked if they would perform a cementless knee based on their perception of final bone cut quality as well as rank the amount of mental effort exerted for required surgical tasks. Two additional fellowship trained orthopaedic assessment surgeons, blinded to the method of preparation, each post-operatively graded the resultant bone cuts of the tibia and femur according to the perceived percentage of cut planarity (grade 1, <25%; grade 2, 25–50%; grade 3, 51–75%; and grade 4, >76%). The grade for medial and lateral tibial bone cuts was averaged and a Wilcoxon signed rank test was used for statistical comparisons. Assessment surgeons also determined whether the knee was balanced in flexion and extension. A balanced knee was defined as relatively equal medial and lateral gaps under relatively equal applied load. Results. Operating surgeons used 9mm polys in all 6 RATKA specimens, and 3/6 MTKA specimens. Operating surgeons said they would do cementless in 4/6 RATKA specimens, and 1/6 MTKA specimen. In MTKA specimens, 5/6 cases had a recut on the tibia or femur to obtain knee balance. With RATKA, 1/6 cases had a recut on the tibia. With RATKA, operating surgeons performed a pre-resection balancing workflow, and made plan adjustments prior to resection. The operating surgeons reported reduced mental effort when performing bone measurements, tibial bone cutting, knee balancing, trialing, and post-resection adjustments with RATKA compared to MTKA. Mental effort was equivalent during femoral bone cutting between the two procedures and increased for RATKA during initial exposure and retractor setup. Assessment surgeons considered all 6 RATKA and 2/6 MTKA specimens to be balanced. Assessment surgeons assigned RATKA specimens a higher grade for perceived planarity (3.86 vs. 3.48, p=0.03) than MTKA specimens. DISCUSSION. In this cadaveric study, RATKA resulted in a higher usage of minimum poly thickness, greater tendency to want to use cementless components, higher number of balanced knees, higher perceived planarity, lower number of recuts, and reduced mental effort than MTKA cases. RATKA may give users more confidence in performing cementless TKA, especially for novice surgeons. Robotic-arm assisted TKA may allow for reduced surgical variability, which may improve patient outcomes, and should be investigated in a clinical setting

Background. Total hip arthroplasty (THA) has been and continues to be the gold standard for treatment of end-stage osteoarthritis. With each year, implant characteristics are evolving to increase patient-reported outcomes and decrease complications. Purpose: to report minimum 2-year outcomes and complications in patients who underwent robotic-arm assisted THA using Corin versus Stryker-type implants. Methods. Data were prospectively collected on patients who underwent THA with Corin-type implants (both cup and stem) and THA using Stryker implants between June 2011 and July 2016. A 1:1 propensity match was performed using the following 5 covariates: age, body mass index, gender, Charlson score and smoking status. Surgical outcomes were assessed at minimum 2-year follow-up using the Forgotten Joint Score (FJS), Harris Hip Score (HHS), Veterans RAND 12-item physical and mental health survey, Short Form 12 physical and mental health survey, Visual Analog Score (VAS), and patient satisfaction. The exclusion criteria were previous hip condition/surgery, workers compensation, or were unwilling. Results. Of the eligible 774 cases, 645 patients (83.3%) had minimum 2-year follow-up and met inclusion and exclusion criteria. Of the 645 patients, 323 had Corin implants, and 155 had Stryker implants. The 1:1 propensity match successfully yielded 290 patients (145 per implant group) which had a minimum 2-year follow-up at a mean 38.3 months (range, 24.1–65.3 months). Average age was 59.9 (range, 34.92–79.89 Stryker group, 30.65–75.92 Corin group) for each group and average BMI were 30.0 (range, 19.05–49.33) kg/m. 2. for the Stryker group and 29.77 (range, 20.15–55.37) kg/m. 2. for the Corin group. FJS (P=0.0388) and patient satisfaction (P=0.0019) were significantly higher in the Stryker implant group than the Corin implant group. There were nine cases of postoperative thigh numbness or paresthesias, three cases of wound infection, and one case of nonunion in the Corin-implant group. There were four cases of postoperative thigh numbness or parasthesias and six cases of wound infection in the Stryker-implant group. Conclusion. At minimum 2-year follow-up, patients who had undergone THA with Stryker-type implants had significantly higher FJS and satisfaction and a trend toward decreased complications than patients with Corin-type implants. These results can help guide decision making for surgical instrumentation by arthroplasty surgeons

Background. Discrepancies in patient outcomes after total knee arthroplasty have encouraged the development of different treatment options including early preventive interventions. In addition, improvements in surgical techniques and instrumentation have increased the accuracy of the surgeries. In this case study, we review the first robotic-arm assisted modular tricompartmental knee arthroplasty in which bone and soft tissues are conserved by employing a precise planning and execution technique. Materials and Methods. A 63 year old Caucasian female with a Body Mass Index (BMI) of 27 presented to the surgeon (SK) with knee pain and a varus mechanical alignment. The patient received modular tri-unicompartmental arthroplasty performed with robotic-arm assistance; (see figure 1 for post-op radiograph). Range of Motion (ROM), Knee Society Score (KSS) and Knee Injury and Osteoarthritis Outcomes Score (KOOS) were measured pre-operatively and post-operatively at 6, 16, and 23 months. At 6 months post-op an in-depth in vivo kinematic analysis was conducted by using a validated fluoroscopic assessment technique [1]. The patient simulated stair climbing, kneeling activity, and deep lunge while under single plane fluoroscopy. Three dimensional models were created from CT scans and were matched to 2D fluoroscopic images for kinematic assessment. Results. ROM, KSS, KOOS improved post-operatively, see Table 1. Patient displayed tibial internal rotation and screw home mechanism like that of normal knees, (Figure 2). Anterior-posterior translation of medial and lateral compartments was observed (Figure 3). The patient demonstrated a maximum flexion of 115 and 114.9 in kneeling and lunge activity, respectively. Tibial external rotation was seen in both kneeling and lunging, although rotation was greater during the lunge activity (3.1 versus 11.5 degrees). Both medial and lateral compartments showed posterior translation during these activities (Table 2). Conclusion. Clinical, radiographic and functional outcomes were achieved for this patient. This case report was the first case of robotically assisted, modular, ACL and PCL sparing tricompartmental arthroplasty. It was anticipated that preserving more soft tissues, particularly the ACL would contribute to improved kinematic function of the knee following arthroplasty, which was the primary differentiating factor between a bicompartmental design and a traditional tricompartmental knee design. The use of robotic techonlogy as described herein has not yet been approved by the FDA

Introduction:. Unicompartmental knee arthroplasty (UKA) has been proven to be an effective treatment for degenerative joint disease confined to a single tibiofemoral compartment. Recently, UKAs have been performed with robotic-arm assistance (RAA) devices to build and improve upon previous computer-assisted navigation. As a pilot study, we have analyzed short term outcomes for a series of robotic-arm assisted medial UKAs and compared them to a comparable cohort of traditionally instrumented medial UKAs. Methods:. Ninety-eight fixed-bearing medial UKAs were isolated in our prospective data collection database for short-term analysis for this study. Included patients completed pre and post-operative Short Form 12 version 1 Health Survey (SF12), Western Ontario and McMaster University Outcome Scores (WOMAC), and Knee Society Function Score (KSFS) questionnaires. Forty-eight RAA UKAs were performed using the MAKO RIO system with Restoris implants, and fifty manual UKAs were performed with the Zimmer® Unicompartmental High-Flex Knee System (ZUK). Results:. Both cohorts experienced increased gains in all categories, except for the change in SF12 mental subscore in the MAKO cohort. Only the WOMAC pain subscore at 1 year showed statistically significant differences between the two cohorts, with MAKO subjects experiencing less pain than ZUK subjects (92.4 MAKO vs. 82.0 ZUK, p = 0.03). The SF12 mental score at three months and the change in SF12 mental score from pre-op to 1 year were also statistically significant; however, the pre-op differences between the two groups in the SF 12 mental category were also significantly different. Within the groups that were not significantly different, ZUK subjects experienced greater changes from pre-operative to three months in SF12 mental, all WOMAC subsets, and KSFS, while MAKO subjects had a greater change in SF12 physical subscore. This pattern held true with changes between pre-operative and 1 year, with the exception that MAKO patients experienced a greater positive change in WOMAC pain scores than ZUK patients. Additionally, age and body mass index were not significantly different between cohorts; however, operative time was significantly longer in the MAKO cohort (p < 0.001). Discussion:. These results suggest that despite the lower WOMAC pain scores at one year, the extra expense and operative time required for RAA UKA may not translate into immediate functional gains. These conclusions are however limited due to the short follow-up time period and the randomization of patients. Future studies must also analyze implant alignment, rotation and position in order to fully analyze the operations

Introduction. Medial unicompartmental knee arthroplasty (UKA) for isolated medial knee arthritis is a highly successful and efficacious procedure. However, UKA is technically more challenging than total knee arthroplasty (TKA). Research has shown that surgical technical errors may lead to high early failure rates. Haptic robotic systems have recently been developed with the goal of improving accuracy, reducing complications, and improving overall outcomes. There is little research comparing robotic-assisted UKA to standard UKA. The goal of this study was to compare clinical and radiographic data for matched cohorts who received robotic-arm assisted UKA or standard instrumentation UKA. Methods. We performed a non-randomized, retrospective review of 30 robotic-arm assisted UKA and 32 manual UKA performed by single fellowship-trained joint arthroplasty surgeon (SKK) over 2.5 years. All procedures completed through a medial parapatellar approach. All components were cemented. All tibial components were a metal-backed onlay design. Average follow-up was 10.1 months (range 5–36). A full clinical/hospital chart review of demographic, intra- and post-operative measures was performed. Radiographic analysis of pre- and post-op images evaluating sagital and coronal alignment, and component positioning was performed by single observer (DCH), using OsiriX imaging system (Pixmeo; Geneva, Switzerland). Radiographs were available for analysis in 28 robotic-assisted and 30 manual patients. Statistical analysis was performed using SPSS v. 20. Comparison between group means was performed as well as calculation of variance in component placement within groups. Results. No demographic differences were seen between groups. Operative time was significantly longer in robotic-assisted UKA compared to the manual group. Minimal clinical post-op differences between groups. The robotic group showed some early advantage in ambulation/ROM during inpatient stay. This ROM difference reversed at 2 weeks post-op. Continued medial-sided knee pain was reported more commonly in robotic group. Radiographic results showed no difference between groups in pre-op mechanical alignment. The robotic group was significantly more accurate at recreating femoral axis. Accuracy in recreation of tibial slope/ was similar between groups. Accuracy of the tibial component in the coronal plane was not significantly different between groups. The robotic group did have significantly larger variance in coronal alignment of the tibial component. Medial overhang of tibial component was significantly greater and more variable in the manual group. Non-significant decrease in resection depth found in robotic group. Conclusion. There were minimal clinical and radiographic differences between techniques. Clinically, both cohorts did very well. Radiographically, both groups had quite accurate placement of components, with the most obvious difference being the increased tibial component overhang in the manual group. Overall, our data suggests that the purported benefits of robotic UKA may be obviated in the hands of a surgeon with training and experience in manual UKA implantation

Medial unicompartmental knee arthroplasty (UKA) for isolated medial knee arthritis is a highly successful and efficacious procedure. However, UKA is technically more challenging than total knee arthroplasty (TKA). Research has shown that surgical technical errors may lead to high early failure rates. Haptic robotic systems have recently been developed with the goal of improving accuracy, reducing complications, and improving overall outcomes. There is little research comparing robotic-assisted UKA to standard UKA. The goal of this study was to compare clinical and radiographic data for matched cohorts who received robotic-arm assisted UKA or standard instrumentation UKA. We performed a non-randomised, retrospective review of 30 robotic-arm assisted UKA and 32 manual UKA performed by single fellowship-trained joint arthroplasty surgeon (SKK) over 2.5 years. All procedures completed through a medial parapatellar approach. All components were cemented. All tibial components were a metal-backed onlay design. Average follow-up was 10.1 months (range 5–36). A full clinical/hospital chart review of demographic, intra- and post-operative measures was performed. Radiographic analysis of pre- and post-op images evaluating sagital and coronal alignment, and component positioning was performed by single observer (DCH), using OsiriX imaging system (Pixmeo; Geneva, Switzerland). Radiographs were available for analysis in 28 robotic-assisted and 30 manual patients. Statistical analysis was performed using SPSS v. 20. Comparison between group means was performed as well as calculation of variance in component placement within groups. No demographic differences were seen between groups. Operative time was significantly longer in robotic-assisted UKA compared to the manual group. Minimal clinical post-op differences were seen between groups. The robotic group showed some early advantage in ambulation/ROM during inpatient stay. This ROM difference reversed at 2 weeks post-op. Continued medial-sided knee pain was reported more commonly in robotic group. Radiographic results showed no difference between groups in pre-op mechanical alignment. The robotic group was significantly more accurate at recreating femoral axis. Accuracy in recreation of tibial slope/ was similar between groups. Accuracy of the tibial component in the coronal plane was not significantly different between groups. The robotic group did have significantly larger variance in coronal alignment of the tibial component. Medial overhang of tibial component was significantly greater and more variable in the manual group. Non-significant decrease in resection depth found in robotic group. There were minimal clinical and radiographic differences between techniques. Clinically, both cohorts did very well. Radiographically, both groups had quite accurate placement of components, with the most obvious difference being the increased tibial component overhang in the manual group. The increased variance in tibial component alignment in the robotic group is likely due to the ability to more specifically alter the resection to fit the patient's specific anatomy. Overall, our data suggests that the purported benefits of robotic UKA may be obviated in the hands of a surgeon with training and experience in manual UKA implantation

Background. Intraoperative balancing of total knee arthroplasty (TKA) can be accomplished by either more prevalent but less predictable soft tissue releases, implant realignment through adjustments of bone resection or a combination of both. Robotic TKA allows for quantifiable precision performing bone resections for implant realignment within acceptable final component and limb alignments. Objective. To provide a direct comparison of patient reported outcomes between implant realignment and traditional ligamentous release for soft tissue balancing in TKA. Methods. IRB approved retrospective single surgeon cohort study of prospectively collected operative and clinical data of consecutive patients that underwent TKA with a single radius design utilizing kinematic sensors to assess final balance with or without robotic assistance allowing for a minimum of 12 months clinical follow up. Operative reports were reviewed to characterize the balancing strategy. In surgical cases using robotic assistance, pre-operative plan changes that altered implant placement were included in the implant realignment group. Any patient that underwent both implant realignment and soft tissue releases was analyzed separately. Kinematic sensor data was utilized to quantify ultimate balance to assure that each cohort had equivalent balance. Patient reported outcome data consisting of Knee Society- Knee Scores (KS-KS), Knee Society- Function Scores (KS-FS), and Forgotten Joint Scores (FJS) were prospectively collected during clinical follow up. Results. 182 TKA were included in the study. 3-Month clinical follow up was available for 174/182 knees (91%), 1-Year clinical follow up was available for 167/182 knees (92%) and kinematic sensor data was available for 169/182 knees (93%). Kinetic sensor data showed that on average all of the balancing subgroups achieved clinically equivalent balance. Use of robotic-arm assistance provided the tools and confidence to decrease from ligament release only in 40.8% of non-robotic cases to 3.8% in the robotic group, and the use of component realignment alone increased from 23.7% in the non-robotic cases to 48.1% in the robotic TKA group. KS-KS, KS-FS and FJS scores showed improvements in outcomes at both the 3-month and 1-year time points in the implant realignment cohort compared to the ligamentous release cohort. KS-KS, KS-FS, and FJS at 1-year were 1.6, 7.6, and 17.2 points higher respectively. While none of the comparisons reached statistical significance, KS-FS at 1 year showed a statistically and clinically significant difference (MCID 6.1–6.4) increase of 7.7 points in the implant realignment cohort compared to the ligamentous cohort. The 1-year trend can be further explained by the outperformance (MCID increase of 6.4 points) of the implant realignment robotic cohort at 1-year compared to the non-robotic ligamentous cohort. Conclusions. Directly comparing TKA patients balanced with implant realignment alone versus ligamentous release alone versus combined technique, a trend toward clinical improvement above a minimally clinical significant difference in KS-FS scores benefiting the implant realignment technique was seen at both 3-months and 1-year post-operatively. We hypothesize that the benefit of implant realignment is achieved through decreased soft tissue trauma as well as potentially greater predictability and sustainability of soft tissue balance than with soft tissue releases alone

While total knee arthroplasty has demonstrated clinical success, final bone cut and final component alignment can be critical for achieving a desired overall limb alignment. This cadaver study investigated whether robotic-arm assisted total knee arthroplasty (RATKA) allows for accurate bone cuts and component position to plan compared to manual technique. Six cadaveric specimens (12 knees) were prepared by an experienced user of manual total knee arthroplasty (MTKA), who was inexperienced in RATKA. For each cadaveric pair, a RATKA was prepared on the right leg and a MTKA was prepared on the left leg. Final bone cuts and final component position to plan were measured relative to fiducials, and mean and standard deviations were compared. Measurements of final bone cut error for each cut show that RATKA had greater accuracy and precision to plan for femoral anterior internal/external (0.8±0.5° vs. 2.7±1.9°) and flexion/extension* (0.5±0.4° vs. 4.3±2.3°), anterior chamfer varus/valgus* (0.5±0.1° vs. 4.1±2.2°) and flexion/extension (0.3±0.2° vs. 1.9±1.0°), distal varus/valgus (0.5±0.3° vs. 2.5±1.6°) and flexion/extension (0.8±0.5° vs. 1.1±1.1°), posterior chamfer varus/valgus* (1.3±0.4° vs. 2.8±2.0°) and flexion/extension (0.8±0.5° vs. 1.4±1.6°), posterior internal/external* (1.1±0.6° vs. 2.8±1.6°) and flexion/extension (0.7±0.6° vs. 3.7±4.0°), and tibial varus/valgus* (0.6±0.3° vs. 1.3±0.7°) rotations, compared to MTKA, respectively, (where * indicates a significant difference between the two operative methods based on 2- Variances testing, with α at 0.05). Measurements of final component position error show that RATKA had greater accuracy and precision to plan for femoral varus/valgus* (0.6±0.3° vs. 3.0±1.4°), flexion/extension* (0.6±0.5° vs. 3.0±2.1°), internal/external (0.8±0.5° vs. 2.6±1.6°), and tibial varus/valgus (0.7±0.4° vs. 1.1±0.8°) than the MTKA control, respectively. In general, RATKA demonstrated greater accuracy and precision of bone cuts and component placement to plan, compared to MTKA in this cadaveric study. For further confirmation, RATKA accuracy of component placement should be investigated in a clinical setting