Introduction. Robotic-assisted total knee arthroplasty (TKA) has demonstrated significant benefits, including improved accuracy of component positioning compared to conventional jig-based TKA. However, previous studies have often failed to associate these findings with clinically significant improvements in patient-reported outcome measures (PROMs). Inertial measurement units (IMUs) provide a more nuanced assessment of a patient's functional recovery after TKA. This study aims to compare outcomes of patients undergoing robotic-assisted and conventional TKA in the early postoperative period using conventional PROMS and wearable sensors. Method. 100 patients with symptomatic end-stage knee osteoarthritis undergoing primary TKA were included in this study (44 robotic-assisted TKA and 56 conventional TKA). Functional outcomes were assessed using ankle-worn IMUs and PROMs. IMU- based outcomes included impact load, impact asymmetry, maximum knee flexion angle, and bone stimulus. PROMs, including Oxford Knee Score (OKS), EuroQol-Five Dimension (EQ-5D-5L), EuroQol Visual Analogue Scale (EQ-VAS), and Forgotten Joint Score (FJS-12) were evaluated at preoperative baseline, weeks 2 to 6 postoperatively, and at 3-month postoperative follow-up. Results. By postoperative week 6, when compared to conventional TKA, robotic-assisted TKA was associated with significant improvements in maximum knee flexion angle (118o ± 6.6 vs. 113o ± 5.4; p=0.04), symmetrical loading of limbs (82.3% vs.22.4%; p<0.01), cumulative impact load (146.6% vs 37%; p<0.01), and bone stimulus (25.1% vs 13.6%; p<0.01). Whilst there were no significant differences in PROMs (OKS, EQ-5D-5L, EQ-VAS, and FJS-12) at any time point between the two groups, when comparing OKS subscales, significantly more robotic-assisted TKA patients achieved an ‘excellent’ outcome at 6 weeks compared to conventional (47% vs 41%, p= 0.013). Conclusions. IMU-based metrics detected an earlier return to function among patients that underwent robotic-assisted TKA compared to conventional TKA that PROMs were unable to detect within the first six weeks of surgery

Introduction. Soft tissue releases are often required to correct deformity and achieve gap balance in total knee arthroplasty (TKA). However, the process of releasing soft tissues can be subjective and highly variable and is often perceived as an ‘art’ in TKA surgery. Releasing soft tissues also increases the risk of iatrogenic injury and may be detrimental to the mechanically sensitive afferent nerve fibers which participate in the regulation of knee joint stability. Measured resection TKA approaches typically rely on making bone cuts based off of generic alignment strategies and then releasing soft tissue afterwards to balance gaps. Conversely, gap-balancing techniques allow for pre-emptive adjustment of bone resections to achieve knee balance thereby potentially reducing the amount of ligament releases required. No study to our knowledge has compared the rates of soft tissue release in these two techniques, however. The objective of this study was, therefore, to compare the rates of soft tissue releases required to achieve a balanced knee in tibial-first gap-balancing versus femur-first measured-resection techniques in robotic assisted TKA, and to compare with release rates reported in the literature for conventional, measured resection TKA [1]. Methods. The number and type of soft tissue releases were documented and reviewed in 615 robotic-assisted gap-balancing and 76 robotic-assisted measured-resection TKAs as part of a multicenter study. In the robotic-assisted gap balancing group, a robotic tensioner was inserted into the knee after the tibial resection and the soft tissue envelope was characterized throughout flexion under computer-controlled tension (fig-1). Femoral bone resections were then planned using predictive ligament balance gap profiles throughout the range of motion (fig-2), and executed with a miniature robotic cutting-guide. Soft tissue releases were stratified as a function of the coronal deformity relative to the mechanical axis (varus knees: >1° varus; valgus knees: >1°). Rates of releases were compared between the two groups and to the literature data using the Fischer's exact test. Results. The overall rate of soft tissue release was significantly lower in the robotic gap-balancing group, with 31% of knees requiring one or more releases versus 50% (p=0.001) in the robotic measured resection group and 66% (p<0.001) for conventional measured resection (table-1) [1]. When comparing as a function of coronal deformity, the difference in release rates for robotic gap-balancing was significant when compared to the conventional TKA literature data (p<0.0001) for all deformity categories, but only for varus and valgus deformities for robotic measured resection with the numbers available (varus: 33% vs 50%, p=0.010; neutral 11% vs 50%, p=0.088, valgus 27% vs 53%, p=0.048). Discussion. Robotic-assisted tibial-first gap-balancing techniques allow surgeons to plan and adjust femoral resections to achieve a desired gap balance throughout motion, prior to making any femoral resections. Thus, gap balance can be achieved through adjustment of bone resections, which is accurate to 1mm/degree with robotics, rather than through manual releasing soft tissues which is subjective and less precise. These results demonstrated that the overall rate of soft tissue release is reduced when performing TKA with predictive gap-balancing and a robotic tensioning system. For any figures or tables, please contact authors directly

Introduction. There has been renewed interest in the use of unicompartmental knee arthroplasty (UKA) for patients with limited degenerative disease of the knee due to improved surgical techniques and prosthetic design, and the desire for minimally invasive surgery. However, patient satisfaction following UKA for lateral compartment disease have been suboptimal with increased revision rates. Robotic-assisted UKA has been shown to improve precision and accuracy of component placement, which may improve outcomes of lateral UKA. The purpose of this study was to compare the outcome of robotic-assisted UKA to conventional UKA for degenerative disease of the lateral compartment with the hypothesis that robotic-assisted lateral UKA results in superior outcomes compared to conventional UKA. Methods. The institution's joint registry was searched for patients who underwent UKA for limited degenerative disease of the lateral knee compartment between 2004 and 2012 and a total of 125 lateral UKAs were identified. The medical records of all patients were reviewed and assessed for the type of surgical procedure used (robotic-assisted versus conventional), length of hospital stay, Oxford knee score, and occurrence of revision surgery. Preoperative and postoperative radiographs were assessed for tibiofemoral angle, femoral and tibial joint line angle, posterior tibial slope, and orientation of the femoral and tibial components. Results. A total of 88 (84 patients) robotic-assisted (Figure 1) and 37 (36 patients) conventional UKA (Figure 2) were analyzed and compared. Patient age and BMI were similar between patients with robotic-assisted (64.2 ± 11.5 years, 28.7 kg/m. 2. ) and conventional UKA (64.2 ± 11.5 years [p = 0.998], 30.5 kg/m. 2. [p = 0.107]). At a mean follow-up of 24.4 ± 1.1 months for robotic-assisted UKA and 64.0 ± 3.0 months (p < 0.05) for conventional UKA, the mean Oxford scores were significantly higher in patients with robotic-assisted UKA (39.4 ± 1.1 versus 34.4 ± 2.5, p = 0.048). The length of stay was significantly shorter after robotic-assisted UKA (1.7 days) compared to conventional UKA (2.3 days, p < 0.001). Correction of the tibiofemoral angle was significantly higher in patients with conventional UKA (8.7 to 176.9 degrees) compared to patients with robotic-assisted UKA (3.4 to 174.3 degrees, p < 0.001). However, the femoral component was in significantly greater varus position in conventional UKA (98.7 degrees) compared to robotic-assisted UKA (88.2 degrees, p < 0.001). There were significantly more revisions in the conventional UKA group (7 conversions to total knee arthroplasty, 2 tibial component exchanges) compared to robotic-assisted UKA (2 conversions to TKA, p < 0.001). Discussion. The findings of this study revealed a decreased revision rate in robotic-assisted lateral UKAs compared to conventional lateral UKA. Furthermore, patients who received robotic-assisted UKAs had a shorter postoperative hospital stay compared to patients who received conventional UKA. Implant orientation was improved in robotic-assisted UKA compared to conventional UKA. UKA is a technically challenging procedure with limited joint visualization and malaligned components may lead to impaired joint biomechanics causing pain and disease progression to other knee compartments. Robotic-assisted UKA systems offer increased accuracy of component placement with objective soft-tissue balancing which may improve the long-term survival of UKA in patients with limited lateral degenerative disease

Introduction. Unicompartmental knee arthroplasty (UKA) has seen renewed interest in recent years due to improved surgical techniques and prosthetic design, and the desire for minimally invasive surgery. For patients with limited degenerative disease, UKA offers a viable alternative to total knee arthroplasty. Historically, the outcomes of lateral compartment UKA have been inferior to medial compartment UKA, with suboptimal patient satisfaction and increased revision rates. Robotic-assisted UKA has been shown to improve precision and accuracy of component placement, which may improve outcomes of lateral UKA. The purpose of this study was to compare the outcome of robotic-assisted UKA to conventional UKA for degenerative disease of the lateral compartment. The hypothesis of the study was that robotic-assisted lateral UKA results in superior outcomes compared to conventional UKA. Materials and methods. A search of the institution's joint registry was conducted to identify patients who underwent UKA for limited degenerative disease of the lateral knee compartment. A total of 130 lateral UKAs were identified that were performed between 2004 and 2012. The mean age of the patients was 63.1 years (range, 20 to 88); patients had a mean BMI of 29.9 (range, 18 to 48). The medical records of all patients were reviewed and assessed for the type of surgical procedure used (robotic-assisted versus conventional), length of hospital stay, Oxford knee score, and occurrence of revision surgery. Results. A total of 93 robotic-assisted and 37 conventional UKA were analysed. At a mean follow-up 35 months (range, 1 to 107 months), the mean Oxford scores in the robotic-assisted and conventional group were similar (39.6 versus 35.9, p=0.135). The length of stay was significantly shorter after robotic-assisted UKA (1.7 days) compared to conventional UKA (2.3 days, p<0.001). There were significantly more revisions in the conventional UKA group [6 conversions to total knee arthroplasty (TKA), 2 tibial component exchanges] compared to robotic-assisted UKA (2 conversions to TKA, p<0.001). Conclusions. The findings of this study revealed a decreased revision rate in robotic-assisted lateral UKAs compared to conventional lateral UKA. Furthermore, patients who received robotic-assisted UKAs had a shorter postoperative hospital stay compared to patients who received conventional UKA. However, overall surgical outcomes were similar in both patient cohorts based on similar postoperative Oxford scores. UKA is a technically challenging procedure with limited joint visualisation and less tolerance for acceptable component position; a two-degree error may lead to UKA failure. Malaligned components may lead to impaired joint biomechanics causing pain and disease progression to other knee compartments. Robotic-assisted UKA systems offer increased accuracy of component placement with objective soft-tissue balancing. Improved component positioning with robotic-assisted UKA systems may improve the long-term survival of UKA in patients with limited lateral degenerative disease, which is performed less often than medial UKA

INTRODUCTION. Successful clinical outcomes following unicompartmental knee arthroplasty (UKA) depend on component positioning, soft tissue balance and lower limb alignment, all of which can be difficult to achieve using manual instrumentation. A new robotic-guided technology has been shown to improve postoperative implant positioning and lower limb alignment in UKA but so far no studies have reported clinical results of robotic-assisted medial UKA. Goal of this study therefore was to assess outcomes of robotic-assisted medial UKA in a large cohort of patients at short-term follow-up. METHODS. This multicenter study with IRB approval examines the survivorship and satisfaction of this robotic-assisted procedure coupled with an anatomically designed UKA implant at a minimum of two-year follow-up. A total of 1007 patients (1135 knees) underwent robotic-assisted surgery for a medial UKA from six surgeons at separate institutions in the United States. All patients received a fixed-bearing metal backed onlay implant as the tibial component between March 2009 and December 2011 (Figure 1). Each patient was contacted at minimum two-year follow-up and asked a series of five questions to determine implant survivorship and patient satisfaction. Survivorship analysis was performed using Kaplan-Meier method and worst-case scenario analysis was performed whereby all patients were considered as revision when they declined study participation. Revision rates were compared in younger and older patients (age cut-off 60 years) and in patients with different body mass index (body mass index cut-off 35 kg/m. 2. ). Two-sided chi-square tests were used to compare these groups. RESULTS. Data was collected for 797 patients (909 knees) with an average follow-up of 29.6 months (range: 22 – 52 months). At 2.5-years follow-up, eleven knees were reported as revised, which resulted in a survivorship of 98.8% (Figure 2). Thirty-five patients declined to participate in the study yielding a worst-case survivorship of 96.0%. Higher revision rates were seen in younger patients (2.60% versus 0.93%, p = 0.09) and in morbidly obese patients (3.36% versus 0.91%, p = 0.03). Of all patients without revision, 92% was either very satisfied or satisfied with their knee function (Figure 3). CONCLUSION. In this multicenter study, robotic-assisted UKA was found to have high survivorship and satisfaction rate at short-term follow-up. Prospective comparison studies with longer follow-up are necessary in order to compare survivorship and satisfaction rates of robotic-assisted UKA to conventional UKA and robotic-assisted UKA to total knee arthroplasty. For any figures or tables, please contact authors directly (see Info & Metrics tab above).

Introduction. Unicompartmental knee arthroplasty (UKA) has seen renewed interest in recent years and is a viable option for patients with limited degenerative disease of the knee as an alternative to total knee arthroplasty. However, the minimally invasive UKA procedure is challenging, and accurate component alignment is vital to long-term survival. Robotic-assisted UKA allows for greater accuracy of component placement and dynamic intraoperative ligament balancing which may improve clinical patient outcomes. The purpose of this study was to analyse the clinical outcomes in a large, consecutive cohort of patients that underwent robotic-assisted UKA at a single institution with a minimum follow-up of 2 years. The study hypothesis was that robotic-assisted UKA improves patient outcomes by decreasing the rate of revision in comparison to conventional UKA. Materials and methods. A search of the institutional joint registry was performed to identify patients that underwent robotic-assisted UKA beginning in August 2008. The patients' electronic medical record was analysed for surgical indication, age at surgery, body mass index (BMI), and American Society of Anesthesiology Physical Status Classification System (ASA). Patient comorbidities were evaluated using the Charlson comorbidity index. Length of surgery and length of hospitalisation were assessed and clinical outcomes were evaluated using the Oxford Knee Score. In addition to postoperative follow-up assessments in clinic, patients without recent follow-up were contacted by telephone to capture the overall revision rate and time to revision. Results. A total number of 481 patients were identified who underwent robotic-assisted UKA with a mean follow-up of 35 months (range, 24 to 53 months). Patients had a mean age of 64 years (range, 30 to 90 years) and a mean BMI of 32.2 (range, 18 to 56). The median ASA score was 3, and the median Charlson comorbidity index was 0 (304 patients). A total number of 147 patients had a score of 1–2, 20 patients a score of 3–4, and 6 patients had scores greater or equal to 5. The mean length of surgery was 64 minutes (range, 25 to 152 minutes), and the mean time of hospitalisation was 1.7 days (range, 0.5 to 9.0 days). At final follow-up, the mean Oxford Knee Score was 37.2 (range, 2 to 48). There were 25 revisions to total knee arthroplasty (5.2%) and 3 revisions of the tibial component (0.6%). Conclusions. The findings of this study revealed that robotic-assisted UKA provided pain relief and functional outcomes at mid-term follow-up. The combined revision rate of robotic-assisted UKA at mid-term follow-up was similar or lower (5.8%) compared to revision rates of conventional UKA (approximately 6% to 8%) in national registries assessing conventional UKA (Australia, New Zealand, Norway, UK). UKA remains a technically challenging procedure that relies on accurate placement of components to avoid failure. Proper patient selection in combination with robotic-assisted UKA may decrease the revision rates encountered with early UKA systems. The improved accuracy of component positioning and dynamic soft-tissue balancing associated with robotic-assisted UKA may improve implant longevity and improve patient outcomes

Total knee arthroplasty is a successful procedure with good long-term results. Studies indicate that 15% – 25% of patients are dissatisfied with their total knee arthroplasty. In addition, return to sports activities is significantly lower than total hip arthroplasty with 34% – 42% of patients reporting decreased sports participation after their total knee arthroplasties. Poor outcomes and failures are often associated with technical errors. These include malalignment and poor ligament balancing. Malalignment has been reported in up to 25% of all revision knee arthroplasties, and instability is responsible for over 20% of failures. Most studies show that proper alignment within 3 degrees is obtained in only 70% – 80% of cases. Navigation has been shown in many studies to improve alignment. In 2015, Graves examined the Australian Joint Registry and found that computer navigated total knee arthroplasty was associated with a reduced revision rate in patients under 65 years of age. Navigation can improve alignment, but does not provide additional benefits of ligament balance. Robotic-assisted surgery can assist in many of the variables that influence outcomes of total knee arthroplasty including: implant positioning, soft tissue balance, lower limb alignment, proper sizing. The data on robotic-assisted unicompartmental arthroplasty is quite promising. Cytech showed that femoral and tibial alignment were both significantly more accurate than manual techniques with three times as many errors with the manually aligned patients. Pearle, et al. compared the cumulative revision rate at two years and showed this rate was significantly lower than data reported in most unicompartmental series, and lower revision rates than both Swedish and Australian registries. He also showed improved satisfaction scores at two years. Pagnano has noted that optimal alignment may require some deviation from mechanically neutral alignment and individualization may be preferred. This is also likely to be a requirement of more customised or bi-cruciate retaining implant designs. The precision of robotic surgery may be necessary to obtain this individualised component alignment. While robotic total knee arthroplasty requires further data to prove its value, more precise alignment and ligament balancing is likely to lead to improved outcomes, as Pearl, et al. and the Australian registry have shown. While it is difficult to predict the future at this time, I believe robotic-assisted total knee arthroplasty is the future and that future begins now

Background. Robotic assistance is being increasingly utilised in the surgical field in an effort to minimise human error. In this study, we report minimum two-year outcomes and complications for robotic-assisted total hip arthroplasty. Methods. Data were prospectively collected and retrospectively reviewed between June 2011 and April 2014. Inclusion criteria were primary robotic-assisted THAs treating idiopathic osteoarthritis with ≥ 2- year follow-up. Demographics, operating time, complications, 2-year outcome scores and satisfaction, and subsequent surgeries were recorded. Results. There were 181 cases eligible for inclusion, of which 162 (89.5%) had minimum 2-year follow- up. Eighty-nine females and 73 males were included. Forty-seven cases used an anterior approach and 115 used posterior approach. Mean age was 61.2 and mean BMI was 29.8. At latest follow-up, mean Visual Analog Scale for pain was 0.7, patient satisfaction was 9.3, Harris Hip Score was 91.1, and Forgotten Joint Score was 83.1. The mean time of surgery was 76.7 min. There were three (1.9%) greater trochanteric fractures and three (1.9%) calcar fractures. Postoperative complications included deep vein thrombosis (2 cases, 1.2%), femoral stem loosening (one case, 0.6%, treated with stem revision), infection (1 case, 0.6%, treated with single stage incision and drainage), aseptic hematoma (1 case, 0.6%, treated with single stage incision and drainage), and dropfoot (1 case, 0.6%). No leg length discrepancies (LLD) or dislocations were reported. Conclusion. Robotic-assisted THA is a safe procedure with favorable short-term outcomes. In particular, the excellent Forgotten Joint Score results suggest that this procedure effectively replicates the feeling of the native hip

Introduction. There is increasing pressure on healthcare providers to demonstrate competitiveness in quality, patient outcomes and cost. Robotic and computer-assisted total knee arthroplasty (TKA) have been shown to be more accurate than conventional TKA, thereby potentially improving quality and outcomes, however these technologies are usually associated with longer procedural times and higher costs for hospitals. The aim of this study was to determine the surgical efficiency, learning curve and early patient satisfaction of robotic-assisted TKA with a contemporary imageless system. Methods. The first 29 robotic-assisted TKA cases performed by a single surgeon having no prior experience with computer or robotic-assisted TKA were reviewed. System time stamps were extracted from computer surgical reports to determine the time taken from the first step in the anatomical registration process, the hip center acquisition, to the end of the last bone resection, the validation of the proximal tibial resection. Additional time metrics included: a) array attachment, b) anatomical registration, c) robotic-assisted femoral resection, d) tibial resection, e) trailing, f) implant insertion, and skin-to-skin time. The Residual Time was also calculated as the skin-to-skin time minus the time taken for steps a) to f), representing the time spent on all other steps of the procedure. Patients completed surveys at 3 months to determine their overall satisfaction with their surgical joint. Results. All time metrics decreased significantly after the first 7 cases, except the residual time (table 1 and figure 1). Mean skin-to-skin time significantly decreased from 83.7min to 57.1min (p=0.0008) beyond 7 cases, and hip center to final cut validation time decreased from 30.2min to 20.3min (p=0.0002). 85.7% (24/29) of patients were “Fully satisfied” and 14.3% (5/29) were “Partly satisfied”. Cost analysis showed there were no capital costs associated with acquisition of the robotic system and per case cost was equal to conventional TKA. Conclusion. Improvements in surgical efficiency and quality are becoming increasing important in today's healthcare environment. The results of this study indicated equal cost, a short learning curve and comparable procedure times to conventional TKA. The Patient Reported Outcomes with this group of patients was very high compared to rates reported in the literature

Introduction/Aim. The NAVIO robotic-assisted TKA (RA-TKA) application received FDA clearance in May 2017. This semi-active robotic technique aims to improve the accuracy and precision of total knee arthroplasty. The addition of robotic-assisted technology, however, also introduces another potential source of surgery-related complications. This study evaluates the safety profile of NAVIO RA-TKA. Materials and Methods. Beginning in May 2017, the first 250 patients undergoing NAVIO RA-TKA were included in this study. All intra-operative complications were recorded, including: bleeding; neuro-vascular injury; peri-articular soft tissue injury; extensor mechanism complications; and intra-operative fracture. During the first 90 days following surgery, patients were monitored for any post-operative complications, including: superficial and deep surgical site infection; pin-tract infection; pin site fractures; peri-prosthetic fractures; axial or sagittal joint instability; axial mal-alignment; patello-femoral instability; DVT/PE; re-operation or re-admission due to surgical-related complications. Surgical technique and multi-modality pain management protocol was consistent for all patients in the study. A combined anesthetic technique was employed for all cases, including: low-dose spinal, adductor canal block and general anesthetic. Patients were mobilized per our institution's rapid recovery protocol. Results. No patients were lost to follow-up. During the study period, no intra-operative complications were recorded. Specifically, no complications related to the introduction of the high-speed burr associated with the NAVIO RA-TKA were noted. Within the 90-day follow-up period, there was one case of deep infection. One patient sustained a fall resulting in a peri-prosthetic femoral fracture, that occurred remote from the femoral pin tracts. No cases of axial or sagittal joint instability, axial mal-alignment, patello-femoral instability, pin site infections or fractures; or DVT/PE were identified. Four patients underwent manipulation under anesthesia. No other patients required a re-operation or re-admission due to surgical-related complications. Discussion/Conclusions. The initial experience with the NAVIO robotic assisted total knee arthroplasty has demonstrated excellent safety profile. Relative to known risks associated with total knee arthroplasty, no increased risk of peri-operative complications, re-operation or re-admission for surgical related complications was identified with the introduction of the NAVIO RA-TKA

Total hip arthroplasty (THA) is an effective operation for patients with hip osteoarthritis; however, patients with hip dysplasia present a particular challenge. Our novel study examined the effect of robotic-assisted THA in patients with hip dysplasia.. Nineteen patients at two centers presented with hip dysplasia. We found that components were placed according to the preoperative plan, there was a significant improvement in the modified Harris Hip Score from 31 to 84 (p<0.001), an improvement in hip range of motion (flexion improvement from 66 º to 91º, p<0.0001), a significant correction of leg length discrepancy (17.5 vs. 4 mm, p<.0002), and no short-term complications.. Robotic-assisted THA can be a useful method to ensure adequate component positioning and excellent outcomes in patients with hip dysplasia

Introduction. Recently robotic-assisted total knee replacement has become a new emerging method of artificial joint implantation, especially in Europe and Asia. We have belived that robotic cutting would result in an improved clinical outcome due to the better fit and alignment of the prosthesis but that has never been proven to our knowledge. The purpose of this study was to compare robotic-assisted implantation of a total knee replacement with conventional manual implantation. Methods. We reviewed 72 patients who were scheduled for total knee arthroplasty, divided to have either conventional manual implantation of a Zimmer LPS prosthesis (30 patients: Group I) or robotic-assisted implantation of such a prosthesis (32 patients: Group II). The five-axis ROBODOC was used for the robotic-assisted procedures. Radiographs were made at this interval and analyzed for evidence of loosening, prosthetic alignment, and other complications. Independent T-test or Mann-Whitney test was used for statistical analysis at probability level of 95%. SPSS for Windows was used. Results. The age of group I was 67.8±6.44 years and that of group II was 62.7±6.51 years. The follow up period of group I was 31.3±3.47 months and that of group II was 27.0±0.69 years. In clinical assessment, there was no difference statistically. In radiological assessment, the postoperative tibiofemoral angles of group I was 5.3±2.6 degrees and that of group II was 6.0±1.8 degrees. There was no difference statistically. The α and β angle of group I was 95.6±2.65, 88.6±2.58 degrees and that of group II was 97.7±0.97, 88.8±1.59 degrees. There was no difference statistically. The γ and δ angle of group I was 4.19±3.28, 85.5±0.92 degrees and that of group II was 0.17±0.65, 89.7±1.7 degrees. There was a significant statistical difference(P<0.05). The complications were observed in Group II: 1 superficial infection, 1 patellar tendon rupture, 1 postoperative supracondylar fracture and 1 peroneal nerve palsy. Discussion. The robotic-assisted technology had definite advantages in terms of preoperative planning, the accuracy of the intraoperative procedure and postoperative follow up in lateral knee radiograph, especially in γ and δ angle. But disadvantages were the high complication rate, which we believe was required for the more careful and experienced operative technique. We need further kinematical study about the clinical importance of γ and δ angle in TKA patients, especially wear pattern etc before robotic popular usage in USA

Introduction. Bicompartmental knee replacement (BKR) may be an alternative to total knee arthroplasty (TKA) for degenerative disease limited to two knee compartments. Most commonly, BKA is a combination of medial compartment and patellofemoral compartment resurfacing. In contrast to TKA, BKA preserves the uninvolved compartment and cruciate ligaments possibly leading to advanced stability and more physiologic knee kinematics. Robotic-assisted systems for unicompartmental knee arthroplasty have shown to provide improved component positioning with dynamic ligament balancing that may improve outcomes of BKA. The purpose of this study was to evaluate the short-term outcomes of patients undergoing BKA at a single institution by a single surgeon using a robotic-assisted system. Methods. A search of the institution's joint registry was conducted to identify patients that underwent robotic-assisted BKA of the patellofemoral compartment and the medial or lateral compartment between December 2009 and April 2012. All medical records were analyzed for patient demographics and comorbidities. The patients were evaluated preoperatively and at 6,12 months and then annually. The patients were contacted by phone when recent follow-up was not available. The radiographic assessment was also undertaken. The orientation of the tibial and femoral implants was assessed radiologically postoperatively. We examined the clinical results with the Oxford Knee Score (OKS). Results. A total number of 29 patients (30 BKR) with a mean age of 63.6 years (range 39 to 82) were identified who received a patellofemoral resurfacing in combination with medial (25, 83%) or lateral (5, 17%) compartment resurfacing. The mean BMI was 33.7 kg/m. 2. (range, 21.5 to 51.8), median Charlson comorbidity index score was 0, median American Society of Anaesthesiologists' (ASA) classification was 3. The mean length of surgery was 40.2 minutes (range, 23 to 151). At a mean follow-up of 15 months (range, 2 to 54), 3 patients (10%, 2 patellofemoral and lateral compartment, 1 patellofemoral and medial compartment) underwent arthroscopic debridement of loose cement fragments following BKA. One patient (3%, patellofemoral and lateral compartment) received manipulation under anesthesia and botulinum neurotoxin injections into the hamstrings for postoperative flexion contracture and another patients (3%, patellofemoral and medial compartment) underwent open lateral retinacular release. There were no component revisions noted during the follow-up period. The preoperative oxford knee score improved from 26.4 to 33. Discussion. Our analysis shows the bicompartmental knee replacement using robotics is a viable option when two out of three components are involved

We sought to evaluate the early post-operative active range-of-motion (AROM) between robotic-assisted total knee arthroplasty (raTKA) and conventional TKA (cTKA). A secondary data analysis on a global prospective cohort study was performed. A propensity score method was used to select a matched control of cTKA from the same database using 1:1 ratio, based on age, sex, BMI, and comorbidity index. This resulted in 216 raTKA and cTKA matched cases. Multivariable longitudinal regression was used to evaluate difference in ROM over time and values are reported as least squares means (95% confidence interval). The longitudinal model tested the treatment effect (raTKA vs cTKA), time effect, and their interaction with control on covariance of patients ‘s age, sex, BMI, comorbidity and pre-operative flexion. Logistic regression was used to analyze the active flexion level at one month (cut by 90°) and three months (cut by 110°). At one-month postoperative the raTKA cases had more AROM for flexion by an average of 5.54 degrees (p<0.001). There was no difference at three months (p=0.228). The raTKA group had a greater improvement from pre-operative values at both one-month, with an average 7.07° (3.6°, 10.5°, p<0.001) more improvement, and at three-months with an average improvement of 4° more (1.61°, 7.24°, p=0.0115). AROM for extension was lower overall in the raTKA group by an average of 0.44° (p=0.029). The raTKA patients had higher odds of achieving ≥90° of flexion at one-month (OR 2.15, 95% CI 1.16, 3.99). raTKA resulted in greater AROM flexion gains in the early postoperative period than cTKA. Additional research is needed to understand if these earlier gains in AROM are associated with improved patient satisfaction and continued improvements with time

Patient-reported outcome measures (PROMs) have failed to highlight differences in function or outcome when comparing knee replacement designs and implantation techniques. Ankle-worn inertial measurement units (IMUs) can be used to remotely measure and monitor the bi-lateral impact load of patients, augmenting traditional PROMs with objective data. The aim of this study was to compare IMU-based impact loads with PROMs in patients who had undergone conventional total knee arthroplasty (TKA), unicompartmental knee arthroplasty (UKA), and robotic-assisted TKA (RA-TKA). 77 patients undergoing primary knee arthroplasty (29 RA-TKA, 37 TKA, and 11 UKA) for osteoarthritis were prospectively enrolled. Remote patient monitoring was performed pre-operatively, then weekly from post-operative weeks two to six using ankle-worn IMUs and PROMs. IMU-based outcomes included: cumulative impact load, bone stimulus, and impact load asymmetry. PROMs scores included: Oxford Knee Score (OKS), EuroQol Five-dimension with EuroQol visual analogue scale, and the Forgotten Joint Score. On average, patients showed improved impact load asymmetry by 67% (p=0.001), bone stimulus by 41% (p<0.001), and cumulative impact load by 121% (p=0.035) between post-operative week two and six. Differences in IMU-based outcomes were observed in the initial six weeks post-operatively between surgical procedures. The mean change scores for OKS were 7.5 (RA-TKA), 11.4 (TKA), and 11.2 (UKA) over the early post-operative period (p=0.144). Improvements in OKS were consistent with IMU outcomes in the RA-TKA group, however, conventional TKA and UKA groups did not reflect the same trend in improvement as OKS, demonstrating a functional decline. Our data illustrate that PROMs do not necessarily align with patient function, with some patients reporting good PROMs, yet show a decline in cumulative impact load or load asymmetry. These data also provide evidence for a difference in the functional outcome of TKA and UKA patients that might be overlooked by using PROMs alone

Background. The JOURNEY™ II Cruciate-Retaining Total Knee System (JIICR) and the JOURNEY™ II Bi-Cruciate Stabilized Total Knee System (JIIBCS) (both, Smith & Nephew, Memphis, TN, USA) are used for the treatment of end-stage degenerative knee arthritis. Belonging to the JOURNEY family of knee implants, the relatively new devices are designed to provide guided motion. Studies suggest that long-term outcomes of robotic-assisted navigation in total knee arthroplasty (TKA) are superior to the classical approach. This is the first report describing early postoperative outcomes of the NAVIO® robotic-assisted surgical navigation using the JOURNEY™ II family of knee implants. Materials & Methods. In this ongoing study, six investigational sites in the US prospectively enrolled 122 patients (122 TKAs, 64 JIIBCS and 58 JIICR). Patients underwent TKA using the NAVIO system (Figure 1), a next-generation semi-autonomous tool that uses handheld miniaturized robotic-assisted instrumentation that the surgeon manipulates in 6 degrees of freedom, but restricts cutting to within the confines of the pre-designated resection area of the patient's bone. The primary outcome was postoperative mechanical alignment on long leg X-ray at one month postoperative compared to operative target alignment. Alignment within ±3 degrees of the target alignment was considered a success. Results. Average age was 65.7 years (range, 39–79); 60.7% were females. All patients underwent patella resurfacing. Two patients had revision prior to the one-month follow-up visit; two patients withdrew from the study. 95% (112/118) attended the one-month follow-up. Four patients were missing either baseline or follow-up long leg X-ray, resulting in 108 evaluated TKAs. Overall, 92.6% (100/108) of TKAs were within 3 degrees of the target alignment. Of these, 24.1%, 39.8-, 19.4%, and 9.3% were at 0, 1, 2, and 3 degrees of the target alignment, respectively. There were two revisions, one at 18 days postoperative and the second at 27 days postoperative. Discussion. At the one-month follow-up, the NAVIO™ Robotic Assisted TKA procedures resulted in a very high success rate of 92.6% in achieving planned mechanical alignment compared to standard instruments as historical control (73.4%) based on literature. 1. This demonstrates the improved accuracy and reliability of the NAVIO™ Robotic Assisted Surgical System for TKA procedures. For any figures or tables, please contact the authors directly

Introduction. Semi-active robots can improve the accuracy and precision of total knee arthroplasty (TKA). The surgical efficiency of the recently introduced NAVIO robotic-assisted (RA-TKA) surgery was assessed in this study to define: (1) the time commitment for RA-TKA; (2) the learning curve for RA-TKA; and (3) to compare RA-TKA surgical time commitment to conventional, instrumented TKA (CI-TKA). Materials and Methods. Beginning in May 2017, the first 100 patients undergoing NAVIO RA-TKA were registered pre-operatively. Operative time, defined as the time from surgical skin incision to capsular closure, was recorded. Exclusion criteria were cases in which surgical time was not recorded. During the same study period, surgical case times for fifty cases of CI-TKA procedures were also assessed. Baseline data, including age, gender, BMI, range of motion, was recorded for all subjects. Surgical and anesthetic technique, multi-modality pain management protocol, and post-operative mobilization was consistent for all patients enrolled in the study. Results. No cases were excluded due to missing data. Demographics were similar in the study groups. Average surgical time for the first 100 RA-TKA cases was 68.2 minutes (range 48–100 minutes). The learning curve, as defined by both absolute (added surgical time) and relative measures (percentage of added time) was forty cases. Significant further surgical efficiency was achieved after 80 cases. In comparison to CI-TKA (average surgical time 51.7 minutes), the first ten RA-TKA cases required an average of 80 minutes, or over 50% increase in surgical time. After case #40, RA-TKA took only 10 minutes longer (18% greater) than CI-TKA. After case #80, RA-TKA required less than 5% more time than RA-TKA. Discussion/Conclusions. The initial experience with the NAVIO RA-TKA produced predictable surgical efficiency as measured by surgical time commitment. The learning curve for this user was forty cases. After eighty cases, RA-TKA was time neutral (<5% added time). This study demonstrates that implementation of robotic-assisted technology in TKA can achieve a high level of surgical efficiency within an acceptable learning curve

Introduction. Total knee arthroplasty (TKA) is a well established treatment option for patients with end stage osteoarthritis. Conventional TKA with manual instruments has been shown to be a cost effective and time efficient surgery. While robotic-assisted operative systems have been shown to have benefits in surgical accuracy, they have also been reported to have longer surgical times. The purpose of this work was to determine surgical time and learning curve for a novel robotic-assisted TKA platform. Methods. Eighty-five subjects underwent robotic-assisted TKA by one of three investigators as part of an FDA and IRB approved Investigational Device Exemption (IDE). All patients received a cruciate retaining total knee implant system. Intra-operative safety, Western Ontario and McMaster Universities Arthritis Index (WOMAC) and Knee Society Scores (KSS) were collected pre-operatively and at three month follow-up. In addition, surgical times were collected as part of a TKA work flow. To identify activities related to surgical steps required for robotic procedures specific time stamps were determined from the system. Capture of the hip center to final bone cut was used to define case time and identify robotic learning curve. Descriptive statistics were used to analyze results. Results. Surgeon one completed 24 cases, surgeon two completed 32, and surgeon three completed 29 cases in the study. An average surgical time of 44 minutes with standard deviation of 15.7 minutes was recorded. On average surgeons improved in surgical time with increasing cases as indicated by linear regression results. During initial cases, surgeons repeated intra-operative planning steps which decreased with the learning curve. In addition, the average WOMAC score improvement from pre-operative to three months was 33.1 ± 20.04 (p<0.0001). The average KSS Knee score improvement was 46.12 ± 19.68 (p<0.0001). Subjects recovered their pre-operative range of motion by three months post-operative. Conclusion. With cost related pressures in healthcare, hospitals and surgeons focus on improvements in surgical efficiency to stay competitive. The results of this study indicated comparable operative times to conventional TKA cases as reported in literature with the added benefit of optimizing surgical accuracy. Robotic solutions in TKA may become increasingly efficient as surgeons complete a learning curve

Introduction. In total hip arthroplasty, the positioning of the acetabular cup, in particular, has been shown to play an important role in the survivorship of the prosthetic joint. The commonly accepted “safe zone” extends from 5–30° of anteversion to 30–50° of inclination. However, several studies have utilized a more restrictive safe zone of 5–25° of anteversion and 30–45° of inclination, a modification of the Lewinnek zone. Many attempts have been made to develop a more reliable method of positioning the acetabular component. Robotic-assisted surgery is one such method. The purpose of this study was to compare the resulting position of the acetabular component after robotic-assisted surgery with the intraoperative robotic data to determine if improved accuracy can be achieved with the robotic-assisted method. Methods. One hundred and nineteen patients received THA, at four different medical centers in the United States, using a haptic robotic arm. Pre-operative CT scans were obtained for all patients and used during the planning of the procedure, at which point the proposed component size and positioning was determined. Preparation of the acetabular bone bed, as well as impaction of the acetabular component itself, was performed using the robotic device. Using an AP Pelvis and Cross-Table Lateral radiograph, each patient's resulting acetabular inclination and version was measured using the Hip Analysis Suite software. The component position retrieved from the robot was compared to the measured values from the radiographs. The positioning data was compared to two safe zones described above. Results. Of the 119 surgeries performed, 110 could be read with the hip analysis suite software. Radiographically, the average inclination was 40.4° ± 4.1° with a range of 27.4°–53.7° and the average anteversion was 21.5° ± 6.1° with a range of 5.2°–42.6°. As measured inter-operatively, 100% of the components fell within the Lewinnek safe zone and 96% fell within the more restrictive safe zone. Radiographically, 88% of the cases fell within the Lewinnek safe zone and 73% fell within the restrictive safe zone. The mean difference between the inclination and version of the component determined by the robot and by radiographic analysis was 0.31° and 2.1° respectively. Conclusions. The inclination and version of the acetabular components implanted with robotic assistance as determined inter-operatively were within the commonly accepted limits in all cases. Variations between the cup positions determined inter-operatively and from the post-operative radiographs are related to differences in the radiographic project of the hip and the robotic registration of the pelvis from CT images. In no procedure was the radiographic inclination greater than 54° or version less than 5°. In this study, the use of robotic-assisted positioning of the acetabular component has significantly reduced the variability of component orientation. This improved reliability of positioning should result in an increase of favourable functioning, and a decrease in early complications such as dislocation, impingement, and component wear

Introduction. Unicompartmental knee arthroplasty (UKA) has seen renewed interest in recent years and is a viable option for patients with limited degenerative disease of the knee as an alternative to total knee arthroplasty. However, the minimally invasive UKA procedure is challenging and accurate component alignment is vital to long-term survival. Robotic-assisted UKA allows for greater accuracy of component placement and dynamic intraoperative ligament balancing which may improve clinical patient outcomes. The purpose of this study was to examine the clinical outcomes in a large, consecutive cohort of patients that underwent robotic-assisted UKA. Materials and Methods. A search of the institutional joint arthroplasty registry identified 507 patients with a mean age of 63 years (range, 28 to 88 years) who underwent robotic-assisted UKA between July 2008 and June 2010. Clinical outcomes were evaluated using the Oxford Knee Score and patients without recent follow-up were contacted by telephone. The revision rate and time to revision were also examined. Results. All patients had a minimum of 2 years follow-up (mean 33 months, range 24 to 47 months). Most patients were doing well at latest clinical follow-up. Preliminary results revealed a mean Oxford Knee Score of 36.1 + 9.92. The preliminary revision rate was found to be 2.6%. Conclusion. Robotic-assisted UKA provides good pain relief and functional outcomes at a minimum of 2-year follow-up. Improved component alignment and ligament balancing increases the probability of favorable outcomes following surgery. Proper patient selection in combination with robotic-assisted UKA may decrease revision rates encountered with early UKA systems