Robot-Assisted versus Conventional Total and Unicompartmental Knee Arthroplasty: A Meta-analysis of Radiological and Functional Outcomes.

Update This article was updated on February 6, 2019, because of a previous error. On page 105, in the subsection titled “Outcomes and Design” the sentence that had read “Furthermore, in a retrospective review, Houdek et al. 48 , at a mean follow-up of 8 years, demonstrated improved survivorship of 9,999 metal-backed compared with 1,645 all-polyethylene tibial components, over all age groups and most BMI categories” now reads “Furthermore, in a retrospective review, Houdek et al. 48 , at a mean follow-up of 8 years, demonstrated inferior survivorship of 9,999 metal-backed compared with 1,645 all-polyethylene tibial components, over all age groups and most BMI categories.” An erratum has been published: J Bone Joint Surg Am. 2019 Mar 20;101(6):e26.

As uptake of robotic-assisted arthroplasty increases there is a need for economic evaluation of the implementation and ongoing costs associated with robotic surgery. The aims of this study were to describe the in-hospital cost of robotic-assisted total knee arthroplasty (RA-TKA) and robotic-assisted unicompartmental knee arthroplasty (RA-UKA) and determine the influence of patient characteristics and surgical outcomes on cost. This prospective cohort study included adult patients (≥ 18years) undergoing primary unilateral RA-TKA and RA-UKA, at a tertiary hospital in Sydney between April 2017 and June 2021. Patient characteristics, surgical outcomes, and in-hospital cost variables were extracted from hospital medical records. Differences between outcomes for RA-TKA and RA-UKA were compared using independent sample t-tests. Logistic regression was performed to determine drivers of cost. Of the 308 robotic-assisted procedures, 247 were RA-TKA and 61 were RA-UKA. Surgical time, time in the operating room, and length of stay were significantly shorter in RA-UKA (p < 0.001); whereas RA-TKA patients were older (p = 0.002) and more likely to be discharged to in-patient rehabilitation (p = 0.009). Total in-hospital cost was significantly higher for RA-TKA cases (AU$18580.02 vs $13275.38; p < 0.001). Robotic system and maintenance cost per case was AU$3867.00 for TKA and AU$5008.77 for UKA. Patients born overseas and lower volume robotic surgeons were significantly associated with higher total cost of RA-UKA. Increasing age and male gender were significantly associated with higher total cost of RA-TKA. Total cost was significantly higher for RA-TKA than RA-UKA. Robotic system costs for RA-UKA are inflated by the software cost relative to the volume of cases compared with RA-TKA. Cost is an important consideration when evaluating long term benefits of robotic-assisted knee arthroplasty in future studies to provide evidence for the economic sustainability of this practice.

With the growing number of robotic knee arthroplasties being performed, new outcomes must be analyzed to provide a database for comparing robotic and nonrobotic surgeries. These results can be utilized in the future to properly assess the significance of utilizing robotic technology in the operating room regarding patient outcomes and cost. The aims of this study are to: (1) analyze adverse outcomes from robotic-assisted knee arthroplasty and its relation to sex, body mass index (BMI), and age; and (2) explore any possible differences in outcomes among robotic-assisted unicompartmental knee arthroplasty (UKA) and robotic-assisted total knee arthroplasty (TKA). It is hypothesized that sex, BMI, and age will play a role in adverse events experienced among robotic-assisted knee arthroplasty. It is hypothesized that adverse outcomes will differ in robotic-assisted TKA v UKA. A retrospective analysis was performed utilizing 1,300 patient cases from a single surgeon that underwent robotic-assisted UKA or TKA utilizing a robotic surgical system. Demographics were sorted by age, sex, and BMI. Outcomes were sorted by the type of adverse event. The most common adverse event was further statistically analyzed by age, sex, and BMI and then compared to the total cohort. The most common adverse event was also broken down by TKA vs. UKA. The average age of the individuals undergoing this procedure was 63.6 years, with 52.3 % being female. The average BMI was 32.2. Of the 87 patients who experienced adverse events, 111 total events were documented. Manipulation under anesthesia (MUA) was the highest experienced adverse event. Among the MUA events, 79.5 % had a BMI over 30 (p=0.067), 72.8 % were female (p=0.014), and the average age was 59 years (p=0.019). Among the MUA adverse events, 76.9 % (n=30) were following a TKA and 23.1 % were following a UKA. When considering the entire sample (n=1,300), there was a statistically significant 12.6 times greater odds that an MUA occurred among those who had a TKA vs. UKA (p<0.001). Similar results were discovered when only considering those who had experienced an adverse event (n=87) because the odds of an MUA occurring among those who underwent a TKA was 4.67 times greater than those who underwent a UKA (p<0.001). MUA was the most common adverse event in this cohort of robotic-assisted knee arthroplasties. The other adverse events did not yield large enough cohort sizes to analyze statistically in relation to specific patient demographics. Younger patients and females were at significantly greater odds of needing MUA. A BMI over 30 was not found to have a statistically significant risk of needing an MUA after robotic-assisted knee arthroplasty. Among the total cohort, those who underwent a TKA were at a 12.6 times greater odds of needing an MUA than those who received a UKA.

Unicompartmental knee arthroplasty (UKA) has significant advantages over total knee arthroplasty (TKA). However, due to its need for precise positioning and soft tissue balancing, UKA failures and revision rates may be higher than that of TKA. Robotic-assisted UKA offers more accurate implant positioning, soft tissue balancing, improved lower limb alignment, and a reduction in surgical error. There are few studies studying functional outcomes post robotic-assisted UKA. The aim of this study was to compare the functional outcomes between robotic-assisted and conventional medial UKA. A retrospective review was done of 159 patients; 110 patients underwent conventional UKA while 49 patients underwent robotic-assisted UKA. Outcome measures included the Oxford Knee Score (OKS), Knee Society Score (KSS), Visual Analogue Score (VAS) for pain, and range of motion (ROM) at three months, one-year and two years post-UKA. Pre-operative patient demographics and outcome scores were not significantly different between both groups. ROM was significantly greater in the MAKO compared to the Oxford group at 3 months (p=0.039), 1 year (0.053) and 2 years (0.001) post-operation. While OKS, KSS and VAS scores improved for both groups, there were no significant differences in the final outcome measures. None of the patients experienced a mechanical failure, infection, or revision post-surgery. One patient each in the Oxford and MAKO group suffered a periprosthetic fracture. Both robotic-assisted MAKO UKA and conventional Oxford UKA showed good clinical outcomes. Robotic-assisted MAKO UKA had superior ROM outcomes compared to conventional Oxford UKA up to two years post-surgery.

Gait analysis study comparing unicompartmental vs. total knee arthroplasty, differences in knee kinematics: a retrospective cohort study. Background and Objectives: Total knee arthroplasty (TKA) is an effective treatment for advanced knee osteoarthritis, although functional outcomes may remain suboptimal in many patients. Unicompartmental knee arthroplasty (UKA) often provides better functional recovery but shows lower long-term implant survival. Recently, personalized TKA approaches have been developed to improve kinematic restoration and patient satisfaction. This study aimed to compare knee kinematics among patients who underwent personalized TKA, medial UKA, and healthy controls. Materials and Methods: This retrospective cohort study included 9 patients treated with robotic-assisted personalized TKA, 9 patients treated with medial UKA, and 9 healthy controls matched for age, sex, and BMI. Inclusion criteria were age 60-80 years, Kellgren-Lawrence grade III-IV, a minimum follow-up of 12 months, deviation from neutral HKA < 15°, healthy contralateral knee, and high postoperative functional scores. Exclusion criteria included valgus knees (HKA > 180°), postoperative complications, and neuromotor disorders. In the TKA group, a Medial Congruent implant was implanted with ROSA robotic assistance using a restricted kinematic alignment (±5° HKA) and asymmetric intercompartmental balancing. In the UKA group, a fixed-bearing medial implant (Physica ZUK) was used. Gait analysis was performed on a markerless instrumented treadmill (WalkerView™; Dalmine, Italy). Differences between groups were analyzed using one-way ANOVA and Tukey's post-hoc test (p < 0.05). Results: UKA patients walked with a stiffer knee during stance. Knee range of motion during stance increased from UKA (6.3° ± 7.2°) to TKA (13.6° ± 8.8°, p = 0.045) and to controls (16.6° ± 4.5°, p = 0.02). During loading response, UKA patients showed lower flexion (10.2° ± 6.1°) than TKA (19.4° ± 7.9°, p = 0.049) and controls (19.6° ± 2.8°, p = 0.004). Knee flexion during swing was comparable between UKA and TKA. Conclusions: UKA patients demonstrated reduced knee flexion during early stance compared with robotic-assisted TKA and healthy controls. The observed differences may reflect multiple factors, including surgical technique, implant design, and patient-related characteristics. Because preoperative functional data were not available, potential selection bias cannot be excluded. These findings should be interpreted cautiously and warrant confirmation in larger prospective studies.

Use of computer-assisted navigation (CAN) and robotic-assisted (RA) surgery in total knee arthroplasty (TKA) and unicompartmental knee arthroplasty (UKA) both necessitate the use of tracking pins rigidly fixed to the femur and tibia. Although periprosthetic fractures through tracking pin sites are rare, there is a paucity of literature on this potential complication. Therefore, the purpose of this study was to perform a systematic review of the current literature to assess the incidence and clinical outcomes of periprosthetic fractures through tracking pin sites following CAN and RA TKA and UKA. A systematic review was performed following PRISMA (Preferred Reporting Items for Systematic reviews and Meta-Analyses) guidelines using the PubMed, MEDLINE, and Cochrane databases in April 2020. Studies were assessed for the presence of pin site fractures, fracture characteristics, and clinical outcomes. Seventeen clinical studies (5 case series, 1 cohort study, and 11 case reports) involving 29 pin-related fractures were included for review. The overall incidence ranged from 0.06% to 4.8%. The mean time from index arthroplasty to fracture was 9.5 weeks (range, 0 to 40 weeks). The majority of fractures occurred in the femoral diaphysis (59%). Nineteen fractures (66%) were displaced and 10 (34%) were nondisplaced or occult. The majority of cases were atraumatic in nature or involved minor trauma and were typically preceded by persistent leg pain. A transcortical pin trajectory, large pin diameter (>4 mm), diaphyseal fixation, multiple placement attempts, and the use of non-self-drilling, non-self-tapping pins were the most commonly reported risk factors for pin-related periprosthetic fractures following CAN or RA TKA. Surgeons should maintain a high index of suspicion for pin-related fractures in patients with ongoing leg or thigh pain after CAN or RA TKA in order to avoid fracture displacement and additional morbidity. As CAN and RA TKA have unique complication risks, the debate regarding the value of technology-assisted TKA and its cost-effectiveness continues. Therapeutic Level IV. See Instructions for Authors for a complete description of levels of evidence.

The purpose of this systematic overview was to identify, synthesise and critically appraise findings of meta-analyses on robot-assisted versus conventional unicompartmental knee arthroplasty (UKA) and total knee arthroplasty (TKA). The hypothesis was that robotic assistance would reduce complications and revision rates, yield better clinical scores, and improve component positioning and alignment. Two researchers independently conducted a literature search using Embase®, MEDLINE®, Web of Science, Allied and Complementary Medicine™ and Cochrane Database of Systematic Reviews on 2 November 2020 for meta-analyses (Level I-IV) on robotic assistance in UKA and/or TKA. Outcomes were tabulated and reported as weighted mean difference (WMD), risk ratio (RR) or weighted odds ratio (WOR), and were considered statistically significant when p < 0.05. A total of ten meta-analyses were identified; four on robot-assisted UKA (n, 1880 robot-assisted vs. 2352 conventional UKA; follow-up, 0 to 60months), seven on robot-assisted TKA (n, 4567 robot-assisted vs. 5966 conventional TKA; follow-up, 0 to 132months). Of the meta-analyses on UKA, one found that robotic assistance reduced complication rates (relative risk (RR), 0.62), one found that it improved clinical scores (weighted mean difference (WMD), 19.67), three found that it extended operation times (WMD, 15.7 to 17.1min), and three found that it improved component positioning and alignment (WMD, - 1.30 to - 3.02 degrees). Of the meta-analyses on TKA, two found that robotic assistance improved clinical scores (WMD, 1.62-1.71), two found that that it extended surgery times (WMD, 21.5-24.26min), and five found that it improved component positioning and alignment (WMD, - 0.50 to - 10.07 degrees). None of the meta-analyses reported differences in survivorship between robot-assisted versus conventional knee arthroplasty. Robot-assisted knee arthroplasty enabled more accurate component positioning and placement within target zones, but extended operation time considerably. Although robotic assistance improved component positioning, its benefits regardingclinical scores, patient satisfaction and implant survivorship remains to be confirmed. Finally, this overview revealed that six of the ten meta-analyses were of 'critically low quality', calling for caution when interpreting results. IV.

HURWA robotic-assisted total knee arthroplasty improves component positioning and alignment - A prospective randomized and multicenter study.

What's New in Adult Reconstructive Knee Surgery.

PurposeThe introduction of robotics for total knee arthroplasty (TKA) into the operating theatre is often associated with a learning curve and is potentially associated with additional complications. The purpose of this study was to determine the learning curve of robotic-assisted (RA) TKA within a multi-surgeon team.MethodsThis prospective cohort study included 83 consecutive conventional jig-based TKAs compared with 53 RA TKAs using the Robotic Surgical Assistant (ROSA) system (Zimmer Biomet, Warsaw, Indiana, USA) for knee osteoarthritis performed by three high-volume (> 100 TKA per year) orthopaedic surgeons. Baseline characteristics including age, BMI, sex and pre-operative Kellgren-Lawrence graded and Hip-Knee-Ankle Axis were well-matched between the conventional and RA TKA groups. Cumulative summation (CUSUM) analysis was used to assess learning curves for operative times for each surgeon. Peri-operative and delayed complications (infection, periprosthetic fracture, thromboembolism, and compromised wound healing) and revisions were reviewed.ResultsThe CUSUM analysis for operative time demonstrated an inflexion point after 5, 6 and 15 cases for each of the three surgeons, or 8.7 cases on average. There were no significant differences (p = 0.53) in operative times between the RA TKA learning (before inflexion point) and proficiency (after inflexion point) phases. Similarly, the operative times of the RA TKA group did not differ significantly (p = 0.92) from the conventional TKA group. There was no discernible learning curve for the accuracy of component planning using the RA TKA system. The average length of post-operative follow-up was 21.3 ± 9.0 months. There was one revision for instability in the conventional TKA group and none in the RA TKA group. There were no significant difference (p > 0.99) in post-operative complication rates between the conventional TKA and RA TKA groups.ConclusionsThe introduction of the RA TKA system was associated with a learning curve for operative time of 8.7 cases. Operative times between the RA TKA and conventional TKA group were similar. The short learning curve implies this RA TKA system can be adopted relatively quickly into a surgical team with minimal risks to patients.

PurposeTo compare joint line restoration after unicompartmental knee arthroplasty (UKA) between conventional and robotic-assisted surgery. Previous studies have shown that joint line distalization can lead to higher failure rates. The hypothesis was that robotic-assisted UKA is associated with less femoral component distalization and a precise tibial cut, which allows a more anatomical restitution of the knee joint line.MethodsRetrospective cohort study of patients undergoing medial or lateral UKA between May 2018 and March 2020. Preoperative and postoperative radiologic assessment of the joint line was performed by two observers, using three different methods, one for tibial slope and one for tibial resection. Robotic assisted UKA and conventional UKA groups were compared.ResultsSixty UKA were included, of which 48 (77.42%) were medial. Robotic-assisted UKA were 40 (64.52%) and 22(35.48%) were conventionalThe distalization of the femoral component was higher in the conventional group despite the method of measurement used In both Weber methods, the difference was statistically different: Conventional 2.3 (0.9 to 5.6) v/s Robotic 1.5 (− 1.1 to 4.1) (p =0.0025*). A higher proportion of patients achieved a femoral component position ≤ two millimeters from the joint line using robotic-assisted UKA compared to the conventional technique .No statistical difference between robotic-assisted and conventional UKA was found in tibial resection and slope.ConclusionRobotic-assisted UKA shows a better rate of joint line restoration due to less femoral component distalization than conventional UKA. No difference was found in the amount of tibial resection between groups in this study.Level of evidenceIII

The introduction of robotics for total knee arthroplasty (TKA) into the operating theatre is often associated with a learning curve and is potentially associated with additional complications. The purpose of this study was to determine the learning curve of robotic-assisted (RA) TKA within a multi-surgeon team.This prospective cohort study included 83 consecutive conventional jig-based TKAs compared with 53 RA TKAs using the Robotic Surgical Assistant (ROSA) system (Zimmer Biomet, Warsaw, Indiana, USA) for knee osteoarthritis performed by three high-volume (&gt; 100 TKA per year) orthopaedic surgeons. Baseline characteristics including age, BMI, sex and pre-operative Kellgren-Lawrence grade were well-matched between the conventional and RA TKA groups. Cumulative summation (CUSUM) analysis was used to assess learning curves for operative times for each surgeon. Peri-operative and delayed complications were reviewed.The CUSUM analysis for operative time demonstrated an inflexion point after 5, 6 and 15 cases for each of the three surgeons, or 8.7 cases on average. There were no significant differences (p = 0.53) in operative times between the RA TKA learning (before inflexion point) and proficiency (after inflexion point) phases. Similarly, the operative times of the RA TKA group did not differ significantly (p = 0.92) from the conventional TKA group. There was no discernible learning curve for the accuracy of component planning using the RA TKA system. The average length of post-operative follow-up was 21.3 ± 9.0 months. There was no significant difference (p &gt; 0.99) in post-operative complication rates between the groups.The introduction of the RA TKA system was associated with a learning curve for operative time of 8.7 cases. Operative times between the RA TKA and conventional TKA group were similar. The short learning curve implies this RA TKA system can be adopted relatively quickly into a surgical team with minimal risks to patients.

Robotic-assisted total knee arthroplasty (TKA) may improve the precision of bone preparation and component alignment when compared to the conventional surgical approach; however, the detailed cost analysis of robotic-assisted TKA is lacking. This study aims to compare in-hospital costs between robotic-assisted and computer-navigated TKA. Patients undergoing primary TKA at a public hospital in Sydney between October 2018 and June 2019 were included. Patient demographics, surgical outcomes and in-hospital cost variables including, staff, critical care, emergency department, diagnostic, prosthesis, operating room, ward and other related costs until the discharge to the community were collected. Differences across in-hospital costs between robotic-assisted and computer-navigated TKA were compared using independent Student's t-tests. Of the 258 primary TKAs, 181 (70.2%) were computer-navigated and 77 (29.8%) robotic-assisted. Surgical time (p < 0.001) and operating time (p < 0.001) were both significantly shorter in computer-navigated TKA, while robotic-assisted TKA cases were more likely to be discharged directly home without extended in-patient rehabilitation (p = 0.014). When removing the capital costs of surgical equipment and maintenance, there was no difference in total in-hospital cost between computer-navigated ($19,512.3) and robotic-assisted TKA ($18,347.1; p = 0.179). When these capital costs were included, the mean in-hospital cost of robotic-assisted surgery was $21,507.6 compared to $19,659.7 for computer-navigated TKA (p = 0.034). The total in-hospital cost, during the implementation period of robotic-assisted TKA, is comparable with computer-navigated TKA. Robotic-assisted TKA was significantly more expensive when the upfront cost of the robotic system and maintenance costs were included. Longer term cost benefit of robotic-assisted TKA should be investigated in future studies.

Background:Robotic arm-assisted unicompartmental knee arthroplasty (UKA) has been recommended for treatment of unicompartmental knee osteoarthritis. However, its effectiveness and safeness remain controversial compared with conventional UKA. Therefore, the goal of this study was to perform a meta-analysis to re-evaluate the effects of robotic arm-assisted UKA on clinical functional outcomes.Methods:PubMed, Embase, and Cochrane Library databases were searched to screen the relevant studies. Continuous data (surgical time, knee excursion during weight acceptance, American knee society score [AKSS], Oxford knee score [OKS], forgotten joint score [FJS], visual analog scale [VAS], and range of motion [ROM]) were pooled using a standardized mean difference (SMD) with their corresponding 95% confidence intervals (CIs) to estimate the effect size, while dichotomous data (complication rate, revision rate) were pooled to obtain the relative risk (RR) with a 95% CI by STATA 13.0 software.Results:Eleven studies involving 498 patients undergoing robotic-assisted UKA and 589 patients receiving conventional UKA were included. Our pooled results demonstrated that robotic-assisted could significantly reduce the complication rate (RR: 0.62, 95% CI: 0.45–0.85; P = .0041) and improve the knee excursion during weight acceptance (SMD: 0.62, 95% CI: 0.25–1.00; P = .001), but prolonged the surgical time (SMD: 0.74, 95% CI: 0.40–1.08; P < .001). No significant difference in the revision rate, AKSS, OKS, FJS, VAS, and ROM between robotic-assisted and conventional UKA groups.Conclusion:This meta-analysis demonstrates robotic-assisted UKA may be an effective and safe surgical procedure for treatment of unicompartmental knee osteoarthritis.

IntroductionRobotic-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.Method100 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.ResultsBy 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&lt;0.01), cumulative impact load (146.6% vs 37%; p&lt;0.01), and bone stimulus (25.1% vs 13.6%; p&lt;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).ConclusionsIMU-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.