Robotic arm-assisted vs conventional unicompartmental knee arthroplasty: A meta-analysis of the effects on clinical outcomes.

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.

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.

The study aims to provide an up-to-date systematic review and meta-analysis comparing radiological and functional outcomes of total knee arthroplasty (TKA) and unicompartmental knee arthroplasty (UKA) using either robotic assistance or conventional methods from the latest assemblage of evidence. This study was conducted according to PRISMA (Preferred Reporting Items for Systematic Reviews and Meta-Analyses) and MOOSE (Meta-analysis of Observational Studies in Epidemiology) guidelines. All studies in PubMed, EMBASE, Medline, and Cochrane that reported radiological and functional outcomes after TKA or UKA with either robotic or conventional methods were included in the review. Selected endpoints for random effects, pairwise meta-analysis included operative details, radiological outcomes (mechanical axis, component angle deviation, and outliers), and functional outcomes (American Knee Society Score, Knee Society Function Score, revision and complication rate, range of motion (ROM), Hospital for Special Surgery score, and Western Ontario and McMaster Universities Osteoarthritis Index). A total of 23 studies comprising 2,765 knees were included from the initial search. Robot-assisted TKA and UKA were associated with significantly better component angle alignment accuracy (low-to-high quality evidence) at the cost of significantly greater operation time. Robot-assisted UKA was found to have significantly better short-term functional outcomes compared with conventional UKA (moderate-to-high quality evidence). Robot-assisted TKA, however, did not exhibit significantly better short- and midterm subjective knee outcome scores compared with its conventional counterpart (high-quality evidence). Robot-assisted TKA and UKA were associated with nonstatistically significant improved ROM and lesser rates of revision. Robot-assisted total and unicompartmental knee arthroplasty leads to better radiological outcomes, with no significant differences in mid- and long-term functional outcomes compared with conventional methods for the former. Larger prospective studies with mid- and long-term outcomes are required to further substantiate findings from the present study.

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

Aim To compare the robotic-assisted unicompartmental knee arthroplasty (UKA) with conventional UKA. Method We systematically searched on four databases till September 2021. The outcomes were pooled as mean difference (MD) or standardized mean difference (SMD) or risk ratio (RR), and 95% confidence interval. We used RevMan to perform the analysis. Results There were 22 included studies. There were no significant differences between the robotic-assisted UKA and the conventional one in satisfaction rate (RR=1.05, 95% CI [0.98, 1.14], p=0.19), complication rate (RR=0.62, 95% CI [0.32, 1.19], p=0.15), and range of motion (MD= -0.23, 95% CI [-5.76, 5.30], p=0.93). However, robotic-assisted UKA showed significant favouring in the outliers of limb alignment (RR= 0.46, 95% CI [0.29, 0.74], p=0.001). On the other hand, the conventional UKA had better surgical time than the robotic assisted one (MD=20.89, 95% CI [11.87, 29.90], p<0.00001). Conclusions There were mainly no significant differences between robotic-assisted UKA and the conventional one in several outcomes such as the satisfaction rate, complication rate, and others. However, robotic-assisted UKA significantly favoured outliers of tibial alignment, and outliers of limb alignment, but prolonged surgical time than the conventional group.

This study conducted a Bayesian network meta-analysis (NMA) to compare the imaging and functional outcomes of patient-specific instrument-assisted unicompartmental knee arthroplasty (P-UKA), robot-assisted unicompartmental knee arthroplasty (R-UKA), and conventional unicompartmental knee arthroplasty (C-UKA). A comprehensive search was performed on five electronic databases and major orthopedic journals as of September 24, 2023. We included randomized controlled studies featuring at least two interventions of P-UKA, R-UKA, or C-UKA. Primary outcomes encompassed the deviation angle of hip-knee-ankle angle, as well as the coronal and sagittal plane alignment of femoral and tibial components. Secondary outcomes included patient-reported outcome measures (PROM), surgery time, revision rate, and complication rate. Bayesian framework was employed for risk ratio (RR) or mean deviation (MD) analysis, and treatment hierarchy was established based on rank probabilities. This NMA included 871 knees from 12 selected studies. In sagittal plane, R-UKA exhibited a significantly reduced deviation angle of femoral component compared to P-UKA (MD: 4.16, 95% CI: 0.21, 8.07), and of tibial component in comparison to C-UKA (MD: -2.45, 95% CI: -4.20, -0.68). Notably, the surgery time was significantly longer in R-UKA than in C-UKA (MD: 15.98, 95% CI: 3.11, 28.88). However, no significant differences were observed in other outcomes. Compared with P-UKA or C-UKA, R-UKA significantly improves the femoral and tibial component alignment in the sagittal plane, although this does not translate into discernible differences in functional outcomes. Comprehensive considerations of economic and learning costs are imperative for the judicious selection of the appropriate procedure.

BackgroundSurvivorship of medial unicompartmental knee arthroplasty (UKA) is technique-dependent. Correct femoral-tibial component positioning associates with improved survivorship. Image-free robotic-assisted unicompartmental knee arthroplasty enables preoperative and intraoperative planning of alignment and assessment of positioning prior to execution. This study aimed to compare the radiological outcomes between robotic-assisted UKA (R-UKA) and conventional UKA (C-UKA).MethodsThis retrospective case control study involved 140 UKA (82 C-UKA and 58 R-UKA) performed at an academic institution between March 2016 to November 2020, with a mean follow-up of 3 years. Postoperative radiographs were evaluated for mechanical axis and femoral-tibial component position. Component position was measured by two methods: (1) femoral-tibial component contact point with reference to four medial-to-lateral quadrants of the tibial tray and (2) femoral-tibial component contact point deviation from the center of the tibial tray as a percentage of the tibial tray width. Baseline demographics and complications were recorded.ResultsThere was a higher mean component deviation in C-UKA compared with R-UKA using method 2 (17.2% vs. 12.8%; P = 0.007), but no difference in proportion of zonal outliers using method 1 (4 outliers in C-UKA, 5.1% vs. 1 outlier in R-UKA, 1.8%; P = 0.403). R-UKA showed no difference in mean mechanical alignment (C-UKA 5° vs. R-UKA 5°; P = 0.250). 2-year survivorship was 99% for C-UKA and 97% for R-UKA. Mean operative time was 18 min longer for R-UKA (P < 0.001).ConclusionImage-free robotic-assisted UKA had improved component medio-lateral alignment compared with conventional technique.

Robotic-assisted medial unicompartmental knee arthroplasty (UKA) can ensure precise preoperative planning, minimise soft tissue damage and restore native coronal alignment. However, few studies have investigated how these advantages translate into differences in early postoperative outcomes. This study aimed to compare differences in early outcomes between conventional UKA (C-UKA) and robotic-assisted UKA (R-UKA). This retrospective study investigated two groups of patients who underwent medial UKA: C-UKA group (n = 35) and R-UKA group (n = 35). We assessed (1) serum indicators (hemoglobin, creatine kinase and C-reactive protein) and pain visual analogue scale (VAS) at postoperative days (PODs) 1, 2, 4 and 6; (2) radiologic parameters including joint line height change and arithmetic and mechanical hip-knee-ankle angle (aHKA and mHKA); (3) patient-reported outcomes including Knee Society Scores, Western Ontario and Mcmaster Universities Arthritis Index (WOMAC) and Forgotten Joint Score-12 (FJS-12) at 1-year follow-up. Despite similar serum indicator results, pain VAS was lower in the R-UKA group than in the C-UKA group at PODs 2 (2.5 ± 1.3 vs. 3.6 ± 1.2, p = 0.02), 4 (2.4 ± 0.9 vs. 3.3 ± 1.0, p = 0.03) and 6 (1.9 ± 1.1 vs. 3.1 ± 1.1, p < 0.01). The joint line height change was significantly lower in the R-UKA group than in the C-UKA group (0.9 mm ± 0.6 mm vs. 2.0 mm ± 1.3 mm, p = 0.02). The equivalence test for preoperative aHKA and postoperative mHKA revealed equivalence in only the R-UKA group (p < 0.01). The R-UKA group showed better WOMAC and FJS-12 compared to C-UKA group at 1-year follow-up. R-UKA led to lower pain VAS in the early postoperative period compared with C-UKA. Additionally, R-UKA effectively restored the joint line and prearthritic lower limb alignment, resulting in superior functional outcomes at 1-year follow-up compared with C-UKA. Level III.

BackgroundThe aim of this study was to compare the clinical and radiologic outcomes of robot-assisted unicompartmental knee arthroplasty (UKA) to those of conventional UKA in Asian patients.MethodsFifty-five patients underwent robot-assisted UKA and 57 patients underwent conventional UKA were assessed in this study. Preoperative and postoperative range of motion (ROM), American Knee Society (AKS) score, Western Ontario McMaster University Osteoarthritis Index scale score (WOMAC), and patellofemoral (PF) score values were compared between the two groups. The mechanical femorotibial angle (mFTA) and Kennedy zone were also measured. Coronal alignments of the femoral and tibial components and posterior slopes of the tibial component were compared. Additionally, polyethylene (PE) liner thicknesses were compared.ResultsThere was no significant difference between the two groups regarding postoperative ROM, AKS, WOMAC and PF score. Robot group showed fewer radiologic outliers in terms of mFTA and coronal alignment of tibial and femoral components (p = 0.022, 0.037, 0.003). The two groups showed significantly different PE liner thicknesses (8.4 ± 0.8 versus 8.8 ± 0.9, p = 0.035). Robot group was the only influencing factor for reducing radiologic outlier (postoperative mFTA) in multivariate model (odds ratio: 2.833, p = 0.037).ConclusionIn this study, robot-assisted UKA had many advantages over conventional UKA, such as its ability to achieve precise implant insertion and reduce radiologic outliers. Although the clinical outcomes of robot-assisted UKA over a short-term follow-up period were not significantly different compared to those of conventional UKA, longer follow-up period is needed to determine whether the improved radiologic accuracy of the components in robotic-assisted UKA will lead to better clinical outcomes and improved long-term survival.

We developed a novel unicompartmental pressure sensor to measure intraoperative medial compartment pressureduring robotic arm-assisted unicompartmental knee arthroplasty (UKA) and conventional jig-based UKA in order to assess the effect and impact of soft-tissue balance. This retrospective study evaluated 80 patients who underwent medial compartment UKA at our institution between November 2022 and June 2023, including 40 patients in conventional jig-based (mobile bearing) UKA and 40 patients in robotic arm-assisted (fixed bearing) UKA. After intraoperative soft-tissue balancing, the medial compartment pressure at 10°, 45°, and 90° of knee flexion was measured using a new unicompartmental pressure sensor. The knee range of motion (ROM), Numerical Rating Scale, and American Knee Society scores were recorded at three months and one year of follow-up. Conventional jig-based UKA did not achieve consistent medial compartment pressures at 10°, 45°, and 90° of knee flexion (p < 0.001), whereas robotic arm-assisted UKA achieved more balanced pressures at these angles (p-values between 10° vs 45°, 10° vs 90°, and 45° vs 90° were 0.132, 0.378, and > 0.999, respectively). In addition, robotic arm-assisted UKA showed better outcome scores and ROM at three months, but no significant clinical differences at the one-year follow-up. Intraoperative pressure measurements using the novel unicompartmental pressure sensor showed that robotic arm-assisted UKA was able to achieve more consistent pressure in the medial compartment than conventional jig-based UKA, which may improve early postoperative rehabilitation.

Background: Robot-assisted (RA) unicompartmental knee arthroplasty (UKA) has been associated with improved implant alignment and accuracy compared to conventional UKA; however, it is unclear if this translates to improved outcomes. The aim of this study was to compare short-term clinical and functional outcomes between RA and conventional UKA. Methods: A retrospective review of primary UKAs performed by a single surgeon from 2002 to 2021 was conducted using the institution’s electronic health records and outcomes database. Outcomes included 90-day complications, cumulative revisions, implant survivorship, and patient-reported outcome measures (PROMs). Oxford Knee Scores (OKS) and SF-12 physical and mental were compared using a mixed-effect regression model. A Kaplan-Meier curve was plotted to illustrate survivorship using revision as the endpoint. Results: A total of 397 cases were included (RA: n=85; conventional: n=312). The RA group had significantly more men (P&lt;0.01) and a lower median BMI (P=0.02). Age and comorbidities were similar between groups (P&gt;0.05). There was no difference in the rates of 90-day complications (RA: n=0, 0% vs. conventional: n=1, 0.9%, P=1). Significantly fewer cumulative revisions occurred in the RA group (RA: n=0, 0% vs. conventional: n=18, 5.8%; P=0.02). The median lengths of follow-up for RA and conventional UKA were 772 and 5,393 days, respectively. Both techniques showed within-group improvement in OKS and SF-12 physical through 2 yr (P&lt;0.01). No between-group differences in PROMs occurred at any time point. Conclusions: Medial, fixed-bearing RA UKA shows no compromise in patient safety or outcomes when compared to conventional UKA through early-term follow-up.

The objectives of this study were to compare postoperative pain, analgesia requirements, inpatient functional rehabilitation, time to hospital discharge, and complications in patients undergoing conventional jig-based unicompartmental knee arthroplasty (UKA) versus robotic-arm assisted UKA. This prospective cohort study included 146 patients with symptomatic medial compartment knee osteoarthritis undergoing primary UKA performed by a single surgeon. This included 73 consecutive patients undergoing conventional jig-based mobile bearing UKA, followed by 73 consecutive patients receiving robotic-arm assisted fixed bearing UKA. All surgical procedures were performed using the standard medial parapatellar approach for UKA, and all patients underwent the same postoperative rehabilitation programme. Postoperative pain scores on the numerical rating scale and opiate analgesia consumption were recorded until discharge. Time to attainment of predefined functional rehabilitation outcomes, hospital discharge, and postoperative complications were recorded by independent observers. Robotic-arm assisted UKA was associated with reduced postoperative pain (p < 0.001), decreased opiate analgesia requirements (p < 0.001), shorter time to straight leg raise (p < 0.001), decreased number of physiotherapy sessions (p < 0.001), and increased maximum knee flexion at discharge (p < 0.001) compared with conventional jig-based UKA. Mean time to hospital discharge was reduced in robotic UKA compared with conventional UKA (42.5 hours (sd 5.9) vs 71.1 hours (sd 14.6), respectively; p < 0.001). There was no difference in postoperative complications between the two groups within 90 days' follow-up. Robotic-arm assisted UKA was associated with decreased postoperative pain, reduced opiate analgesia requirements, improved early functional rehabilitation, and shorter time to hospital discharge compared with conventional jig-based UKA.

The robotic-assisted unicompartmental knee arthroplasty (UKA) is proposed to improve the accuracy of component positioning. We conducted a literature search in Medline, Embase, Web of Science and the Cochrane Library until April 2020. Our meta-analysis included 10 articles, involving 1231 knees. Our meta-analysis demonstrated that the robotic group had significantly better results in outliers of limb alignment (p < 0.001) and outliers of tibial alignment (p < 0.001). No statistical differences were found in the American Knee Society Score (p = 0.63), range of motion (p = 0.93), pain (p = 0.27), rate of revisions (p = 0.73) and rate of complications (p = 0.67). Robotic-assisted UKA has better component position accuracy compared with conventional UKA. But there was no significant difference in clinical results. In order to further evaluate the utility of robotic-assisted UKA, long-term follow-up randomized controlled trials (RCTs) are needed, as well as studies to evaluate the correlation between postoperative alignment and long-term clinical results.

Background It is not clear whether unicompartmental knee arthroplasty (UKA) or total knee arthroplasty (TKA) leads to better outcomes in the treatment of unicompartmental knee osteoarthritis. The purpose of our meta-analysis was to compare the clinical outcomes of UKA and TKA in the treatment of unicompartmental knee osteoarthritis. Methods We searched all major medical databases for randomized controlled trials or well-designed quasi-randomized trials that compared UKA with TKA in the treatment of unicompartmental knee osteoarthritis and conducted a meta-analysis with RevMan software (The Cochrane Collaboration, Oxford, England) to compare the clinical outcomes after assessment of study quality and heterogeneity. Results The results of the meta-analysis indicated that UKA required more revisions in the group with follow-up of less than 5 years after operation (risk ratio [RR]=3.47; 95% confidence interval [CI]: 1.23-9.77; P=0.02), but the difference was not significant after 5 years (RR=0.87; 95% CI: 0.29-2.60; P=0.81). Patients who underwent UKA had better range of motion (weighted mean difference [WMD]=6.43°; 95% CI: 3.46-9.40; P<0.001) and fewer complications (RR=0.20; 95% CI: 0.08-0.52; P=0.0009) than those who had TKA. Knee Society Scores were similar between the groups (WMD=0.16; 95% CI: -2.12-2.45; P=0.89), but functional scores were higher for the UKA than TKA group (WMD=1.96; 95% CI: 0.15-3.78; P=0.03). Conclusions UKA provided better postoperative function and fewer complications than TKA. UKA called for more revisions in the group with follow-up of 5 years or less (follow up 0–5 years), but the difference was not significant after 5 years (follow-up 5–15 years).

ObjectivesThis study reports on a secondary exploratory analysis of the early clinical outcomes of a randomised clinical trial comparing robotic arm-assisted unicompartmental knee arthroplasty (UKA) for medial compartment osteoarthritis of the knee with manual UKA performed using traditional surgical jigs. This follows reporting of the primary outcomes of implant accuracy and gait analysis that showed significant advantages in the robotic arm-assisted group.MethodsA total of 139 patients were recruited from a single centre. Patients were randomised to receive either a manual UKA implanted with the aid of traditional surgical jigs, or a UKA implanted with the aid of a tactile guided robotic arm-assisted system. Outcome measures included the American Knee Society Score (AKSS), Oxford Knee Score (OKS), Forgotten Joint Score, Hospital Anxiety Depression Scale, University of California at Los Angeles (UCLA) activity scale, Short Form-12, Pain Catastrophising Scale, somatic disease (Primary Care Evaluation of Mental Disorders Score), Pain visual analogue scale, analgesic use, patient satisfaction, complications relating to surgery, 90-day pain diaries and the requirement for revision surgery.ResultsFrom the first post-operative day through to week 8 post-operatively, the median pain scores for the robotic arm-assisted group were 55.4% lower than those observed in the manual surgery group (p = 0.040).At three months post-operatively, the robotic arm-assisted group had better AKSS (robotic median 164, interquartile range (IQR) 131 to 178, manual median 143, IQR 132 to 166), although no difference was noted with the OKS.At one year post-operatively, the observed differences with the AKSS had narrowed from a median of 21 points to a median of seven points (p = 0.106) (robotic median 171, IQR 153 to 179; manual median 164, IQR 144 to 182). No difference was observed with the OKS, and almost half of each group reached the ceiling limit of the score (OKS > 43). A greater proportion of patients receiving robotic arm-assisted surgery improved their UCLA activity score.Binary logistic regression modelling for dichotomised outcome scores predicted the key factors associated with achieving excellent outcome on the AKSS: a pre-operative activity level > 5 on the UCLA activity score and use of robotic-arm surgery. For the same regression modelling, factors associated with a poor outcome were manual surgery and pre-operative depression.ConclusionRobotic arm-assisted surgery results in improved early pain scores and early function scores in some patient-reported outcomes measures, but no difference was observed at one year post-operatively. Although improved results favoured the robotic arm-assisted group in active patients (i.e. UCLA ⩾ 5), these do not withstand adjustment for multiple comparisons.Cite this article: M. J. G. Blyth, I. Anthony, P. Rowe, M. S. Banger, A. MacLean, B. Jones. Robotic arm-assisted versus conventional unicompartmental knee arthroplasty: Exploratory secondary analysis of a randomised controlled trial. Bone Joint Res 2017;6:631–639. DOI: 10.1302/2046-3758.611.BJR-2017-0060.R1.