Background: Robotic-assisted unicompartmental arthroplasty (rUKA) is gradually gaining more popularity than its conventional counterpart (cUKA). Current studies are highly heterogenic in terms of methodology and the reported results; therefore, establishing the optimal recommendation for patients becomes less straightforward. For this reason, this meta-analysis aims to provide an up-to-date evidence-based analysis on current evidence regarding clinical outcomes and complication rates following rUKA and cUKA. Methods: A meta-analysis was conducted following PRISMA guidelines. Five databases were searched, PubMed via MEDLINE, Epistemonikos, Cochrane Library, Web of Science, and Scopus. The relevant inclusion criteria were as follows: comparative clinical studies in which medial rUKA was compared to medial cUKA (prospective or retrospective designs), (2) human studies, (3) meta-analyses for cross-referencing, and (4) English language. The relevant extracted data were patient demographics, patient-reported outcome measures (PROMs), range of motion, and complications. A random-effects meta-analysis and subgroup analysis were conducted. The results include mean differences (MDs) and odds ratios (ORs), along with 95% confidence intervals (CIs) for continuous and binary variables, respectively. Results: rUKA showed a higher overall FJS-12 score compared to cUKA, with MD = 6.02 (95%CI: −0.07 to 12.1), p = 0.05. At 6 months postoperatively, the MD increased to 10.31 (95%CI: 5.14 to 15.49), p < 0.01. At a minimum 36-month follow-up, cUKA had a higher all-cause revision rate, with OR = 3.31 (95%CI: 1.25 to 8.8), p = 0.02, and at a minimum 60-month follow-up, a higher aseptic loosening rate, with OR = 3.86 (95%CI: 1.51 to 9.91), p < 0.01, compared to rUKA. Conclusions: rUKA provides better FJS-12 results compared to cUKA, as well as lower all-cause revision and aseptic loosening rates at 36- and 60-month follow-up, respectively. However, long-term follow-up is still pending.

Background: Robotic-assisted unicompartmental knee arthroplasty (UKA) enhances the precision of component alignment compared to conventional techniques. Although various robotic systems exist, direct comparisons assessing their relative clinical performance remain limited. The purpose of this study is to provide a comparison between image-based and imageless robotic UKA. Methods: A systematic review was conducted in accordance with PRISMA guidelines. Five databases were searched: PubMed (via MEDLINE), Epistemonikos, Cochrane Library, Web of Science, and Scopus. Inclusion criteria were (1) studies comparing rUKA and cUKA with radiologic parameters and revision rates (prospective or retrospective), (2) human subjects, (3) meta-analyses for cross-referencing, and (4) English language. Data collected included (1) pre- and postoperative radiologic parameters, (2) radiologic outliers, and (3) revisions and their causes. A random-effects meta-analysis was employed to enable a generalizable comparison. Mean differences (MDs) with 95% confidence intervals (CIs) were calculated for continuous variables, and log odds ratios (LORs) with 95% CIs for binary outcomes. Results: Image-based robotic UKA was associated with fewer joint line height outliers (LOR = 3.5, 95% CI: 0.69–6.30, p = 0.015) using a 2° threshold. HKA outliers (thresholds 2–3°) were also reduced (LOR = 0.6, 95% CI: 0.09–1.19, p = 0.024). Posterior tibial and posterior femoral implant fit were significantly lower with image-based systems (LOR = 1.7, 95% CI: 1.37–2.03, respectively, LOR = 1.7, 95% CI: 1.29–1.91; p < 0.001 for both). No significant differences in revision rates were observed. Conclusions: Image-based robotic systems may result in fewer outliers in key radiologic parameters, including hip–knee angle, joint-line height, posterior tibial, and posterior femoral fit, though reporting remains highly heterogeneous.

Purpose: Registry data suggests that robotic-assisted unicompartmental knee arthroplasty (rUKA) significantly reduces all-cause revisions compared to conventional implantation (cUKA). This study aims to compare joint line-related parameters and their reconstruction accuracy between rUKA and cUKA. Methods: Five databases were searched using a pre-defined strategy and inclusion criteria: (1) comparative studies reporting radiological outcomes, (2) human studies, (3) English language, and (4) meta-analyses for cross-referencing. Cadaveric or saw-bone studies were excluded. Data extracted included demographics data, pre- and postoperative radiological parameters (HKA, MPTA, LDFA, posterior tibial slope, femoral sagittal angle, joint line height, implant congruency), and outliers. A random-effects meta-analysis was conducted using mean difference (MD) and odds ratio (OR) as main effect estimators. Risk of bias was assessed using the Newcastle-Ottawa Scale (NOS), and publication bias was evaluated with funnel plots. Results: A total of 18 studies assessing 2470 patients (1112 rUKA, 1358 cUKA) were included in the analysis. No significant baseline differences were found in age, sex, BMI, follow-up period, MPTA, LDFA, or tibial slope. Postoperative radiological parameters showed no significant differences between groups for HKA, LDFA, MPTA, or tibial slope ( p > 0.05). Joint line height was significantly lower in cUKA compared to rUKA (MD = -1.37 mm, 95% CI: -2.06 to -0.69, p < 0.001). Outlier analysis revealed that rUKA had significantly fewer outliers across relevant radiological parameters, including HKA, joint line height, tibial slope, femoral flexion, femoral implant congruency, and medial, anterior, and posterior tibial congruency. Conclusion: Reporting pre- and postoperative mean alignment parameters undermines patient-specific anatomy reconstruction with advanced technologies. Outlier reporting showed significant variability, with limited evidence supporting its clinical relevance. Future studies should focus on patient-specific reconstruction and define clinical thresholds for outliers.