Andrej Maria Nowakowski

Purpose: To evaluate contemporary trends in total knee arthroplasty (TKA) research published in Knee Surgery, Sports Traumatology, Arthroscopy ( KSSTA ) over the last decade, with a focus on alignment concepts and surgical assistance technologies. Methods: KSSTA articles on primary TKA published between 2015 and 2024 were identified through Scopus. After exclusions, 856 articles were analysed. Bibliometric data were extracted and manually classified according to alignment concepts (mechanical [MA], kinematic [KA] or functional [FA]), surgical assistance technologies (manual, navigation, patient‐specific instrumentation [PSI] or robotic‐assisted surgery), study design and the use of patient‐reported outcome measures (PROMs). Analyses and visualizations were performed using R (Bibliometrix) and VOSviewer. Results: Alignment concepts shifted after 2022; KA increased to 40% (16/40 articles) and FA to 30% (12/40 articles) in 2024, whereas MA declined to 30% (12/40 articles). Manual TKA dominated overall (455/699 articles, 65%), whereas navigation (118 articles, 17%) and PSI (63 articles, 9%) contributed steadily at lower levels. Robotic‐assisted surgery emerged after 2021, overall reaching 63/699 articles (9%) and peaking at 26/104 articles (25%) in 2023. Artificial intelligence (AI)‐based studies appeared after 2020, reaching 6/112 articles (5%) in 2022, showing steady growth. International collaboration rates were higher in Europe and North America (up to ~58% multiple‐country publications [MCP]) than in Asia (KSSTA TKA literature (2015–2024) reflects a shift toward personalization (KA/FA) and precision (robotics), alongside the emergence of AI. The convergence of phenotype‐aware planning, precise execution and data‐driven evaluation outlines a coherent path forward. Continued methodological rigour and standardized reporting are essential to translate these trends into durable improvements in TKA outcomes. Future research should prioritize high‐quality comparative studies to clarify the clinical impact of emerging alignment strategies and technological innovations in TKA. Level of Evidence: Level IV.

Purpose Controversy still remains regarding the necessity of primary retropatellar resurfacing (RPR) in total knee arthroplasty (TKA). While some studies suggest retropatellar resurfacing reduces anterior knee pain (AKP) and revision rates, others report no significant differences compared to non-resurfaced TKA. This study aims to evaluate postoperative complications, pain levels, and functional outcomes in patients undergoing TKA with and without RPR. Methods A retrospective, single-center observational study was conducted including 121 patients who underwent primary TKA. Fifty-five patients (45.5%) had RPR, while 66 patients (54.5%) retained their native patella. Clinical outcomes were assessed using the knee society score (KSS), while radiological parameters such as femoral and patellar offset were analyzed. Statistical comparisons were performed using independent t-tests and chi-square tests, with significance set at p < 0.05. Results Radiological analysis revealed a significant reduction in femoral offset postoperatively (p < 0.001), with greater changes observed in the non-RPR group (p = 0.009). Patellar offset was also significantly reduced in non-RPR patients compared to RPR patients (p < 0.001). The revision rate was higher in the RPR group (10 cases) compared to the non-RPR group (1 case). Functional assessment using the KSS showed no significant differences in knee pain (p = 0.418) or knee scores (p = 0.461) between groups. However, patients in the RPR group were more likely to require walking aids postoperatively (p = 0.012). Conclusions RPR in primary TKA did not result in superior pain relief or functional outcomes compared to non-resurfacing but was associated with a higher revision rate and increased postoperative use of walking aids. These findings suggest that the decision to resurface should be individualized based on clinical and anatomical considerations. Level of evidence Level III (Retrospective Cohort).

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.

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.

Introduction: Tuberculous coxitis accounts for about 15% of all osteoarticular tuberculosis cases and is the second most common after spinal tuberculosis. In extensive cases, Girdlestone resection arthroplasty is an option for primary surgical treatment followed in the course of time, with total hip arthroplasty (THR) to increase function. However, the remaining bone stock is generally poor. In these cases, the Wagner cone stem offers good pre-conditions for bone restoration even seven decades after Girdlestone, as presented here. Case Report: A 76-year-old male patient was admitted to our department with a painful hip, who had previously been treated with Girdlestone at the age of 5 years after being diagnosed with tuberculous coxitis. After an intensive and very detailed evaluation of treatment options, the decision fell on rearticulating with a THR, even though primary surgery lay seven decades back. Since it was not possible to insert an appropriate non-cemented pressfit-cup, an acetabular reinforcement ring and a PE low profile cup were inserted, cemented with less inclination to avoid or reduce hip instability. A fissure around the implant (Wagner cone stem) was secured with numerous cerclages. Surgery was performed by the senior author (A.M.N.) postoperatively, the patient suffered a prolonged delirium. Ten months after surgery, the patient was satisfied with the result and reported a meaningful improvement in his daily quality of life. His mobility increased significantly and represented by his ability to climb stairs without being in pain or needing walking aids. Today, 2 ½ years after THR surgery, the patient still reports being satisfied and pain free. Conclusion: Despite transient complications postoperatively, we are happy to report a very satisfactory clinical and radiologic outcome after 10 months. The today 79-year-old patient reports having a higher quality of life since rearticulation of his Girdlestone situation. However, the long-term effects and survival rate of this procedure need to be observed furthermore.

The principles of the hip arthroplasty, as we know them today, were established about 60 years ago by Sir John Charnley. Replacement of the hip joint became one of the most successful and safest therapeutic procedures. Hip arthroplasty has been shown to yield good long-term results without complications. Over the last 20 years, the development and establishment of minimally invasive operation techniques has contributed to rapid changes. Additionally, perioperative patient management was optimized. Improvements in the material and tribology of the implants led to promising developments. Nonetheless, analysis of possible complications, shows potential for further developments, for example in cup geometry. Enhanced training concepts for surgeons, operation simulators, simple navigation aids for component positioning can surely achieve improvements in surgical safety.