PurposeMedial meniscus extrusion (MME) refers to the protrusion of the medial meniscus beyond the tibial edge by more than 3 mm, leading to a deficiency of the hoop strain. MME commonly occurs in conjunction with osteoarthritis (OA) or medial meniscal tears (MMT). However, factors associated with concomitant MME in patients with OA or MMT have not been systematically reviewed. This study aims to perform a systematic review and meta‐analysis to identify factors associated with concomitant MME in OA or MMT. MethodsThe systematic review of the literature was performed according to PRISMA. A literature search was conducted in 4 databases. All original human studies that reported the available evidence on factors associated with concomitant MME in patients with OA or MMT were included. Pooled binary variables were analyzed by odds ratios (OR) and 95% CIs, and pooled continuous variables were evaluated by mean difference (MD) and 95% CIs. ResultsTen studies on OA (5993 patients) and eight studies on MMT (872 patients) met the inclusion criteria. The overall pooled incidence of MME was 43% (95% CI, 37–50%) for OA, 61% (95% CI 43–77%) for MMT, and 85% (95% CI 72–94%) for medial meniscal root tears (MMRT). For the population with OA, Factors significantly associated with MME included radiographic OA [OR 4.24; 95% CI 3.07–5.84; P < 0.0001], bone marrow lesions [OR, 3.35; 95% CI 1.61–6.99; P = 0.0013], cartilage damage [OR, 3.25; 95% CI 1.60–6.61; P = 0.0011], and higher body mass index (BMI) [MD, 1.81; 95% CI 1.15–2.48; P < 0.0001]. Factors strongly associated with increased risk of MME for MMT included medial meniscal root [OR, 8.39; 95% CI 2.84–24.82; P < 0.0001] and radial tears [OR, 2.64; 95% CI 1.18–5.92; P < 0.0001]. ConclusionRadiographic OA, bone marrow lesions, cartilage damage, and higher BMI were significantly associated with concomitant MME with OA. Furthermore, medial meniscal root and radial tears were significantly associated with an increased risk of MME in patients with MMT. Level of evidenceIV.

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Background: Patellar dislocation is attracting considerable research interest. Purpose: To assess studies on patellar dislocation using a scientometric method to better understand the current status of research and explore future study directions. Study Design: Scoping review. Methods: The Web of Science Core Collection database was selected to retrieve publications on patellar dislocation. Articles and reviews written in English with patellar dislocation as the main topic were included. Conference abstracts, notes, letters, expert opinions, and animal studies were excluded. A total of 4632 articles were identified in our initial search. In addition, Excel 2019, CiteSpace 6.1.R1, and VOSviewer 1.6.9 were used to analyze the h-index, the most highly cited publication, publication essentials, and research themes. Results: A total of 1485 articles were included in our analysis, with 36,608 citations and an h-index of 93. Overall, 1494 institutions and 195 journals were identified from these studies. The United States (n = 531) was the most productive country. The institution and journal with the largest number of articles were the Hospital for Special Surgery (n = 59) and Knee Surgery, Sports Traumatology, Arthroscopy (n = 212), respectively. The article “Scoring of Patellofemoral Disorders” by Kujala et al in 1993 was the most highly cited reference. The most commonly found terms used were patellar dislocation, patellar instability, medial patellofemoral ligament, knee, recurrent patellar dislocation, and soft tissue restraints. Four topics were identified after clustering analysis of key terms: risk factors, medial patellofemoral ligament reconstruction, patellar dislocation in skeletally immature patients, and lateral retinacular release. Conclusion: This scientometric review of articles on patellar dislocation summarized the current status of research (countries, institutions, and authors) and identified potential research directions.