Radiographic OA, bone marrow lesions, higher body mass index and medial meniscal root tears are significantly associated with medial meniscus extrusion with OA or medial meniscal tears: a systematic review and meta‐analysis

Abstract Purpose Medial 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. Methods The 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. Results Ten 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]. Conclusion Radiographic 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 evidence IV.