Correlation of medial meniscus extrusion with meniscus injury location, type and genu varum

Abstract

Objective To investigate the correlation of medial meniscus extrusion with meniscus injury location, type and genu varum. Methods From March 2014 to March 2015, a total of 97 patients with injury of medial meniscus undergoing arthroscopy and surgery were selected as subjects, including 40 males and 57 females, aged 32-66 years, with a mean age of 51.2± 10.71 years. Based on the MRI of knee, there were 38 cases with medial meniscus extrusion ≥3 mm (extrusion group) and 59 cases without medial meniscus extrusion (non-extrusion group). Genu varus was measured on X-ray (Femur-Tibia-Angle <182°). The medial meniscus tear type was observed under arthroscopy (longitudinal tear, horizontal tear, oblique tear, radial tear, complex tear), as well as the meniscus tear location (anterior tear, body tear, posterior tear, root tear). The age, gender, BMI and involved side were compared between two groups. Multifactor unconditioned Logistic regression analysis was employed to analyze risk factors of medial meniscus extrusion. Results Two groups of patient showed no statistically significant difference in age (t=-1.511,P= 0.135), gender (χ2=0.208,P=0.648), BMI (t=0.249,P=0.650) and side (χ2=0.052,P=0.820). The incidence of meniscus extrusion in patients with genu varum was 89% (25/28), and the incidence of meniscus extrusion in patients with meniscus root tear was 78% (18/23). Significant difference could be spotted in the analysis of meniscal root tear (χ2=19.329,P=0.000), complex tear (χ2=5.111,P=0.024), genu varus (χ2=41.481,P=0.000) between patients with medial meniscus extrusion or without medial meniscus extrusion. Meanwhile, meniscus anterior tear (χ2=0.044,P=1.000), body tear (χ2=0.261,P=0.661), posterior tear (χ2= 3.722,P=0.086), longitudinal tear (χ2=0.054,P=0.816), horizontal tear (χ2=0.317,P=0.790), oblique tear (χ2=0.198,P=0.819), radial tear (χ2=1.188,P=0.385) no statistical significance. By multifactor analysis,OR values of genu varus and root tear were 101.976 (95%CI: 15.973, 651.041,P=0.000) and 35.517 (95%CI: 6.804, 185.399,P=0.000), respectively. Conclusion Meniscal root tear and genu varum were risk factors of medial meniscus extrusion. Key words: Menisci, tibial; Lacerations; Genu varum; Risk factors