Medial meniscus extrusion is correlated with varus alignment in patients without meniscus tear

INTRODUCTION: There is a well-established connection between both medial meniscus lesions and varus leg alignment, and medial meniscus lesions like posterior root tears is known to cause meniscus extrusion. However, evidence is controversial about the relation between varus alignment and meniscus extrusion in knees without meniscus lesions. Our study aimed to evaluate the correlation between varus alignment and meniscus extrusion in knees without meniscus lesions.
METHODS: 130 knees of 113 patients (mean age 48.8±11.3 years, 33.8% male) without meniscus lesions and with long leg radiographs and knee MRIs were retrospectively analyzed. Extrusion was considered positive if exceeds 3 mm. Varus malalignment of legs were grouped as mild (0°-4.9°), moderate (5°-9.9°) and severe (≥10°) according to hip-knee-ankle angle (HKA) measurement and bone edema in medial compartment was noted. Correlation between extrusion measurement and varus malalignment (HKA) and bone marrow edema was analyzed.
RESULTS: 57 knees (43.8%) had extruded menisci. The mean HKA angle was 4.6±3.6. 82 legs (63.1%) had mild, 37 legs (28.5%) had moderate, and 11 legs (8.5%) had severe varus. Bone marrow edema was noted in 88 knees (66.7%). Relationship between extrusion and severity of varus (p<0.001) and bone marrow edema (p<0.001) were signigicant. Extent of meniscal extrusion showed significant correlation with HKA angles (coefficient=0.481, p<0.001)
DISCUSSION AND CONCLUSION: Varus malalignment was revealed to correlate with medial meniscus extrusion in knees without meniscal damage.