Role of the mechanical axis of lower limb and body weight in the horizontal tear and root ligament tear of the posterior horn of the medial meniscus

To compare and analyse the relationship between horizontal tear and root ligament tear of the posterior horn of the medial meniscus (PHMM) and the degree of varus in the axis of lower limb and body weight. One hundred and nineteen patients underwent surgical treatment as they were diagnosed with medial meniscus tear in our hospital from May 2006 to December 2009. Of these, 19 cases (group 1), underwent partial meniscectomy as they were confirmed to solely have horizontal tear of the PHMM on arthroscopic examination and 27 cases (group 2), underwent subtotal meniscectomy as they were confirmed to solely have root ligament tear of the PHMM on arthroscopic examination, were chosen for retrospective study. Standing radiographs were taken of every case prior to arthroscopic surgery to measure varus angle. Also, we checked body mass index (BMI) of two groups. The difference of varus angle and BMI between two groups were statistically verified using the Levene’s test, paired t-test. Group 1 showed mean value of varus angle of 2.30 ± 0.54, and BMI of 25.32 ± 3.23. Group 2 showed mean value of varus angle of 5.64 ± 0.54, and BMI of 25.67 ± 3.12. The degree of varus of group 2 was statistically significantly higher than group 1 (p = 0.002). Comparison between the BMI of two groups showed no statistical significance (p = 0.053). Through a comparative study of sole horizontal tear and root ligament tear of the PHMM, the authors have found that sole root ligament tear of the PHMM is more relative to the genu varum than sole horizontal tear of the PHMM. However, body weight was statistically irrelevant to the incidence of the two lesions.