Factors Related to Meniscal Extrusion and Cartilage Lesions in Medial Meniscus Root Tears.

The purpose of this study was to identify factors affecting medial meniscus extrusion and cartilage degeneration in medial meniscus root tears (MMRT) and to determine the optimal cut-off values for the factors that predict disease severity. We retrospectively evaluated 86 consecutive patients diagnosed with an isolated MMRT by magnetic resonance imaging (MRI) examinations and arthroscopic procedures for 2 years. Patient-specific factors such as age, sex, the time between injury and MRI (mTIME), the time between injury and surgery (sTIME), the time between MRI and surgery (dTIME), Kellgren-Lawrence (KL) grades, and the mechanical tibiofemoral axis angle (mTFA) were documented. Regression analyses and receiver operating characteristic (ROC) curve analyses were performed. The mTIME was only positively correlated with meniscal extrusion ( = 0.425,  < 0.001). The patients who had grades 3 and 4 cartilage lesions had only significantly higher KL grades and longer sTIME than the patients who had lower grades of cartilage lesion (6.5 months [interquartile range (IQ): 3.0-12.0) vs. 2.5 months [IQ: 0.9-3.9];  < 0.001). The cut-off value of mTIME and sTIME were 2.5 and 6 months. Relapse times greater than 2.5 months and 6 months after a specific event were associated with a 7.8-fold increased risk for meniscus extrusion and an 18.2-fold increased risk for cartilage lesions, respectively. The risk of medial extrusion of the meniscus and the severity of articular cartilage lesions increased with time after an injury. The period of time from 2.5 to 6 months after traumatic event might be a critical window for intervention in the patients with MMRT to perform the repair in the status which the meniscus did not extrude more than 3 mm and the cartilage lesion did not progress more than grade 3. This study is a retrospective and uncontrolled case series and reflects level IV of evidence.