Cephalic laxity of the posterior root of lateral meniscus: Arthroscopic sign of meniscal hypermobility. Proposal for a new arthroscopic classification.

Abstract

The lateral meniscus (LM) has greater mobility than the medial meniscus (MM) due to the lack of meniscocapsular insertions at the popliteal hiatus. Hypermobile lateral meniscus (HLM) refers to excessive anterior translation of the posterior horn of the lateral meniscus (PHLM), often causing knee pain and locking, particularly during kneeling. This study investigates cephalic laxity of the posterior root of the lateral meniscus as an arthroscopic sign of meniscal hypermobility. To assess whether the degree of cephalic laxity correlates with lateral meniscus hypermobility and determine its potential as an arthroscopic diagnostic sign for HLM to establish a classification. This observational descriptive case series study was conducted at a sports medicine center in Ecuador from November 2023 to May 2024. Inclusion criteria comprised patients undergoing knee arthroscopy within the study period, excluding those with posterior root injury, unstable meniscal tears, diffuse grade IV Outerbridge chondropathy, and posterolateral corner injuries. Data were analyzed using statistical software, focusing on arthroscopic findings and patient symptoms. Among 106 patients (57% male, 43% female; average age 38.9), a significant correlation was found between posterolateral knee pain and meniscal hypermobility. There was a 76% probability of increased pain during hyperflexion in patients with posterolateral knee pain. Pearson correlation coefficients confirmed the relationship between cephalic laxity and meniscal hypermobility. Cephalic laxity of the posterior root of the lateral meniscus may serve as a valid arthroscopic diagnostic sign for HLM. The classification of lateral meniscus posterior root laxity (LMPRL) is reliable for surgical management. IV.