Hypermobile Anterior Horn of the Lateral Meniscus: A Retrospective Case-Series Study of Presentation, Imaging, Treatment, and Outcomes

<i>Background and Objectives</i>: Hypermobility of the lateral meniscus is typically associated with the posterior part of this structure, with occurrences in the anterior part rarely reported. However, a hypermobile anterior horn of the lateral meniscus can manifest clinical symptoms. This study aimed to increase awareness regarding hypermobility in the anterior horn of the lateral meniscus by presenting its clinical presentations, magnetic resonance imaging (MRI) findings, arthroscopic findings, treatment approaches, postoperative protocols, and clinical outcomes. <i>Materials and Methods</i>: A retrospective case-series involving patients diagnosed as having hypermobile anterior horn of the lateral meniscus through arthroscopy. The clinical presentations, preoperative image findings, arthroscopic findings, treatments, postoperative protocols, and clinical outcomes following meniscal stabilization were all reviewed. <i>Results</i>: A total of 17 patients (17 knees) with a mean age of 45.9 ± 18.4 years were analyzed. The mean follow-up period was 18.2 ± 7.6 months (range, 6-24 months). Primary symptoms included anterior lateral knee pain, tenderness in the lateral joint lines, and a locking sensation in six of the knees. MRI revealed hypodense lesions anterior to the meniscus, fluid accumulation, degenerative changes, and anterior horn deformities. Following meniscal stabilization, the Lysholm Knee Scoring Scale score increased from 65.8 ± 12.7 before surgery to 91.1 ± 9.6 at the final follow-up (<i>p</i> < 0.001). All the analyzed knees achieved a full range of motion by the final follow-up, with no patient experiencing any complication or requiring reoperation. <i>Conclusions</i>: There is no specific sign or test that can be used to detect a hypermobile anterior horn of the lateral meniscus. A thorough arthroscopic examination is essential for diagnosing hypermobility in the anterior horn of the lateral meniscus. Arthroscopic meniscal stabilization yields favorable outcomes.