Accessory Meniscus Causing Medial Knee Impingement

Abstract

Accessory meniscal tissue is a rare anatomical variant of the knee and may present with mechanical symptoms when it impinges between the femoral condyle and tibial plateau. We report a 23-year-old female with right knee pain, intermittent catching, and medial joint-line tenderness following a twisting injury of 2 months duration. Radiographs were unremarkable. Magnetic resonance imaging suggested a complex tear of the posterior horn/body of the medial meniscus with an additional curvilinear meniscal-like band. Arthroscopy confirmed a mobile accessory meniscal band overlying the posterior horn and body of the medial meniscus, associated with a complex medial meniscal tear. Arthroscopic partial meniscectomy with excision of the accessory band was performed while preserving a stable meniscal rim. The postoperative course was uneventful, pain improved by postoperative day 2, and at 6 weeks the patient was asymptomatic with full range of motion and no catching or locking. This case highlights the need to consider anomalous meniscal anatomy in young patients with persistent mechanical knee symptoms and atypical MRI findings. Arthroscopy remains both diagnostic and therapeutic, and targeted excision can provide rapid symptom relief while preserving meniscal tissue.