The 'Floating Medial Meniscus' Lesion in KD3M Knee Dislocations

An unusual meniscal tear involving avulsion of both anterior and posterior roots of the medial meniscus with extra-articular displacement of the meniscus in the medial soft-tissues has occasionally been observed in high energy knee dislocations. We have termed this tear pattern as a 'floating medial meniscus' lesion. This study aims to define this lesion, report its incidence, assess its impact on surgical timing, describe the repair technique, and evaluate healing rates and outcomes.

We retrospectively analysed a database of multiple ligament knee injury surgeries performed between 2008 and 2022 at a referral centre for complex knee injuries and identified cases with a floating medial meniscus lesion. The surgical procedure involved a combined arthroscopic and medial open approach that addressed the meniscus tear and ligament tears in one stage. Early intervention was defined as surgery within 3 weeks of injury. We evaluated injury characteristics, surgical challenges, and clinico-radiological outcomes at a minimum 2-year follow-up.

Seven patients (all male, mean age 27.2 years) with floating medial meniscus lesions were identified from 341 knees with multiple ligament injuries. Five patients underwent early surgery, while two had delayed intervention. Preoperative MRI effectively identified the lesions. Early surgery facilitated easier meniscus identification, reduction, and repair, whereas delayed surgery posed challenges. At follow-up, all patients had regained a minimum 0 to 130 degrees knee range of motion, with no residual instability or pain. MRI confirmed healed meniscal roots, and the mean IKDC score was 89.5. There were two competitive elite athletes in this series and both returned to their previous level of sports.

Although floating medial meniscus lesions are daunting at presentation, they can be successfully repaired with a systematic surgical approach, resulting in satisfactory functional outcomes. Early surgery enables easier meniscus dissection, reduction and repair.