Arthroscopic management of mucoid degeneration of anterior cruciate ligament

BACKGROUND: Mucoid degeneration of the anterior cruciate ligament (ACL) is a less understood entity. The purpose of this study was to diagnose mucoid degeneration of anterior cruciate ligament and to assess the effectiveness of arthroscopic treatment in these patients. MATERIALS AND METHODS: Between December 2007 and November 2011, 20 patients were diagnosed to be suffering from mucoid degeneration of anterior cruciate ligament (ACL) on the basis of magnetic resonance imaging (MRI), histopathology, and arthroscopy findings. 12 patients were males and 8 patients were females, with mean age of 42.2 years for males (range 28-52 years) and 39.4 years for females (range 30–54 years). They presented with pain on terminal extension (n=10) and on terminal flexion (n=2) without history of significant preceding trauma. MRI showed an increased signal in the substance of the ACL both in the T1- and T2-weighted images, with a mass-like configuration that was reported as a partial or complete tear of the ACL by the radiologist. At arthroscopy, the ACL was homogenous, bulbous, hypertrophied, and taut, occupying the entire intercondylar notch. A debulking of the ACL was performed by a judicious excision of the degenerated mucoid tissue, taking care to leave behind as much of the intact ACL as possible. Releasing it and performing a notchplasty treated impingement of the ACL to the roof and lateral wall. In one patient, we had to replace ACL due to insufficient tissue left behind to support the knee. RESULTS: Good to excellent pain relief on terminal flexion–extension was obtained in 19 of 20 knees. The extension deficit was normalized in all knees. Lachman and anterior drawer test showed a firm endpoint in all, and 85% (n=17) showed good to excellent subjective satisfaction. CONCLUSIONS: Mucoid hypertrophy of the ACL should be suspected in elderly persons presenting pain on terminal extension or flexion without preceding trauma, especially when there is no associated meniscal lesion or ligamentous insufficiency. They respond well to a judicious arthroscopic release of the ACL with notchplasty.