Mucoid degeneration of the anterior cruciate ligament: A case study

Mucoid degeneration of anterior cruciate ligament (ACL) is a rare pathological condition characterized by knee pain and restriction of movements. In this condition, ACL is infiltrated by mucoid (glycosaminoglycans) like material within its substance. We discuss the case and present a review of literature including clinical and radiological features and management options. We encountered a 33-year-old female complaining of increasing pain in right knee since last 6 years with difficulty in squatting and sitting cross-legged. There was no history of significant trauma or instability of the knee. Clinical examination demonstrated pain on deep knee flexion, negative Lachman, and anterior drawer test. Plain radiograph of knee suggested early onset degenerative changes of knee in the form of medial joint space reduction. Magnetic resonance imaging (MRI) showed hyperintense signal in ACL substance in T1W and T2W images which is classically described as Celery Stalk appearance on T2 STIR images. This was often mistaken as partial tear of ACL. Patient was planned for diagnostic arthroscopy. During arthroscopy, ACL was occupying the whole intercondylar notch. It was hypertrophied, homogenous, and firm. Arthroscopic debulking of ACL was done cautiously and mucoid tissue was removed. The specimen was sent for histopathological examination which confirmed the diagnosis of mucoid degeneration. Post-operatively patient was relieved of symptoms and was doing well without any specific complaints like instability till last follow up at 18 months. Repeat MRI was not done as patient was not symptomatic. Mucoid ACL degeneration affects active persons in third to fourth decade of life without significant trauma. MRI is the most useful tool for diagnosis with specific findings. If this disease is considered preoperatively, it can be diagnosed early. Treatment with debulking or partial resection shows good functional results.