Management of hypertrophic anterior cruciate ligament mucoid degeneration by arthroscopy

Abstract

Introduction: Mucoid degeneration of the anterior cruciate ligament (ACL) is a less common entity. The primary pathology is the damage to the functional synovial lining protecting the ACL with no significant preceding trauma. Two types are described i.e., cystic (synovial and mucoid cysts) and infiltrating (mucoid degeneration). These lesions can be asymptomatic. When symptomatic, the patient complained of posterior knee pain with restriction of flexion in the knee. The diagnosis is confirmed by Magnetic Resonance Imaging of the Knee. Recent trends include arthroscopic procedures, including ACL debridement, i.e. partial resection. Total resection can be required in a few cases with ACL reconstruction. Inclusion Criteria: Diagnosed cases of ACL mucoid degeneration on MRI. Exclusion Criteria: Post-traumatic knee injuries-meniscal or ligamentous or bony, ACL synovial or mucoid cysts. Materials and Methods: A total of 18 patients diagnosed with ACL mucoid degeneration were included in the study. The study was conducted from August 2019-August 2021. The patients were assessed clinically with history and clinical examination. MRI was advised in patients with clinical suspicion of ACL mucoid degeneration. Results: The study sample consisted of 18 patients (7 females and 11 males) with ages ranging from 30 to 55 years (mean age, 43.2 years) in males and 35 to 55 years (mean age, 41.5 years) in females. On clinical assessment, exacerbation of pain was more commonly related with terminal flexion in 10 patients (58.8%) as compared to terminal extension (7 patients, 41%). No motion-related exacerbation of pain was seen in 1 case. 17 patients had an extension deficit. No complaint of instability was seen except for 2 cases. Postoperatively an average improvement of the Visual analogue scale by 4 was seen. No flexion or extension deformity was noted. No patient had any major complication. On follow up Anterior Lachman test was grade 1 in 16 cases and in others it was same as opposite non-affected knee. A complete resection of ACL with reconstruction using hamstring graft was done in 1 patient. The same patient showed a pain improvement of 4 scales on VAS. The patient however had episodes of instability. Conclusion: A clinical suspicion of mucoid degeneration of ACL with confirmatory classical appearance on MRI are key to diagnosis. Symptomatic pain relief is better provided with ACL debridement with mild laxity in upcoming future.