Mucoid degenerated anterior cruciate ligament (ACL) managed by arthroscopic ACL reconstruction: A case series

Abstract

Introduction: Mucoid degeneration of the Anterior Cruciate Ligament is a rare degenerative condition affecting the middle age population (16 to 50 years). The infiltration of glycosaminoglycan into the substance of the ACL causes the ligament to swell up and impinge on the intercondylar notch and Posterior Cruciate Ligament. This results in posterior knee pain and restriction of terminal movements. The current trend of management is debulking the ligament by stripping the degenerated part and preserving the native thin ACL. This poses two problems - 1. Difficulty in identifying the degenerated parts by the arthroscope. Stripping is done with the aid of pre-op MRI; 2. Chances of under stripping (recurrence of the symptoms) or over stripping (laxity and ACL failure). Studies have shown high incidence of grade 1/grade 2 laxity by Lachman test 6 months post-op and a requirement of Secondary ACL reconstruction in many patients. Goal: The goal of this study is to assess the functional outcome of Primary ACL reconstruction with autologous quadrupled hamstring tendon graft after complete excision of the native degenerated ACL. Materials and Methods: This is a prospective study of 13 patient (7 male, 6 female) of average age 41 (25-63) years presenting with posterior knee pain and restriction of flexion for an average period of 6 months (15 days – 36 months) diagnosed with Mucoid degeneration of ACL by MRI, arthroscopy and by histo-pathological examination. They were operated by ACL reconstruction following complete excision of degenerated ACL, as a single stage procedure. Evaluation: The patients were evaluated both pre-operatively and post-operatively by Lysholm knee scoring system and VAS (visual analog score) pain scoring system. Results: Postoperatively, patients were followed up for a minimum of 1 year (average of 14.9 months). There was no evidence of recurrence or instability at the end of follow-up. There was significant improvement in Lysholm score (34.6 to 83.2) and VAS (5.76 to 0.54). Conclusion: Treatment of ACL mucoid degeneration by this modality is effective in preventing recurrence, post-operative laxity and provides better functional outcome compared to the classical partial resection of the degenerated ACL.