Anterior translation of the tibia in relation to femur in mucoid degeneration of ACL - An observational study

Background: Mucoid degeneration (MD) of the anterior cruciate ligament (ACL) are a well-known pathological entity.We have encountered several patients with MD of the ACL, found to have a anterior translation of tibia a exceeding 5 mm with an intact ACL. We studied this cohort and investigated the likely cause of this.

Methods: A retrospective search of our department's radiology system to identify all patients referred from the knee orthopaedic clinic for MR imaging over a span of 10 years. All patients had MD within the substance of the ACL and an intact ACL. We evaluated the degree of anterior translation of the tibia (ATT) in relation to the femur in mucoid degeneration of ACL.

Results: We identified 464 consecutive cases. The mean age was 52 years. There was a male predominance of 261 to 203 female. The average PTF measurement was 2.4 mm with a range of 0-20mm. Of the 464 cases, 3 397 patients had an insignificant ATT of < 5 mm. (0mm. 67. 67 67 patients had a ATT >5 mm. Of them, 32.8% had a ATT of 6 mm, 53.7% had a ATT range between 7 and 9 mm, with the remaining 13.4% above 9 mm in length.

Conclusion: It is essential to look for other secondary signs of ACL tears and not only focus on ATT as well as correlate this with clinical findings.