Mucoid Degeneration of the Anterior Cruciate Ligament: Characteristics and Conservative Management

Clinical and radiographic characteristics of mucoid degeneration of the anterior cruciate ligament (MD-ACL) were poorly documented in previous literature. And the optimal management strategy for MD-ACL remains unclear. Here, we summarized the characteristics associated with MD-ACL, and evaluated the clinical outcome of conservative management to MD-ACL.A total of 18 knees in 18 patients diagnosed with MD-ACL were collected and reviewed retrospectively. Sixteen patients underwent conservative management and two patients underwent arthroscopic surgery. Baseline demographic, clinical data, and pathologic changes of knee in magnetic resonance imaging (MRI) were recorded. Clinical outcome was evaluated with Visual Analogue Scale (VAS) and Oxford Knee Score (OKS).The most common clinical characteristic in patients with MD-ACL was knee pain (18/18), and seconded by mobility limitation (38.9%, 7/18). All patients presented a typical celery stalk sign with increased signal and diffuse thickening volume in the ACL in MRI. Thirteen patients companied with meniscus tear (72.2%, 13/18), and nine complicated with cartilage injury (50.0%, 9/18). Sixteen patients who underwent conservative treatment were followed up for 21.8 months, and a positive clinical outcome was observed with VAS decreasing from 5.3 ± 2.3 to 1.5 ± 1.9 and OKS decreasing from 27.5 ± 12.7 to 17.9 ± 11.8 (p < 0.001). The post-OKS score was highly correlated with age, duration of disease, and meniscus tear (r = 0.844, 0.707, and 0.474, p < 0.05, respectively). And the post-VAS highly correlated with age (r = 0.693, p < 0.05). Two patients who underwent arthroscopic surgery were followed up for 24.5 months, and the pain and function of knee was improved.Knee pain and meniscus tear was the main characteristic of MD-ACL in clinical and radiographic exam. Conservative treatment could be an alternative management for treatment of MD-ACL with positive clinical outcome. Old age, long duration of disease and complications from meniscus tears were associated with inferior outcome of conservative treatment for MD-ACL. LEVEL OF EVIDENCE:  IV.