Hypertrophic Syndesmotic Impingement and Its Effect on the Ankle Joint

CATEGORY: Ankle, Arthroscopy INTRODUCTION/PURPOSE: During ankle arthroscopic surgery, chronic syndesmotic instability is a common combined finding of ankle instability and induces the development of a hypertrophic synovial fold. This pathologic lesion protrudes into the ankle joint cavity in various tissue types, such and hypertrophied synovium, fat or fibrosis. However, the effect of this impingement tissue on the ankle joint and the associated clinical significance have not been well-evaluated. This study aimed to identify the histological type of the syndesmotic impingement tissue and analyze its effect on the lateral talar dome cartilage, in addition to the clinical correlation with the tissue type. METHODS: A total of 62 patients (64 ankles) with chronic ankle instability and syndesmotic impingement who underwent arthroscopic surgical management from January 2017 to June 2018 were enrolled in this study. During arthroscopic surgery, we visually classified the hypertrophic syndesmotic tissue and performed biopsy. We also evaluated the prevalence of cartilage lesions at the lateral talar dome with its location. The association between the duration of symptoms and tissue diagnosis was also evaluated. RESULTS: Based on the pathologic results, 4 samples with fat degeneration, 37 samples with fibrosis, 7 samples with synovial hypertrophy, 12 samples showing mixed type hypertrophy, and 4 samples with other type of hypertrophy were identified. Among the 64 cases, articular cartilage lesions at the lateral talar dome were present in 15 cases. In 10 of 15 cases, the pathologic results revealed the presence of fibrous tissue, while 5 cases of other type including synovial hypertrophy, were identified. In 13 cases, the cartilage lesions were located in the middle third of the lateral talar dome. The patients experienced ankle joint instability for 35.5 ± 33.7 months. Longer duration (>24 months) of instability was associated with a higher rate (81.8%) of fibrotic change in the syndesmosis. CONCLUSION: Repetitive syndesmotic impingement can cause hypertrophic synovial changes; the hypertrophic synovial tissue may evolve into fibrotic impingement tissue as the duration of symptom persistence increases. If the hypertrophic tissues are fibrotic, they may be harder in terms of physical properties and may cause the development of cartilage lesions at the talar dome due to the repetitive load. Considering our results, prophylactic debridement may be effective to prevent the development of cartilage lesions at the talar dome, when hypertrophic tissues are observed during arthroscopic surgeries.