Prevalence Of Tarsal Coalition And Imaging Considerations In Children With Osteochondritis Dissecans Of The Talus

Osteochondritis dissecans (OCD) is an injury to articular cartilage and subchondral bone, with estimated incidence 6.8 per 100,000 in children 12-19 years old. OCD commonly affects the talus. Patients present with pain, locking, and inability to bear weight. The etiology of these lesions is controversial. Tarsal coalition is the irregular fusion of tarsal bones. Estimated prevalence in healthy patients is 11-13%. Bridging of tarsal bones alters biomechanics, which may cause microtrauma and lead to talar OCD. Currently, talar OCD patients are not evaluated for tarsal coalition, leaving a potential aggravating factor unresolved. Ankle imaging of talar OCD may not capture all tarsal coalitions. Defining the relationship between talar OCD and tarsal coalition may allow more comprehensive management. PURPOSE: This study aimed to determine the prevalence of tarsal coalition and evaluate the relationship between foot imaging and tarsal coalition diagnosis in talar OCD patients. METHODS: A retrospective chart review was conducted of patients under 18 diagnosed with talar OCD. Patients with a history of neoplasm, arthritis, or osteonecrosis were excluded. Tarsal coalition prevalence was calculated and OCD characteristics were described. The relationship between tarsal coalition diagnosis and foot imaging was investigated using a Fisher’s exact test. RESULTS: The cohort included 236 patients. Of these, 6 (2.5%) had a diagnosis of tarsal coalition. In the non-tarsal coalition group, 166 (72.2%) had medial talar OCD and 132 (57.4%) had stage 1 OCD according to the Berndt and Harty classification. In the tarsal coalition group, 5 (83.3%) had medial talar OCD and 4 (66.7%) had stage 1 OCD. In the non-tarsal coalition group, 57 (24.8%) underwent dedicated foot imaging. Two (33.3%) patients with tarsal coalition received foot imaging. There was not a significant relationship between tarsal coalition diagnosis and foot imaging (p = 0.64). CONCLUSIONS: The relationship between tarsal coalition and OCD has not been characterized. In this study, tarsal coalition prevalence in talar OCD patients was 2.5%. This is less than the prevalence reported for healthy individuals; however, this study is limited by sample size and the low foot imaging rate. Further investigation using larger cohorts is warranted.