Characterizing posterior calcaneal spur fractures in insertional Achilles tendinopathy: A case control study

BACKGROUND Despite being common in clinical practice, posterior calcaneal spur fractures in insertional Achilles tendinopathy (IAT) remain poorly studied. AIM To investigate spur fractures in patients with IAT. METHODS Patients with IAT who underwent surgery at our institution were retrospectively evaluated. Demographics and spur length were compared between patients with and without spur fractures. The diagnostic cutoff value of spur length for predicting fracture was determined via the receiver operating characteristic curve analysis. RESULTS This study included 227 feet (59 females, 168 males). The mean age was 53.9 years, and the mean body mass index was 27.3. Spur fractures were observed in 87 cases (38.3%), including 11 of 59 females (18%) and 76 of 168 males (45%). Spur length was significantly greater in patients with spur fractures than in those without fractures (12.3 vs 5.7 mm, P < 0.001), whereas height, weight, and body mass index were comparable. The optimal cutoff value for spur length in predicting fracture was 9 mm (specificity: 0.857; sensitivity: 0.816; area under the curve: 0.902). CONCLUSION Spur fractures were present in 38.3% of feet with IAT, occurring more commonly in males. Spur length was significantly associated with fracture, with a 9-mm cutoff predicting spur fractures. Given their nature as stress fractures caused by sustained traction forces from the Achilles tendon, spur fractures may warrant surgical intervention.