Incidence of tendon entrapment and dislocation with calcaneus and pilon fractures on CT examination.

OBJECTIVE: To examine the association between tibial pilon and calcaneal fracture classification and tendon entrapment or dislocation.

MATERIALS AND METHODS: After institutional review board approval, we retrospectively reviewed consecutive CT scans with calcaneal or pilon fractures from 5 years at a level 1 trauma center. We categorized calcaneal fractures according to the Sanders classification, and pilon fractures according to the Ruedi and Allgower and the Arbeitsgemeinschaft für Osteosynthesefragen-Orthopaedic Trauma Association (AO-OTA) classifications. Ankle tendons were assessed for dislocation or entrapment. Fisher's exact test was used for statistical analysis with significance at p < 0.05.

RESULTS: A total of 312 fractures (91 pilon only, 193 calcaneal only, and 14 ankles with ipsilateral pilon and calcaneal fractures) were identified in 273 patients. Twenty-two pilon, 42 calcaneal, and nine combination fractures were associated with 99 occurrences of tendon entrapment or superior peroneal retinacular injury. Such findings were associated with multiple fractures (p = 0.002). Multifragmentary pilon fractures were associated with posterior tibial and flexor digitorum longus tendon entrapment (p < 0.0001 and p = 0.0003 for Ruedi/Allgower and AO-OTA, respectively), and multifragmentary Sanders type 3 or 4 calcaneal fractures were associated with superior peroneal retinacular injury (p = 0.0473) compared to simple fracture patterns. Thirty-nine percent of tendon entrapments or retinacular injuries were prospectively identified, 85 % by musculoskeletal radiologists (p < 0.0001).

CONCLUSIONS: Approximately 25 % of calcaneal and pilon fractures were retrospectively identified to contain posteromedial tendon entrapment or superior peroneal retinacular injury. Radiologists should meticulously search for such injuries, particularly when analyzing multifragmentary and multiple fractures.