Superior Tuber Displacement in Intra-articular Calcaneus Fractures

Background: Intra-articular calcaneus fractures result in heel shortening, widening, varus malalignment, and loss of height. Little has been written regarding superior displacement of the calcaneal tuber, which warrants consideration as previous literature has demonstrated issues arising from a shortened triceps surae. We sought to determine the amount of tuber elevation seen in calcaneus fractures as compared to normal calcanei and propose 2 new measurements that aid in quantifying displacement and may aid in the surgical management of calcaneus fractures. Methods: Lateral radiographs of 220 normal calcanei were examined. Two novel measurements, the talo-tuber angle and talo-tuber distance, were used to establish normative data for calcaneal tuber positioning. Lateral radiographs of 50 calcaneus fractures treated operatively were examined and the same measurements were obtained before and after surgery to determine the amount of superior tuber elevation. Results: Normative data demonstrated a mean of 38.6 degrees (±SD = 4.3, range: 26.2-58.4) when using the talo-tuber angle and 54.5 mm (±SD = 7.3, range: 36.2-72.6) when using the talo-tuber distance in normal calcanei. Patients sustaining calcaneus fractures demonstrated a mean of 29.5 degrees (±SD = 5.9, range: 20-46.4) for the talo-tuber angle and 39.0 mm (±SD = 9.4, range: 24.0-62.9) for the talo-tuber distance. These values changed to a mean of 37 degrees (±SD = 5.2, range: 26.4-50) for the talo-tuber angle and 51.8 mm (±SD = 8.6, range: 33.2-75.7) for the talo-tuber distance after surgery. There was a statistically significant difference ( P value < .01) for both talo-tuber angle and distance between normal and fractured calcanei. Inter- and intra-observer agreement was excellent. Conclusion: Superior displacement of the calcaneal tuber is a deformity seen in intra-articular calcaneus fractures that has been poorly described that warrants increased awareness and correction at the time of surgery. We propose 2 novel measurements with associated normative data that may aid surgeons in quantifying this deformity and assessing anatomic reduction. Level of Evidence: Level III, comparative study.