The subtalar calcaneal angle: A novel angle for evaluation of displaced calcaneal fractures - A retrospective study.

Objectives: The radiological measurement of the Böhler angle (BA) and the critical angle of Gissane (CAG) is used not only to diagnose and corroborate the suspicion of the presence of calcaneal fractures but also to assess the prognosis of different injury patterns and to evaluate the operative reduction of calcaneal fractures. Notwithstanding, many previous studies indicated the poor intra- and interobserver reproducibility of both angles. In this retrospective study, we present the subtalar calcaneal angle (SCA) as an additional diagnostic tool -to BA and CAG-which can be applied on pre- and postoperative radiographs to assess calcaneal fractures involving the posterior facet. Design: Retrospective Study. Methods: Two retrospective groups were established, a 'CF-group' including radiographs of patients diagnosed with a calcaneal fracture and underwent operative treatment in the authors' traumatology department, and a 'control group' with 50 lateral calcaneal radiographs clear of skeletal lesions. Initially, the SCA, BA, and CAG were measured in both groups by three examiners. Those measurements were repeated one month later. The intra- and intertester reliabilities of all three angles were tested by determining the intraclass correlation coefficient (ICC). A paired Results: The intra- and interobserver reliability of the SCA and the BA was in close proximity. The values of the SCA in both the control and postoperative groups were significantly different compared to the measurements of the preoperative group. The CAG showed poor intertester reliability. Conclusion: The subtalar calcaneal angle is a new instrument with proven reliability in estimating the prognosis of displaced calcaneal fractures and the postoperative alignment of the posterior facet. Level of clinical evidence: Diagnostic, Level III.