The Occurrence of Sustentaculum Tali Displacement in Intra-articular Calcaneal Fracture and Its Effect on Operation

Objective: To investigate the incidence of sustentaculum tali displacement in intra-articular calcaneal fracture and its influence on surgical outcome. Methods: A retrospective analysis was performed on 71 patients with fresh intra-articular calcaneal fractures who were hospitalized in our hospital from August 2017 to August 2022. Preoperative CT measurements were used to determine whether there was displacement of sustentaculum tali, preoperative and postoperative X-ray measurements were used to evaluate the reduction effect, and Maryland score was used to evaluate foot and ankle function. Displacement was defined as the separation of sustentaculum tali from any plane of subtalar articular surface, dislocation exceeding 3mm or angulation exceeding 10° in CT images. Intra-articular calcaneal fractures were divided into displaced group (20 cases) and undisplaced group (51 cases) according to whether the sustentaculum tali was displaced or not. The changes of calcaneus height, width, Bohler Angle and Maryland score 1 year after operation were compared between the two groups. Results: A total of 71 patients were included in this study. Preoperative CT measurements showed that 20 patients (28.2%) had a carrier shift, and 51 patients (71.8%) did not. Among the patients with displacement, 2 cases (2.8%) had angulation ≥10°, 10 cases (14.1%) had separation ≥3 mm, 2 cases (2.8%) had dislocation degree ≥3 mm, 1 case (1.4%) had angulation combined with separation, 3 cases (4.2%) had dislocation combined with separation, and 2 cases (2.8%) had angulation and dislocation combined with separation. The postoperative calcaneus height change was 3.76±2.88mm in the no-displacement group and 2.20±1.56mm in the displacement group, and the difference was statistically significant (P<0.05). The postoperative calcaneus width change was 2.94±3.70mm in the no-displacement group and 1.23±4.51mm in the displacement group, with no statistical significance (P>0.05). The postoperative Bohler Angle change was 10.99±5.59° in the non-displaced group and 7.66±6.58° in the displaced group, and the difference was statistically significant (P<0.05). Maryland evaluation: the excellent and good rate of the non-shift group was 94.1%; The excellent and good rate of the shift group was 90.0%. Conclusion: In the case of intra-articular calcaneal fracture, there is a large incidence of angulation, separation and dislocation between calcaneal and talus. The quality of reduction may be affected by using sustentaculum tali as a reference for reduction. It is recommended to evaluate the anatomic alignment of the calcaneal bone mass before operation.