An anatomic study and clinical application of sustentaculum talus for displaced intraarticular calcaneal fractures

Abstract

Objective To study the anatomy and clinical application of sustentaculum talus for displaced intraarticular calcancal fractures. Methods The anterior tilt angles of the sustentaculum talus and the anterior part of posterior calcaneal facet, the maximal width of the middle calcaneum and the maximal and minimal thicknesses of the sustentaculum talus base were measured in 40 pieces of adult calcaneal spec-imens. The intraarticular structures of normal calcaneum were observed, including anatomical relations of the sustentaculum talus. The internal screw fixation of middle calcaneum was simulated to measure the positions and angles of screws. Follow-ups were conducted in 27 patients with displaced intraarticular calcaneal fractures treated by ORIF through an extensile right-angled lateral incision. The accuracy of screw insertion and func-tional outcome were assessed. Results The anterior tilt angle of the sustentaculum talus is 50°±5°, the anterior tilt angle of anterior part of posterior calcaneal facet is 69°±5°, the width of the middle calcaneum is (41.75±1.76) mm, and the maximal and minimal thicknesses of sustentaculum tali base are (12.14±1.60) mm and (4.81±1.07) mm respectively. The compact structure of bone trabecula beneath the sus-tentaculum talus progresses to the inferior part of the posterior calcaneal facet. The sustentaculum talus is closely connected with the tendons and vessels running along medially. The best 3 positions for screw insertion measured on coronal plane from the posterior facet to the sustentaculum talus are as follows: the lowest position is 25°±5° upwards, the highest point is 3°±3° downwards and the middle position is 13°±3°. The excellent and good rate of functional outcome was 88.9%. Conclusions ORIF through an extensile right-angled lateral incision is effective for displaced intraarticular calcaneal fractures. The sustentaculum talus is a good place for screw insertion. The length of screws can be determined by the width of the middle calcaneum. The diameter of the screws depends on the minimal thicknesses of sustentaculum tali base. The angles of insertion are determined by the relations between the sustentaculum talus and the posterior facet. Key words: Calcaneus; Fracture; Fracture fixation,internal; Anatomy