Posterior malleolar stabilization of syndesmotic injuries is equivalent to screw fixation

Abstract

Background: Fixation of unstable ankle fractures, including fixation of posterior malleolus fracture fragments with the attached, intact posteroinferior tibiofibular ligament (PITFL), reportedly provides more stable fixation than transsyndesmotic screws.

Questions/purposes: To confirm this observation we compared the Foot and Ankle Outcome Score (FAOS) and radiographic maintenance of fixation for fractures treated through direct posterior malleolar fixation versus syndesmotic screw fixation.

Methods: We prospectively followed 31 one patients with unstable ankle fractures treated with (1) open posterior malleolus fixation whenever the posterior malleolus was fractured, regardless of fragment size (PM group; n = 9); (2) locked syndesmotic screws in the absence of a posterior malleolar fracture (S group; n = 14); or (3) combined fixation in fracture-dislocations and more severe soft tissue injury (C group; n = 8). All patients had preoperative MRI confirming syndesmotic injury and an intact PITFL; postoperative and followup radiographs were evaluated for syndesmotic congruence. The minimum followup was 12 months (mean, 15 months; range, 12-31 months).

Results: Postoperative and followup FAOS scores were similar in the three groups. The tibiofibular clear space was greater in the S versus the PM group, but we found no other differences in the postoperative versus followup measurements between the PM, S, and C groups.

Conclusions: Syndesmotic fixation through the posterior malleolus and PITFL is maintained at followup, and these patients have functional outcomes at least equivalent to outcomes for patients having syndesmotic screw fixation.

Level of evidence: Level II, therapeutic study. See Guidelines for Authors for a complete description of levels of evidence.

Figures

Fig. 1A–D

(A) Anteroposterior and (B) lateral radiographs are shown of an injury treated with posterior malleolar fixation. Medial clear space widening and a small posterior malleolus fracture can be seen. (C) Anteroposterior and (D) lateral radiographs obtained after surgery show posterior malleolus stabilization to recreate the tibial incisura. The posterior malleolus and fibula are restored anatomically with plate and screw constructs, and no syndesmotic screws are used.

Fig. 2A–B

(A) Anteroposterior and (B) lateral radiographs show syndesmotic screw stabilization through a locking one-third tubular plate. In these cases, the medial and lateral malleoli are fixed, and the syndesmosis then is tested. If it still widens under stress, the syndesmotic screw construct is placed.

Fig. 3A–D

(A) Anteroposterior and (B) lateral radiographs show a fracture-dislocation with complete dislocation and trimalleolar fractures. This is a typical example of a patient treated with combined fixation. (C) Anteroposterior and (D) lateral radiographs show combined posterior malleolar and syndesmotic screw fixation.

Fig. 4

The drawing shows the measurements as described in the text. TCS = tibiofibular clear space; TFO = tibiofibular overlap; MCS = medial clear space.