SLR - June 2019 - Zachary A. Cohen

Open Reduction and Internal Fixation of the Posterior Malleolus Fragment Frequently Restores Syndesmotic Stability

Reference: Baumbach SF, Herterich V, Damblemont A, Hieber F, Bocker W, Polzer, H. Open Reduction and Internal Fixation of the Posterior Malleolus Fragment Frequently Restores Syndesmotic Stability. Injury. 2019 Feb;(50)2:564–570.

Scientific Literature Review

Reviewed By: Zachary A. Cohen, DPM
Residency Program: John Peter Smith Hospital, Fort Worth, TX

Podiatric Relevance: When to fix the posterior malleolus (PM) fracture is still a hotly debated topic. Historically, the PM fracture is not fixed unless the fragment is at least 25 percent of the articular surface. The authors argue for anatomical reduction of the PM fragment regardless of size because with an intact PITFL, the syndesmosis is restored, and the fibula is reduced anatomically into the incisura. The aim of the current study was to investigate the frequency of transsyndesmotic fixation in patients suffering trimalleolar fractures where the PM fragment was treated without fixation, CRIF by AP screws or ORIF via the prone posterolateral approach. The secondary aim was to determine the quality of reduction between the three groups. They hypothesized that ORIF of the PM fragment would significantly reduce the need for transsyndesmotic fixation.

Methods: The study is a retrospective database study. The ankle fracture database used found 648 ankle fractures from January 2010–December 2016 that were operatively treated, were >18 years old and did not have considerable concomitant injuries. Of these, 236 patients were eligible for the study having met the inclusion criteria of trimalleolar/trimalleolar equivalent fractures with preop CT scans. Patients were placed in three groups based on the treatment approach decided by the surgeon. After fracture fixation, stability of the syndesmosis was tested using either the hook test or external rotation test.

Results: The study had 114 patients (48.3 percent) in group 1 (no PM fixation), 44 patients (18.6 percent) in group 2 (CRIF) and 78 patients (33.1 percent) in group 3 (ORIF). The classification system used for the PM fracture, the location and the size were all significantly different for each group. Transsyndesmotic fixation was needed 25 percent of the time in group 3 compared to 61 percent and 63 percent for groups 2 and 1, respectively. ORIF resulted in a significantly superior reduction compared to CRIF and untreated PM fractures.

Conclusions: Indirect reduction of the PM can be achieved by ligamentotaxis by reducing the distal fibula. This, however, can lead to unsatisfactory reduction of the PM fragment affecting the congruency of the tibiotalar joint and can influence syndesmosis stability. The PM fragment can be considered an avulsion fracture of the PITFL, and through fixation, you can restore the syndesmosis. The authors believe that regardless of size, the PM should be fixated directly. This study demonstrated a 60 percent decrease in transsyndesmotic fixation following ORIF of the PM fragment and a significantly superior quality of reduction compared to CRIF by AP screws or untreated PM fractures. There is utility in direct ORIF of the PM fragment when indicated, but operating on wafer-thin PM fragments seems unrealistic and unnecessary. 

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