Posterior Malleolar Fracture Morphology Determines Outcome in Rotational Type Ankle Fractures

SLR - December 2019 - Brian Houng

Reference: Blom RP, Meijer DT, de Muinck Keizer R, Stufkens S, Sierevelt IN, Schepers T, Kerkhoffs G, Goslings JC, Doornberg JN. Posterior Malleolar Fracture Morphology Determines Outcome in Rotational Type Ankle Fractures. Injury. 2019 Jul;50(7):1392-1397.

Scientific Literature Review

Reviewed By: Brian Houng, DPM
Residency Program: Grant Medical Center – Columbus, OH

Podiatric Relevance: Fixation of posterior malleolus (PM) fractures has often been deemed necessary when there is 25-33 percent involvement of the tibial plafond on plain lateral radiographs. However, recent literature has challenged this concept of size and argue that PM fracture morphology assessed with computed tomography (CT) may be more predictive of poorer clinical outcomes. The Haraguchi PM fracture classification is CT-based and distinguishes three PM fracture types: Type I, posterolateral-oblique; Type II, transverse medial-extension; type III, small-shell fragment. There are currently no studies that aim to correlate PM fracture morphology on CT to clinical outcome. Therefore, the purpose of this study was to investigate the correlation between PM fracture morphology and functional outcome. The authors hypothesized that Haraguchi Type II (transverse medial-extension) PM fractures are associated with poorer clinical outcomes than the Haraguchi Type I and III PM fractures.  

Methods: Seventy-three patients met inclusion criteria and had a rotational-type, intra-articular ankle fracture with associated PM fracture. Two observers not involved in patient care assessed all CT scans and divided the patients into three groups based on the Haraguchi classification. Group I, II and III included 20, 21 and 32 patients, respectively. The primary outcome measure was functional outcome assessed utilizing the Foot and Ankle Outcome Score (FAOS) at two years post-operatively. The secondary outcome measures were  FAOS scores at 12 weeks and one year post-operatively, and the 36-Item Short Form Health Survey (SF-36) at 12 weeks, one year, and two years post-operatively. Each fracture was treated accordingly by one of eight surgeons with either no fixation, direct fixation with plates and screws and/or syndesmotic screws. All patients were immobilized and non-weightbearing in a short-leg cast for six weeks, then underwent physical therapy.

Results: Primary study outcomes: Haraguchi Type II PM fractures had significantly lower FAOS outcomes scores in all domains compared to  Type III and lower outcome scores in Symptoms and Activities of Daily Living scores compared to  Type I. Secondary study outcomes: Haraguchi Type II PM fractures showed no difference in FAOS domain scores at 12 weeks and alower Symptoms score compared to Type I at one year. Type II PM fractures showed significantly lower SF-36 scores compared to Type III for Physical Functioning and Role of Physical Problems domains scores at two years.  

Conclusions: This study revealed that Haraguchi Type II PM fractures resulted in significantly worse clinical outcomes compared to Type I and III after two years post-operatively. Several explanations include: lack of fixation of the posteromedial fragment, failure to stabilize the deltoid ligament, and the association between Type II PM fractures and higher impact injuries with subsequent insult to the talar dome or tibial plafond. Therefore, accurately evaluating PM fractures with CT scans may be beneficial in identifying the morphology of the fractures. Limitations include having eight different surgeons deciding on fixation without a consistent operative approach. The study may benefit from a more standardized fixation protocol to more accurately assess functional outcome after fixation of PM fractures.