SLR - June 2014 - John Baca

Comparison of Clinical Outcome of Pronation External Rotation versus Supination External Rotation Ankle Fractures

Reference: Schottel PC, Berkes MB, Little MTM, Garner MR, Fabricant PD, Lazaro LE, Helfet DL, and Lorich DG. Comparison of Clinical Outcome of Pronation External Rotation versus Supination External Rotation Ankle Fractures. Foot Ankle Int 2014 35(4): 353-359.

Scientific Literature Review

Reviewed By: John Baca, DPM
Residency Program: The Western Pennsylvania Hospital, Pittsburgh, PA

Podiatric Relevance: Ankle fractures are commonly treated by foot and ankle surgeons. Although PER ankle fracture patterns occur less frequently compared to SER fracture patterns, it is important to understand how functional outcomes compare for patients sustaining these types of ankle injuries.

Methods: Twenty-two PER IV and 108 SER IV fractures were identified between 2004 and 2010 from a single surgeon’s prospectively collected database. All patients were treated by the same surgeon with fracture fragment and ligament specific fixation. Preoperative MRI was used to accurately determine the Lauge-Hansen fracture pattern as either SER IV or PER IV and to evaluate for deep deltoid ligament and PITFL disruption. Ankle incongruity, syndesmotic malreduction, and loss of reduction were evaluated using postoperative radiographs and bilateral ankle CT scans. At the latest follow up visit clinical outcome measures including the Foot and Ankle Outcome Score (FAOS) and ankle range of motion (ROM) were collected. Patients with clinical follow up less than one year were excluded.

Results: The authors found no difference in the rate of wound complications, fracture nonunion, or loss of reduction between the PER IV and SER IV groups. There were also no clinical or statistically significant differences between the two groups in any FAOS domains. No significant difference in the incidence of postoperative articular incongruity was found between PER IV and SER IV groups (19 percent vs 8 percent , p = .23). The PER IV group, however, was found to have a significantly higher rate of syndesmotic malreduction (40 percent  vs 18 percent , p = .04). They also found that more than 68 percent  of PER IV patients sustained deltoid ligament tears instead of medial malleolus fractures, a rate notably higher than the SER IV cohort.

Conclusions: The authors concluded that fracture fragment and ligament specific fixation resulted in good short-term outcomes between the two cohort groups of operatively treated patients. Most importantly, however, PER IV patients were found to have a higher rate of articular malreduction as well as a significantly increased incidence of syndesmotic malreduction based on postoperative CT scans. Therefore, they recommend heightened scrutiny when treating PER IV patients with syndesmotic disruption due to the higher propensity for malreduction.  

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