Fracture-Dislocations Demonstrate Poorer Postoperative Functional Outcomes Among Pronation External Rotation IV Ankle Fractures.

BACKGROUND: Pronation external rotation (PER) ankle fractures are relatively uncommon but serious ankle injuries. Although recent studies have demonstrated good outcomes of PER IV fractures after operative treatment, the effect of dislocation on functional outcomes has not yet been evaluated. The objective of this study was to compare short-term functional outcomes in PER IV ankle fractures with and without dislocation. METHODS: Our database of ankle fractures surgically treated using an anatomic fixation approach by the senior author from 2003 to 2013 was reviewed. All PER IV ankle fracture patients older than 18 years with a minimum of 12 months of follow-up, including Foot and Ankle Outcome Score (FAOS), were included for analysis. Patient demographics, injury characteristics, FAOS, ankle range of motion (ROM), and rate of postoperative complications were compared in PER IV fractures with and without dislocation. Of the 47 PER IV fractures included for analysis, 20 (43%) were fracture-dislocations and 27 (57%) had no dislocation. Mean age of the study cohort was 49 years (range, 24-91 years). RESULTS: The fracture-dislocation cohort demonstrated significantly poorer FAOS (symptoms, 46 vs 70, P = .002; pain, 56 vs 82, P < .001; activities of daily living, 61 vs 84, P = .002; sports, 37 vs 59, P = .036; quality of life, 25 vs 59, P < .001) than the nondislocation cohort. Articular malreduction (33% vs 14%, P = .147) was also more common in the PER IV dislocation group. Rates of syndesmotic malreduction (44% vs 48%, P = .951) were similar between PER IV fractures with and without dislocation. CONCLUSION: PER IV fracture-dislocations had higher rates of articular malreduction and demonstrated statistically poorer functional outcomes than PER IV fractures with no dislocation. Dislocation in this select subset of ankle fracture patients likely represents a higher energy injury resulting in substantial articular damage and should spur appropriate preoperative patient counseling by the orthopaedic surgeon concerning functional outcome expectations. LEVEL OF EVIDENCE: Level III clinical outcome comparison.