Effect of Posterior Malleolus Fracture on Outcome After Unstable Ankle Fracture
Reference: Tejwani N, Pahk B, Egol K. (Sept 2010) Effect of Posterior Malleolus Fracture on Outcome After Unstable Ankle Fracture. The Journal of Trauma, Injury, Infection, and Critical Care, Vol 69, #3, 666-669.
Scientific Literature Review
Reviewed by: Aaron Bellew, DPM PGY 2
Residency Program: New York Hospital Queens
Unstable ankle fractures that include a posterior malleolus fracture are commonly seen in both podiatric and orthopaedic practices.
A prospective database was created to collect all unstable ankle fractures treated operatively at the authors’ institution from October 2000 to July 2005. Data was collected on 456 patients with unstable fractures that were treated surgically and prospectively followed. All patients were followed at 3, 6, and 12 months respectively. Patients were evaluated clinically, radiographically and functionally. Functional outcomes were assessed using Short Musculoskeletal Function Assessment Score (SF-36), American Orthopaedic Foot and Ankle Society Scores (AOFAS) and the Short Musculoskeletal Function Assessment (SMFA).
Of the 309 patients who had at least 1 year follow up, 255 patients had no involvement of the posterior malleolus, and 54 patients with an ankle fracture involved the posterior malleolus. These 54 fractures were classified using the Orthopedic Trauma Association (OTA) classification. 34 (64%) had OTA 44B3.2 or 44B3.3. The remaining 20 patients had OTA 44C3.2 or 44C3.3 injuries. 33 (62%) had supination external rotation injuries using Lauge-Hansen classification.
20 posterior malleolar fractures were deemed to require fixation based on fragment size and tibiotalar stability. These 20 fractures demonstrated a mean fragment size encompassing 25.2% of the articular surface, versus 16.1% for those not fixed. 10 fractures were fixated using posterior antiglide plate through a posterolateral approach and 10 were fixated using screws alone after indirect reduction.
At 1-year follow-up, patients with posterior malleolus fractures were significantly worse with respect to total score and pain function (based on AOFAS scores). In addition, using SF-36 scores there was a significant difference seen with vitality and social function subgroups at 1 year. The SMFA also demonstrated that there was a significant difference at 1 year for dysfunction. There was no significant difference in the complication rates, with the most common being removal of hardware due to pain 1 year postoperatively. However, at the 2-year follow-up mark, there was no significant difference in a smaller group of patients (41/54).
The presence of a posterior malleolus fracture may indicate an injury of high energy and seems to result in worse outcomes at 1 year. At 2 year follow-up no significant difference was noted overall in this studies population. Educating your patient regarding the time frame to return to normal function is important so that they may understand the treatment course.