Biomechanical and clinical evaluation of posterior malleolar fractures. A systematic review of the literature

Introduction: Ankle fractures often have involvement of the posterior malleolus. Treatment guidelines exist based on limited biomechanical evidence and still is considered controversial. The objective of this article is to review the biomechanical literature concerning changes in tibiotalar contract area, changes in contact pressures, changes in ankle stability and incongruency of the joint after a posterior malleolar ankle fracture, and to review the clinical literature concerning the outcome of operative and nonoperative treatment of these fractures. Ultimately, the goal is to try to formulate helpful recommendations for clinical practice. Material: The databases Pubmed/Medline, Cochrane Database of Systematic Reviews, Cochrane Clinical Trial Register, and Embase were searched from 1988 to November 2007 to identify studies relating to changes in tibiotalar contact area, contact pressures, ankle stability, clinical outcome, and radiographic osteoarthritis after a posterior malleolar fracture. The search was restricted to articles written in the English, German, and Dutch language. Results: Eight biomechanical studies, involving 96 cadaveric ankles were included and 10 clinical studies, involving 447 fractured ankles, were included. Discussion: No consensus in the literature was found as to which fragment size of the posterior malleolus (posterior tibial margin) should be internally fixed. This is partially because of the lack of standardization in examining functional outcomes, making it difficult to compare results. It is not the peak pressure or changes in tibiotalar contact area, but rather the changes in peak pressure distribution that play a large role in posttraumatic arthritis development. It seems important to restore the medial and lateral constraints of the ankle because these, rather than the articular surfaces, provide the majority of ankle stability after an ankle fracture involving the posterior malleolar ankle fracture.