title: Posterior malleolar ankle fractures: an in vitro biomechanical analysis of stability in the loaded and unloaded states.
abstract: The use of internal fixation for posterior malleolar fractures remains controversial. This study assessed the contribution of the posterior malleolus/posterior tibiofibular (PM/PTF) complex to ankle stability in the loaded condition. Total plantarflexion and dorsiflexion, torsion, version, and drawer were measured with 15- and 70-kg loads before and after creation of posterior malleolar fractures that measured 25% of the distal articular surface. After internal fixation, specimens were retested. Fractures caused significant increases with internal rotation and posterior drawer at 15- and 70-kg loads in the neutral position. External rotation, anterior drawer, and dorsiflexion increased at 15-kg load. Fixation increased stability of fractured specimens, but not significantly. Fractures of the PM/PTF ligament complex may lead to excessive internal rotation and posterior instability in the loaded state.
authors.affiliation: Department of Orthopaedic Surgery, Medical College of Wisconsin, Milwaukee.
authors.forename: K B
authors.initials: KB
authors.lastname: Scheidt
authors.forename: J B
authors.initials: JB
authors.lastname: Stiehl
authors.forename: D A
authors.initials: DA
authors.lastname: Skrade
authors.forename: T
authors.initials: T
authors.lastname: Barnhardt
mesh_terms: D016512:Ankle Injuries / Q000473:pathology / Q000503:physiopathology* / Q000601:surgery; D001696:Biomechanical Phenomena; D002102:Cadaver; D005069:Evaluation Studies as Topic; D005360:Fibula / Q000293:injuries*; D005593:Fracture Fixation, Internal / Q000379:methods / Q000592:standards*; D006801:Humans; D013978:Tibial Fractures / Q000473:pathology / Q000503:physiopathology* / Q000601:surgery; D014102:Torsion Abnormality; D016474:Weight-Bearing