Does intra-articular load distribution change after lateral malleolar fractures? An in vivo study comparing operative and non-operative treatment

Abstract

PurposeThe impact of isolated malleolar fractures on the intra-articular load distribution within the ankle joint has been studied in several biomechanical cadaver studies during the last decades. Recently, computed tomography osteoabsorptiometry (CT-OAM) has been proposed as a valuable tool to assess intra-articular joint load distribution in vivo. The purpose of this retrospective matched pair analysis was to apply CT-OAM to evaluate in vivo changes of talar load distribution after lateral malleolar fractures in patients treated with open anatomic reduction and internal fixation (ORIF) compared to patients treated non-operatively. MethodsTen matched pairs of patients with isolated lateral malleolar fractures with a maximum fracture dislocation of 3mm and a median follow-up of 42 month were included into the study. Patients were matched for age, gender, and fracture dislocation. Range of ankle motion (ROM), the AOFAS hindfoot score and the Short Form 36 (SF-36) were evaluated.CT-OAM analysis of the injured and the uninjured contralateral ankles were performed. ResultsPatients treated with ORIF showed a significant lower ROM compared to the uninjured contralateral ankle. No differences were found regarding clinical scores between patients treated by ORIF and those treated non-operatively.CT-OAM analysis showed symmetrical distribution of subchondral bone mineralization in comparison to the uninjured contralateral ankles for both groups of patients. ConclusionsThe data of this study suggest that isolated lateral malleolar fractures with fracture gaps up to 3mm are not associated with a change of the tibio-talar joint load distribution in vivo. Therefore, patients with isolated minimally displaced lateral malleolar fractures may achieve good clinical long-term outcome following non-operative treatment.Level of Evidence: Level III, retrospective cohort study