STRENGTH OF INTERNAL-FIXATION FOR CALCANEAL FRACTURES

Objective. To compare the strength of two types of fixation method for calcaneal fractures. Design. A biomechanical testing examined the sta bility of 12 fractured calcaneal specimens fixed with two different me thods. Background. Though anatomic reduction and internal fixation for the treatment of intraarticular fractures of the calcaneus has become popular, biomechanical data on the fixation strength is lacking. Meth ods. Twenty fresh frozen specimens of amputated human legs were impact ed by a 20 kg weight dropped from a 155 cm height to create calcaneal fractures. Twelve specimens which demonstrated a longitudinal and a tr ansverse primary fracture lines were selected for open reduction and i nternal fixation. Group 1: a lateral buttress plate and parallel screw s placed in the latero-medial direction were used. Group 2: a longitud inal screw was added in addition to the fixation used in group 1. Biom echanical testing was performed by applying a tibial shank load until the internal fixation failed. Results. All mechanical failures of the reconstructed calcaneus occurred through the transverse primary fractu re line. The average failure load was 805 +/- 356 N in group 1 and 290 5 +/- 910 N in group 2 (Wilcoxon p <0.05). Conclusions. A longitudinal transfixing screw could significantly improve the stability of the tr ansverse primary fracture line in calcaneal fractures. Relevance. A lo ngitudinal screw is recommended for clinical use so that early range o f motion can be instituted post-operatively. (C) 1998 Elsevier Science Ltd. All rights reserved.