Comparison of cannulated lag screw versus buttress plate fixation for posterior malleolar fractures

Abstract

Objective To compare the clinical outcomes of percutaneous cannulated lag screws versus posterior buttress plate in the fixation for posterior malleolar fractures. Methods We reviewed the 167 patients who had been treated between January 2010 and December 2014 for ankle fracture involving larger than 25% of the articular surface of the posterior malleolus. They received posterior malleolus fixation with percutaneous cannulated lag screws or with a buttress plate. In the cannulated screw group (84 patients), there were 47 males and 37 females, aged from 23 to 72 years (average, 49.7±9.1 years), and 39 cases of type B and 45 ones of type C according to the Dennis-Webber classification. In the buttress plate group (83 patients), there were 38 males and 45 females, aged from 31 to 69 years (average, 52.3±8.3 years), and 45 cases of type B and 38 ones of type C according to the Dennis-Webber classification. At 6 and 12 months postoperation and the final follow-up, the ankle motion was evaluated using American Orthopaedic Foot and Ankle Society (AOFAS) score and range of motion (ROM). Results The average operation time for the cannulated screw group was significantly shorter than for the buttress plate group (Z=-9.145, P 0.05); the AOFAS scores at the final follow-up for all the patients were significantly different from those at 6 and 12 months postoperation (P 0.05). Conclusions As there are no significant differences between the percutaneous cannulated lag screws and posterior buttress plate in AOFAS score and ROM of the ankle after fixation for posterior malleolar fractures, the 2 fixation methods can both achieve good clinical outcomes. Fixation with cannulated lag screws has advantages of indirect reduction and minimal invasion but also a disadvantage of uncertain quality of reduction; fixation with buttress plates has an advantage of anatomical reduction under direct vision but also shortcomings of relatively large invasion and high cost. Key words: Ankle; Fractures fixation, internal; Bone nails; Bone plates; Posterior malleolus