Does functional outcome depend on the quality of the fracture fixation? Inter-observer variability of radiological evaluation of surgical ankle fracture fixation. Analysis of 61 cases

S. Lipscombe, K. Studnicka, A. Molloy

Introduction: Inadequate reduction and fixation of ankle fractures leads to poor clinical outcomes although there are no well-established criteria to evaluate the quality of surgical fracture fixation of the ankle. The aim of our study was to validate Pettrone’s criteria that can be used in the radiological assessment of the quality of ankle fracture fixation that predict the functional outcome.

Methods: A retrospective study was completed following the operative management of ankle fractures at a University teaching hospital between 1st January 2009 and 31st December 2009 were included in the study. Exclusion criteria were paediatric fractures, polytrauma, and fractures involving the tibial plafond. The fracture pattern was classified using the AO classification system. Three independent Foot and Ankle Consultants assessed the quality of surgical ankle fracture fixation using Pettrone’s criteria. Aproximately one year following the surgery, functional outcome was obtained using Lower Extremity Function Score (LEFS) and a modified American Orthopaedic Foot and Ankle Society score (AOFAS). The Mann-Whitney test was used for the LEFS and AOFAS functional scores. Logistic regression was performed upon age and gender with regards to functional outcome. Given that the Kappa coefficient is a pair wise statistic, the average pair wise agreement for each category of the Pettrone criteria was also determined.

Results: Sixty-one consecutive patients were included in the study with a mean age of 51years (17-74years) and a mean follow-up of 17.41 months (13-24months). Using Pettrone’s criterias, mean interobserver agreement was 90.0% (89.4-92.6%) with inadequate reduction in 20 cases (32.5%). Mean LEFS following inadequate reduction was 47.5 (1-79) and following satisfactory reduction was 55.9 (9-80) p=0.03.

Conclusion: Pettrone’s criteria has high interobserver agreement for the quality of surgical fracture fixation of the ankle which correlates with functional outcome.