Objective CT-based metrics of articular fracture severity to assess risk for posttraumatic osteoarthritis.

Abstract

Intra-articular fractures predispose patients to posttraumatic osteoarthritis (PTOA) with associated chronic joint pain and decreased function. The success of articular fracture management is dependent on how the fracture is treated and on fracture type and severity. The purpose of the present study was to correlate objective computed tomography (CT)-based indices of intra-articular fracture severity with subsequent joint degeneration. It was hypothesized that an injury severity metric that included objective measures of articular disruption, of fracture energy, and of fragment displacement/dispersal would be a useful predictor of PTOA. Novel CT-based image analysis techniques were used to quantify acute injury characteristics in a prospective series of 20 tibial plafond fractures managed by articulated external fixation with later definitive surgical fracture reduction performed after soft tissue swelling had sufficiently resolved. PTOA severity was assessed 2 years postinjury using the Kellgren-Lawrence radiographic grading scale. A predictive model was developed by linearly regressing these 2-year Kellgren-Lawrence outcomes on the CT-based severity metrics. A combined acute severity score involving articular disruption and fracture energy successfully predicted PTOA severity (R2 = 0.70), whereas fragment displacement/dispersal and surgeon opinion correlated much less well with degeneration (R = 0.42 and 0.47). The concordance between the combined metric and PTOA severity was 88%. The findings of this study indicate that objective CT-based metrics of acute injury severity can reliably predict intermediate-term PTOA outcomes in this challenging class of articular fractures. Quantitative biomechanical assessment of injury characteristics provides new possibilities to improve fracture management and to guide PTOA research.