Objective CT-Based Metrics of Articular Fracture Severity to Assess Risk for Posttraumatic Osteoarthritis

Abstract

Objectives Intra-articular fractures predispose patients to post-traumatic 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 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. Methods Novel CT-based image analysis techniques were utilized to quantify acute injury characteristics in a prospective series of twenty 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 two years post-injury using the Kellgren-Lawrence (KL) radiographic grading scale. A predictive model was developed by linearly regressing these two-year KL outcomes on the CT-based severity metrics. Results 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 (R2 = 0.42 and 0.47). The concordance between the combined metric and PTOA severity was 88%. Conclusions 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.

Intraarticular Matrix Metalloproteinases and Aggrecan Degradation Are Elevated After Articular Fracture

“…Prior research on inflammatory cytokine concentrations between high-and lowenergy injuries demonstrated no difference [19]. In a study using CT-based metrics, Thomas et al [44]found that both fracture energy and articular comminution combined served as a better predictor of eventual development of posttraumatic OA than each individual component alone. The Schatzker classification does not account for articular comminution, and the presence of articular comminution may be more indicative of some elements of fracture energy than condylar involvement.…”

A Clinically Realistic Large Animal Model of Intra-Articular Fracture

“…The current technique does not permit discriminating the energy absorption directly associated with bony fracture versus these non-fracture factors. (Imaging techniques for estimating bone fracture energy from CT-based assessment of de novo inter-fragmentary free surface area have recently been developed [20], but are outside the scope of the present study.) However, the present survival experiment results indicate that, at least in this range of impaction parameters for this particular surgical preparation, delivered energy is clearly not a sufficient measure of the energy actually absorbed in creating tissue injury.…”

Joint Injury and Post-Traumatic Arthritis

“…Recent advances in injury severity assessment following fractures of the tibial plafond in human patients suggest that increasing levels of both energy of injury as well as increasing fracture area in the joint are predictive of developing PTA without considering reduction [17]. These same authors also found a critical threshold for residual articular displacement over which the development of PTA was more likely [10].…”

“…Furthermore, recent studies suggest that battlefield orthopaedic injuries represent the majority of long term disability in wounded soldiers in on-going military conflicts, and degenerative arthritis developing following injury is the most common reason for a wounded soldier to be considered unfit for return to duty [6]. Recent developments in injury severity assessment suggest that increasing fracture involvement of the articular surface may be predictive of developing PTA in humans [17]. The unique features of intra-articular fractures include impaction injury to the articular surface, disruption of the osteochondral composite layer, residual displacement of the articular surface, and exposure of the joint to blood and marrow contents.…”