Weight-Bearing CT: An Incremental Step in Addressing Posttraumatic Ankle Arthritis
Orthopaedic surgeons recognize that an intra-articular fracture of the distal tibia (pilon fracture) is the worst actor when it comes to the sequela of posttraumatic ankle osteoarthritis. Despite decades of focusing on surgical techniques that yield the best-looking postoperative radiographs, we have come to realize that, to reduce the risk of subsequent arthritis, limiting the extent of the surgical approach may be as important as achieving the “perfect” articular reduction. Slowly we have come to understand that articular cartilage damage from the injury (and in some instances exacerbated by overaggressive surgical dissection) is as big a factor as the bone injury in terms of postoperative joint-space narrowing and its associated ankle stiffness and pain.
Thankfully, the orthopaedic trauma community is making strides toward new biologic, mechanical, and rehabilitative interventions that have the potential to limit this articular narrowing. But to meaningfully evaluate the effectiveness of these strategies, we need not only validated patient-oriented functional outcome measures, but also more reliable and reproducible ways to assess the joint-space narrowing.
In the May 6, 2020 issue of The Journal, Willey et al. report on a standardized technique using weight-bearing computed tomography (WBCT), which yields a 3D assessment of the postoperative joint space with the ankle in a loaded, functional position (see Figure above). When this technique was applied to 20 patients (mean age of 44 years) with a partial or complete articular pilon fracture 6 months after surgical treatment, the authors found significantly less tibiotalar joint space in the injured ankle compared with the uninjured ankle. Interrater correlation and test-retest data indicated that this method has good measurement reliability and reproducibility.
Any safe, reliable, and reproducible measure of early joint-space narrowing after pilon fracture surgery is an important incremental step in designing clinical trials that will assess new interventions designed to preserve postoperative joint space—and hopefully reduce the incidence of posttraumatic ankle arthritis. Willey et al. have demonstrated the usefulness of WBCT as such a modality.
Marc Swiontkowski, MD