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
JBJS Editor-in-Chief
Pelvic Fracture Classification Will Benefit Elderly Patients
The orthopaedic community began to move away from individual fracture classifications in the mid-1980s. The basis for that shift was the need for wider recognition that fractures represent a “continuous variable,” with infinite varieties of orientations and combinations of fracture lines. Trying to fit fractures into a narrow classification system can lead to confusion and misinformation. Furthermore, surgeons often disagree when determining a fracture’s classification and, therefore, which treatment is best.
To move away from individual classification systems, orthopaedic journals have generally moved toward the compendium of fracture classifications approved by the OTA and AO. Still, there are times when a new fracture classification seems appropriate, and in the June 5, 2019 issue of The Journal, Pieroh et al. have provided us with an example that classifies fragility fractures of the pelvis (FFP). The 4-group FFP classification is based on fracture morphology with different degrees of instability and includes treatment recommendations.
The authors collected the CT scans of 60 patients from 6 different hospitals who were ≥60 years old and had sustained a pelvic fracture from low-energy trauma. These CT scans were shown to 6 experienced surgeons, 6 inexperienced surgeons, and 1 surgeon who had direct experience/training with the FFP system. Each surgeon was asked to classify the pelvic fractures according to the FFP classification. Inter- and intra-rater reliabilities for the fracture classifications were calculated from these readings, and the overall inter-rater Kappa coefficient was found to be 0.53, while the overall intra-rater Kappa coefficient was 0.46 (Kappa coefficients of 0.61 to 0.41 constitute “moderate” reliability). In terms of percent agreement, there was greater agreement between surgeons when it came to classifying FFP Group 1 fractures than for FFP Group 2 and 3 fractures. This is noteworthy because Group 3 fractures are thought to require surgical treatment, while primary treatment for Group 2 fractures is usually nonoperative.
Pelvic fractures that are associated with low bone density and low-energy trauma are becoming increasingly frequent as our population continues to skew older. Having a validated, relatively straightforward classification system like the FFP to assist us in managing these patients will be of great assistance. The sound methodology used to develop the FFP classification system and its decent reliability, face validity, and construct and criterion validity can assure all of us about the usefulness of the FFP classification as the basis for future clinical investigations and to advance the care of these patients.
Marc Swiontkowski, MD
JBJS Editor-in-Chief
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