SLR - February 2021 - Andrea C. Batra

Weight-Bearing CT Scan After Tibial Pilon Fracture Demonstrates Significant Early Joint-Space Narrowing

Reference: Willey MC, Compton JT, Marsh JL, Kleweno CP, Agel J, Scott EJ, Bui G, Davison J, Anderson DD. Weight-Bearing CT Scan After Tibial Pilon Fracture Demonstrates Significant Early Joint-Space Narrowing. J Bone Joint Surg Am. 2020 May 6;102(9):796-803. doi: 10.2106/JBJS.19.00816. PMID: 32379120.

Level of Evidence: 4

Scientific Literature Review

Reviewed By: Andrea C. Batra, DPM
Residency Program: Highlands/Presbyterian St. Luke’s Medical Center – Denver, CO

Podiatric Relevance: Post-traumatic osteoarthritis (PTOA) is a common and costly sequela after foot and ankle trauma and a cause of significant morbidity particularly after pilon fractures. Current research into imaging modalities aims to develop methods to analyze changes in joint space in order to anticipate the development of PTOA or to evaluate the effectiveness of emerging interventions. This research analyzes the inter rater and intra-rater reliability of a novel standardized method of evaluating weight-bearing computed tomography (WBCT) after pilon fractures and aims to quantify the loss of joint space in tibiotalar joints six months after operative intervention for pilon fractures. 

Methods: This study prospectively included 20 patients with intra-articular pilon fractures treated via open reduction with internal fixation (ORIF) at two level one trauma centers. Operative intervention was performed by eight fellowship-trained orthopedic trauma surgeons. Patients underwent bilateral WBCT 6 months after ORIF to assess the postoperative tibiotalar joint space vs. the uninjured side. The authors described a standard technique for measuring tibiotalar joint space in nine discrete areas in three different sagittal cut images. Four reviewers, two residents, and one research coordinator all independently measured the joint space on bilateral ankles the same day six months postoperatively on all patients. These measurements were performed twice with the second measurement occurring two weeks after the first. 

Results: Interrater correlation coefficient (ICC) was 0.88 with an ICC of 0.73 for a single measurement, which indicates good reliability. The test-retest reproducibility at two weeks was 0.80, which indicates good reliability and reproducibility of the measurement method. The minimum detectable measurement difference in this system was 0.18 millimeters. The mean tibiotalar joint space in all regions in the uninjured ankles was 2.76 millimeters compared to 2.17 millimeters in the injured ankles. This demonstrates a statistically significant 21 percent reduction in joint space in the injured ankles with the greatest differences in the middle-lateral region of the joints. 

Conclusions: The authors concluded that there is a significant joint space loss after pilon fractures and WBCT was shown to be reliable and reproducible for measuring this loss at 6 months post-operatively. Although this research further elucidates the use of WBCT to detect changes in joint space, it makes no comparison to other radiographic modalities or longitudinal comparisons at different time points. Furthermore, this research does not include discussion of the clinical correlation of this joint space narrowing. Longer-term evaluation and correlated symptomatology would be prudent to analyze the ability of WBCT to predict patient-related morbidity. Future research may also consider using WBCT to determine the effectiveness of interventions on PTOA after pilon fractures. 

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