Ninety consecutive patients were identified as having a tibia fracture caused by gunshot at a Level-1 trauma center. Forty-four of these patients were fractures of the mid to distal third shaft. Twenty-eight patients had ankle CT scans available for review, and 24 patients had dedicated ankle films. Three orthopaedic surgeons and a radiologist read the radiographs and CT scans. Sensitivity and specificity analysis was performed for the ankle radiographs using ankle CT scans as the gold standard.
Seven of the twenty-eight fractures evaluated with a CT scan proved to have intra-articular involvement (Prevalence: 25%, 95% CI: 11.4%–45.2%). One of the seven intra-articular fractures was not seen on dedicated ankle radiographs (14.3%). The sensitivity of diagnosing an intra-articular extension on ankle radiographs was 0.85, 95%CI: 0.42–0.99. The specificity of diagnosing an intra-articular extension on ankle radiographs was 1.00, 95%CI: 0.81–1.00. Of the seven intra-articular fractures, three required additional treatment to address the intra-articular extension.
The incidence of intra-articular involvement for tibial shaft fractures secondary to gunshot is less than that reported for spiral type fractures (11–45% vs. 25–58%). Although radiographs have a high specificity, the sensitivity is lower than expected, with worse outcomes if a fracture is missed. We recommend that a CT scan should be utilized to determine intra-articular extension in the setting of tibial shaft fractures caused by gunshots.