Mid to distal third tibial shaft fractures caused by gunshots: Characterization and incidence of distal intra-articular extension.

INTRODUCTION: Spiral tibial shaft fractures are known to have a high rate of distal intra-articular extension; however, the risk of joint involvement caused by gunshots has not been thoroughly evaluated. The purpose of this study was to determine the incidence of intra- articular involvement in tibial shaft fractures caused by gunshots. The secondary purpose of this study was to assess the usefulness of ankle radiographs versus computed tomography (CT) scans in identifying these fractures.

MATERIALS AND METHODS: 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.

RESULTS: 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.

CONCLUSION: 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.