Considerations When Diagnosing and Treating an Extra-Articular Fracture of Distal Radius Based on Plain Radiographs

Background: The aim of this study was to investigate what should be considered when diagnosing and treating displaced extra-articular fractures based on plain radiographs. Methods: We included 181 extra-articular distal radius fractures with marked displacement requiring surgery, which were diagnosed with posteroanterior (PA) + lateral (Lat) + oblique views (obl). We compared the plain radiographs with CT scans to determine whether the diagnosis was properly made. We described the types of articular involvement incidentally found on CT scans and how the articular involvement was treated. We tested the inter-observer and intra-observer reliability with three orthopedic surgeons. Results: Forty-two (32%) out of 181 displaced extra-articular fractures diagnosed by plain radiographs had intra-articular involvement on CT scans. Dorso-ulnar intra-articular fragment was most commonly found. Thirty-three (78.6%) out of 42 intra-articular involvements required additional reduction and a dorsal approach was used in eight patients. Inter-observer and intra-observer reliability ranged from "substantial" to "almost perfect". Conclusions: When treating displaced extra-articular fractures requiring surgery, CT scans might be necessary to find intra-articular involvement and at least, an oblique view showing the dorso-ulnar corner of the articular surface should be added. Surgeons should consider that extra-articular fractures with marked displacement, which are diagnosed by plain radiographs alone, might have intra-articular involvement requiring additional reduction or fixation via a different incision.