Accuracy and Reliability of Radiographic Estimation of Volar Lip Fragment Size in PIP Dorsal Fracture-Dislocations

Background: A cadaveric study was performed to evaluate the accuracy and reliability of radiographic estimation of the volar lip fragment size in proximal interphalangeal joint fracture-dislocations. Methods: Middle phalangeal base volar lip fractures of varying size and morphology were simulated in 18 digits. Radiographs and digital photographs of the middle phalangeal joint surface were obtained pre- and postinjury. Ten orthopedic surgeons of varying levels of training estimated the fracture size based on radiographs. The estimated joint involvement on radiograph was compared with the digitally measured joint involvement. Results: Radiographic estimation underestimated the volar lip fragment size by 9.02%. Estimations possessed high intraobserver (0.76-0.98) and interobserver (0.88-0.97) reliabilities. No differences were detected between levels of surgeon training. Conclusions: The significant underestimation of the volar lip fragment size demonstrates the lack of radiographic estimation accuracy and suggests that surgeons should be mindful of these results when making treatment plans.