Accuracy of radiologic assessment of tibial shaft fracture union in humans.

In a series of 208 tibial shaft fractures, 166 were treated nonoperatively, and of these, 157 had an uncomplicated course of healing. The process of union was followed by repeated noninvasive measurements of fracture stability. Full unprotected weight-bearing was permitted when stability measurements indicated solid union. A group of 127 fractures was evaluated by seven senior radiologists for assessment of the stage of union on anteroposterior and lateral radiographs exposed at the time of measurements of stability. The time for assessment ranged from four to 46 weeks. The radiologic assessment was difficult to correlate to the stability of union; in 55% of unstable fractures, the films pointed to satisfactory union. Of the 93 fractures that were mechanically stable, the films suggested that no union had been achieved in 44%. The probability of a correct radiographic evaluation of stage of union was approximately 0.5. The period required to achieve solid union after tibial shaft fracture is relatively long and unpredictable. Definitions of stage and progress of union are controversial. Conventional roentgenographic examinations as a means of assessing the stage of union are generally inconclusive.