Background: In the lower extremity, studies have suggested an optimal nail diameter to medullary canal diameter (ND/MCD) ratio to minimize postoperative complications. The goal of this study was to determine whether a correlation exists between the occurrence of complications, angulation, and range of motion and the ratio of the ND/MCD in the upper extremity.
Methods: A total of 85 radius and ulna fractures treated with flexible intramedullary nails had ND/MCD ratios measured. Random-effects models were developed to determine the association between complications and ND/MCD ratio, angulation and ND/MCD ratio, and range of motion and ND/MCD ratio. The results were reported for unadjusted models and adjusted models.
Results: Of the 85 forearm fractures treated with intramedullary nailing, there were 3 complications. The average follow-up was 6 months. The ND/MCD ratios were categorized as <0.50, 0.50 to 0.59, and ≥0.60. There was not a significant association between the different ratios and angulation, or risk of complication. There was an association between the ND/MCD ratio ≥0.60 and decreased pronation of -1.58° (-2.77° to -0.38°) and supination of -2.68° (-4.91° to -0.46°) (P < .05).
Conclusion: This study found that there was not an association between the nail to canal diameter ratio and postoperative angulation in forearm fractures treated with flexible intramedullary nails. When choosing a flexible nail for forearm fractures, there does not appear to be an optimal ratio; it is therefore reasonable to use the ND that passes more easily.
Keywords: anatomy; basic science; bone; diagnosis; forearm; fracture/dislocation; pediatric; trauma.