Femoral non-elongating rodding in osteogenesis imperfecta - The importance of purchasing epiphyseal plate

Background: Corrective osteotomy and intramedullary rodding are widely used in children with osteogenesis imperfecta (OI), but revision rodding is often required. This study aims to investigate the effect of purchasing distal femoral epiphysis on the longevity of fixation using non-elongating rod. Methods: We investigated children with Sillence type III or IV OI who received antegrade femoral Rush rod fixations at age between 4 and 10 years in our institution. The fixations were classified into group A in which the rod reached distal femoral epiphysis and group B in which the rod stopped at femoral metaphysis. Failure of fixation is defined as rod cutting out of the cortex or when revision surgery was performed. Calculation of longevity of each rod fixation and Kaplan-Meier survival analysis were performed and compared between the two groups. Results: Eighteen children had the first femoral rodding at a mean age of 6.9 years and received a total of 61 femoral roddings with a mean follow-up of 11.4 years. Group A included 38 roddings performed at a mean age of 7.1 years and group B included 23 roddings performed at a mean age of 6.6 years. Group A had less revision rate (58% vs. 87%), more chance of survival >3 years (74% vs. 43%), and longer median survival time (80 months vs. 33 months) than group B. Conclusions: Less revision rate and better 3-year and 5-year survival rate were proved in the roddings that purchased epiphysis. We emphasize on using the precise implant length to purchase distal femoral epiphysis when non-elongating rod is the only available implant for fixation in children with OI.