Does Retrograde Femoral Nailing through a Normal Physis Impair Growth? An Experimental Porcine Model

Abstract

A bstract Materials and methods The study was carried out using an experimental porcine model. Eleven juvenile female porcines were randomized for insertion of a retrograde femoral nail in one limb. The other limb acted as a control. The animals were housed for 8 weeks before the nail was removed and housed for 8 additional weeks, that is, 16 weeks in total. Growth was assessed by interphyseal distance on 3D magnetic resonance imaging (MRI) after 16 weeks and the operated limb was compared to the non-operated limb. Histomorphometric analysis of the physeal canal was performed. Results No difference in longitudinal growth was observed when comparing the operated femur to the non-operated femur using MRI after 16 weeks. No osseous tissue crossing the physis was observed on MRI or histology. The empty canal in the physis after nail removal was filled with fibrous tissue 16 weeks after primary surgery. Conclusion Growth was not impaired and no bone bridges were seen on MRI or histology 16 weeks after insertion and later removal of the retrograde femoral nail. Clinical significance The insertion of a retrograde intramedullary femoral nail centrally through the physis and later removal might be safe, however, long-term follow-up is needed. Aim and objective The insertion of an intramedullary nail may be beneficial in certain cases of leg length discrepancy (LLD) in children. However, it is unknown if the physeal injury due to the surgery may cause bone bridge formation and thereby growth arrest after removal. This study aimed to assess longitudinal interphyseal growth 16 weeks after insertion and later removal of a retrograde femoral nail passing through the physis. Moreover, to analyse the tissue forming in the empty physeal canal after removal of the nail. How to cite this article Abood AA, Rahbek O, Olesen ML, et al . Does Retrograde Femoral Nailing through a Normal Physis Impair Growth? An Experimental Porcine Model. Strategies Trauma Limb Reconstr 2021;16(1):8–13.

The Influence of Retrograde Femoral Nail Removal With and Without Interpositional Fat Grafting on Distal Femoral Physeal Behavior: A Sheep Study

“…As a previous study found no limb length discrepancy with the placement of nails violating 7% or less of the physis, 2 we suspect that growth inhibition may have occurred with implant removal. This supports a recent study by Abood et al, 3 which found retrograde femoral nailing did not impair growth 8 weeks after nail removal in a porcine model. Our study had longer follow-up of 3 to 5 months after nail removal, with both gross and histologic changes noted between these 2 later time points.…”

“…[12][13][14] However, when a retrograde femoral nail is placed across the physis, growth can continue as long as the nail violates only a subcritical portion of the distal femoral physis. [1][2][3] Despite the significant differences in limb length discrepancy when compared with contralateral control limbs in sheep sacrificed at 3 months after implant removal, evidence of normalization of this discrepancy was appreciated in sheep sacrificed 5 months after implant removal. As a previous study found no limb length discrepancy with the placement of nails violating 7% or less of the physis, 2 we suspect that growth inhibition may have occurred with implant removal.…”

“…Previous ovine data have demonstrated that up to 7% of the distal femoral physis can be violated using a rigid nail without causing subsequent growth inhibition or arrest,2 which is well above the percentage typically violated in traditional clinical practice 1. Similarly, retrograde femoral nailing has not been shown to impair growth or increase the risk of bony bridge formation across the physis in a porcine model 3…”

“…1 Similarly, retrograde femoral nailing has not been shown to impair growth or increase the risk of bony bridge formation across the physis in a porcine model. 3 In skeletally immature patients with open distal physes, in the absence of growth inhibition, retrograde nailing leads to the implant becoming positioned within the metaphysis because of continued physeal growth away from the epiphysis. 1 As a result, there is an argument for implant removal after successful fracture healing.…”

“…7 A previous porcine study investigated fat grafting after distal femoral nail removal observed no obvious bony bar formation or growth inhibition; however, the study was limited because of short follow-up time (8 wk), whereas all measurements were performed using magnetic resonance imaging. 3 The purpose of this investigation was to evaluate the behavior of the distal femoral physis after retrograde femoral nail insertion and removal, with and without interpositional fat grafting in skeletally immature sheep. Specifically, we sought to better understand the influence of retrograde nail removal with and without fat grafting on physeal growth by assessing limb length and histologic changes at 3 and 5 months after implant removal.…”