The Effect of timing of conversion from external fixation to secondary intramedullary nailing in experimental tibial fractures

Abstract

Diaphyseal tibial fractures with initial temporary external fixation (EF) are usually converted to intramedullary nailing (IMN) within 2 weeks, and no consensus on the optimal conversion time point exists. Current clinical practice is mainly based on estimation of the risk of postoperative infection. This is the first investigation of the effect of timing of such conversion on fracture healing. Forty male rats received a standardized tibial shaft osteotomy and EF. The animals were then randomly assigned to conversion to IMN at either 7 (group A, N = 10), 14 (group B, N = 10), or 30 (group C, N = 10) days after initial fixation. Group D (N = 10) served as a control group without conversion. Evaluation at 60 days included X-ray, DXA, and mechanical testing. Group A had significantly increased bone mineral content and callus area compared to the control group. Groups B and C showed significantly inferior mechanical bending strength and rigidity compared to both group A and the control group (D). The timing of the conversion procedure has a significant effect on fracture healing. Early conversion procedure did not improve healing compared to control, but was advantageous compared to late conversion (at 2 or 4 weeks) with higher mineralization and superior biomechanical properties.

Modulation of fixation stiffness from flexible to stiff in a rat model of bone healing

“…1982) and conversion from an external fixator to an intramedullary nail (Sigurdsen et al. 2011, Recknagel et al. 2013) on fracture healing.…”

Conversion from external fixator to intramedullary nail causes a second hit and impairs fracture healing in a severe trauma model

“…Thus the question arises, whether the conversion from an external fixator to an intramedullary nail enhances the systemic inflammatory response in terms of a second hit, resulting in further impairment of fracture healing. Additionally, it was shown in rodents that the conversion of the fracture fixation, even in a model of isolated fracture, could impair fracture healing in comparison to external fixation alone over the entire healing time 22, 23. However, in these studies the conversion was not performed following initial severe trauma.…”

Enclouage différé secondaire après fixateur externe des fractures diaphysaires tibiales : facteurs de risque relatifs à la consolidation et l’infection. Une série de 55 cas

“…Bhandari et al [23] sur une méta-analyse observaient pour les enclouages secondaires un taux moyen de complication septique de 9 % et de consolidation de 90 %. Sigurden et al [17], dans une étude expérimentale sur des rats observaient ainsi un meilleur cal dans le groupe encloué à 1 semaine versus les populations enclouées à 2 et 3 semaines. On peut également supposer que le bénéfice de l'enclouage sur la consolidation osseuse est corrélé à sa précocité.…”