The ideal timing for nail dynamization in femoral shaft delayed union and non-union

Nail dynamization is one of the proposed surgical options to manage femoral shaft non-union. This study aims to assess the efficacy and the ideal timing for dynamization in patients with femoral shaft delayed union or non-union.

Sixty-eight patients (38 male and 30 female, mean age 36.85 years old, range 22-58) were recruited. The patients were divided into three groups according to the fracture healing time: groupa A, fracture healing occurred within nine months; group B, fracture healing occurred between nine and 12 months; and group C, fracture healing after 12 months or secondary procedure needed for union. Callus-to-diaphysis ratio was calculated on femur X-rays at the time of dynamization.

In 30 patients out of 68, the fracture healing was observed at nine month follow-up; in 26 patients, the fracture healed within 12 months; eight fractures healed in more than 12 months and only four fractures required a secondary procedure for union. Dynamization was successful in 64 patients out of 68 (94.12%). The mean callus-diaphysis ratio was significantly different in group A (p = 0.001) and in group B (p = 0.03), compared with group C. The timing of dynamization resulted significantly different between the three groups. Linear regression analysis revealed that nail dynamization should be performed between three and six months after trauma. The optimal callus-to-diaphysis ratio should be comprised between 1.47 and 1.19, at the time of dynamization.

Nail dynamization revealed safe and effective in the treatment of femoral delayed union and non-union. It should be considered as a first-line treatment for femoral non-union or delayed union.