Long-term residual musculoskeletal deficits after femoral shaft fractures treated with intramedullary nailing

Background: Locked intramedullary (IM) nailing has been recognized as one o f the most reliable methods for treatment of femoral shaft fractures, Altho ugh IM nails are routinely used in the treatment of these fractures, the lo ng-term effects of retained IM nails are unknown. Methods: seventeen patients with radiographically documented healed fractur e of femoral diaphysis after locked IM nailing technique were evaluated at a follow-up of at least 18 months postoperatively, All patients had returne d to their preinjury level of function and activity before the study, The b one mineral densities (EMD) of the injured and contralateral femora were me asured using dual energy x-ray absorptiometry (DEXA), BMD of symmetrical re gions in the femoral neck and medial and lateral Femoral cortex of the impl anted and contralateral femorawere compared. Postinjury muscle function was assessed from measurement of the isometric strength of six separate muscle groups (quadriceps, hamstrings, hip extensors, hip flexors, hip abductors, and hip adductors) in treated and control extremities, Results: The average BMD of the femoral neck region of instrumented femora was 9% less than in contralateral control. Within the medial cortex, BMD of the control femora was an average of 20% greater than in the implanted sid e. In the lateral cortex, the difference averaged 13%, The isometric dynamo metric data demonstrated a statistically significant reduction in the stren gth of the quadriceps of the instrumented extremities as compared with the contralateral ones, There was no significant difference in the strength of the hamstrings, hip extensors, hip flexors, abductors, or adductors, In the control extremities, the average torque generated by isometric contraction of the quadriceps was 3.45 +/- 1.35 times greater than by the hamstrings. Torque in extension/flexion and abduction/adduction was also observed, Conclusion: Our data suggest that limbs with long-term retained IM nails ex perience a significant reduction in the femur BMD and quadriceps muscle str ength. These findings may not be simply related to the implant, and further study is warranted to determine the causes of these changes.