Modification of ESIN-osteosynthesis in a Femoral Fracture Model and Its Transmission to Clinical Practice

Elastic stable intramedullary nailing (ESIN) is the standard treatment for displaced diaphyseal femoral fractures in children. However, some literature report high complication rates (10-50%) in complex fractures. Data of our own patients with special emphasis on complications showed also mediocre results. Thus, a biomechanical study was conducted to search for modifications. In this study the stiffness with a 3rd nail implanted was compared to the classical 2 C-shaped configuration. For each of the 3 configurations of retrograde ESIN (titanium nails) eight composite femoral grafts (Sawbones®) with an identical spiral fracture were used: 2C configuration (2 C-shaped nails, 2x3.5 mm), 3CM configuration (3rd from antero-medial, + 1x2.5 mm) and 3CL configuration (3rd from antero-lateral, + 1x2.5 mm). Each group underwent biomechanical testing in 4-point bending, IRO/ERO and axial compression (0°/9°). Due to a significantly higher stiffness of 3CL in the anterior-posterior, internal rotation and 9° compression directions implantation of 3 nails became standard treatment for all dislocated femoral fractures at our department.

All patients were followed prospectively. The following data was collected: Type of osteosynthesis, any kind of complication (additional procedures like cast or external fixateur, Re-Do operations, misalignment, pseudarthrosis, skin irritation, infection), time until full weight bearing and time until implant removal. At follow-up the legs were controlled for a possible length discrepancy and a possible deviation of axis. Patients' satisfaction was controlled by CSQ (clients satisfaction score, Larsen et al 2002). Further on the Harris Hip Score was used. X-ray controls were done as standard care protocol after 1 and 3-4 months (dependend on age).

Level of Evidence IV Keywords: Elastic stable intramedullary nailing, biomechanical testing, fracture, femur, treatment, children, adolescents.