Subtrochanteric femur fracture after slipped capital femoral epiphysis pinning: a novel treatment.

Slipped capital femoral epiphysis is a common injury suffered by adolescents worldwide. Treatment of most slips can be accomplished by percutaneous screw fixation, as this is an accepted and proven method associated with minimal morbidity. Complications, although limited, can be problematic for both the patient and treating physician. These include avascular necrosis, chondrolysis, infection, and fracture. We report a case of an individual who sustained a subtrochanteric femure fracture three weeks after in situ pinning of his left hip treated with a reconstruction intramedullary nail. This option allowed both the subtrochanteric fracture and SCFE to be treated concomitantly with minimized morbidity.

Mechanical testing of small fracture implants for comparison of insertion and failure torques.

INTRODUCTION: Small fracture screws are among the most commonly used implants in the field of orthopedic surgery. The goal of this study was to compare the insertion and failure torques of three screw types: cortical, partially threaded cancellous, and fully threaded cancellous from three manufacturers: Zimmer, Richards, and Synthes. MATERIALS AND METHODS: Each type of screw was subjected to biomechanical tests to determine the insertion ( n=6/group) and failure ( n=10/group) torques. RESULTS: Two-factor ANOVA tests were run to determine whether the insertion or failure torques were different for the different screw types and manufacturers. In the case of insertion torques, neither the screw nor the manufacturer had any significant effect. In the case of failure torque, significant differences were found based on both the screw type and the manufacturer, with the cortical screws manufactured by Zimmer being the strongest. Although there were strength differences, the most important comparison clinically is between the failure torque and the insertion torque of each screw. In all cases, the failure torques were approximately 20 times larger than the insertion torques, and therefore no failures should occur if only torsional loads are applied during insertion. This comparison shows that factors other than screw strength and manufacturing processes may be involved in cases of screw failure during insertion. CONCLUSION: All three screw types from all three manufacturers appear to be mechanically reliable, with the proper insertion to failure torque ratio. The surgeon's choice of implant should be based on other considerations.