[Gamma nail osteosynthesis of per- and subtrochanteric femoral fractures. 4 years experiences and their consequences for further implant development].

The Gamma nail can be used in all types of per- and subtrochanteric fractures because of its biomechanical characteristics. In this prospective evaluation of our 330 patients treated between November 1989 and November 1993 the usefulness of the Gamma nail for the osteosynthesis of all types of fracture was evaluated. The rate of intraoperative and postoperative complications but also gait function, postoperative weight bearing, general complications, and survival were analysed. We compared the results of four therapy periods to evaluate the importance of the expertise of the surgeon and the 'learning curve'. The Gamma nail osteosynthesis was performed in 72-98% in unstable per- and subtrochanteric fractures. The nail diameters used shifted to the 12 mm nail (99%) and the 130 degrees angle (93%) in the fourth examination period. The intraoperative complication rate is highly dependent from the expertise of the surgeon and the experience with the system. The rate decreased from 42.2% in the first to 17.2% in the fourth examination period. The most important complications were: additional fractures (1.7%), distal locking screw problems (7%), femoral head rotation (2,4%), and not sufficient fracture reduction (4.1%). Whereas in general these did not influence the postoperative management the use of a too short femoral neck screw lead to instability. Postoperative local complications were: rotation of the femoral head and neck (0.6-5.5%), related to the gliding of the neck screw (0.6-4%), fracture at the end of the nail (1.8-4%), fatigue break of the nail (1 case) and hematoma (1.2-8.3%). In all these cases reoperation was needed. To reduce the rate of intra- and postoperative complications a new gliding nail (GN) is presented. Due to the double T-profile of the femoral neck blade the implant is stable for neck rotation. The blade has a collar which makes it impossible to implant the blade to deep in the femoral neck. The larger nail profile at the femoral neck perforation reduces the risk of implant failure. The implant can be used as dynamic compression as well as static implant both in the direction of femoral neck and shaft.