Interfragmentäre Kompression bei der Humerusschaftnagelung mit einem speziellen Kompressionsgerät

Abstract

Unto now effective interfragmentary compression in the treatment of humeral shaft fractures was possible only for plate osteosynthesis. Creating compression through retraction of an intramedullary nail, that is already fixed by bolts at the nail tip, is not well controllable. Simple oblique or transverse fractures own a reduced bone healing capacity through little fracture fragment contact and minor resistance against rotational forces. In these cases interfragmentary compression is important to avoid late bone healing or non-unions. Being able to use the biologic advantages of intramedullary nailing compared to plating also in these cases, the unreamed humeral nail (UHN) offers through a compression device the possibility of interfragmentary compression. What are the biomechanical characteristics of such a system? Materials and methods: 7 fresh pairs of cadaveric humeri had been explanted and randomised stabilised with an UHN after mid-shaft osteotomy. Each pair contained one UHN with and one without interfragmentary compression. With mechanical testing devices the biomechanical characteristics had been measured under 4-point-bending and torsion. Results: In each bone pair a significant higher stiffness has been found for bending loading (a.p.: 7.68 Nm/° versus 3.88 Nm/°: m.l.: 6.63 Nm/° versus 5.04 nM/°) as well as for torsional loading (0.58 Nm/° versus 0.44 Nm/°) (p < 0.0001 each). Conclusion: Especially in transverse fractures of the humeral shaft interlocked nailing with interfragmentary compression offers higher stability and a better probability for uneventfull and rapid bone healing.