Intramedullary Osteosynthesis of Metadiaphyseal Proximal Tibial Fractures: An Optimized Implant Geometry Can Help to Solve the Problem

Abstract

Aim: The surgical treatment of proximal tibial fractures by means of intramedullary nailing was considered as clinically critical and biomechanically unsatisfactory. A solution for the treatment of these fractures was intended by optimizing the geometry of a newly developed Proximal Tibial Nail (PTN). Material and Methods: After analysis of mechanisms and causes of failures of osteosyntheses of proximal tibial fractures, new nail geometries were developed and their specific performance analysed. The optimised new PTN was implanted in 43 patients with a proximal or a combined proximal and shaft fracture of the tibia in a prospective documentation series. The complete clinical and radiological data of all patients was collected. A biomechanical comparative study between PTN and conventional osteosyntheses (Double Plate Osteosynthesis=DPO and External Fixator=EF) was performed. Results: During the whole documentation phase no implant related complication led to operative revision. One deep wound infection after treatment of a II° open fracture occurred. Sequential revisions and exchanging of the nail to another PTN had to be performed. Secondary displacement of the proximal fracture fragment was seen in one case and breakage of the proximal locking screws after early postoperative full weight bearing in another. For the axial loading, the values for the PTN and DPO were 372 N/mm and 155 N/mm at 350 N. This was much higher than that of ExFix compared to PTN with 64 N/mm and 421 N/mm respectively. Conclusion: The new PTN makes a stable fixation of proximal tibia fractures possible which is superior to DPO and EF for the relevant axial loading condition. The proven biomechanical superiority of intramedullary nailing in shaft fractures can also be used in proximal tibial fractures. The clinical results are promising but require further prospective evaluation.

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