Augat Peter, Penzkofer Rainer, Nolte Alexander, Maier Michael, Panzer Stefanie, v Oldenburg Geert, Pueschl Klaus, Simon Ulrich, Bühren Volker
Biomechanics Research Laboratory, Paracelsus Medical University, Salzburg, Austria. biomechanik@bgu
J Orthop Trauma. 2008 Jan;22(1):30-6. doi: 10.1097/BOT.0b013e31816073cb.
Biomechanical study on cadaveric bones using physiological loading conditions to quantify interfragmentary movements in a tibial shaft fracture model fixed by intramedullary nailing.
Six fresh frozen human cadaveric tibiae were sequentially tested in axial, torsional, 4-point bending, and shear loading configurations. Tests were performed in intact specimens and osteotomized specimens equipped with interlocked intramedullary nails. The amount of clearance of the nail within the intramedullary canal was measured on computed tomography scans. Linear and angular deformations of the fragments were continuously measured in all directions to obtain the exact interfragmentary movements.
The amount of movement at the site of the fracture was substantial. Especially shear and torsion resulted in gap movements of up to 10 mm. Movements in the transverse plane were significantly larger than axial movements for all loading conditions. For torsion and bending, a significant portion of the movement of the fracture gap resulted from the flexibility of the intramedullary nail; for compression and shear, the majority of the movement was related to the clearance of the nail within the bone.
Clearance of the implant within the medullary canal, the flexibility of the implant itself, and the compliance of the implant (nail and locking screws) within the bone determine the extent of movement. The implant flexibility and the clearance are strongly dependent on the thickness of the intramedullary nail.
利用生理负荷条件对尸体骨骼进行生物力学研究，以量化髓内钉固定的胫骨干骨折模型中的骨折块间运动。
对六具新鲜冷冻的人体尸体胫骨依次进行轴向、扭转、四点弯曲和剪切负荷配置测试。测试在完整标本和配备锁定髓内钉的截骨标本上进行。通过计算机断层扫描测量髓内钉在髓腔内的间隙量。连续测量骨折块在各个方向上的线性和角变形，以获得精确的骨折块间运动。
骨折部位的运动量很大。特别是剪切和扭转导致间隙运动高达10毫米。在所有负荷条件下，横向平面内的运动明显大于轴向运动。对于扭转和弯曲，骨折间隙运动的很大一部分是由髓内钉的柔韧性引起的；对于压缩和剪切，大部分运动与钉在骨内的间隙有关。
植入物在髓腔内的间隙、植入物本身的柔韧性以及植入物（钉和锁定螺钉）在骨内的顺应性决定了运动程度。植入物的柔韧性和间隙强烈依赖于髓内钉的厚度。
