Teubner E
Chirurg. 1985 Jul;56(7):454-60.
By mechanical definition an intramedullary nail is not a nail but rather a bendable feather, subject to longitudinal tension and to a lesser degree to transverse pressure. Reaming the medullary canal is necessary for centralization of the nail as well as to increase the area of contact with the bone. However, this procedure is detrimental to the bone metabolism and reduces its elasticity against torsional forces. The dynamic locking nail-system is more biologic than conventional nailing and it reduces rotatory instability with the help of additional components, such as transverse screws. Only static locking allows true static weight bearing with crutches, but not dynamic mobilisation. Nails with conventional strength and in leaf of trefoil formation are superior to other designs. However, an improved angle in the proximal locking is suggested, as this would allow for a three to four times greater weight bearing.
从力学定义上讲，髓内钉并非钉子，而是一根可弯曲的羽毛，承受纵向拉力，在较小程度上承受横向压力。扩髓对于髓内钉的居中以及增加与骨的接触面积是必要的。然而，该操作对骨代谢有害，并降低其抗扭力的弹性。动力锁定钉系统比传统钉更具生物性，它借助额外部件（如横向螺钉）减少旋转不稳定性。只有静态锁定允许使用拐杖进行真正的静态负重，但不允许动态活动。具有传统强度且呈三叶形的髓内钉优于其他设计。然而，建议改进近端锁定角度，因为这样可使负重能力提高三到四倍。
