Werner C M L, Jacob H A C, Ramseier L E, Favre P, Exner G U
Department of Orthopaedics, University of Zurich, Switzerland.
J Orthop Res. 2005 Sep;23(5):1065-72. doi: 10.1016/j.orthres.2004.12.013.
Extensively porous coated segmental replacement prostheses with intramedullary cementless fixation to bone over the whole length of stem often exhibit resorption of the surrounding bone due to stress-shielding. This makes them particularly susceptible to aseptic loosening.
A finite element analysis of the state of loading of a short-length fixation in a new prosthetic stem design has shown a definite advantage over long-length fixation. The stress pattern within the bone surrounding the prosthesis confirmed that shortening of the ongrowth area in length increases the stress values at the resection level significantly. This stem (Endlock) has been used for diaphyseal anchorage in the treatment of tumors in combination with an artificial joint of proven design in order to reduce stress shielding.
No Endlock stem fractures or aseptic loosenings were observed at recent follow-up. The early clinical results comply with the theoretical assumptions.
A short-length fixation system based on intramedullary anchorage of segmental replacement endoprostheses would possibly support physiologic adaptive processes more than fixation over the full length of the stem.
具有髓内非骨水泥固定且在柄的整个长度上与骨结合的广泛多孔涂层节段性置换假体，由于应力遮挡，常常表现出周围骨的吸收。这使得它们特别容易发生无菌性松动。
对一种新型假体柄设计中的短长度固定加载状态进行的有限元分析表明，其相对于长长度固定具有明显优势。假体周围骨内的应力模式证实，生长区域长度的缩短会显著增加切除水平处的应力值。这种柄（Endlock）已用于骨干固定，与经过验证设计的人工关节联合用于治疗肿瘤，以减少应力遮挡。
在最近的随访中未观察到Endlock柄骨折或无菌性松动。早期临床结果符合理论假设。
基于节段性置换内置假体髓内锚固的短长度固定系统可能比柄的全长固定更能支持生理适应性过程。
