Zlowodzki Michael, Williamson Scott, Cole Peter A, Zardiackas Lyle D, Kregor Philip J
Department of Orthopedic Surgery, University of Minnesota, Regions Hospital, St. Paul, MN, USA.
J Orthop Trauma. 2004 Sep;18(8):494-502. doi: 10.1097/00005131-200409000-00004.
To evaluate the stability of the retrograde intramedullary nail (IMN), angled blade plate (ABP), and a locked internal fixator (Less Invasive Stabilization System [LISS], Synthes, Paoli, PA) for internal fixation of distal femur fractures.
Destructive biomechanical testing of matched pairs of fresh-frozen human cadaveric bone-implant constructs.
Biomechanical laboratory.
A fracture model was created to simulate an AO/OTA33-A3 fracture. Forty-eight matched pairs of specimens were used. Six groups of 8 pairs each were tested to failure: LISS versus ABP and LISS versus IMN (axial, torsional, and cyclical axial).
Load to failure, mode of failure, energy to failure, displacement at the load to failure, and stiffness.
Fixation strength (load/moment to failure) of the LISS constructs was 34% greater in axial loading (P = 0.01) and 32% less in torsional loading (P = 0.05) compared with ABP constructs and 13% greater in axial loading (P = 0.35) and 45% less in torsional loading (P < 0.01) compared with IMN constructs. Loss of distal fixation in axial loading occurred in 1 of 16 cases with the LISS, in 3 of 8 cases with the ABP, and in 8 of 8 cases with the IMN. Cyclical axial loading demonstrated significantly less plastic deformation for the LISS construct compared with ABP constructs (P < 0.01) and similar plastic deformation compared with IMN constructs (P = 0.98).
All 3 fixation devices (LISS, ABP, and IMN) offer sufficient torsional stability and sufficient proximal fixation that withstands axial loading without failing. The LISS provides improved distal fixation, especially in osteoporotic bone, at the expense of more displacement at the fracture site.
评估逆行髓内钉（IMN）、角钢板（ABP）和锁定内固定器（微创稳定系统[LISS]，辛迪思公司，宾夕法尼亚州波利）用于股骨远端骨折内固定的稳定性。
对新鲜冷冻的人尸体骨植入物配对构建体进行破坏性生物力学测试。
生物力学实验室。
创建骨折模型以模拟AO/OTA 33 - A3骨折。使用48对配对标本。将其分为六组，每组8对，测试至失效：LISS与ABP对比以及LISS与IMN对比（轴向、扭转和周期性轴向）。
失效载荷、失效模式、失效能量、失效载荷下的位移和刚度。
与ABP构建体相比，LISS构建体在轴向加载时的固定强度（失效载荷/力矩）高34%（P = 0.01），在扭转加载时低32%（P = 0.05）；与IMN构建体相比，LISS构建体在轴向加载时高13%（P = 0.35），在扭转加载时低45%（P < 0.01）。在轴向加载中，LISS的16例中有1例出现远端固定丧失，ABP的8例中有3例，IMN的8例中有8例。周期性轴向加载显示，与ABP构建体相比，LISS构建体的塑性变形明显更小（P < 0.01），与IMN构建体相比，塑性变形相似（P = 0.98）。
所有三种固定装置（LISS、ABP和IMN）都具有足够的扭转稳定性和近端固定能力，能够承受轴向加载而不失效。LISS提供了更好的远端固定，尤其是在骨质疏松性骨中，但代价是骨折部位的位移更大。
