Markolf Keith L, Zemanovic Jason R, McAllister David R
Department of Orthopaedic Surgery, University of California at Los Angeles 90095-6902, USA.
J Bone Joint Surg Am. 2002 Apr;84(4):518-24. doi: 10.2106/00004623-200204000-00002.
The optimal method of replacement of the posterior cruciate ligament with a bone-patellar tendon-bone graft is not known. The purpose of this study was to compare the mechanical responses to cyclic loading tests of bone-patellar tendon-bone allograft replacements fixed to the tibia with one of two methods: a tibial tunnel or a tibial inlay technique.
The proximal ends of sixty-two posterior cruciate graft replacements, thirty-one fixed with the tibial tunnel technique and thirty-one fixed with the tibial inlay technique in cadaver knees, were subjected to 2000 cycles of tensile force of 50 to 300 N with the angle of pull at 45 to the tibial plateau. The central 10 mm of the medial and lateral halves of previously fresh-frozen bone-patellar tendon-bone preparations from cadaver knees were used as the grafts. Two pairs of tibiae were used for testing; the two types of fixation and the medial and lateral halves of the patellar tendons were distributed between the tibial pairs. Graft thickness was measured at the point of highest anticipated tissue deformation and at two additional locations at distances from these points. The total change in graft length after cyclic loading at an applied force level of 200 N was recorded. Elongation of the graft during loading cycles between 20 and 200 N of applied tensile force was also measured. A repeated-measures analysis of variance was used to compare all measurements between the inlay and tunnel techniques, and between the medial and lateral halves of the graft used for the inlay method.
Ten of the thirty-one grafts that had been passed through a tibial tunnel failed at the acute angle before 2000 cycles of testing could be completed; all thirty-one grafts that had been fixed to the tibia with use of the inlay method survived the testing intact. Evaluation of the twenty-one graft pairs that survived testing after both fixation techniques revealed that the grafts that had been fixed with the inlay method had significantly less thinning at all three measurement sites at the completion of testing; the mean reduction of thickness was 40.6% (at the acute angle) in the grafts fixed with the tunnel method and 12.5% (adjacent to the bone block) in those fixed with the inlay method. After 2000 cycles, the mean lengths of the grafts fixed with the inlay and tunnel methods increased 5.9 and 9.8 mm, respectively; 38% of this increase occurred during the first six loading cycles. After both methods of fixation, the mean graft elongation during a loading cycle decreased approximately 50% from cycle 1 to cycle 2000, resulting in an effectively stiffer graft construct. There was no significant difference in any measured parameter between medial and lateral graft halves.
These tests showed that the inlay technique of posterior cruciate ligament replacement was superior to the tunnel technique with respect to graft failure, graft thinning, and permanent increase in graft length.
采用骨-髌腱-骨移植替代后交叉韧带的最佳方法尚不清楚。本研究的目的是比较采用两种方法之一固定于胫骨的骨-髌腱-骨同种异体移植替代物在循环加载试验中的力学反应：胫骨隧道技术或胫骨嵌体技术。
在尸体膝关节中，62个后交叉韧带移植替代物的近端，31个采用胫骨隧道技术固定，31个采用胫骨嵌体技术固定，以与胫骨平台呈45°的拉力角度施加50至300 N的拉力进行2000次循环。取自尸体膝关节的新鲜冷冻骨-髌腱-骨标本的内侧和外侧中央10 mm用作移植物。使用两对胫骨进行测试；两种固定类型以及髌腱的内侧和外侧部分分布在两对胫骨之间。在预期组织变形最大的点以及距这些点一定距离的另外两个位置测量移植物厚度。记录在200 N的施加力水平下循环加载后移植物长度的总变化。还测量了在20至200 N的施加拉力加载循环期间移植物的伸长。采用重复测量方差分析比较嵌体技术和隧道技术之间以及用于嵌体方法的移植物内侧和外侧部分之间的所有测量值。
31个通过胫骨隧道的移植物中有10个在完成2000次测试循环之前于锐角处失败；所有31个采用嵌体方法固定于胫骨的移植物在测试中均完整存活。对两种固定技术后均存活测试的21对移植物进行评估发现，采用嵌体方法固定的移植物在测试完成时在所有三个测量部位的变薄明显更少；采用隧道方法固定的移植物厚度平均减少40.6%（在锐角处），采用嵌体方法固定的移植物厚度平均减少12.5%（与骨块相邻处）。2000次循环后，采用嵌体和隧道方法固定的移植物平均长度分别增加5.9和9.8 mm；其中38%的增加发生在前六个加载循环期间。两种固定方法后，加载循环期间移植物的平均伸长从第1个循环到第2000个循环大约减少50%，从而形成有效更硬的移植物结构。移植物内侧和外侧部分之间的任何测量参数均无显著差异。
这些测试表明后交叉韧带替代的嵌体技术在移植物失败、移植物变薄和移植物长度永久性增加方面优于隧道技术。
