Markolf K L, Willems M J, Jackson S R, Finerman G A
Department of Orthopaedic Surgery, University of California at Los Angeles, USA.
J Orthop Res. 1998 Jul;16(4):464-71. doi: 10.1002/jor.1100160411.
The arthroscopically implantable force probe transducer, which measures the effects of local ligament fiber tension, was inserted into the anteromedial band of the anterior cruciate ligament after measurements with the differential variable reluctance transducer were completed in Part I of this study. The overall goals in Part II remained the same, with additional experiments included to determine the sensitivity of output voltage from the transducer to medial-lateral placement of the device within the anteromedial band and to depth of placement within a given insertion hole. Calibration curves of output voltage from the arthroscopically implantable force probe transducer versus resultant force in the ligament were generated during a separate series of knee-loading experiments identical to those performed in Part I. The output voltage for a given probe placement was highly sensitive to the depth of implantation into the anteromedial band. When the probe was completely buried within the ligament, voltage outputs were often sporadic or absent even though surface fibers had clearly developed tension. When the probe was only partially inserted into the hole, such that the end of the probe was slightly proud to the surface, voltage output was significantly higher as the device measured tension in the superficial fibers. Voltage outputs for proud placement were always significantly higher than corresponding voltages for deep placements for all test conditions. With proud placements, voltage outputs were not sensitive to small deviations in medial-lateral position within the anteromedial band. Mean coefficients of variation for output voltage (four repeated placements of the probe into the same central hole) ranged from 0.156 to 0.359 (deep and proud insertions). Output voltage from the probe generally followed the pattern of resultant force in the ligament during passive knee extension. For anterior tibial loading, the contribution of deep fibers to resultant force did not depend on the knee flexion angle at which the test was conducted; the contribution of superficial fibers was greatest beyond 45 degrees of flexion and least at full extension. The contributions of the anteromedial band to resultant force in the ligament were not significantly different between the three modes of loading (anterior tibial force, internal tibia torque, and varus moment) at either 0 or 10 degrees of flexion; this was true for both superficial and deep fibers. We found it necessary to secure the probe within the insertion site using a suture (for both deep and proud placements) to obtain repeatable readings. Puncturing the anteromedial band clearly produced tissue damage; the insertion hole often produced a permanent plane of cleavage in the anteromedial band. However, this tissue damage did not alter the overall ability of the ligament to generate resultant force.
在本研究的第一部分使用差动可变磁阻传感器完成测量后，将用于测量局部韧带纤维张力影响的关节镜可植入式力探针换能器插入前交叉韧带的前内侧束。第二部分的总体目标保持不变，增加了一些实验，以确定换能器输出电压对该装置在前内侧束内的内外侧位置以及在给定插入孔内的插入深度的敏感性。在与第一部分进行的相同的一系列单独的膝关节加载实验中，生成了关节镜可植入式力探针换能器的输出电压与韧带合力的校准曲线。对于给定的探针放置，输出电压对植入前内侧束的深度高度敏感。当探针完全埋入韧带内时，即使表面纤维明显产生了张力，电压输出也常常是零星的或没有输出。当探针仅部分插入孔中，使得探针末端略高于表面时，由于该装置测量了浅层纤维中的张力，电压输出显著更高。在所有测试条件下，高于表面放置的电压输出总是显著高于相应的深层放置的电压。对于高于表面放置，电压输出对前内侧束内的内外侧位置的小偏差不敏感。输出电压的平均变异系数（将探针四次重复放置到同一个中心孔中）范围为0.156至0.359（深层和高于表面插入）。在被动膝关节伸展过程中，探针的输出电压通常遵循韧带合力的模式。对于胫骨前负荷，深层纤维对合力的贡献不取决于进行测试时的膝关节屈曲角度；浅层纤维的贡献在屈曲超过45度时最大，在完全伸展时最小。在0度或10度屈曲时，前内侧束对韧带合力的贡献在三种加载模式（胫骨前力、胫骨内扭矩和内翻力矩）之间没有显著差异；浅层和深层纤维都是如此。我们发现有必要使用缝线将探针固定在插入部位（对于深层和高于表面放置）以获得可重复的读数。穿刺前内侧束显然会造成组织损伤；插入孔常常在前内侧束中产生一个永久性的裂开平面。然而，这种组织损伤并没有改变韧带产生合力的整体能力。
