Pape Dietrich, Duchow Jochen, Rupp Stefan, Seil Romain, Kohn Dieter
Department of Orthopaedic Surgery, University of Saarland, Kirrbergerstrasse, 66421 Homburg/Saar, Germany.
Knee Surg Sports Traumatol Arthrosc. 2006 Feb;14(2):141-8. doi: 10.1007/s00167-005-0649-2. Epub 2005 May 14.
To perform an open-wedge high-tibial osteotomy (HTO), the medial proximal tibia is frequently exposed by partial distal release of the overlying insertion of the medial collateral ligament (MCL). Biomechanically, any release of the MCL can increase knee laxity when valgus stress is applied. Clinically however, post-surgical valgus instability following HTO with partial MCL release is an uncommon complication. It is known that the open-wedge procedure can re-tention an intact MCL by the width of the base of the wedge. However, this re-tentioning effect is uncertain in small wedge sizes, preexisting medial compartment laxity and in the presence of a partially detached MCL. Considering the good clinical results after HTO, we hypothesized that a partial release of the superficial MCL for HTO does not play a crucial role in stabilizing valgus forces in the human knee. We therefore measured the effect of partial versus complete release of the superficial MCL to determine medial knee laxity represented by the amount of medial joint opening (MJO) under valgus stress in this human cadaver study. In ten knee pairs, the superficial and deep MCL were sectioned in sequence with a standardized abduction force of 15 kp with a Scheuba apparatus applied. In group 1 (5 knee pairs), the superficial MCL was completely sectioned whereas in group 2 (5 knee pairs), sectioning of the superficial MCL was restricted to the anterior border to mimic the surgical exposure for an HTO. To account for the interindividual variability of ligamentous laxity, only increments of MJO within knee pairs were statistically evaluated. Stress radiography did not reveal any significant differences in increments of MJO between knee pair specimens with complete versus partial release of the superficial MCL. We disproved our hypothesis and concluded that the anterior fibers of the superficial MCL do play a crucial role in maintaining valgus stability in this biomechanical setting. Therefore, the release of the superficial MCL for open-wedge HTO should be kept to a minimum to decrease the potential of late valgus instability. This is especially important in patients with small wedge sizes and medial compartment laxity since the anterior MCL fibers are the main contributor to medial joint stability and the re-tentioning effect of the remaining MCL fibers is presumably decreased.
为了进行开放性楔形高位胫骨截骨术（HTO），常通过部分松解内侧副韧带（MCL）在上胫腓关节处的附着来暴露胫骨近端内侧。从生物力学角度来看，在施加外翻应力时，任何对MCL的松解都会增加膝关节的松弛度。然而在临床上，HTO术后伴部分MCL松解的外翻不稳定是一种不常见的并发症。已知开放性楔形手术可以通过楔形基底的宽度使MCL保持完整。然而，在小楔形尺寸、术前内侧间室松弛以及存在部分分离的MCL的情况下，这种保持作用尚不确定。考虑到HTO术后良好的临床效果，我们推测HTO时部分松解浅层MCL在稳定人体膝关节外翻力方面并非起关键作用。因此，在这项人体尸体研究中，我们测量了部分与完全松解浅层MCL对以内侧关节开口（MJO）量表示的膝关节内侧松弛度的影响，该开口量是在外翻应力下测得的。在十对膝关节中，使用Scheuba器械以15kp的标准化外展力依次切断浅层和深层MCL。在第1组（5对膝关节）中，浅层MCL被完全切断，而在第2组（5对膝关节）中，浅层MCL的切断仅限于前缘，以模拟HTO的手术暴露。为了考虑韧带松弛度的个体间差异，仅对膝关节对之间MJO的增量进行统计学评估。应力X线摄影未显示浅层MCL完全与部分松解的膝关节对标本之间MJO增量有任何显著差异。我们推翻了我们的假设，并得出结论，在这种生物力学环境下，浅层MCL的前部纤维在维持外翻稳定性方面确实起关键作用。因此，开放性楔形HTO时浅层MCL的松解应保持在最低限度，以降低晚期外翻不稳定的可能性。这在小楔形尺寸和内侧间室松弛的患者中尤为重要，因为MCL前部纤维是内侧关节稳定性的主要贡献者，而其余MCL纤维的保持作用可能会降低。
