Berger Pieter, Shah Darshan S, Taylan Orçun, Slane Josh, De Corte Ronny, Scheys Lennart, Vandenneucker Hilde
Division of Orthopaedics, Department of Orthopaedics, University Hospitals Leuven, Herestraat 49, 3000, Leuven, Belgium.
Institute for Orthopaedic Research and Training (IORT), Department of Development and Regeneration, KU Leuven, 3000, Leuven, Belgium.
Arch Orthop Trauma Surg. 2023 Apr;143(4):2165-2173. doi: 10.1007/s00402-022-04534-x. Epub 2022 Jun 29.
Despite the existence of diverse total knee implant designs, few data is available on the relationship between the level of implant constraint and the postoperative joint stability in the frontal plane and strain in the collateral ligaments. The current study aimed to document this relation in an ex vivo setting.
Six fresh-frozen lower limbs underwent imaging for preparation of specimen-specific surgical guides. Specimens were dissected and assessed for joint laxity using the varus-valgus stress tests at fixed knee flexion angles. A handheld dynamometer applied tensile loads at the ankle, thereby resulting in a knee abduction-adduction moment of 10 Nm. Tibiofemoral kinematics were calculated using an optical motion capture system, while extensometers attached to medial collateral (MCL) and lateral collateral ligament (LCL) measured strain. Native joint testing was followed by four TKA designs from a single implant line-cruciate retaining, posterior stabilised, varus-valgus constrained and hinged knee (HK)-and subsequent testing after each implantation. Repeated measures linear mixed-models (p < 0.05) were used to compare preoperative vs. postoperative data on frontal plane laxity and collateral ligament strain.
Increasing implant constraint reduced frontal plane laxity across knee flexion, especially in deep flexion (r > 0.76), and MCL strain in extension; however, LCL strain reduction was not consistent. Frontal plane laxity increased with knee flexion angle, but similar trends were inconclusive for ligament strain. HK reduced joint laxity and ligament strain as compared to the native condition consistently across knee flexion angle, with significant reductions in flexion (p < 0.024) and extension (p < 0.001), respectively, thereby elucidating the implant design-induced joint stability. Ligament strain exhibited a strong positive correlation with varus-valgus alignment (r = 0.96), notwithstanding knee flexion angle or TKA implant design.
The study demonstrated that increasing the constraint of a TKA resulted in lower frontal plane laxity of the knee. With implant features impacting laxity in the coronal plane, consequentially affecting strain in collateral ligaments, surgeons must consider these factors when deciding a TKA implant, especially for primary TKA.
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尽管存在多种全膝关节置换植入物设计，但关于植入物限制程度与术后额状面关节稳定性及侧副韧带应变之间关系的数据却很少。本研究旨在在体外环境中记录这种关系。
对六个新鲜冷冻的下肢进行成像，以制备特定标本的手术导板。解剖标本并在固定的膝关节屈曲角度下使用内翻-外翻应力试验评估关节松弛度。手持测力计在踝关节处施加拉伸载荷，从而产生10牛米的膝关节外展-内收力矩。使用光学运动捕捉系统计算胫股关节运动学，同时附着在内侧副韧带（MCL）和外侧副韧带（LCL）上的引伸计测量应变。在进行天然关节测试后，使用来自单一植入物系列的四种全膝关节置换设计——保留交叉韧带型、后稳定型、内翻-外翻受限型和铰链膝关节（HK）——并在每次植入后进行后续测试。采用重复测量线性混合模型（p < 0.05）比较术前与术后额状面松弛度和侧副韧带应变的数据。
增加植入物限制可降低整个膝关节屈曲过程中的额状面松弛度，尤其是在深度屈曲时（r > 0.76），并降低伸直时的MCL应变；然而，LCL应变的降低并不一致。额状面松弛度随膝关节屈曲角度增加而增加，但韧带应变的类似趋势尚无定论。与天然状态相比，HK在整个膝关节屈曲角度下均持续降低关节松弛度和韧带应变，在屈曲（p < 0.024）和伸直（p < 0.001）时分别有显著降低，从而阐明了植入物设计引起的关节稳定性。无论膝关节屈曲角度或全膝关节置换植入物设计如何，韧带应变与内翻-外翻对线均呈强正相关（r = 0.96）。
该研究表明，增加全膝关节置换的限制会导致膝关节额状面松弛度降低。由于植入物特征会影响冠状面的松弛度，进而影响侧副韧带的应变，外科医生在决定全膝关节置换植入物时必须考虑这些因素，尤其是对于初次全膝关节置换。
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