Smith Lauren A, LaCour Michael T, Cates Harold E, Komistek Richard D
Center for Musculoskeletal Research, University of Tennessee-Knoxville, Knoxville, Tennessee.
Tennessee Orthopaedic Clinics, Knoxville, Tennessee.
J Arthroplasty. 2025 Apr;40(4):1074-1082. doi: 10.1016/j.arth.2024.10.054. Epub 2024 Oct 18.
The non-implanted knee differs in comparison to total knee arthroplasty (TKA) designs, with regard to asymmetry and functionality of the anterior cruciate ligament and the posterior cruciate ligament. While surgeons may choose to implant either posterior stabilized (PS) or bi-cruciate stabilized (BCS) TKAs, substituting for one or both cruciate ligaments, the effects of symmetry versus asymmetry in substituting TKA designs have not been widely analyzed to determine possible benefits. Therefore, the objective of this research study was to determine if either TKA asymmetry and/or anterior ligament stabilization can lead to more normal-like kinematics and clinical benefit for patients.
In vivo, femoro-tibial kinematics for 64 subjects were evaluated in this retrospective study. Overall, 10 subjects had a normal, nonimplanted knee, 20 had a BCS TKA, and 34 had one of two different PS TKAs. All three TKAs had varying degrees of symmetry incorporated into the design, and all were implanted by the same surgeon and were analyzed using fluoroscopy during a deep knee bend.
At full extension, the BCS TKA subjects demonstrated a statistically more anterior position of both condyles compared to both PS TKAs. The BCS TKA subjects also experienced more posterior femoral rollback (PFR) and axial rotation in early flexion and from full extension to maximum knee flexion. Additionally, the TKAs in this study having asymmetry experienced greater amounts of PFR and weight-bearing knee flexion.
The results from this study indicated that in early flexion, the anterior cam/post mechanism does pull the femoral component more anterior, and all TKAs experienced PFR when the posterior cam engaged the post. The asymmetric designs also achieved greater rollback and axial rotation compared to the symmetric designs.
与全膝关节置换术（TKA）设计相比，未植入假体的膝关节在前交叉韧带和后交叉韧带的不对称性和功能方面存在差异。虽然外科医生可以选择植入后稳定型（PS）或双交叉韧带稳定型（BCS）TKA，以替代一条或两条交叉韧带，但在替代TKA设计中对称与不对称的影响尚未得到广泛分析以确定可能的益处。因此，本研究的目的是确定TKA不对称和/或前韧带稳定是否能为患者带来更接近正常的运动学表现和临床益处。
在这项回顾性研究中，对64名受试者的体内股骨 - 胫骨运动学进行了评估。总体而言，10名受试者有正常的未植入假体的膝关节，20名有BCS TKA，34名有两种不同PS TKA中的一种。所有三种TKA在设计中都融入了不同程度的对称性，并且均由同一位外科医生植入，并在深屈膝时使用荧光透视进行分析。
在完全伸展时，与两种PS TKA相比，BCS TKA受试者的两个髁在统计学上显示出更靠前的位置。BCS TKA受试者在早期屈曲以及从完全伸展到最大屈膝过程中也经历了更多的股骨后滚（PFR）和轴向旋转。此外，本研究中具有不对称性的TKA经历了更大程度的PFR和负重屈膝。
本研究结果表明，在早期屈曲时，前凸轮/后机制确实会将股骨组件拉得更靠前，并且当后凸轮与后部件接合时，所有TKA都会经历PFR。与对称设计相比，不对称设计还实现了更大的后滚和轴向旋转。
