Scientific Evaluation of a New Alignment Method for Total Knee Arthroplasty

PI: Hull, Maury l .提案号：1067527目标和目的：拟议研究的总体目的是通过体外测试来确定运动学对齐是否比传统的机械对齐方法更好地提供膝关节功能，运动学对齐是一种有争议的全膝关节置换术（TKA）中对齐部件的新方法。两种对齐方法将通过确定哪一种更好地恢复胫骨股骨关节的运动轴正常，运动的被动包络正常，更均匀地平衡和集中胫骨部件上的内侧和外侧接触力来评估。这四大类因变量是膝关节功能的重要决定因素，必须在体外进行测试，因为在体内使用这种复杂程度的仪器是不可能的。拟议的研究将测试以下四个假设：1)与机械对齐的TKA相比，运动学对齐的TKA恢复了股骨横轴的位置和方向，胫骨的弯曲和伸展是围绕股骨横轴进行的，胫骨的纵向旋转轴是围绕胫骨的内外旋转更接近正常的。2)与机械对齐TKA相比，运动学对齐TKA恢复了屈伸、内翻、内外旋转和前后平移被动运动包膜的中性和双向限制，更接近正常。3)运动对齐TKA比机械对齐TKA更能平衡内侧和外侧室的接触力。4)与机械对齐的TKA相比，运动对齐的TKA能更好地集中内侧和外侧隔室的接触力。我们的研究小组有独特的能力进行这些研究，因为我们开发了一种确定运动轴的新方法，我们有使用定制的六自由度负载应用膝关节测试系统的经验，我们在运动学和机械对齐tka方面有广泛的开发和临床经验。知识价值：调整TKA的方法是患者和外科医生非常感兴趣的，因为调整决定了膝关节的运动、稳定性、疼痛缓解、患者满意度、耐久性和修复率。机械对齐TKA，努力实现0°机械轴，具有良好的长期耐久性，但一些研究表明，20-25%的患者由于持续不明原因的疼痛、僵硬和不稳定而不满意。结果不尽如人意的一个原因是将肢体对准0º机械轴改变了膝关节的运动学。运动学的改变需要韧带释放来恢复运动，这可能导致不稳定。运动学对齐是一种有争议但令人兴奋的新方法，它致力于恢复膝关节的运动学正常，在这种情况下不需要韧带释放。与机械对齐TKA相比，运动学对齐TKA提高了患者满意度，缩短了手术时间，减少了输血，加快了恢复。运动轴、被动运动包络和接触力的体外评估将为不同方法的临床结果差异提供可量化的解释。更广泛的影响：全膝关节置换术（TKA）是一种外科手术，用于减轻疼痛，恢复关节功能，改善膝关节骨关节炎（OA）患者的生活质量。2006年，美国进行了54.2万例TKA手术，预计到2030年，每年将进行348万例TKA手术。由于20-25%的患者不满意[5,45]，因此需要改善临床结果，并需要减少与翻修手术相关的发病率和费用。如果提出的体外尸体研究确定运动学对齐的TKA能更好地恢复股骨横轴、被动运动包络、接触力分布，并更好地将接触力集中，那么这种对齐技术在体内的应用将进一步得到证明。运动学TKA的广泛应用可能会改善临床结果，降低翻修率，并减少数千万将在未来二十年接受TKA的患者的社会和医疗费用。

PI: Hull, Maury L.Proposal Number: 1067527Goals and Objectives: The general aim of the proposed research is to use in vitro testing to determine whether kinematic alignment, which is a controversial new method of aligning components in total knee arthroplasty (TKA), gives better knee function than mechanical alignment, which is the traditional method of alignment. The two alignment methods will be assessed by determining which better restores the kinematic axes of the tibiofemoral joint to normal, the passive envelopes of motion to normal, more evenly balances and centers the medial and lateral contact forces on the tibial component. These four general categories of dependent variables are important determinates of knee function, which must be tested in vitro because the use of instrumentation with this level of sophistication in vivo is not possible. The proposed research will test the following four hypotheses: 1) Kinematically aligned TKA restores the position and orientation of both the transverse axis in the femur about which the tibia flexes and extends and the longitudinal rotational axis in the tibia about which the tibia internally and externally rotates closer to normal than mechanically aligned TKA. 2) Kinematically aligned TKA restores the neutral and bidirectional limits of the passive envelopes of motion of flexion-extension, varus-valgus, and internal-external rotations and anterior-posterior translation closer to normal than mechanically aligned TKA. 3) Kinematically aligned TKA better balances the contact forces in the medial and lateral compartments than mechanically aligned TKA. 4) Kinematically aligned TKA better centers the contact forces in the medial and lateral compartments than mechanically aligned TKA. Our research group is uniquely able to perform these studies because we have developed a new method for determining the axes of motion, we have experience using our custom built six degree-of-freedom load application knee testing system, and we have extensive developmental and clinical experience with kinematically and mechanically aligned TKAs. Intellectual Merit: The method of aligning a TKA is of keen interest to the patient and surgeon because alignment determines knee motion, stability, pain relief, patient satisfaction, durability, and revision rate. Mechanically aligned TKA, which strives to achieve a 0° mechanical axis, has good long-term durability, but several studies have shown that 20-25% of patients are less than satisfied due to persistent unexplained pain, stiffness, and instability. One reason for the less than satisfied outcome is that aligning the limb to a 0º mechanical axis changes the kinematics of the knee. The change in kinematics requires ligament releases to restore motion, which can cause instability. Kinematic alignment is a controversial but exciting new method that strives to restore the kinematics of the knee to normal in which case ligament releases are not required. Kinematically aligned TKA has increased patient satisfaction, shortened surgery, reduced transfusions, and quickened recovery compared to mechanically aligned TKA. The in vitro assessment of axes of motion, passive envelopes of motion, and contact forces will provide quantifiable explanations for the differences in clinical results between methods. Broader Impact: Total knee arthroplasty (TKA) is a surgical procedure used to reduce pain, restore joint function, and improve the quality of life of patients suffering from osteoarthritis (OA) of the knee. In 2006, 542,000 TKA procedures were performed in the US, and it has been projected that by 2030, 3.48 million TKA procedures will be performed annually. Because 20-25% of patients are less than satisfied [5, 45], there is a need to improve the clinical outcome and a need to reduce the morbidity and expense associated with revision surgery. If the proposed in vitro cadaveric study determines that kinematically aligned TKA better restores the transverse axis in the femur, passive envelopes of motion, distribution of contact forces, and better centers the contact forces, then the use of this alignment technique in vivo would be further justified. The broad impact of the increased use of kinematically TKA would likely translate into improved clinical outcome, a reduction in the revision rate, and reduction in the social and medical costs for the tens of millions of patients that will undergo TKA in the next two decades.