Center for Orthopedic Biomechanics, University of Denver, Denver, CO 80208, USA.
J Biomech. 2013 May 31;46(9):1568-75. doi: 10.1016/j.jbiomech.2013.03.016. Epub 2013 Apr 26.
Patellar resection thickness during total knee replacement (TKR) has been cited as a contributor to patellar fracture, anterior knee pain and quadriceps efficiency; however, optimal thickness required to minimize clinical complications remains unclear. The objectives of the current study were to determine how patellar resection thickness and bone quality impacts patellar bone strain, kinematics, and quadriceps efficiency. A series of specimen-specific finite element models of the knee joint with distributed patellar bone material properties were developed. Each specimen was virtually implanted with a TKR system. Each specimen was analyzed with patellar bone resected to thicknesses which varied from 9 to 14 mm. Simulations with reduced modulus bone were also performed. Each model perturbation was evaluated during a dynamic squat cycle, and bone strain, quadriceps force and six-degree-of-freedom kinematics were predicted. Highest peak bone strain was predicted in the thinnest patellae, indicating greatest risk of patellar fracture; highest median bone strain was predicted in the thickest patellae. Consistent differences in quadriceps efficiency were predicted; in early flexion the thickest patellae required the least quadriceps force. Greater sagittal plane tilt was observed for the thinnest patellae. Reduced modulus models (50% lower modulus) demonstrated an increase in peak bone strain of up to seven times the original modulus models. Understanding the complex interactions between patellar resection thickness, muscle requirements, kinematics, bone quality, and bone property distribution may aid in developing an understanding of which patients are most at risk from patellar fracture and anterior knee pain and how best to treat individuals to reduce potential complications.
全膝关节置换术中（TKR）髌骨切除的厚度被认为是髌骨骨折、膝关节前痛和股四头肌效率降低的原因；然而，为了最小化临床并发症所需的最佳厚度仍不清楚。本研究的目的是确定髌骨切除厚度和骨质量如何影响髌骨骨应变、运动学和股四头肌效率。开发了一系列具有分布式髌骨骨材料特性的膝关节的特定于标本的有限元模型。每个标本都被虚拟植入了 TKR 系统。每个标本的髌骨切除厚度从 9 到 14 毫米不等进行了分析。还对具有降低的模量骨的模拟进行了分析。在动态下蹲循环期间评估了每个模型扰动，预测了骨应变、股四头肌力和六自由度运动学。预测最薄的髌骨具有最高的峰值骨应变，表明髌骨骨折的风险最大；最厚的髌骨具有最高的中位数骨应变。预测了股四头肌效率的一致差异；在早期弯曲时，最厚的髌骨需要的股四头肌力最小。观察到最薄的髌骨的矢状面倾斜更大。降低的模量模型（模量降低 50%）显示出高达原始模量模型的七倍的峰值骨应变增加。了解髌骨切除厚度、肌肉需求、运动学、骨质量和骨特性分布之间的复杂相互作用可能有助于了解哪些患者最容易发生髌骨骨折和膝关节前痛，以及如何最好地治疗患者以降低潜在并发症的风险。
