Myers Casey A, Laz Peter J, Shelburne Kevin B, Judd Dana L, Huff Daniel N, Winters Joshua D, Stevens-Lapsley Jennifer E, Rullkoetter Paul J
Center for Orthopaedic Biomechanics, University of Denver, Denver, CO, USA.
Center for Orthopaedic Biomechanics, University of Denver, Denver, CO, USA.
Clin Biomech (Bristol). 2018 Mar;53:93-100. doi: 10.1016/j.clinbiomech.2018.02.010. Epub 2018 Feb 14.
Component alignment is an important consideration in total hip arthroplasty. The impact of changes in alignment on muscle forces and joint contact forces during dynamic tasks are not well understood, and have the potential to influence surgical decision making. The objectives of this study were to assess the impact of femoral head/stem and cup component placement on hip muscle and joint contact forces during tasks of daily living and to identify which alignment parameters have the greatest impact on joint loading.
Using a series of strength-calibrated, subject-specific musculoskeletal models of patients performing gait, sit-to-stand and step down tasks, component alignments were perturbed and joint contact and muscle forces evaluated.
Based on the range of alignments reported clinically, variation in head/stem anteversion-retroversion had the largest impact of any degree of freedom throughout all three tasks; average contact forces 413.5 (319.1) N during gait, 262.7 (256.4) N during sit to stand, and 572.7 (228.1) N during the step down task. The sensitivity of contact force to anteversion-retroversion of the head/stem was 31.5 N/° for gait, which was similar in magnitude to anterior-posterior position of the cup (34.6 N/m for gait). Additionally, superior-inferior cup alignment resulted in 16.4 (4.9)° of variation in the direction of the hip joint contact force across the three tasks, with the most inferior cup placements moving the force vector towards the cup equator at the point of peak joint contact force.
A quantitative understanding of the impact and potential tradeoffs when altering component alignment is valuable in supporting surgical decision making.
组件对线是全髋关节置换术中的一个重要考量因素。对线变化对动态任务期间肌肉力量和关节接触力的影响尚未得到充分理解，并且有可能影响手术决策。本研究的目的是评估股骨头/股骨柄和髋臼组件放置对日常生活任务期间髋部肌肉和关节接触力的影响，并确定哪些对线参数对关节负荷影响最大。
使用一系列经过强度校准的、针对特定患者的肌肉骨骼模型，这些模型用于模拟患者进行步态、从坐到站和下台阶任务，对组件对线进行扰动，并评估关节接触力和肌肉力量。
根据临床报告的对线范围，在所有三项任务中，股骨头/股骨柄前倾角-后倾角的变化对任何自由度的影响最大；步态期间平均接触力为413.5（319.1）N，从坐到站期间为262.7（256.4）N，下台阶任务期间为572.7（228.1）N。步态期间接触力对股骨头/股骨柄前倾角-后倾角的敏感度为31.5 N/°，其大小与髋臼前后位置的敏感度相似（步态期间为34.6 N/m）。此外，髋臼上下方向的对线导致三项任务中髋关节接触力方向有16.4（4.9）°的变化，髋臼放置位置最靠下时，在关节接触力峰值点处使力向量朝向髋臼赤道方向移动。
定量了解改变组件对线时的影响和潜在权衡，对于支持手术决策具有重要价值。
