Lee Haena-Young, Boettner Friedrich, Blevins Jason L, Rodriguez Jose A, Lipman Joseph D, Quevedo González Fernando J, Bostrom Mathias P, Wright Timothy M, Sculco Peter K
Department of Biomechanics, Hospital for Special Surgery, New York, New York, USA.
Stavros Niarchos Foundation Complex Joint Reconstruction Center, Hospital for Special Surgery, New York, New York, USA.
J Orthop Res. 2025 Apr;43(4):834-841. doi: 10.1002/jor.26037. Epub 2025 Jan 5.
Patient-specific flanged acetabular components are utilized to treat failed total hip arthroplasties with severe acetabular defects. We previously developed and published a finite element model that investigated the impact of hip joint center lateralization on construct biomechanics during gait conditions. This model consisted of a patient-specific implant designed to address a superior-medial defect created in a standard pelvic geometry. This study aims to utilize the same model and examine how cortical shell thickness and ischial cancellous bone density affect the strain distribution in the bone and bone-implant micromotion. Using published studies and bone density analyses of patients who had undergone total hip arthroplasties with flanged acetabular components, we established a thickness range for the cortical shell (1.5, 1, and 0.75 mm) and two levels of ischial cancellous bone density (100% and 25%). We compared the resulting bone strains against the fatigue strength of the bone (0.3% strain) as a criterion for local bone failure and the bone-implant micromotion against the threshold associated with bone ingrowth (20 µm). A thinner pelvic cortical shell and lower ischial cancellous bone density increased areas of bone at risk of failure, particularly at the ischial screws (from 6% to 38%), and decreased areas compatible with bone ingrowth. These findings agree with our clinical knowledge that compromised ischial bone and inadequate ischial fixation negatively impact the survivorship of flanged acetabular components. This series establishes our modeling approach of a computational model that can be utilized to guide implant design to best treat unique acetabular defects.
定制带凸缘髋臼组件用于治疗伴有严重髋臼缺损的全髋关节置换失败病例。我们之前开发并发表了一个有限元模型，该模型研究了步态条件下髋关节中心外移对假体生物力学的影响。此模型包含一个定制植入物，旨在解决标准骨盆几何形状中产生的上内侧缺损。本研究旨在利用同一模型，研究皮质骨壳厚度和坐骨松质骨密度如何影响骨内的应变分布以及骨 - 植入物微动。通过对接受带凸缘髋臼组件全髋关节置换术患者的已发表研究和骨密度分析，我们确定了皮质骨壳的厚度范围（1.5、1和0.75毫米）以及两种坐骨松质骨密度水平（100%和25%）。我们将所得的骨应变与骨的疲劳强度（0.3%应变）进行比较，以此作为局部骨失效的标准，并将骨 - 植入物微动与与骨长入相关的阈值（20微米）进行比较。较薄的骨盆皮质骨壳和较低的坐骨松质骨密度增加了有失效风险的骨区域，特别是在坐骨螺钉处（从6%增至38%），并减少了与骨长入相容的区域。这些发现与我们的临床认知相符，即坐骨骨质量受损和坐骨固定不足会对带凸缘髋臼组件的生存率产生负面影响。本系列研究确立了我们的计算模型建模方法，该方法可用于指导植入物设计，以最佳方式治疗独特的髋臼缺损。
