School of Biomedical Engineering, University of British Columbia, Vancouver, BC, Canada.
Center for Hip Health and Mobility, University of British Columbia, Vancouver, BC, Canada.
BMC Musculoskelet Disord. 2021 Nov 23;22(1):972. doi: 10.1186/s12891-021-04820-6.
Cam and/or pincer morphologies (CPM) are potential precursors to hip osteoarthritis (OA) and important contributors to non-arthritic hip pain. However, only some CPM hips develop OA and/or pain, and it is not clear why. Anterior impingement between the femoral head/neck contour and acetabular rim during motion is a proposed pathomechanism. Understanding how activity and deformity combine to produce impingement may shed light on the causes of hip degeneration/pain. The objective of this study was to determine the accuracy of a subject-specific hip model driven by subject-specific motion data in predicting anterior impingement.
We recruited 22 participants with CPM (both with and without pain) and 11 controls. We collected subject-specific 3D kinematics during squatting and sitting flexion, adduction, and internal rotation (FADIR) (an active and a passive maneuver, respectively, proposed to provoke impingement). We then developed 3D subject-specific hip models from supine 3T hip MRI scans that predicted the beta angle (a measure of anterior femoroacetabular clearance) for each frame of acquired kinematics. To assess the accuracy of these predictions, we measured the beta angle directly in the final position of squatting and sitting FADIR using open MRI scans. We selected the frame of motion data matching the static imaged posture using the least-squares error in hip angles. Model accuracy for each subject was calculated as the absolute error between the open MRI measure of beta and the model prediction of beta at the matched time frame. To make the final model accuracy independent of goodness of match between open MRI position and motion data, a threshold was set for least-squares error in hip angles, and only participants that were below this threshold were considered in the final model accuracy calculation, yielding results from 10 participants for squatting and 7 participants for sitting FADIR.
For squatting and sitting FADIR, we found an accuracy of 1.1°(0.8°) and 1.3°(mean (SD), and root mean squared error, respectively) and 0.5°(0.3°) and 0.6°, respectively.
This subject-specific hip model predicts anterior femoroacetabular clearance with an accuracy of about 1°, making it useful to predict anterior impingement during activities measured with motion analysis.
凸轮和/或钳子形态（CPM）是髋关节骨关节炎（OA）的潜在前兆，也是非关节炎性髋关节疼痛的重要原因。然而，并非所有的 CPM 髋关节都会发展为 OA 和/或疼痛，原因尚不清楚。运动过程中股骨头/颈轮廓与髋臼缘之间的前撞击被认为是一种发病机制。了解活动和畸形如何共同导致撞击，可能有助于阐明髋关节退变/疼痛的原因。本研究的目的是确定由特定于个体的运动数据驱动的特定于个体的髋关节模型预测前撞击的准确性。
我们招募了 22 名患有 CPM（伴有或不伴有疼痛）的参与者和 11 名对照者。我们在深蹲和坐姿屈曲、内收和内旋（FADIR）期间收集了特定于个体的 3D 运动学数据（分别是一种主动和被动的动作，旨在引起撞击）。然后，我们从仰卧位 3T 髋关节 MRI 扫描中开发了特定于个体的 3D 髋关节模型，该模型预测了获取运动学数据的每一帧的β角（一种测量前髋关节间隙的指标）。为了评估这些预测的准确性，我们使用开放式 MRI 扫描直接测量深蹲和坐姿 FADIR 的最终位置的β角。我们使用髋关节角度的最小二乘误差选择与静态成像姿势匹配的运动数据帧。为每个个体计算模型准确性，即开放式 MRI 测量的β角与匹配时间帧的模型预测的β角之间的绝对误差。为了使最终模型的准确性不受开放式 MRI 位置与运动数据之间匹配程度的影响，我们设定了髋关节角度最小二乘误差的阈值，只有低于该阈值的参与者才会被纳入最终的模型准确性计算中，因此深蹲的结果来自 10 名参与者，坐姿 FADIR 的结果来自 7 名参与者。
对于深蹲和坐姿 FADIR，我们发现准确性分别为 1.1°（0.8°）和 1.3°（平均值（标准差）和均方根误差）和 0.5°（0.3°）和 0.6°。
这种特定于个体的髋关节模型可以以约 1°的精度预测前髋关节间隙，因此对于预测运动分析测量的活动期间的前撞击非常有用。
