Center for Gait and Motion Analysis, Gillette Children's Specialty Healthcare, St Paul, MN, United States.
Center for Gait and Motion Analysis, Gillette Children's Specialty Healthcare, St Paul, MN, United States; Department of Orthopedic Surgery, University of Minnesota, Minneapolis, MN, United States.
Gait Posture. 2021 Jun;87:43-48. doi: 10.1016/j.gaitpost.2021.04.018. Epub 2021 Apr 14.
The clinical utility of motion capture modeling relies on the accurate tracking of segment motions. Soft tissue artefact presents a particular challenge for modeling hip rotation, knee rotation, and knee varus-valgus motions. The integration of a patella marker has been shown to significantly improve hip rotation tracking for models that utilize anatomical definitions of joint axes (e.g. anatomical models). However, these modeling improvements have not been extended to models that use functional segment motion to define joint axes (e.g. functional models).
How does the positioning of a patella marker influence functional model performance?
A patella functional model (PFM) was created by integrating a patella marker into the functional model (FM) used at our center. Nine distinct versions of the PFM were created using a 3 × 3 grid of markers placed across the patella. Ten typically developing participants performed controlled hip rotation, controlled knee flexion-extension, and free speed walking trials to assess FM and PFM performance differences.
The top performing PFM modeled 98 ± 8 % of the reference hip rotation range of motion compared to 71 ± 9 % for the FM. This PFM had low sensitivity to knee flexion-extension motion, 5 ± 10 %. For walking kinematics, this top performing PFM reported 14 % greater hip rotation ROM during stance, 46 % less knee rotation ROM over the entire gait cycle, and 32 % less knee varus-valgus during swing compared to the FM. The differences in modeling are nearly identical to those reported between skin mounted marker and fluoroscopy-based models, indicating that utilization of the patella marker leads to improvements in tracking accuracy.
Utilization of a precisely placed patella marker led to substantial improvements in modeled hip rotation, knee rotation, and knee varus-valgus. These improvements have the potential to positively impact those specialties that rely on motion capture modeling for clinical decision-making, such as orthopedic surgery.
运动捕捉建模的临床实用性依赖于对节段运动的准确跟踪。软组织伪影给髋关节旋转、膝关节旋转和膝关节内翻-外翻运动的建模带来了特别的挑战。已经证明，在使用关节轴解剖定义（例如解剖模型）的模型中，加入髌骨标记可以显著提高髋关节旋转的跟踪精度。然而，这些建模改进尚未扩展到使用功能节段运动来定义关节轴的模型（例如功能模型）。
髌骨标记的定位如何影响功能模型的性能？
通过将髌骨标记集成到我们中心使用的功能模型（FM）中，创建了一个髌骨功能模型（PFM）。使用横跨髌骨的标记的 3×3 网格创建了 9 个不同版本的 PFM。10 名正常发育的参与者进行了受控髋关节旋转、受控膝关节屈伸和自由速度步行试验，以评估 FM 和 PFM 的性能差异。
表现最佳的 PFM 模拟了 98±8%的参考髋关节旋转运动范围，而 FM 为 71±9%。这个 PFM 对膝关节屈伸运动的灵敏度较低，为 5±10%。对于步行运动学，表现最佳的 PFM 在站立时报告髋关节旋转 ROM 增加 14%，整个步态周期膝关节旋转 ROM 减少 46%，摆动时膝关节内翻-外翻减少 32%，与 FM 相比。这些建模差异与皮肤贴附标记和基于荧光透视的模型之间报告的差异几乎相同，表明精确放置的髌骨标记的使用导致跟踪精度的提高。
精确放置的髌骨标记的使用导致髋关节旋转、膝关节旋转和膝关节内翻-外翻的模拟得到了显著改善。这些改进有可能对那些依赖运动捕捉建模进行临床决策的专业领域产生积极影响，例如矫形外科。
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