A Multi-Scale Biomechanical model of the Infant Hip to Progress Innovation in Pediatric Hip Dysplasia Rehabilitation

该提案将首次通过实验和计算评估闭合复位治疗对婴儿发育性髋关节发育不良（DDH）的机械影响，从而开发创新的儿科康复干预措施，以缩短治疗时间并改善结果。1000名婴儿中有2名DDH需要治疗。早期诊断和使用帕夫利克背带进行治疗是纠正DDH的关键。帕夫利克背带是一种有70年历史的解决方案，可以使婴儿的臀部在长达20周的时间内每天24小时处于弯曲和外展的位置。然而，这种治疗有20%的失败率，需要手术干预。运动、肌肉活动和充分的关节接触是新生儿肌肉骨骼发育的关键，但目前还没有研究试图了解被动躺着、主动踢腿和身体姿势对婴儿髋关节发育的作用。我们的中心假设是，在被动躺卧和主动运动期间，由Pavlik安全带产生的活动肌肉和髋关节位置的可量化组合在髋关节处诱导特定但目前未知的机械负荷，从而促进正确的髋关节发育。目的1将量化接受DDH治疗的婴儿的被动和主动髋关节力学。新诊断为DDH的婴儿将在Pavlik套治疗前后在我们的实验室进行2次生物力学测试。我们将使用活动传感器监测DDH婴儿的日常生活，量化身体方向和被动与主动的时间。临床结果将在治疗期间和治疗后随访6次，为期2年。这一目标将有助于了解患者选择闭合复位治疗，帮助确定理想的治疗时间，并导致有针对性的治疗。目的2将评估Pavlik安全带对健康髋关节的机械负荷。佩戴Pavlik背带时，由于主动踢腿或被动躺着，髋关节受力的大小、方向和频率尚不清楚，这阻碍了DDH新疗法的发展。我们将用传感器测量Pavlik背带，以评估在佩戴期间施加在背带上的力，以了解在活动和被动躺着期间，背带是如何对健康婴儿的髋关节进行机械负荷的。目的3将建立闭合复位婴儿髋关节的计算模型。DDH婴儿的实验肌肉和髋关节运动、Aim 1中患者特定的几何形状以及Aim 2中主动运动和被动躺卧时对Pavlik安全带产生的力将作为肌肉骨骼和有限元模型的输入。这些接受闭合复位的婴儿髋关节的计算模型将支持改进DDH治疗的发展。这项工作的预期结果是更全面地了解帕夫利克挽具如何将被动和主动力量转化为婴儿髋关节。这些结果将提供有效的实验数据和计算模型，为我们未来的研究提供基础，旨在为受DDH影响的婴儿和家庭开发创新的解决方案。

This proposal will be the first to experimentally and computationally assess the mechanical impact of closed reduction treatment on infants with developmental dysplasia of the hip (DDH), enabling the development of innovative pediatric rehabilitation interventions to decrease treatment duration and improve outcomes. DDH requires medical treatment in 2/1000 infants. Early diagnosis and treatment with a Pavlik harness, a 70-year-old solution that holds the infant’s hips in a flexed and abducted position for 24 hours/day for up to 20 weeks, are key to correcting DDH. However, the treatment has a 20% failure rate, requiring surgical intervention. Motion, muscle activity, and adequate joint contact are key to neonatal musculoskeletal development, yet no research has sought to understand the role of passive lying, active kicking, and body position on the development of the infant hip. Our central hypothesis is that a quantifiable combination of active muscles and hip position produced by the Pavlik harness induce a specific but currently unknown mechanical loading at the hip joint, during passive lying and active motion, which encourages correct hip development. Aim 1 will quantify passive and active hip mechanics of infants undergoing DDH treatment. Infants newly diagnosed with DDH will undergo 2 biomechanical test sessions in our laboratory before and after Pavlik harness treatment. We will monitor DDH infants in their daily life using activity sensors to quantify body orientation and time spent passive versus active. Clinical outcomes will be tracked during and after treatment during 6 visits over 2 years. This Aim will lend insight into patient selection for closed reduction treatment, help define the ideal treatment duration, and lead to directed therapies. Aim 2 will evaluate mechanical loading of the healthy hip by the Pavlik harness. The magnitude, direction, and frequency of forces at the hip due to active kicking attempts or passive lying while wearing the Pavlik harness are unknown, preventing the development of new therapies for DDH. We will instrument the Pavlik harness with sensors to evaluate the forces applied to the harness during wear to understand how the harness works to mechanically load the healthy infant hip during activity and passive lying. Aim 3 will develop computational models of the infant hip undergoing closed reduction. Experimental muscle and hip motion of DDH infants and patient-specific geometry from Aim 1 and forces induced on the Pavlik harness during active motion and passive lying from Aim 2 will serve as inputs to musculoskeletal and finite element models. These computational models of the infant hip joint undergoing closed reduction will support the development of improved DDH therapies. The expected outcome of this work is a more complete understanding of how the Pavlik harness works to translate passive and active forces to the infant hip. The results will provide valid experimental data and computational models that can serve as the basis for our future investigations aimed at developing innovative solutions for infants and families impacted by DDH.