Quantifying the Biomechanical and Neural Factors Contributing to Shoulder Instability

项目摘要 多向不稳定（MDI）是年轻人中常见的肩关节病理， 军事，受雇于重型职业，并参加高需求的活动。MDI的特点是 多方向非创伤性肩关节松弛，同时伴有疼痛，限制了日常活动的参与， living. MDI的治疗始于非手术物理疗法，但短期和长期结果是 往往无效。随后的手术治疗是不可预测的，特别是与类似的手术治疗相比， 单向不稳定性的治疗。与MDI相反，许多个体在临床上表现为 多方向无创肩关节松弛，但报告肩关节功能无疼痛（无症状）。是 我假设，与MDI患者不同，无症状松弛的个体使用神经激活， 肩部肌肉系统，以弥补任何缺陷，在被动的肩膀结构。然而，研究还 研究或量化肩部肌肉组织的神经激活对被动的 MDI的不足。该提案将侧重于确定和量化主动和被动 MDI患者与无症状松弛患者之间的肩关节稳定性，以分离肩关节组件 独特的机械与MDI的肩膀。目标1将量化平移阻抗（对关节的阻力 运动）以及在肩部放松期间的多个手臂姿势。目标2将 量化在三个旋转中产生恒定等长扭矩期间肩部的平移阻抗 自由度无源和有源平移阻抗将在临床- 诊断为MDI、无症状肩关节松弛和无症状肩关节临床松弛阴性。一 自适应直线电机将适用于长慢速（目标1）和小快速随机（目标1和目标2） 肩部的平移扰动。阻抗的刚度分量将用以下公式量化： 平移扰动后肩部位移和力的计算分析。的结果 这项工作将首次提供个人被动和主动平移肩阻抗的比较 与MDI和无症状松弛，通知未来的研究，旨在预测个人的进展， MDI的无症状松弛，并开发个性化MDI治疗，以针对个体生物力学 赤字

PROJECT SUMMARY Multidirectional instability (MDI) is a common shoulder pathology in younger individuals impacting those in the military, employed in heavy lifting occupations, and participating in high demand activities. MDI is characterized by multidirectional atraumatic shoulder laxity with concurrent pain that limits participation in activities of daily living. Treatment for MDI begins with non-operative physiotherapy, but short-term and long-term outcomes are often ineffective. Subsequent surgical treatment is unpredictable, especially when compared to similar surgical treatment for unidirectional instability. In contrast to MDI, many individuals present clinically with multidirectional atraumatic shoulder laxity but report no pain (asymptomatic) with shoulder function. It is hypothesized that individuals with asymptomatic laxity, unlike patients with MDI, use neural activation of shoulder musculature to compensate for any deficits in passive shoulder structures. However, research has yet to investigate or quantify the inability to compensate with neural activation of shoulder musculature for passive deficits in MDI. This proposal will focus on identifying and quantifying differences in active and passive shoulder stability between individuals with MDI and asymptomatic laxity to isolate components of shoulder mechanics unique to shoulders with MDI. Aim 1 will quantify translational impedance (resistance to joint motion) of the shoulder in multiple directions and multiple arm postures during shoulder relaxation. Aim 2 will quantify translational impedance of the shoulder during constant isometric torque production in three rotational degrees-of-freedom. Passive and active translational impedance will be assessed in individuals with clinically- diagnosed MDI, asymptomatic shoulder laxity, and asymptomatic shoulders negative for clinical laxity. A custom-adapted linear motor will apply long slow (Aim 1) and small quick stochastic (Aim 1 and Aim 2) translational perturbations to the shoulder. The stiffness component of impedance will be quantified with computational analysis of shoulder displacement and forces following translational perturbations. The results of this work will provide the first comparison of passive and active translational shoulder impedance in individuals with MDI and asymptomatic laxity, informing future studies designed to predict individuals that progress from asymptomatic laxity to MDI and develop personalized MDI treatments to target individual biomechanical deficits.