Expandable Shape-Memory Polymers for Suture Anchors

描述（由申请人提供）：该项目将开发一种能够动态扩展的形状记忆聚合物缝合锚，专门为骨密度低的患者设计。缝合锚钉是螺钉或楔形装置，固定在骨头上，用于将脱离的肌腱固定在骨头上。肩袖修复是常用的外科手术，包括缝合锚钉，以减少疼痛和恢复受伤肩膀的功能。2007年，在美国进行了超过460,000例肩袖修复，使用了1,030,000个缝合锚。大约25 - 35%的肩袖修复被认为是不成功的。肩袖修复的一个普遍挑战和限制是必须放置大量柔软的松质骨，这使得锚钉更容易移动、松动/隧道拓宽和拔出。此外，越来越多的60岁以上的患者接受肩袖修复并患有骨质疏松症。在最近的研究中，超过54%的60岁以上肩关节疼痛的患者有肩袖撕裂的证据。骨密度低的患者设备失效的风险很高，因为骨密度与缝合锚钉的固定强度有关。所提出的形状记忆缝合锚将被开发为一种插接式装置，在这种装置中，形状记忆效应将被机械激活，扩展成一个翼形装置，并提供即时固定。该装置的主要优点是其在软骨中的优越固定强度和由于设计使用形状记忆聚合物而增加的循环性能。形状记忆缝合锚作为一种接入式装置，可以采用无结缝合方式，在安装过程中降低了复杂性和时间。无结缝合锚钉在锚钉插入时立即确保肌腱固定，不需要外科医生像传统锚钉那样将缝合结从锚钉打到肌腱上。这项工作的广泛影响将挑战缝合锚如何设计用于软骨的范例，利用形状记忆材料和模型来预测拔出强度，这是在第一阶段开发的。第二阶段将继续并扩展在该项目成功的第一阶段工作中所证明的可行性和获得的基本信息。第二阶段的目的是从根本上研究缝合锚的设计和性能，同时积极寻求监管部门的批准。目的包括(1)最终确定设计，(2)开发仪器，(3)评估生物相容性，(4)验证灭菌，(5)验证性能，以及(6)进行实验性动物研究以证明形状记忆缝合锚在体内的使用。主要研究团队将包括形状记忆聚合物和设备测试专家Chris Yakacki博士（PI）；Ken Gall博士，佐治亚理工学院的正教授，专门研究形状记忆材料和医疗设备测试；以及骨科医生、关节镜肩关节修复专家里德·巴茨医学博士。公共卫生相关性：随着年龄的增长，越来越多的人口保持身体活动。这个项目与那些经历过使人衰弱的损伤（如肩袖撕裂）和骨骼质量差的人有关。该项目将提供一种方法，使修复后的损伤部位恢复功能，减少手术失败的发生，提高患者的生活质量。

DESCRIPTION (provided by applicant): This project will develop a shape-memory polymer suture anchor capable of dynamic expansion that will be specifically designed for patients with poor bone mass density. Suture anchors are screw or wedge-like devices that fasten into the bone and are used to secure a detached tendon back onto the bone. Rotator cuff repairs are common surgical procedures involving suture anchors to reduce pain and restore use to an injured shoulder. In 2007, over 460,000 rotator cuff repairs were performed in the US using 1,030,000 suture anchors. Approximately 25 to 35% of rotator cuff repairs are considered unsuccessfully. A general challenge and constraint in rotator cuff repair is the large amount of soft cancellous bone where the anchors must be placed, which makes the anchors more susceptible to migration, loosening/tunnel widening, and pullout. Furthermore, a growing number of patients over 60 years of age are receiving rotator cuff repairs and suffer from osteoporosis. In recent studies, over 54% of patients over the age of 60 with shoulder pain had evidence of rotator cuff tears. Patients with poor bone mass densities are highly at risk of device failure as bone density have been correlated to the fixation strength of the suture anchors. The proposed shape-memory suture anchor will be developed as a tap-in style device, in which the shape- memory effect will be mechanically activated to expand into a wing-shaped device and offer instant fixation. The main advantages of this device are its superior fixation strength in soft bone and increased cyclic performance due to the design's use of shape-memory polymers. The shape-memory suture anchor will also offer reduced complexity and time during installation as a tap-in device, which can utilize a knotless suture approach. Knotless suture anchors instantly secure tendon fixation upon anchor insertion and do not require the surgeon to tie and pass knots of suture from the anchor to the tendon as in traditional anchors. The broad impact of this work will challenge the paradigm of how suture anchors are designed to work in soft bone by utilizing shape-memory materials and a model to predict pullout strength, which was developed in Phase I. This Phase II looks to continue and expand upon the feasibility demonstrated and fundamental information obtained in the successful Phase I efforts of this project. The aims of the Phase II have specifically been designed to fundamentally investigate the design and performance of suture anchors while following an aggressive path towards regulatory approval. The aims involve (1) finalizing the design, (2) developing instrumentation, (3) assessing biocompatibility, (4) validating sterilization, (5) validating performance, and (6) performing a pilot animal study to prove the use of shape-memory suture anchors in-vivo. The primary research team will consist of Chris Yakacki PhD (PI), who is an expert in shape-memory polymers and device testing; Ken Gall PhD, a full professor from Georgia Tech who specializes in shape-memory materials and medical device testing; and Reed Bartz MD, an orthopedic surgeon and expert in arthroscopic shoulder repair. PUBLIC HEALTH RELEVANCE: A growing percentage of the population is remaining physically active as they age. This project is relevant to this percentage of people that experience a debilitating injury such as a rotator cuff tear and suffer from poor bone quality. This project will provide a means to restore function to repaired injury sites with less occurrence of surgical failure and increase patient quality of life.