How Do Wrist Surgical Salvage Procedures Limit Hand Strength?

手腕骨关节炎被描述为“人类最常见的疾病之一” 整形外科医生“。在60岁以上的男性中，严重的骨关节炎更多地出现在手腕上，而不是 臀部。手腕是一个复杂的关节，植入技术未能有效复制。结果, 外科挽救手术通常用于治疗腕部的骨性关节炎，而不是髋部或膝部的骨性关节炎。 关节置换术是黄金标准。两种最常见的外科抢救程序是 腕舟骨切除四角融合术(SE4CF)和近排腕骨切除术(PRC)。在每个过程中， 关节炎的舟状骨被移除。在SE4CF中，指腕中关节(剩余骨骼之间的界面 近端和远端)融合，以防止腕关节缺失时腕骨塌陷。在中国， 腕骨和上肢远端的长度缩短是因为增加了两块骨头(月骨、三角骨) 与前臂相连的关节也被移除。这些激进的几何和运动学重新设计 永久性地降低手腕的活动范围和握力。失去握力尤其有害； 它限制了患者进行日常生活活动的能力，如拿起平底锅、拧开罐子 盖上盖子，打开一扇门。外科抢救手术后握力丧失的原因尚不清楚。我们的 长期目标是开发针对手腕骨关节炎的创新型骨科手术干预措施。目标是 这项提议的下一步是确定为什么握力受到限制。 PRC和SE4CF。我们的中心假设是PRC和SE4CF中腕关节的外科重新设计 腕关节肌肉功能的机械差异，正是这些影响最终限制了手 术后力量恢复情况。我们的假设是在我们的初步工作的基础上发展出来的，在这些工作中，我们首先 非损伤组和非损伤组肌肉力学性能的生物力学特征差异 在身体标本中手术挽救腕关节，然后展示这些机械的影响 计算机模拟对侧向挤压强度的影响。这项拟议研究的基本原理 改善手腕骨关节炎的手术干预首先需要了解如何改变 手腕关节的运动学和几何设计会影响手产生力量的能力。归根结底， 这里提出的研究将提高对如何设计手腕的科学理解 影响手腕和手的功能。这些知识将有助于治疗师设计康复方案。 针对特定的生物力学弱点和外科医生开发新的外科技术 减少生物力学变化。例如，如果肌肉适应导致手腕伸肌变弱 在PRC后，可以进行肌腱移位以加强这些肌肉。或者，SE4CF可以 通过优化腕骨融合的位置，对其进行改进，以最大限度地减少运动耦合的影响。 此外，工程师将能够利用我们的发现来设计更有效地复制的手腕植入物 手腕设计的关键部件。所有这些结果都将改善手腕的治疗选择 治疗骨性关节炎，从而改善患者的预后和生活质量。取得压倒性的成功 髋关节和膝骨性关节炎的治疗选择，以及在 这些领域在过去的25年里，强调了增加研究投资的潜在影响 可能与手腕骨关节炎有关。因为退伍军人更容易患上手腕 与普通人群相比，退伍军人最终将从这种改善中获得最大的好处 在临床治疗腕骨性关节炎中的作用。

Wrist osteoarthritis has been described as “one of the most common conditions encountered by the orthopaedic surgeon”. In men older than 60, severe osteoarthritis is more frequently present at the wrist than the hip. The wrist is a complicated joint that implant technology has failed to effectively replicate. As a result, surgical salvage procedures are commonly used to treat osteoarthritis at the wrist, unlike at the hip or knee where joint replacement is the gold standard. The two most common surgical salvage procedures are scaphoid-excision four-corner fusion (SE4CF) and proximal row carpectomy (PRC). In each procedure, the arthritic scaphoid bone is removed. In SE4CF, the midcarpal joint (the interface between the remaining bones in the proximal and distal rows) is fused to prevent carpal collapse in the absence of the scaphoid. In PRC, the lengths of the carpus and distal upper limb are shortened because the two additional bones (lunate, triquetrum) that articulate with the forearm are also removed. These drastic geometric and kinematic re-designs permanently decrease wrist range of motion and grip strength. Loss of grip strength is particularly detrimental; it limits patient's abilities to perform activities of daily living, such as picking up a saucepan, unscrewing a jar lid, and opening a door. Why grip strength is lost following surgical salvage procedures is not understood. Our long-term goal is to develop innovative orthopaedic surgical interventions for wrist osteoarthritis. The objective of this proposal, the next step toward attainment of that goal, is to determine why grip force is limited following PRC and SE4CF. Our central hypothesis is that the surgical re-design of the wrist in PRC and SE4CF impose mechanical differences in muscle function at the wrist joint, and it is these effects that ultimately limit hand strength post-operatively. Our hypothesis was developed based on our preliminary work, in which we first characterized biomechanical differences between muscle mechanical capabilities in nonimpaired and surgically salvaged wrist joints in cadaveric specimens, and then demonstrated the impact of these mechanical effects on lateral pinch strength using computer simulation. The rationale that underlies the proposed research is that improving surgical interventions for wrist osteoarthritis first requires understanding how changing the kinematic and geometric design of the wrist joint influences the hand's ability to generate force. Ultimately, the research studies proposed here will improve the scientific understanding of how the design of the wrist influences both wrist and hand function. This knowledge will aid therapists in designing rehabilitation protocols targeted at specific points of biomechanical weakness and surgeons in developing novel surgical techniques to reduce biomechanical changes. For example, if muscle adaptations cause wrist extensors to be weaker following PRC, a tendon transfer to strengthen these muscles could be performed. Alternatively, SE4CF could be modified to minimize the effects of motion coupling by optimizing the position in which the carpals are fused. Additionally, engineers will be able to use our findings to design wrist implants that more effectively replicate key components of the wrist's design. All of these outcomes will improve the treatment options for wrist osteoarthritis, and thereby lead to improved patient outcomes and quality of life. The overwhelming success of treatment options for hip and knee osteoarthritis, as well as the scientific advances that have been achieved in these areas over the past 25 years, emphasizes the potential impact that an increased investment in research relevant to wrist osteoarthritis could have. Because the veteran population is so much more susceptible to wrist injuries than the general population, veterans would ultimately reap the most benefits from such improvements in clinical treatment of wrist osteoarthritis.