Adverse loading of the hip joint after joint preserving and joint replacement surgery

拟议的研究将确定自然健康的髋关节如何保护自己免受潜在的破坏性负荷。当股骨头和髋臼之间的力矢量的方向接近髋臼表面的边缘（边缘载荷）时，就会产生这些。可用于支持负荷的髋臼表面积减少，可增加软骨表面的接触压力，并增加唇部的应变。这些类型的负荷是在臀部接近其运动范围限制时产生的，例如旋转，从低椅子上站起来或系鞋带。当髋关节旋转到这些位置时，髋关节韧带拉紧以限制旋转并防止撞击。然而，我们的试验数据表明，当韧带拉紧时，它们也会对髋关节力矢量的方向做出贡献，使其旋转到髋臼，远离髋缘，从而有助于防止髋缘负荷。拟议的研究将测量天然髋关节中韧带的功能，使用尸体标本来最好地代表髋关节韧带的特性。一旦我们确定了自然髋关节如何保护自身免受边缘负荷的影响，我们将模拟不同类型的(a)髋关节保留手术和(b)髋关节置换手术，以研究手术后是否保持这种功能。我们怀疑它没有得到维持，因为在手术中韧带被切断以进入髋关节（它们必须是-它们完全包围关节），并且目前的修复程度，如果有的话，是可变的。如果我们发现术后韧带功能丧失，我们将研究不同的修复方法如何恢复其功能，并根据需要提出新的修复方法。该研究对于髋关节保留手术具有重要意义，该手术旨在纠正关节病理并预防骨关节炎的发展，因为上述不利负荷会增加软骨退变和唇裂的风险。关节保留手术只有在不加速它所寻求的预防的情况下才会成功，因此这项研究的重要性。这项研究对髋关节置换手术也很重要。边缘载荷是一种已建立的机制，据报道发生在70%的髋关节中，并且与吱吱声和翻修有关。减少边缘载荷的风险将减少这些并发症的发生，并可能使新的治疗概念不需要承受这种载荷机制。

The proposed research will determine how the natural healthy hip protects itself against potentially damaging loads. These can be generated when the direction of the force vector between the femoral head and acetabulum passes close to the edge of the acetabular surface (edge loading). The reduced acetabular surface area available to support the load can increase contact pressure on the cartilage surface and increase strain in the labrum. These types of load are generated when the hip is close to its range of motion limit, for example pivoting, standing up from a low chair or tying a shoelace. When the hip is rotated into these positions, the hip ligaments pull taut to constrain rotation and protect against impingement. However, our pilot data indicates that when the ligaments pull taut they also make a contribution to the direction of the hip force vector, rotating it into the acetabulum, away from the edge and thus help protect against edge loading. The proposed research will measure this function of the ligaments in the natural hip, using cadaver specimens to best represent the properties of the hip ligaments. Once we have established how the natural hip protects itself against edge loading, we will simulate different types of (a) hip joint preserving surgery and (b) hip replacement surgery to investigate whether this function is maintained after surgery. We suspect it is not maintained because the ligaments are cut during surgery to access the hip (they have to be - they completely surround the joint), and the extent of repair currently practiced, if any, is variable. If we find that ligament function is disabled after surgery, we will investigate how different repair methods can restore their function, and propose new repair methods if required. This research is important for hip joint preserving surgery, which aims to correct joint pathology and prevent osteoarthritis developing, because the adverse loading described above would increase the risk of cartilage degeneration and labral tears. Joint preserving surgery will only be a success if it does not accelerate what it seeks to prevent, hence the importance of the research. The research is also important for hip replacement surgery. Edge loading is an established mechanism that is reported to occur in 70% of hips and has been related to squeaking and revision. Reducing the risk of edge loading will reduce the occurrence of these complications and may enable new treatment concepts that do not have to withstand this loading mechanism.