Prietzel T, Drummer N, Farag M, Richter K-W, von Salis-Soglio G
Orthopädische Klinik und Poliklinik, Universität Leipzig.
Z Orthop Unfall. 2010 Aug;148(4):436-42. doi: 10.1055/s-0029-1240586.
Aim of our study was to create artificial labra for joint models of different diameters (28, 32 and 36 mm) and to measure their stability potential at rest (SPR). The experiment was performed under the same conditions as a previous one with capsulated joint models. Our target was to prove the hip stabilising effect of the atmospheric pressure (AP) as well as the parameters for joint stability and to test the function of the artificial labra.
Uncapsulated joint models having 28 (A), 32 (B) and 36 (C) mm diameters were sealed with moulded preformed silicone labra. An increasing traction force was applied under water on the fixed joint. Using specially designed software, the exerted force and the dislocation distance were simultaneously and continuously recorded on a computer. The SPR of the examined joint models was calculated as the difference between the maximal exerted force and the weight of the ball-neck component.
Statistical analyses showed that SPR had mean values of 58.12 +/- 2.23 N for the 28 mm joint model (n = 118; A), 75.66 +/- 2.75 N for the 32 mm model (n = 88; B) and 99.91 +/- 1.30 N for the 36 mm model (n = 82; C).
The traction force required for dislocation agreed closely to the expected precalculated SPR values of 58.6 N (A), 76.4 N (B) and 96.7 N (C), which proves the joint stabilising effect of AP in the presence of the essential prerequisites (spherical ball articulating in a hemispherical socket, hermetically closed joint capsule and/or labrum, which contains a small amount of fluid and excludes air). The measured SPR was directly proportional to the square of the joint diameter. Indirectly, it was concluded that the dislocation work at rest is directly proportional to the joint diameter cubed. Consequently, the risk of dislocation after total hip arthroplasty (THA) can be reduced by applying bigger, size-adapted hip balls, whose diameter grows according to the outer diameter of the cup. The increasing range of motion is a favourable side-effect. With careful reconstruction of the capsule and insertion of an intracapsular drain, the risk of dislocation in the early postoperative period could be furtherly reduced. Theoretically, artificial labra could be a useful alternative to augment joint stability in THA with a high dislocation tendency instead of constrained liners.
本研究的目的是为不同直径（28、32和36毫米）的关节模型制作人工盂唇，并测量其静止时的稳定潜能（SPR）。实验在与先前有囊关节模型相同的条件下进行。我们的目标是证明大气压（AP）对髋关节的稳定作用以及关节稳定性参数，并测试人工盂唇的功能。
对直径为28（A）、32（B）和36（C）毫米的无囊关节模型，用模制预制硅酮盂唇进行密封。在水下对固定关节施加逐渐增加的牵引力。使用专门设计的软件，在计算机上同时连续记录施加的力和脱位距离。所检查关节模型的SPR计算为最大施加力与球颈部件重量之差。
统计分析表明，28毫米关节模型（n = 118；A）的SPR平均值为58.12 +/- 2.23牛，32毫米模型（n = 88；B）为75.66 +/- 2.75牛，36毫米模型（n = 82；C）为99.91 +/- 1.30牛。
脱位所需的牵引力与预期的预先计算的SPR值58.6牛（A）、76.4牛（B）和96.7牛（C）非常接近，这证明了在具备基本前提条件（球形球在半球形窝内关节运动、密封的关节囊和/或盂唇，其中含有少量液体且排除空气）时AP对关节的稳定作用。测得的SPR与关节直径的平方成正比。间接得出结论，静止时的脱位功与关节直径的立方成正比。因此，通过应用更大的、尺寸适配的髋关节球头（其直径根据髋臼外径增大），可降低全髋关节置换术（THA）后脱位的风险。活动范围增加是一个有利的副作用。通过仔细重建关节囊并插入囊内引流管，可进一步降低术后早期脱位的风险。理论上，对于脱位倾向高的THA，人工盂唇可能是增强关节稳定性的有用替代物，而非限制型衬垫。
