Karduna A R, Williams G R, Williams J L, Iannotti J P
Department of Orthopaedic Surgery, University of Pennsylvania, Philadelphia, USA.
J Bone Joint Surg Am. 1997 Aug;79(8):1166-74. doi: 10.2106/00004623-199708000-00008.
The purpose of the present study was to examine the motions of natural and prosthetically reconstructed glenohumeral joints without capsular contracture in the laboratory to obtain a better understanding of joint motion as it may relate to failure of the implant. Seven joints from fresh-frozen human cadavera were instrumented with a six-degrees-of-freedom magnetic tracking device to study patterns of translation and rotation with and without the application of simulated muscle forces (active and passive models). The specimens were tested before and after reconstruction of the joint with use of modified operative techniques and implants that had from zero to five millimeters of radial mismatch between the humeral head and glenoid components. The natural and reconstructed joints had similar patterns of translation, with larger rotations and translations observed in the passive model. On the average, the active translations of the natural joints were best reproduced by the reconstructed joints with less conforming articulations. The mean active translation in the natural joints was 1.5 millimeters along the anterior-posterior axis and 1.1 millimeters along the superior-inferior axis. The active translations in the reconstructed joints were observed to increase consistently as the conformity of the components decreased: the mean active anterior-posterior translations ranged from 0.3 millimeter for conforming components to 1.7 millimeters for components with a five-millimeter radial mismatch, and the mean active superior-inferior translations ranged from 0.4 to 1.1 millimeters. The patterns of translation during passive motions were less consistent, presumably because of the influence of capsular ligaments and because the translations were large enough for the articular surface of the humeral head to lose contact with the articular surface of the glenoid component.
Glenohumeral translations during active motions were found to depend on articular conformity, which indicates that the choice of implants may have important consequences for normal motions. Totally conforming designs may impose a degree of restraint to translations that is higher than that in the natural joint. The patterns of translation may influence the longevity of the joint replacement with respect to stability, loosening of the glenoid component, and wear of the components.
本研究的目的是在实验室中检查无关节囊挛缩的天然和假体重建的盂肱关节的运动，以便更好地理解关节运动与植入物失效之间的关系。对来自新鲜冷冻人体尸体的七个关节使用六自由度磁跟踪装置，以研究在施加和不施加模拟肌肉力的情况下（主动和被动模型）的平移和旋转模式。在使用改良手术技术和肱骨头与关节盂部件之间径向不匹配为零至五毫米的植入物对关节进行重建之前和之后对标本进行测试。天然关节和重建关节具有相似的平移模式，在被动模型中观察到更大的旋转和平移。平均而言，关节面贴合度较低的重建关节能最好地重现天然关节的主动平移。天然关节沿前后轴的平均主动平移为1.5毫米，沿上下轴为1.1毫米。随着部件贴合度降低，重建关节中的主动平移持续增加：对于贴合部件，平均主动前后平移范围为0.3毫米，对于径向不匹配为五毫米的部件，为1.7毫米，平均主动上下平移范围为0.4至1.1毫米。被动运动期间的平移模式不太一致，可能是由于关节囊韧带的影响，并且由于平移足够大，肱骨头的关节面与关节盂部件的关节面失去接触。
发现主动运动期间的盂肱平移取决于关节面贴合度，这表明植入物的选择可能对正常运动产生重要影响。完全贴合的设计可能对平移施加高于天然关节的约束程度。平移模式可能会影响关节置换在稳定性、关节盂部件松动和部件磨损方面的使用寿命。
