肱骨近端四部分骨折假体置换术中结节复位程度对肩关节力学平衡的影响

目的通过生物力学测试，评估肱骨近端四部分骨折术后结节复位程度对肩关节力学平衡的影响。方法新鲜国人肩关节标本4具，先测定记录其正常情况下外展、外旋等力学数据，定为正常组。然后将标本造成肱骨近端四部分骨折模型，随机分为2组进行人工肱骨头置换术，1组为大、小结节解剖复位，另1组为大、小结节未能解剖复位。在标本肱骨头大、小结节处布置T型应变片，测量肩关节置换术前、后在不同功能位时结节处的应力强度变化，并在冈下肌、肩胛下肌布置软组织韧带型桥式应变型传感器，测量不同功能位时肩关节的肌张力。结果结节解剖复位时其轴向刚度和水平剪切刚度高于正常对照组2％～4％，但差异无显著性（P〉0．05）；处于非解剖位时则低于正常对照组26％-41％，差异有显著性（P〈0．05）。轴向刚度随外展角度的增加而减少，水平剪切刚度则不断增加。结论手术中肱骨大小结节复位程度十分重要，否则会引起假体刚度削弱、位移扩大、脱位率增加，影响术后肩关节功能的恢复。术后结节的强度因假体位置而变化，并随着肱骨外展0—90°及内、外旋变化而变化。

Effect of tubercle reposition on mechanical balance of shoulder in the shoulder hemiarthroplasty for four-part fractures of the proximal humerus

Objective To evaluate the effect of tubercle reposition on mechanical balance of shoulder in the shoulder hemiarthroplasty for four-part fractures of the proximal humerus through biomechanical experiment.Methods Four fresh Chinese intact human shoulder cadaveric specimens were used in the experiment.The mechanical properties were assessed in functional positions and the data were used as control.Four-part proximal humeral fractures models were set up in all the four specimens and underwent hemiarthroplasty ...