Walker P S, Erkman M J
Clin Orthop Relat Res. 1975 Oct(112):349-56.
In the normal joint, the conformity of the joint surfaces can provide appreciable dorsal-volar shear stability when a compressive joint force acts. The centers of rotation were within 3 mm of the center of the metacarpal ball. Passive radial-ulna motion at 0 degrees flexion was close to 60 degrees, active motion being half of this; at 90 degrees flexion, there was 37 degrees passive and 23 degrees active motion. Studies of canal shapes and sizes showed that a transverse section deviated from circular by 1-2.5 mm; longitudinal sections were trumpet-shaped but had waves and ripples of about 0.5 mm. This is relevant to cement fixation. A metal-plastic prosthesis was tested in positions and with forces considered applicable to arthritics. It is possible that with plastic components, permanent deformation will progressively occur. The pull-out strength between cement and bone in cadaver bones was about 100 kg; metal stems in cement pulled out at about 50 kg, and plastic stems at 10-20 kg. Slippery stems pulled out at much lower values.
在正常关节中，当关节受到压缩力作用时，关节面的贴合度可提供相当可观的掌背侧剪切稳定性。旋转中心位于掌骨球中心的3毫米范围内。在0度屈曲时，尺桡侧被动活动接近60度，主动活动为其一半；在90度屈曲时，被动活动为37度，主动活动为23度。对髓腔形状和大小的研究表明，横截面积偏离圆形1至2.5毫米；纵截面呈喇叭形，但有大约0.5毫米的波状起伏。这与骨水泥固定相关。对一种金属-塑料假体在适用于关节炎患者的位置和力的情况下进行了测试。塑料部件可能会逐渐发生永久变形。尸体骨中骨水泥与骨之间的拔出强度约为100千克；骨水泥中的金属柄在约50千克时拔出，塑料柄在10至20千克时拔出。光滑柄的拔出值要低得多。
