Davies J P, O'Connor D O, Burke D W, Jasty M, Harris W H
Orthopaedic Research Laboratory, Massachusetts General Hospital, Boston 02114.
Clin Orthop Relat Res. 1988 Apr(229):156-61.
Reduction of the porosity of bone cement by centrifugation significantly improves the fatigue life of the cement when smooth, waisted specimens are tested. However, bone cement in vivo has surface irregularities at the interdigitation of the cement with the trabecular bone. The effect of centrifugation on the fatigue life of Simplex P in specimens containing surface irregularities was investigated by examining both composite specimens of trabecular bone and bone cement and specimens containing a sharp, circumferential notch. For the specimens with the sharp notch, the bone cement that had been centrifuged lasted significantly longer in fatigue (47,039 +/- 40,277 cycles) than the uncentrifuged specimens (3103 +/- 1950 cycles). Eleven of 15 uncentrifuged specimens broke at the location of a void, rather than the notch. In contrast, when the porosity was reduced by centrifugation, 13 of the 15 specimens broke at the notch. For the specimens that were a composite of bone cement and trabecular bone, the centrifuged specimens had a significant increase in fatigue life compared to the uncentrifuged specimens when tested at both 7 MPA (641,056 +/- 444,131 cycles vs. 237,969 +/- 124,153 cycles) and 15 MPA (8800 +/- 4673 cycles vs. 1534 +/- 719 cycles). Reduction of porosity in bone cement by centrifugation significantly extends its fatigue life even in the presence of trabecular bone or sharp surface notches as used in total joint replacements. These data support the concept that reduction of porosity of bone cement by centrifugation may extend the duration of fixation of the components in cemented total joint arthroplasties.
当对光滑、腰部形状的骨水泥试件进行测试时，通过离心法降低骨水泥的孔隙率可显著提高其疲劳寿命。然而，体内的骨水泥在与松质骨的交错处存在表面不规则性。通过检查松质骨与骨水泥的复合试件以及带有尖锐圆周切口的试件，研究了离心对含表面不规则性的Simplex P骨水泥疲劳寿命的影响。对于带有尖锐切口的试件，经离心处理的骨水泥在疲劳试验中的持续时间（47,039 ± 40,277次循环）明显长于未离心处理的试件（3103 ± 1950次循环）。15个未离心处理的试件中有11个在孔隙处而非切口处断裂。相比之下，当通过离心降低孔隙率时，15个试件中有13个在切口处断裂。对于骨水泥与松质骨的复合试件，在7兆帕（641,056 ± 444,131次循环对237,969 ± 124,153次循环）和15兆帕（8800 ± 4673次循环对1534 ± 719次循环）下进行测试时，经离心处理的试件的疲劳寿命相比未离心处理的试件有显著增加。即使存在松质骨或全关节置换中使用的尖锐表面切口，通过离心降低骨水泥的孔隙率也能显著延长其疲劳寿命。这些数据支持了这样一种观点，即通过离心降低骨水泥的孔隙率可能会延长骨水泥固定型全关节置换中部件的固定时间。
