Cornu Olivier, Libouton Xavier, Naets Bénédicte, Godts Bernard, Van Tomme John, Delloye Christian, Banse Xavier
Orthopaedic Research Laboratory, Université Catholique de Louvain, Brussels, Belgium.
Acta Orthop Scand. 2004 Jun;75(3):309-14. doi: 10.1080/00016470410001240.
Defatted bone chips with or without freeze-drying and irradiation have mechanical advantages as compared to fresh-frozen controls in in vitro models of impaction. These improved results have been ascribed to replacement of viscous bone marrow by saline and embrittlement of the freeze-dried bone by irradiation.
To determine which of these hypotheses is correct, we compared the development of stiffness and compactness of morselized bone graft that had been: 1) fat-reduced with saline, and 2) fresh-frozen, solvent-detergent defatted, 3) freeze-dried irradiated and 4) not irradiated. We used 12 osteoarthrotic femoral heads to prepare these four batches of morselized bone, and impacted 18 samples from each batch in a cylinder. The frozen bone grafts were tested after thawing at room temperature for 2 hours and the freeze-dried grafts were tested after 30 minutes of rehydration. We monitored the development of compactness and stiffness of the material during impaction.
The stiffness of the freeze-dried irradiated bone was greater than that of the other three series after 10, 50 and 150 impactions. The freeze-dried bone chips that were not irradiated and the chips defatted with saline alone were less stiff than the fresh-frozen control after 150 impactions.
The brittleness of freeze-dried irradiated bone, caused by loss of the capacity to absorb energy in a plastic way, increases the compactness and stiffness of the morselized grafts. Washing bone with saline alone or treating bone with solvent-detergent but no irradiation had no similar mechanical advantage and the bone did not impact better than fresh-frozen undefatted bone in our model.
在体外嵌压模型中，经或未经冻干及辐照处理的脱脂骨碎片与新鲜冷冻的对照相比具有机械优势。这些改善的结果归因于盐水替代了粘性骨髓以及辐照使冻干骨变脆。
为确定这些假设中哪一个正确，我们比较了以下几种碎骨移植物的硬度和紧实度发展情况：1）用盐水减脂的；2）新鲜冷冻、溶剂去污剂脱脂的；3）冻干辐照的；4）未辐照的。我们使用12个骨关节炎股骨头制备这四批碎骨，并在圆柱体中对每批的18个样本进行嵌压。冷冻骨移植物在室温下解冻2小时后进行测试，冻干移植物在复水30分钟后进行测试。我们在嵌压过程中监测材料紧实度和硬度的发展。
在进行10次、50次和150次嵌压后，冻干辐照骨的硬度大于其他三个系列。在进行150次嵌压后，未辐照的冻干骨碎片和仅用盐水脱脂的碎片比新鲜冷冻对照的硬度小。
冻干辐照骨因失去以塑性方式吸收能量的能力而变脆，增加了碎骨移植物的紧实度和硬度。仅用盐水冲洗骨头或用溶剂去污剂处理但不进行辐照没有类似的机械优势，并且在我们的模型中，这种骨头的嵌压效果并不比新鲜冷冻的未脱脂骨好。
