Steen H, Fjeld T O, Bjerkreim I, Tevik A, Aldegheri R, Trivella G
Sophies Minde Orthopaedic Hospital, University of Oslo, Norway.
J Orthop Res. 1988;6(5):730-5. doi: 10.1002/jor.1100060516.
Limb lengthening of the left femur was performed in 12 sheep, 7-8 months of age. After weakening of the cortex by drill holes, a controlled fracture was created in the diaphysis. The bone segments were fixed in reduced position using a unilateral external fixation device. The fixator was left in neutral position for 10 days postoperatively when lengthening started. By means of daily distraction at a rate of 1.0 mm once a day for 3 weeks, an average lengthening of 1.9 cm (11.9%) was obtained. Two weeks after distraction had been discontinued, distinct callus bridging of the lengthening zone was confirmed radiographically in all animals. At this time the rigid state of fixation was converted to a system allowing axial compression by loading in half the animals. The other half of the animals served as controls with the fixator remaining unchanged. The external device was left on until 5 weeks after the end of distraction. At this time the animals were killed. Both femora of all animals were tested mechanically in torsion. The average ultimate torsional strength of the elongated femur compared with control was 71% in the group with dynamic axial fixation and 65% in the control group. No significant difference in relative strength of the tested bones in the two groups was found. We conclude that intermittent axial compression by loading during consolidation had no significant effect on the bone-healing process evaluated by radiography and mechanical testing.
对12只7 - 8月龄的绵羊进行了左侧股骨延长术。通过钻孔削弱皮质骨后，在骨干处制造可控骨折。使用单侧外固定装置将骨段固定在复位位置。术后10天，在开始延长时将固定器置于中立位。通过每天以1.0毫米的速率进行牵引，持续3周，平均延长了1.9厘米（11.9%）。在停止牵引两周后，通过X线检查证实所有动物延长区均有明显的骨痂桥接。此时，将一半动物的固定器状态从刚性固定转换为允许轴向加压的系统，另一半动物作为对照组，固定器保持不变。外固定装置一直保留到牵引结束后5周。此时处死动物。对所有动物的双侧股骨进行扭转力学测试。与对照组相比，动态轴向固定组延长后股骨的平均极限抗扭强度为71%，对照组为65%。两组受试骨的相对强度无显著差异。我们得出结论，在骨痂形成期通过加载进行间歇性轴向加压，对通过X线检查和力学测试评估的骨愈合过程没有显著影响。
