Fjeld T O, Steen H
Norwegian College of Veterinary Medicine, Oslo, Norway.
J Orthop Res. 1988;6(3):360-8. doi: 10.1002/jor.1100060307.
Low-rate epiphyseal distraction of the left proximal tibia using a modified bilateral Hoffmann external fixation device, was accomplished in 14 goats (age 6-7 months). Daily distraction at a rate of 0.5 mm was continued for 5.5 weeks. Epiphysiolysis occurred after 5-9 days. After distraction had been discontinued, the external device was left in situ for fixation for 4 weeks. The animals in group 1 (n = 6), group 2 (n = 3), and group 3 (n = 5) were killed at 4, 16, and 32 weeks, respectively, from the end of the distraction period. The proximal growth plate of the elongated tibia appeared radiolucent at the conclusion of the study but was less distinct and reduced in height as compared with the control leg. The gained length at the end of the distraction period was on the average 2.2 cm (11.9%). This gain in length was reduced with further growth. In group 3, the final gain in length was reduced to half. A reduced cortical thickness of the bone within the area subjected to distractional force was observed. This finding is attributable to stress protection. An interesting observation comparing control and operated tibia was an increase of the cross-sectional diameter of the elongated bone. Both tibiae of all animals were tested mechanically. The torsional strength of the elongated tibiae as compared with controls was on the average 29% in group 1, 79% in group 2, and 95% in group 3. We conclude that leg lengthening by low-rate epiphyseal distraction in the proximal tibia is a justifiable alternative to other lengthening procedures in individuals approaching adolescence. In juveniles, lengthening by epiphyseal distraction may result in reduction in the longitudinal growth.
采用改良双侧霍夫曼外固定装置对14只6 - 7月龄山羊的左胫骨近端进行低速率骨骺牵张。以0.5毫米/天的速率持续牵张5.5周。5 - 9天后发生骨骺分离。牵张停止后，将外固定装置留在原位固定4周。分别在牵张期结束后的4周、16周和32周处死第1组（n = 6）、第2组（n = 3）和第3组（n = 5）的动物。研究结束时，延长胫骨的近端生长板呈透亮状，但与对照腿相比，不太清晰且高度降低。牵张期结束时获得的长度平均为2.2厘米（11.9%）。随着进一步生长，这种长度增加有所减少。在第3组中，最终长度增加减少到一半。观察到在受到牵张力的区域内骨皮质厚度减小。这一发现归因于应力保护。比较对照胫骨和手术胫骨的一个有趣观察结果是延长骨的横径增加。对所有动物的双侧胫骨进行力学测试。与对照相比，延长胫骨的扭转强度在第1组平均为29%，在第2组为79%，在第3组为95%。我们得出结论，对于接近青春期的个体，通过低速率骨骺牵张延长胫骨是其他延长手术的合理替代方法。在青少年中，通过骨骺牵张延长可能会导致纵向生长减少。
