Institute of Orthopedic Research and Biomechanics, Center of Musculoskeletal Research, University of Ulm, Ulm, Germany.
PLoS One. 2018 Aug 23;13(8):e0202702. doi: 10.1371/journal.pone.0202702. eCollection 2018.
Callus distraction is sometimes associated with a delay in the maturation process and serious complications. It is believed that these complications are often caused by instability of the bone segment fixation. Typical fixation devices, such as ring-fixators, show significant deformations in all directions under external loading and muscle forces. This leads to axial compression and tension as well as shear movements in the healing area. Herein we investigated the hypothesis that the direction of interfragmentary movement after callus distraction affects the bone formation and revascularization during the maturation process. Two custom fixator systems were designed to apply a protocol of lateral callus distraction and subsequent cyclic stimulation of the regenerate tissue. One fixator system was used to apply either compressive or tensile stimulation while the other was used to apply shearing stimulation. The fixators were applied to the tibial surface of the right hind leg of sheep specimens. During lateral callus distraction, a titanium plate was elevated by 0.275 mm perpendicular to the long axis of the bone twice daily, resulting in a 5.5 mm gap at the end of the ten-day distraction phase. Following a seven-day consolidation phase, the regenerate in the gap between tibial cortex and titanium plate was stimulated once daily by cyclic movement for 120 cycles. The stimulation was applied for 18 days with amplitudes of 0.6 mm in compression (Group C) or tension (Group T), or a 1.0 mm shear amplitude (Group S). Seven weeks postoperatively the specimens were analyzed for quantity of bone formation, the presence of cartilage and fibrous tissue, and blood vessel density. There was a significantly higher blood vessel density (4.6 ± 1.6%) in Group C than in Group T (1.2 ± 0.4%) or Group S (1.0 ± 0.5%) (p < 0.01). The amount of bone was significantly higher in Group C (25.6% ± 13.0%) than in Group T (13.5 ± 4.9%) (p < 0.05). Group S showed a similar amount of bone (14.0 ± 10.7%) to Group T. The results show that bone formation and revascularization are dependent on the direction of interfragmentary movement and that the cyclic compression best stimulates the healing process.
骨痂牵张有时与成熟过程的延迟和严重并发症有关。据信，这些并发症通常是由骨段固定的不稳定性引起的。典型的固定装置，如环式固定器，在外力和肌肉力作用下，在各个方向上都会发生显著的变形。这导致在愈合区域中产生轴向压缩、张力和剪切运动。在此，我们研究了骨痂牵张后骨间碎片运动的方向是否会影响成熟过程中的骨形成和再血管化的假设。设计了两种定制的固定器系统来应用侧向骨痂牵张和随后对再生组织进行周期性刺激的方案。一种固定器系统用于施加压缩或拉伸刺激，而另一种用于施加剪切刺激。将固定器应用于绵羊标本右后腿的胫骨表面。在侧向骨痂牵张期间，每天两次将钛板垂直于骨的长轴升高 0.275 毫米，导致在 10 天的牵张阶段结束时在骨端形成 5.5 毫米的间隙。在 7 天的巩固阶段之后，每天通过 120 个循环的周期性运动来刺激胫骨皮质和钛板之间间隙中的再生组织。用 0.6 毫米的压缩（C 组）或拉伸（T 组）或 1.0 毫米的剪切幅度（S 组）施加 18 天的刺激。手术后 7 周，对标本进行骨形成量、软骨和纤维组织存在情况以及血管密度分析。C 组的血管密度（4.6 ± 1.6%）明显高于 T 组（1.2 ± 0.4%）或 S 组（1.0 ± 0.5%）（p < 0.01）。C 组（25.6% ± 13.0%）的骨量明显高于 T 组（13.5% ± 4.9%）（p < 0.05）。S 组的骨量与 T 组相似（14.0 ± 10.7%）。结果表明，骨形成和再血管化取决于骨间碎片运动的方向，周期性压缩最能刺激愈合过程。
