Department of Orthopedic Surgery, University of Texas Health Science Center, San Antonio, Texas.
The Center for Excellence in Limb Lengthening & Reconstruction, Texas Scottish Rite Hospital for Children, Dallas, Texas.
J Bone Joint Surg Am. 2021 Feb 3;103(3):257-263. doi: 10.2106/JBJS.20.00380.
Reverse dynamization is a mechanical manipulation regimen designed to accelerate bone-healing and remodeling. It is based on the hypothesis that a fracture that is initially stabilized less rigidly allows micromotion to encourage initial cartilaginous callus formation. Once substantial callus has formed, the stabilization should then be converted to a rigid configuration to prevent the disruption of neovascularization. The aim of the present study was to investigate whether bone-healing can be accelerated using a regimen of reverse dynamization in a large-animal osteotomy model.
Transverse 2-mm tibial osteotomies were created in 18 goats, stabilized using circular external fixation, and divided into groups of 6 goats each: static fixation (rigid fixation), dynamic fixation (continuous micromotion using dynamizers), and reverse dynamization (initial micromotion using dynamizers followed by rigid fixation at 3 weeks postoperatively). Healing was assessed with the use of radiographs, micro-computed tomography, and mechanical testing.
Radiographic evaluation showed earlier and more robust callus formation in the dynamic fixation and reverse dynamization groups compared with the static fixation group. After 8 weeks of treatment, the reverse dynamization group had reduced callus size, less bone volume, higher bone mineral density, and no evidence of radiolucent lines compared with the static fixation and dynamic fixation groups. This appearance is characteristic of advanced remodeling, returning closest to the values of intact bone. Moreover, the tibiae in the reverse dynamization group were significantly stronger in torsion compared with those in the static fixation and dynamic fixation groups.
These findings confirmed that tibial osteotomies under reverse dynamization healed faster, healed objectively better, and were considerably stronger, all suggesting an accelerated healing and remodeling process.
This study demonstrates that the concept of reverse dynamization challenges the current understanding regarding the optimal fixation stability necessary to maximize the regenerative capacity of bone-healing. When reverse dynamization is employed in the clinical setting, it may be able to improve the treatment of fractures by reducing the time to union and potentially lowering the risk of delayed union and nonunion.
反动态化是一种旨在加速骨愈合和重塑的机械操作方案。它基于这样的假设，即最初稳定性较差的骨折允许微动，从而促进初始软骨痂的形成。一旦形成了大量的骨痂，就应该将稳定性转换为刚性配置，以防止新生血管化的破坏。本研究旨在探讨在大型动物截骨模型中，使用反动态化方案是否可以加速骨愈合。
在 18 只山羊中创建了 2mm 宽的胫骨横向截骨，使用环形外固定器固定，并将其分为 6 只羊一组：静态固定（刚性固定）、动态固定（使用动力器持续微动）和反动态化（术后 3 周初始使用动力器微动，然后刚性固定）。使用 X 射线、微计算机断层扫描和机械测试评估愈合情况。
放射学评估显示，与静态固定组相比，动态固定组和反动态化组更早、更活跃地形成骨痂。治疗 8 周后，与静态固定组和动态固定组相比，反动态化组的骨痂体积减小，骨量减少，骨密度增加，且没有射线可透线。这种表现是高级重塑的特征，最接近完整骨的数值。此外，与静态固定组和动态固定组相比，反动态化组的胫骨在扭转方面明显更强。
这些发现证实了胫骨截骨在反动态化下愈合更快、愈合更好、强度更高，这表明骨愈合和重塑过程加速。
本研究表明，反动态化的概念挑战了目前关于最大限度发挥骨愈合再生能力所需的最佳固定稳定性的理解。在临床环境中使用反动态化时，它可以通过缩短愈合时间并降低延迟愈合和不愈合的风险来改善骨折的治疗。
