In bone fracture healing, new tissue gradually forms, ossifies, and eventually remodels itself to restore mechanical stiffness and strength across injury site. Mechanical strain at the fracture site has been implicated in controlling the process of healing and numerical mechanoregulation models with strain-based fuzzy logic rules have been applied to simulate bone healing for simple fracture geometries. However, many of these simplified models cannot capture in vivo observations such as delays in healing with torsional instability or differences in healing rate between different fracture types. Accordingly, the purpose of this work was to apply a fuzzy logic mechanoregulation fracture healing simulation technique to 3D models representing a range of clinically inspired fracture geometries with intramedullary nail fixation and multiaxial loading conditions. The models predicted that the rate of healing depends on the geometry of the fracture and that all fracture types experience a small healing delay with torsional instability. The results also indicated that when realistic torsional loading and fixator mechanics are included, previously published strain-based rules for tissue destruction lead to simulated nonunions that would not be expected in vivo. This suggested that fracture healing may be more robust to distortional strain than has been previously reported and that fuzzy logic models may require parameter tuning to correctly capture clinically relevant healing. The strengths of this study are that it includes fracture morphology effects, realistic implant mechanics, and an exploratory adaptation of the upper distortional strain threshold. These findings may help future researchers extend these methods into clinical fracture healing prediction.

在骨折愈合过程中，新组织逐渐形成、骨化并最终自我重塑以恢复整个损伤部位的机械刚度和强度。骨折部位的机械应变与控制愈合过程有关，具有基于应变的模糊逻辑规则的数值机械调节模型已应用于模拟简单骨折几何形状的骨愈合。然而，许多这些简化模型无法捕捉体内观察结果，例如扭转不稳定导致的愈合延迟或不同骨折类型之间愈合率的差异。因此，这项工作的目的是将模糊逻辑机械调节骨折愈合模拟技术应用于 3D 模型，该模型代表具有髓内钉固定和多轴负载条件的一系列临床启发的骨折几何形状。这些模型预测愈合速度取决于骨折的几何形状，并且所有骨折类型都会经历小的愈合延迟和扭转不稳定。结果还表明，当包括现实的扭转载荷和固定器力学时，先前发布的基于应变的组织破坏规则会导致模拟的骨不连，这在体内是无法预料的。这表明骨折愈合可能比之前报道的对扭曲应变更稳健，并且模糊逻辑模型可能需要参数调整才能正确捕捉临床相关愈合。这项研究的优势在于它包括断裂形态效应、真实的种植体力学以及对上畸变应变阈值的探索性适应。这些发现可能有助于未来的研究人员将这些方法扩展到临床骨折愈合预测中。