Martin James, Johnson Nick A, Shepherd Jenny, Dias Joseph
Leicester Medical School, University of Leicester, Leicester, UK.
Department of Health Sciences, University of Leicester, Leicester, UK.
Bone Jt Open. 2023 Aug 21;4(8):612-620. doi: 10.1302/2633-1462.48.BJO-2023-0058.R1.
There is ambiguity surrounding the degree of scaphoid union required to safely allow mobilization following scaphoid waist fracture. Premature mobilization could lead to refracture, but late mobilization may cause stiffness and delay return to normal function. This study aims to explore the risk of refracture at different stages of scaphoid waist fracture union in three common fracture patterns, using a novel finite element method.
The most common anatomical variant of the scaphoid was modelled from a CT scan of a healthy hand and wrist using 3D Slicer freeware. This model was uploaded into COMSOL Multiphysics software to enable the application of physiological enhancements. Three common waist fracture patterns were produced following the Russe classification. Each fracture had differing stages of healing, ranging from 10% to 90% partial union, with increments of 10% union assessed. A physiological force of 100 N acting on the distal pole was applied, with the risk of refracture assessed using the Von Mises stress.
Overall, 90% to 30% fracture unions demonstrated a small, gradual increase in the Von Mises stress of all fracture patterns (16.0 MPa to 240.5 MPa). All fracture patterns showed a greater increase in Von Mises stress from 30% to 10% partial union (680.8 MPa to 6,288.6 MPa).
Previous studies have suggested 25%, 50%, and 75% partial union as sufficient for resuming hand and wrist mobilization. This study shows that 30% union is sufficient to return to normal hand and wrist function in all three fracture patterns. Both 50% and 75% union are unnecessary and increase the risk of post-fracture stiffness. This study has also demonstrated the feasibility of finite element analysis (FEA) in scaphoid waist fracture research. FEA is a sustainable method which does not require the use of finite scaphoid cadavers, hence increasing accessibility into future scaphoid waist fracture-related research.
舟状骨腰部骨折后，安全允许活动所需的舟状骨愈合程度存在模糊性。过早活动可能导致再骨折，但延迟活动可能会导致僵硬并延迟恢复正常功能。本研究旨在使用一种新型有限元方法，探讨三种常见骨折模式下舟状骨腰部骨折愈合不同阶段的再骨折风险。
从一只健康手和腕部的CT扫描中，使用3D Slicer免费软件对舟状骨最常见的解剖变异进行建模。该模型被上传到COMSOL Multiphysics软件中，以实现生理增强的应用。按照鲁斯分类法产生了三种常见的腰部骨折模式。每个骨折具有不同的愈合阶段，从10%到90%的部分愈合，以10%的愈合增量进行评估。对远极施加100 N的生理力，使用冯·米塞斯应力评估再骨折风险。
总体而言，90%至30%的骨折愈合显示，所有骨折模式的冯·米塞斯应力有小幅逐渐增加（从16.0兆帕至240.5兆帕）。所有骨折模式从30%至10%的部分愈合显示冯·米塞斯应力有更大增加（从680.8兆帕至6288.6兆帕）。
先前的研究表明，25%、50%和75%的部分愈合足以恢复手和腕部的活动。本研究表明，30%的愈合足以使所有三种骨折模式恢复正常的手和腕部功能。50%和75%的愈合既无必要，还会增加骨折后僵硬的风险。本研究还证明了有限元分析（FEA）在舟状骨腰部骨折研究中的可行性。FEA是一种可持续的方法，不需要使用有限的舟状骨尸体，从而增加了未来舟状骨腰部骨折相关研究的可及性。
