Department of Plastic and Hand Surgery, University Hospital Zurich, Zurich, Switzerland.
Laboratory for Movement Biomechanics, Swiss Federal Institute of Technology (ETH) Zurich, Zurich, Switzerland.
J Hand Surg Eur Vol. 2023 May;48(5):435-444. doi: 10.1177/17531934231157565. Epub 2023 Feb 22.
Assessment of scaphoid fracture union on computed tomography scans is not currently standardized. We investigated the extent of scaphoid waist fracture union required to withstand physiological loads in a finite element model, based on a high-resolution CT scan of a cadaveric forearm. For simulations, the scaphoid waist was partially fused at the radial and ulnar sides. A physiological load of 100 N was transmitted to the scaphoid and the minimal amount of union to maintain biomechanical stability was recorded. The orientation of the fracture plane was varied to analyse the effect on biomechanical stability. The results indicate that the scaphoid is more prone to re-fracture when healing occurs on the ulnar side, where at least 60% union is required. Union occurring from the radial side can withstand loads with as little as 25% union. In fractures more parallel to the radial axis, the scaphoid seems less resistant on the radial side, as at least 50% union is required. A quantitative CT scan analysis with the proposed cut-off values and a consistently applied clinical examination will guide the clinician as to whether mid-waist scaphoid fractures can be considered as truly united.
目前，在计算机断层扫描（CT）上评估舟状骨骨折愈合情况尚未标准化。我们基于对尸体前臂的高分辨率 CT 扫描，研究了在有限元模型中需要多大程度的舟状骨腰部骨折愈合才能承受生理负荷。在模拟中，舟状骨腰部在桡侧和尺侧部分融合。将 100N 的生理负荷传递到舟状骨上，并记录维持生物力学稳定性所需的最小愈合量。改变骨折平面的方向，以分析其对生物力学稳定性的影响。结果表明，当愈合发生在尺侧时，舟状骨更容易再次骨折，此时至少需要 60%的愈合。而从桡侧开始愈合，则只需 25%的愈合即可承受负荷。在更平行于桡骨轴的骨折中，舟状骨在桡侧的抵抗力似乎较弱，因为至少需要 50%的愈合。定量 CT 扫描分析和提出的截断值以及一致的临床检查将指导临床医生确定是否可以认为舟状骨腰部中段骨折已经完全愈合。
