Matsuki Hiroshi, Horii Emiko, Majima Masataka, Genda Eiichi, Koh Shukuki, Hirata Hitoshi
Department of Orthopedic Surgery, Nishio Municipal Hospital, Nishio, Japan.
J Orthop Sci. 2009 Mar;14(2):144-9. doi: 10.1007/s00776-008-1310-y. Epub 2009 Apr 1.
Distal fragment resection is one of the salvage procedures for scaphoid nonunion with osteoarthritis. Despite being reported as a simple procedure with favorable midterm outcomes, further arthritic changes remain a concern in the long term. Scaphoid waist fracture is classified into volar or dorsal types according to the displacement pattern, but the indications for distal fragment resection have never been discussed for these fracture types.
We reconstructed a normal wrist model from computed tomography images and performed theoretical analysis utilizing a three-dimensional rigid body spring model. Two types of scaphoid fracture nonunion followed by distal fragment resection were simulated.
With volar-type nonunion, the force transmission ratio of the radiolunate joint increased, and the pressure concentration was observed in the dorsal part of the scaphoid fossa and volar part of the lunate fossa of the radius; no deterioration was seen in the midcarpal joint. In the distal fragment resection simulation for volar-type nonunion, pressure concentrations of the radiocarpal joint resolved. With dorsal-type nonunion, force transmission ratio in the radiocarpal joint resembled that of the normal joint model. Pressure concentrations were observed in the dorsoulnar part of the scaphoid fossa and radial styloid. The pressure concentration in the dorsoulnar part of the scaphoid fossa disappeared in the resection model, whereas the concentration in the radial styloid remained. In the midcarpal joint, pressure was concentrated around the capitate head in the nonunion model and became aggravated in the resection model.
With volar-type scaphoid nonunion, distal fragment resection seems to represent a reasonable treatment option. With dorsal-type nonunion, however, pressure concentration around the capitate head was aggravated with the simulated distal fragment resection, indicating a potential risk of worsening any preexisting lunocapitate arthritis.
远侧骨折块切除术是舟骨不愈合伴骨关节炎的挽救手术之一。尽管该手术被报道为一种简单的手术，中期效果良好，但长期来看，进一步的关节炎改变仍是一个问题。舟骨腰部骨折根据移位模式分为掌侧型或背侧型，但对于这些骨折类型，远侧骨折块切除术的适应证从未被讨论过。
我们从计算机断层扫描图像重建了一个正常腕关节模型，并利用三维刚体弹簧模型进行了理论分析。模拟了两种类型的舟骨骨折不愈合并进行远侧骨折块切除术。
对于掌侧型不愈合，桡月关节的力传递比增加，在舟骨窝的背侧部分和桡骨月骨窝的掌侧部分观察到压力集中；腕中关节未见恶化。在掌侧型不愈合的远侧骨折块切除模拟中，桡腕关节的压力集中得到缓解。对于背侧型不愈合，桡腕关节的力传递比与正常关节模型相似。在舟骨窝的背尺侧部分和桡骨茎突处观察到压力集中。在切除模型中，舟骨窝背尺侧部分的压力集中消失，而桡骨茎突处的压力集中仍然存在。在腕中关节，不愈合模型中头状骨头部周围压力集中，在切除模型中加重。
对于掌侧型舟骨不愈合，远侧骨折块切除术似乎是一种合理的治疗选择。然而，对于背侧型不愈合，模拟远侧骨折块切除术后头状骨头部周围压力集中加重，表明存在使任何先前存在的月头关节炎恶化的潜在风险。
