Melamed Eitan, Hinds Richard M, Gottschalk Michael B, Kennedy Oran D, Capo John T
New York University Hospital for Joint Diseases, NY, USA.
Hand (N Y). 2016 Dec;11(4):421-426. doi: 10.1177/1558944716628485. Epub 2016 Mar 8.
Recently, intramedullary headless screw (IMHS) has shown promise as an alternative to dorsal plate fixation of metacarpal fractures. The purpose of this study was to assess the biomechanical performance of IMHS versus plating. We hypothesized that IMHS fixation provides inferior stability to plating. Metacarpal fracture model with 3-mm of volar gapping in forty-four human cadaveric metacarpals was created. The specimens were divided into 5 groups: Group 1, 1.5-mm non-locking plate; Group 2, 1.5-mm locking plate; Group 3, 2.0-mm non-locking plate; Group 4, 2.0-mm locking plate; and Group 5, 2.4-mm short cannulated IMHS. A 4-point bending model was used to assess load-to failure (LTF) and stiffness. Mean LTF was 364 ± 130 N for 1.5-mm non-locking plates, 218 ± 94 N for 1.5-mm locking plates, 421 ± 86 N for 2.0-mm non-locking plates, 351 ± 71 N for 2.0-mm locking plates, and 75 ± 20 N for IMHS. Mean stiffness was 91 ± 12 N/mm for 1.5-mm non-locking plates, 110 ± 77 N/mm for 1.5-mm locking plates, 94 ± 20 N/mm for 2.0-mm non-locking plates, 135 ± 16 N/mm for 2.0-mm locking plates, and 55 ± 15 N/mm for IMHS. IMHS demonstrated significantly lower LTF and stiffness than plates. IMHS fixation of unstable metacarpal shaft fractures offers less stability compared to plating when loaded in bending. The LTF and stiffness of IMHS versus plating of metacarpal shaft fractures has not been previously quantified. Our results reveal that IMHS fixation is less favorable biomechanically and should be carefully chosen in regards to fracture stability.
最近，髓内无头螺钉（IMHS）已显示出有望成为掌骨骨折背侧钢板固定的替代方法。本研究的目的是评估IMHS与钢板固定的生物力学性能。我们假设IMHS固定提供的稳定性低于钢板固定。在44根人体尸体掌骨上创建了伴有3毫米掌侧间隙的掌骨骨折模型。标本分为5组：第1组，1.5毫米非锁定钢板；第2组，1.5毫米锁定钢板；第3组，2.0毫米非锁定钢板；第4组，2.0毫米锁定钢板；第5组，2.4毫米短空心IMHS。采用四点弯曲模型评估破坏载荷（LTF）和刚度。1.5毫米非锁定钢板的平均LTF为364±130牛，1.5毫米锁定钢板为218±94牛，2.0毫米非锁定钢板为421±86牛，2.0毫米锁定钢板为351±71牛，IMHS为75±20牛。1.5毫米非锁定钢板的平均刚度为91±12牛/毫米，1.5毫米锁定钢板为110±77牛/毫米，2.0毫米非锁定钢板为94±20牛/毫米，2.0毫米锁定钢板为135±16牛/毫米，IMHS为55±15牛/毫米。IMHS的LTF和刚度明显低于钢板。与钢板固定相比，在弯曲加载时，IMHS固定不稳定掌骨干骨折提供的稳定性较差。此前尚未对IMHS与掌骨干骨折钢板固定的LTF和刚度进行量化。我们的结果表明，IMHS固定在生物力学方面不太理想，在骨折稳定性方面应谨慎选择。
