Romere Chase M, Sidrak Jason P, Hollenbeck Justin F M, Schafer Kevin A, Haytmanek Craig T, Backus Jonathon D
The Steadman Clinic, Vail, CO, USA.
Steadman Philippon Research Institute, Vail, CO, USA.
Foot Ankle Int. 2025 Aug;46(8):895-902. doi: 10.1177/10711007251341886. Epub 2025 Jun 28.
Metatarsophalangeal (MTP) arthrodesis is the gold standard for treatment of end-stage degeneration or severe hallux valgus deformities. Traditional fixation uses stainless steel or titanium plates, often with a crossing screw. Nitinol, a superelastic nickel-titanium alloy, offers dynamic compression. Nevertheless, it is unknown how nitinol implantation in the context of first-MTP arthrodesis performs biomechanically. We hypothesized that nitinol constructs would demonstrate biomechanical performance comparable or superior to a traditional plate-and-screw construct.
Twelve pairs of cadaveric metatarsophalangeal joints were organized into 3 groups according to a balanced incomplete block design: (1) a traditional titanium plate and cross-screw (PS) construct, (2) a nitinol staple and cross screw (NSS) construct, and (3) a proprietary nitinol hybrid screw (NHS) construct. The PS construct consisted of a plate with a compression cross screw; the NSS construct consisted of a nitinol staple with a compression cross screw; and the NHS construct consisted of a hybrid nitinol staple with a compression cross screw. Each specimen was cyclically loaded over 100 cycles at 1 Hz from 20 to 90 N followed by failure testing. A high-definition camera recorded gapping. Failure load, deflection, and stiffness were recorded.
Compared with the PS construct, both nitinol constructs (NSS and NHS) demonstrated significantly higher failure loads (NSS: 196 ± 101 N, = .011; NHS: 161 ± 45 N, = .045), greater stiffness (NSS: 33 ± 15 N/mm, = .012; NHS: 29 ± 12 N/mm, = .042), reduced deflection after cyclic loading (NSS: 6 ± 3 mm, = .047; NHS: 7 ± 3 mm, = .048), and decreased gapping at failure (NSS: 1 ± 1 mm, = .003; NHS: 2 ± 1 mm, = .008). No significant differences were observed between NSS and NHS.
Nitinol constructs for MTP arthrodesis demonstrated superior mechanical performance compared with a traditional plate-and-screw construct, with higher failure load and stiffness.
These results support the growing use of nitinol for joint fusion, highlighting its potential to improve load to failure and reduce displacement under cyclic loading.
跖趾关节（MTP）融合术是终末期退变或重度拇外翻畸形治疗的金标准。传统固定方式使用不锈钢或钛板，常搭配交叉螺钉。镍钛诺，一种超弹性镍钛合金，可提供动态加压。然而，在第一跖趾关节融合术中植入镍钛诺的生物力学性能尚不清楚。我们假设镍钛诺结构在生物力学性能上可与传统钢板螺钉结构相当或更优。
根据平衡不完全区组设计，将12对尸体跖趾关节分为3组：（1）传统钛板加交叉螺钉（PS）结构；（2）镍钛诺U形钉加交叉螺钉（NSS）结构；（3）专利镍钛诺混合螺钉（NHS）结构。PS结构由带加压交叉螺钉的钢板组成；NSS结构由带加压交叉螺钉的镍钛诺U形钉组成；NHS结构由带加压交叉螺钉的混合镍钛诺U形钉组成。每个标本在1Hz频率下从20N到90N循环加载100次，随后进行破坏试验。用高清摄像机记录间隙。记录破坏载荷、位移和刚度。
与PS结构相比，两种镍钛诺结构（NSS和NHS）均表现出显著更高的破坏载荷（NSS：196±101N，P = 0.011；NHS：161±45N，P = 0.045）、更大的刚度（NSS：33±15N/mm，P = 0.012；NHS：29±12N/mm，P = 0.042）、循环加载后更小的位移（NSS：6±3mm，P = 0.047；NHS：7±3mm，P = 0.048）以及破坏时更小的间隙（NSS：1±1mm，P = 0.003；NHS：2±1mm，P = 0.008）。NSS和NHS之间未观察到显著差异。
用于MTP融合术的镍钛诺结构与传统钢板螺钉结构相比，表现出更优的力学性能，具有更高的破坏载荷和刚度。
这些结果支持镍钛诺在关节融合中越来越多的应用，突出了其在提高破坏载荷和减少循环加载下位移方面的潜力。
