Tohoku J. Exp. Med., 2023 November, 261(3)

Low Young’s Modulus TiNbSn Alloy Locking Plates Accelerate Osteosynthesis in Rabbit Tibiae

Masashi Koguchi,¹ Yu Mori,¹ Masayuki Kamimura,¹ Kentaro Ito,¹ Hidetatsu Tanaka,¹ Hiroaki Kurishima,¹ Tomoki Koyama,¹ Naoko Mori,² Naoya Masahashi³ and Toshimi Aizawa¹

¹Department of Orthopaedic Surgery, Tohoku University Graduate School of Medicine, Sendai, Miyagi, Japan
²Department of Radiology, Akita University Graduate School of Medicine, Akita, Akita, Japan
³Institute for Material Research, Tohoku University, Sendai, Miyagi, Japan

A new beta TiNbSn alloy with a Low Young’s modulus of approximately 40 GPa has been developed to resolve the stress shielding by Young’s modulus divergence. In this study, the efficacy of TiNbSn alloy locking plates on bone repair is compared to that of commercially pure titanium (CP-Ti). The TiNbSn alloy and CP-Ti, which have Young’s moduli of 49.1 GPa and 107 GPa, respectively, were compared. Male Japanese white rabbits were anesthetized, and osteotomy and osteosynthesis with locking plates were performed on the right tibia. The bone repair was assessed using micro-computed tomography (CT), histomorphometry, immunohistochemistry, and mechanical testing. Micro-CT, histomorphometry, immunohistochemistry, and mechanical testing were performed four weeks after osteotomy. Six weeks after surgery, micro-CT and mechanical testing were performed. Micro-CT analysis at four weeks after surgery showed that the intramedullary fracture callus in the TiNbSn alloy group had more bone volume and numerous bridging structures compared to the CP-Ti group (CP-Ti vs. TiNbSn alloy, 34.3 ± 13.1 mm³ vs. 61.3 ± 19.6 mm^3, p = 0.02; mean ± standard deviation). At four weeks post-osteotomy, the healed tibia showed significantly higher strength in the TiNbSn alloy group compared with CP-Ti (CP-Ti vs. TiNbSn alloy, 81.3 ± 31.2 N vs. 133.7 ± 46.6 N, p = 0.04). TiNbSn alloy locking plates had a more positive impact on bone formation and bone strength restoration than the CP-Ti locking plates during the early phase of bone healing.

Key words —— locking plate; Low Young’s modulus; osteosynthesis; osteotomy; TiNbSn alloy

© 2023 Tohoku University Medical Press

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Tohoku J. Exp. Med., 2023 November, 261(3), 199-209.

Correspondence: Yu Mori, Department of Orthopaedic Surgery, Tohoku University Graduate School of Medicine, 1-1 Seiryo-machi, Aoba-ku, Sendai, Miyagi 980-8574, Japan.

e-mail: yu-mori@med.tohoku.ac.jp