Evaluation of the mechanical properties and clinical application of nickel-titanium shape memory alloy anal fistula clip

Heng Deng; Ming Li; Xiaoli Fang; Jun Zhang; Jianmin Wang; Kun Tang; Ran Tang; Ru Jia; Ying Han; Yang Shi; Yu'ang Dong

doi:10.3389/fsurg.2023.1235666

Evaluation of the mechanical properties and clinical application of nickel-titanium shape memory alloy anal fistula clip

Front Surg. 2023 Aug 23:10:1235666. doi: 10.3389/fsurg.2023.1235666. eCollection 2023.

Authors

Heng Deng¹, Ming Li², Xiaoli Fang², Jun Zhang³, Jianmin Wang², Kun Tang², Ran Tang², Ru Jia¹, Ying Han², Yang Shi², Yu'ang Dong³

Affiliations

¹ Department of Anorectal Surgery, Second Affiliated Hospital of Anhui University of Chinese Medicine, Hefei, China.
² Department of Anorectal Surgery, First Affiliated Hospital of Anhui University of Traditional Chinese Medicine, Hefei, China.
³ College of Traditional Chinese Medicine, Anhui University of Chinese Medicine, Hefei, China.

Abstract

Objective: The study investigates the mechanical properties of a nickel-titanium shape memory alloy anal fistula clip (NiTi-AFC), studies the surgical method of treating anal fistula, and evaluates its clinical efficacy.

Methods: The anal fistula clip was formed in nickel-titanium alloy with a titanium content of 50.0%-51.8%. The mechanical properties and chemical properties were tested. A total of 31 patients with anal fistula were enrolled between 1 January 2020 and 1 January 2023. All patients underwent internal orifice closure surgery using NiTi-AFC, and anorectal magnetic resonance or ultrasound was performed before surgery and 6 months after surgery for diagnosis and evaluation. Fistula cure rates, length of stay, perianal pain, and Wexner incontinence scores were retrospectively compared between patients treated with NiTi-AFC and patients treated with other surgical methods.

Result: NiTi-AFC has a density of 6.44-6.50 g·cm^-3, with a shape-restoring force of 63.8 N. The corrosion rate of NiTi-AFC in 0.05% hydrochloric acid solution at atmospheric pressure and 20°C is approximately 6.8 × 10^-5 g·(m·h)^-1. A total of 31 patients (male/female: 19/12, age: 43.7 ± 17.8 years) were included. Among them, 22.6% (7) had multiple anal fistula, 16.1% (5) had high anal fistula, and 48.3% (15) had perianal fistula Crohn's disease. In total, 12.9% (4/31) did not achieve primary healing, underwent fistula resection, and eventually recovered. A retrospective analysis showed that the fistula healing rate, length of stay, and anal pain of NiTi-AFC treatment were similar to those of other traditional surgeries, but the Wexner incontinence score was significantly lower.

Conclusion: NiTi-AFC has shape memory properties, corrosion resistance, superelastic effect, and surface cell adhesion. It is applied to internal orifice closure surgery of anal fistula, with good therapeutic effect, and can protect the anal function.

Keywords: anal fistula clip; clinical application; internal orifice; mechanical properties; nickel–titanium alloy.

Grants and funding

The Natural Science Foundation of Anhui Province (grant number 2008085QH388) and Clinical Research Foundation of Anhui University of Chinese Medicine (grant number 2021efylc02) funded the study.