Application of stretchable strain sensors and an inertial measurement unit for simulative tension analysis of the calcaneofibular ligament in formalin-fixed cadavers

• Published in: Clinical biomechanics (Bristol) 2024-12, Vol.120, p.106358, Article 106358
• Main Authors: Yoshizuka, Hisayoshi, Nakao, Yutaro, Kuraoka, Akio
• Format: Article
• Language: English
• Subjects: Aged; Ankle Joint - physiology; Biomechanical Phenomena; Cadaver; Calcaneofibular ligament; Equipment Design; Female; Formaldehyde; Formalin-fixed cadaver; Humans; Inertial measurement unit; Lateral ankle ligament complex; Lateral Ligament, Ankle; Male; Range of Motion, Articular - physiology; Stress, Mechanical; Stretchable strain sensor; Tensile Strength
• ISSN: 0268-0033; 1879-1271; 1879-1271
• DOI: 10.1016/j.clinbiomech.2024.106358

The calcaneofibular ligament, a component of the lateral ligament complex of the ankle joint, plays an essential role in ankle-joint stability. To understand the mechanism of sprain-induced calcaneofibular ligament injury, the effect of ankle positions on calcaneofibular ligament tension needs to be ascertained. We propose a convenient method that combines stretchable strain sensors and an inertial measurement unit for simulative tension analysis of the calcaneofibular ligament in formalin-fixed cadavers. The stretchable strain sensor was pre-stretched approximately 1.3 times and, then set along the direction of the calcaneofibular ligament; a capacitance value from the sensor was used as a parameter to reflect the tension generated. Accurate three-axial inertial measurement unit-based monitoring of joint angles was undertaken for ten cadaveric ankles in measurements at 10° intervals from 30° plantarflexion to 20° dorsiflexion, followed by the investigation of additional effects with 10° inversion and eversion. Two-way repeated-measures ANOVA revealed a significant interactive effect for plantar/dorsiflexion × inversion/eversion and main effects for plantar/dorsiflexion and inversion/eversion. Post hoc pairwise analysis confirmed that 20° dorsiflexion or 10° inversion induces tension, whereas 10° eversion causes relaxation. Moreover, a promotional interactive effect by 20° dorsiflexion and 10° inversion and an offsetting effect by 10° eversion to 20° dorsiflexion were revealed. The measured values showed high levels of reliability and reproducibility (intraclass correlation coefficient [1,1] = 0.89). These results appropriately demonstrate the tensile action of calcaneofibular ligament. The novel approach investigated herein potentially opens new avenues for precise ligament-function evaluation. •We proposed a new practical method for functional analysis of cadaveric ligaments.•This easy-to-install method can be applied to formalin-fixed specimens.•Typical, significant calcaneofibular ligament behaviors were detected.•Unknown complicated tensile actions of calcaneofibular ligament were detected.•This strategy potentially opens a new avenue to evaluate precise ligament function.