Abstract
An injury to the elbow's lateral ulnar collateral ligament (LUCL) is an orthopedic emergency that can impair joint stability and functional biomechanics throughout the upper extremity. The development and application of synthetic ligament substitutes, particularly short-chain-length and medium-chain-length polyhydroxyalkanoate (SCL-PHA and MCL-PHA) co-polymers, represent a promising innovation for lateral elbow stabilization. This experimental cadaveric study aimed to (1) compare biomechanical parameters of torque and angular rotation among control, damage, repair, and reconstruction groups and (2) compare stress and strain responses across the same groups. Twenty-four cadaveric elbows were allocated among six experimental conditions. The control group consisted of intact elbows (n = 4), while the damage group (n = 4) involved transection of the anterior capsule and extensor carpi radialis brevis (ECRB) to simulate ligament injury. The repair group (n = 4) underwent anterior capsular suturing. The reconstruction group (n = 12) was divided into three subgroups: palmaris longus (PL) autograft alone, PL with SCL-PHA co-polymer augmentation, and PL with MCL-PHA augmentation. Biomechanical testing measured maximum torque, angular displacement, shear stress, and strain, with statistical analysis conducted using descriptive statistics, one-way ANOVA, and post hoc multiple comparisons. The results demonstrated that maximum torque (F = 24.930, p < 0.001) and maximum shear stress (F = 8.130, p < 0.001) significantly differed among groups. The control group exhibited the highest mechanical performance (30.700 ± 9.368 Nm and 0.880 ± 0.216 MPa), whereas the damage group showed the lowest values (10.300 ± 2.904 Nm and 0.210 ± 0.073 MPa). The reconstruction group using palmaris longus with SCL-PHA co-polymer reinforcement (RC-PLSCL) demonstrated torque (29.550 ± 7.656 Nm) and shear stress (0.610 ± 0.206 MPa) comparable to those of the control group (p > 0.05), indicating near-physiological mechanical behavior. These findings suggest that SCL-PHA co-polymer augmentation offers superior biomechanical restoration relative to standard repair and other reconstruction strategies, highlighting its potential as an advanced biomaterial for ligament reconstruction in LUCL injuries.