Figure 5

Motion analysis of tendons with double and triple hemisection treatment (Group A and Group B). The distance between sections is 1 cm. (A) The F-L curves. The black curve represents the double-hemisection group and the blue curve represents the triple-hemisection group. The black spots on the curve represent (A1, B1) before the test, (A2, B2) when the failure load was reached, and (A3, B3) when the tendon was divided into two parts. As the tendon stretched, the force on the tendon rapidly increased until it reached its peak (A2, B2), which was the failure load. The failure load led to the initiation of a relative split between tendon hemisections. Thereafter, the force on the tendon decreased rapidly to a force that could maintain the tendon split until the tendon almost split into two parts (A3 and B3). (B) Video screenshots of the double- and triple-hemisection groups before the test (A1, B1), when the tendon reached the failure load (A2, B2), and when the tendon nearly split into two parts (A3, B3). The length of the tendon test area was 6 cm before beginning the tensile test. The distance from the clamping line to the plane of the nearest hemisection was measured before and after the tendon split. There was no significant difference in the distance between the clamp line and nearest hemisection between the groups (A2 and A3; B2 and B3). (C) The FEM of tendons of double- and triple-hemisection groups before the test (A1, B1), when the tendon reached the failure load (A2, B2), and when the tendon nearly split into two parts (A3, B3). The figure shows the stress distribution in tendons. Red indicates the greatest stress, and blue indicates the lowest stress. When the tendon was stretched, the stress inside the tendon increased and was greatest at the hemisection site (A2, B2). With an increase in stress at the hemisection, the tendon appeared to split between hemisections, and the stress at the splitting hemisection continued to support the split further (A3, B3). The stress on the hemisections without splits decreased after the initiation of splitting in the other two hemisections, but the deformation at this non-split hemisection was maintained (B3).