The Effect of surface modification on gliding ability of decellularized flexor tendon in a canine model in vitro

Purpose: To investigate the gliding ability and mechanical properties of decellularized intrasynovial tendons with and without surface modification designed to reduce gliding resistance. Methods: We randomly assigned 33 canine flexor digitorum profundus tendons to 1 of 3 groups: untreated fresh tendons, to serve as a control; tendons decellularized with trypsin and Triton X-100; and tendons decellularized as in group 2 with surface modification using carbodiimide-derivatized hyaluronic acid and gelatin (cd-HA-gelatin). Tendons were subjected to cyclic friction testing for 1,000 cycles with subsequent tensile stiffness testing. We qualitatively evaluated the surface roughness after 1,000 cycles using scanning electron microscopy. Results: The gliding resistance of the decellularized group was significantly higher than that of both the control and cd-HA-gelatin tendons (0.20, 0.09, and 0.11 N after the first cycle; and 0.41, 0.09, and 0.14 N after 1,000 cycles, respectively). Gliding resistance between the control and cd-HA-gelatin groups was not significantly different. The Young modulus was not significantly different between groups. The surfaces of the control and cd-HA-gelatin-treated tendons appeared smooth after 1,000 cycles, whereas those of the decellularized tendons appeared roughened under scanning electron microscopy observation. Conclusions: Decellularization with trypsin and Triton X-100 did not change tendon stiffness. However, although this treatment was effective in removing cells, it adversely altered the tendon surface in both appearance and gliding resistance. Surface modification with cd-HA-gelatin improved the tendon surface smoothness and significantly decreased the gliding resistance. Clinical relevance: The combination of decellularization and surface modification may improve the function of tendon allografts when used clinically.