Tendon Surface Modification by Chemically Modified HA Coating after Flexor Digitorum Profundus Tendon Repair

Carbodiimide derivatized HA (cd-HA) is less soluble in water than normal HA, and therefore has an increased tissue residence time. The purpose of this study was to study the effect of cd-HA gel on gliding and repair integrity during simulated repetitive motion of a repaired tendon in vitro. A total of 36 flexor digitorum profundus (FDP) tendons from six adult mongrel dogs were used and divided into three groups of control, simple HA, and cd-HA. The gliding resistance between the FDP and the proximal pulley, FDS, and bone was measured before laceration and after modified Kessler technique repair at 1, 5, 10, 50, 100, 200, 300, 400, and 500 cycles. After gliding testing, failure load, tendon stiffness, and resistance to gap formation were measured. The results showed from the first cycle to the 10th cycle, there were no significant differences in gliding resistance between the three testing groups (p > 0.05). From the 50th cycle onwards, the friction was significantly lower in the cd-HA gel group than in the control group (p < 0.05). Neither breaking strength, nor tendon stiffness, nor resistance to gap formation of the repairs were significantly different between the three groups (p > 0.05).