Application of carbodiimide derivatized synovial fluid to enhance extrasynovial tendon gliding ability

Abstract

Purpose: To investigate the effects of surface modification of extrasynovial tendon with a carbodiimide derivatized synovial fluid (SF) on the gliding ability of extrasynovial tendon for a possible tendon graft application.

Methods: We used 63 peroneus longus tendons from canine hind legs. We immediately assessed 3 tendons morphologically using a scanning electron microscope (SEM); these served as the normal tendon group. The other 60 tendons were randomly assigned to each of 6 experimental groups treated with (1) control (saline); (2) 1% 1-ethyl-3-(3-dimethylaminopropyl) carbodiimide hydrochloride (EDC) plus 1% N-hydroxysuccinimide (NHS) (cd only); (3) 1% EDC/NHS plus 10% gelatin (cd-G); (4) SF plus 1% EDC/NHS plus 10% gelatin (cd-SF-G); (5) SF only; or (6) SF plus 1% EDC/NHS (cd-SF). We measured the gliding resistance for 1,000 cycles of simulated flexion-extension motion. We also observed the tendon surface smoothness by SEM.

Results: Compared with the first cycle in each group, the gliding resistance after 1,000 cycles of tendon motion was significantly increased in the control, cd only, cd-gelatin, SF only, and cd-SF groups (p<.05). In contrast, we found no significant difference in gliding resistance between the first cycle and 1,000 cycles for the cd-SF-G-treated group. In addition, the gliding resistance in the cd-SF, cd-G, and cd-SF-G groups was significantly lower than the control group after 1,000 cycles of tendon motion (p<.05) and the gliding resistance of the cd-SF-G group was significantly lower than both the cd-G and cd-SF groups (p<.05). On SEM, the surface treated with cd-SF-G was smooth after 1,000 cycles, whereas the other surfaces were rough.

Conclusions: Surface modification of extrasynovial tendon with cd-SF-G improves tendon gliding ability. This treatment may be useful clinically in improving the outcomes of tendon autografts.

FIGURE 1

Pulley unit: The proximal phalanx and intact A2 pulley were mounted on the device and fixed in full extension of the proximal interphalangeal joint by a longitudinal K-wire.

FIGURE 2

Carbodiimide derivitization reaction.

FIGURE 3

Frictional force at first cycle and 1,000 cycles in each group. Different letters indicate significant differences (p<.05).

FIGURE 4

The trend of gliding resistance from the first cycle to 1,000 cycles.

FIGURE 5

Scanning electron microscope images after 1,000 cycles of motion. (Low magnification, ×25.) A smoother surface was noted in the groups treated with cd-SF-gelatin and cd-gelatin.

FIGURE 6

Scanning electron microscope images after 1,000 cycles of motion. (High magnification, ×5,000.) A smoother surface was noted in the groups treated with cd-SF-gelatin and cd-gelatin.