Improving Gliding Ability After Flexor Tendon Repair
Principal Investigator: Peter C. Amadio, M.D.
Project Coordinator: Chunfeng Zhao, M.D. — zhao.chunfeng@mayo.edu
Surface Modification of Extrasynovial Tendon
Although extrasynovial tendons are often used for tendon grafts, their rough surface leads to a higher frictional force, which is associated with more adhesions than the intrasynovial tendon graft. The purpose of this study was to use carbodiimide derivatization to chemically modify hyaluronic acid (cd-HA) and bind the substance to exposed amino acid groups on the extrasynovial tendon surface. The results showed that the modified HA significantly reduced the tendon gliding resistance and maintained a smoother surface as examined by scanning electron microscopy (SEM) (Figure 1).
Figure 1. A: PL tendon after 500 cycles gliding under the pulley (25 X); B: PL tendon treated with cd-HA gelatin after 500 cycles motion (25 X). C: PL tendon after 500 cycles motion (10K X); D: FDP tendon (intrasynovial) surface (20K X)
Surface Modification after FDP Tendon Repair
Since the extrasynovial tendon modified by cd-HA gelatin demonstrated a reduced gliding resistance, the next study considered the surface treatment on a repaired tendon. Following 500 cycles of simulated flexion/extension tendon motion, repaired tendons coated with a cd-HA gelatin exhibited decreased gliding resistance without affecting tendon mechanical properties.
Surface Modification of Extrasynovial Tendon Graft In Vivo
The preliminary in vitro work on improving the tendon gliding using a surface treatment provided the data to continue the study in an in vivo model. Using a canine model cd-HA gelatin was applied to an extrasynovial tendon that was used as a graft to replace the FDP tendon. Studies are ongoing for 1, 3, and 6 weeks post-operative, but p reliminary results show that gliding resistance appears lower in the surface modified group compared to control. These results are encouraging and are validating our central hypothesis that lower gliding resistance results in an improved outcome.
Lubricin as a Lubricant for Extrasynovial Canine Tendon
Lubricin is a superficial zone protein that is present in normal tendons. The purpose of this study was to see if lubricin could be used as an exaganous substance to reduce tendon gliding resistance. The results showed that lubricin was effective in reducing the gliding resistance compared to the control. We believe this preliminary work using lubricin validates our plan to investigate not only hyaluronan and its modifications, but also lubricin, and modifications of lubricin, to improve tendon gliding in our canine model.
