Recovery of flexor tendon gliding after tendon laceration and repair within the fibro-osseous pulley system remains a difficult problem. In particular, injuries in Zone 2 produce significant loss of functional strength and motion after repair. Adhesions often restrict the normal excursion of the tendon. After repair, early mobilization of the tendon is crucial in prevention of post-operative adhesions. Passive mobilization techniques are currently preferred, but, because passive flexion may result in tendon buckling within the sheath, these may not produce complete gliding of the tendon within the sheath, even under ideal conditions. This buckling, in turn, may depend upon the degree of gliding resistance, or friction, within the tendon sheath. The purpose of this study is to compare the gliding resistance of commonly used methods to repair human flexor digitorum profundus (FDP) tendon, with the gliding resistance of a normal tendon, by direct measurement at the tendon-pulley interface. The protocol will test the hypothesis that adequate gliding of the repaired tendon by passive mobilization can only be accomplished if the gliding resistance is overcome by the passive motion protocol. The proposal will also test the hypothesis that if adequate gliding is truly accomplished, then post-operative adhesions will be reduced. Finally, it will evaluate the effect of postoperative rehabilitation on tendon repair breaking strength. Human cadaver specimens will be used for the initial in vitro assessment of gliding resistance. A canine model will then be adopted for both the in vitro, and in vivo evaluation. The combination of human and canine testing of similar repairs, in vitro, will permit some point of comparison for the canine in vivo results. Thus, if repairs behave similarly in vitro, in dogs and humans, it may be reasonable to expect that canine in vivo results may predict human in vivo (i.e., clinical) findings. A method recently developed and validated by the applicant laboratory will be used to measure gliding resistance between tendon and pulley. The concept of synergistic wrist motion, developed and validated in the past few years, will be adopted for post-operative mobilization to achieve tendon gliding.
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