ANALYTIC MODEL TO PREDICT THE STRENGTH OF TENDON REPAIRS

We developed an analytic model to predict suture load-sharing immediat ely after flexor tendon repair in the hand. Tendon repair was mathemat ically modeled as two nonlinear springs in parallel, representing sepa rate core and peripheral sutures that were in series with a third nonl inear spring representing the tendon. To serve as a basis for, and val idation of, our analytic model, fresh human flexor digitorum profundus tendons were harvested and mechanically tested either intact or after surgical repair in a variety of ways: core suture alone, superficial peripheral suture alone, deep peripheral suture alone, core suture plu s superficial peripheral suture, and core suture plus deep peripheral suture. The stiffness and strength of the composite repairs predicted with use of the analytic model were comparable with those determined e xperimentally. Furthermore, the model predicted inequities in suture l oad-sharing, with 64% of the applied load carried by the peripheral su ture when it was placed superficially, as compared with 77% when the p eripheral suture was placed deep. Our results demonstrate a disparity in load-sharing within composite suture systems, the rectification of which may lead to significant improvement in the repair strength. To t his end, we expect that our analytic model will serve as a basis for t he design of more efficient, and consequently stronger, suture techniq ues.