The effects of multiple-strand suture techniques on the tensile properties of repair of the flexor digitorum profundus tendon to bone

We examined the effects of multiple-strand suture techniques on the tensile properties of flexor digitorum profundus tendon-to-bone repairs in a human cadaver finger model. Forty-four fingers were obtained from the cadavera of fifteen donors who had been an average of seventy-four years old (range, fifty-four to eighty-nine years old) at the time of death. Four or eight-strand proximal grasping sutures were secured to the distal phalanx of each finger with use of either a suture anchor or a dorsally placed button. There were four subgroups of eleven fingers each. We found that repairs performed with use of a dorsally placed button had greater yield force, ultimate force, and rigidity than those performed with use of an anchor and that repairs performed with eight strands had greater ultimate force than those performed with four strands. These differences were significant (p < 0.05). We could detect no differences among the four types of repairs with regard to the amount of relative tendon-bone elongation at twenty newtons of force. The repairs performed with eight strands and a dorsally placed button had an average yield force (and 95 per cent confidence interval) of 50.0 ± 14.1 newtons, an average ultimate force of 68.5 ± 14.6 newtons, an average rigidity of 744 ± 327 newton/(millimeter/millimeter), and an average tendon- bone elongation of 3.4 ± 0.7 millimeters at twenty newtons of force. Multiple-comparison testing showed that the eight-strand repairs performed with a dorsally placed button had greater ultimate force than the other three types of repairs as well as greater yield force and rigidity than the four and eight-strand repairs performed with a suture anchor.