The Effect of Epitendinous Suture Technique on Gliding Resistance During Cyclic Motion After Flexor Tendon Repair: A Cadaveric Study

Purpose: To investigate the effects of motion following repair with a modified Kessler core suture and 5 different epitendinous suture designs on the gliding resistance, breaking strength, 2-mm gap force, and stiffness of flexor digitorum profundus tendons in a human in vitro model. Methods: The flexor digitorum profundus tendons of the index, middle, ring, and little fingers of 50 human cadavers were transected and repaired with a 2-strand modified Kessler suture and assigned to 5 groups based on type of epitendinous suture design. The 5 epitendinous designs tested were a simple, running epitendinous suture whose knot was outside the repair (simple running KO); a simple, running epitendinous suture whose knot was inside the repair (simple running KI); a cross-stitch epitendinous suture; an interlocking, horizontal mattress (IHM) epitendinous suture; and a running-locking epitendinous suture. The tendon repair strength and 2-mm gap force were measured after 1,000 cycles of tendon motion. The resistance to gap formation, a measure of repair stiffness, was obtained from the force versus gap data. Results: None of the repairs showed any gap formation after 1,000 cycles of tendon motion. The cross-stitch epitendinous suture, IHM epitendinous suture, and running-locking epitendinous suture all had significantly lower gliding resistance than the simple running KO epitendinous suture after 1 cycle. The simple running KI epitendinous suture had significantly lower gliding resistance than the simple running KO epitendinous suture after 100 cycles and 1,000 cycles. The differences for gap force at 2 mm and stiffness of the repaired tendon evaluation were not statistically significant. The cross-stitch epitendinous suture, IHM epitendinous suture, and running-locking epitendinous suture all had significantly higher maximal failure strength after 1,000 cycles than the simple running KI epitendinous suture. Conclusions: The cross-stitch, IHM, and running-locking epitendinous sutures had the best combination of higher strength and lower gliding resistance in this study. Although these findings suggest a potential for these suture types to be preferred as epitendinous sutures, these repairs should first be investigated in vivo to address their effect on tendon healing and adhesion formation.