Biomechanical comparison of two techniques for arthroscopic suprapectoral biceps tenodesis: interference screw versus implant-free intraosseous tendon fixation.

BACKGROUND

A novel arthroscopic technique allows for intraosseous tendon placement in biceps tenodesis using bone tunnels and suture while avoiding the expense of an implant. No biomechanical characterization exists for this construct.

METHODS

Tensile tests were used to compare a suture-only biceps tenodesis technique (arthroscopic biceps intraosseous tenodesis [ABIT]) with interference screws in 7 pairs of cadaveric shoulders. The ABIT used a modified finger-trap suture method to secure the tendon to itself through an intraosseous bone tunnel. Interference screw placement followed the manufacturer's protocol for implantation. An open technique was used to provide consistency during laboratory preparation.

RESULTS

During cyclic loading, the screws were significantly stiffer (P = .040) but dissipated more energy (P = .002). During failure loading, suture-only specimens showed significantly greater failure loads (P < .001) and deformation (P = .046). The failure mechanism for the ABIT method was tendon elongation with progressive tensioning and slippage of the tendon through the suture mass. No complete tendon failure occurred for the ABIT. Gross tendon failure occurred in all interference screw tests at the bone-tendon-screw interface. No screw or suture failed in any biceps tendon test.

CONCLUSION

The ABIT construct showed significantly higher failure loads and deformation compared with interference screws. The comparable stiffness after cycling of both constructs suggests that micromotion at the bone-tendon interface is similar, which-in addition to the intraosseous fixation-may be important in promoting healing. The ABIT construct was found to absorb and restore more energy (hysteresis), suggesting potential for greater tendon preservation, which may translate into improved construct longevity. The suture-only method can eliminate the expense of an implant.