Optimization of the MGH repair using an algorithm for tenorrhaphy evaluation

Previous investigations have demonstrated the superior strength and toughness of the MGH four-strand tendon repair technique and shown that it neither weakens during maximum tendon softening nor interferes with healing in an in vivo rabbit model. In the current study, the biomechanical performance of the modified Becker (MGH) and the modified Kessler repairs were compared in situ using a dynamic human cadaveric model to evaluate strength, toughness, glide efficiency, and operator variability. Three different surgeons performed a total of 42 zone II flexor digitorum profundus repairs in 14 fresh human cadaver hands. The modified Becker (MGH) repairs were stronger (79 +/- 3 versus 64 +/- 4 N; p < 0.01) and tougher (0.092 +/- 0.002 versus 0.078 +/- 0.003 J; p < 0.01) than the Kessler repairs while allowing equally efficient glide (32 +/- 6 versus 33 +/- 4 percent; p > 0.9). Strength was operator-dependent only for the modified Kessler repair (p < 0.005). We then established the optimal configuration of the MGH tenorrhaphy (number of preloaded crosses on either side of the tendon transection) by examining gap resistance ex vivo. Fifty-one MGH flexor tendon repairs were performed on explanted fresh human cadaver tendons. The experimental groups were randomly assigned to receive 0, 1, 2, 3, or 4 crosses on each side of the tenorrhaphy. Strength and toughness to gap formation and to ultimate failure were assessed tensiometrically. The MGH two-cross configuration was most resistant to gap formation (peak load 39 +/- 3 N; p < 0.05), establishing this configuration as the optimal design of this four-strand crisscrossing repair technique. The augmented Becker (MGH) repair is significantly stronger and tougher than the modified Kessler repair and demonstrates no operator dependence. It is a superior technique for zone II tenorrhaphy in the human hand. An algorithm is presented as a systematic approach that includes the important elements necessary for the rigorous biomechanical evaluation of any tendon repair technique.