Transosseous-equivalent repair with and without medial row suture tying: a cadaveric study of infraspinatus tendon strain measurement

BACKGROUND: How the use of the transosseous-equivalent (TOE) technique effects the stress concentration in repaired rotator cuff tendon is unknown. This study was conducted to determine the strain between the intact rotator cuff tendon and the tendon repaired using the TOE technique with and without medial row suture tying. MATERIALS AND METHODS: Strain of the infraspinatus tendon from 10 fresh-frozen cadavers was measured at the (A) tendon insertion, (B) tendon footprint, (C) tendon of the medial suture level, and (D) musculotendinous junction of the tendon. The strain was measured during 2 cycles of internal and external rotations while applying 4 different loads to the infraspinatus. After the intact tendon was evaluated, an artificially created tear of the infraspinatus was repaired using the TOE technique. Medial row sutures were tied in 5 shoulders (T group) and untied in the rest (UT group). The strains at 4 sites were compared between the intact and the TOE-repaired tendon and between the T and UT groups. RESULTS: The strain was significantly reduced at site B in the repaired tendon in the T and UT groups compared with the intact tendon for all loads (P < .05). At site C, the strain increased for all loads in the T group compared with the intact tendon (P < .05). CONCLUSION: The strain of the tendon over the footprint area was significantly smaller than the intact tendon when repaired with the TOE technique. The strain at the medial suture level was significantly greater when the medial sutures were tied compared with those untied.