Surgical repair of the rotator cuff: a biomechanical evaluation of different tendon grasping and bone suture fixation techniques.

OBJECTIVE: This study investigated the initial strength and failure mode of different rotator cuff repair techniques.
BACKGROUND: Full or partial re-rupture of the repair is one of the main post-operative complications for rotator cuff repair. The rate of failure is strongly affected by the extension of the tear, increasing in case of large or massive tears up to 62%.
DESIGN: The study was planned to assess the three individual components of the tendon-to-bone repair (tendon grasping, suture knotting, suture-to-bone fixation) and to identify the best combinations in terms of mechanical strength to failure. The best combinations were tested to compare the mechanical behaviour of the entire repair and suggest potential improvements in the repair technique.
METHODS: Experimental tests were performed using sheep shoulders. Three tendon-grasping techniques, two suture knotting techniques, and the effect of bone augmentation with metallic plate and bone quality on suture-to-bone fixation were investigated.
RESULTS: This study assessed the mechanical behaviour of different repair components. The best combinations of the investigated techniques showed that the weakest link was the tendon-suture interface. More importantly, the compliance of the investigated repairs was large.
CONCLUSIONS: The initial strength of the rotator cuff repair can be improved by changing the repair technique. Nevertheless, even a low physiological load stressing the repaired tendon may cause a gap formation at the tendon-bone interface without necessarily producing failure of the repair. RELEVANCE: Post-operative protection of the repaired rotator cuff from tension load is necessary to reduce the risk of delaying or preventing of the healing process.