Anchored Transosseous-Equivalent Versus Anchorless Transosseous Rotator Cuff Repair: A Biomechanical Analysis in a Cadaveric Model.

BACKGROUND: The original approach for the repair of torn rotator cuffs involved an open technique with sutures passing through the greater tuberosity and tendon. The development of suture anchors allowed for an all-arthroscopic approach with anchor configurations attempting to re-create a transosseous fixation pattern. Presently, an arthroscopic approach can be combined with a transosseous suture configuration without using anchors.

PURPOSE: To evaluate cyclic loading, ultimate load to failure, and the failure mechanisms of transosseous-equivalent (TOE) repair with anchors and anchorless transosseous (AT) repair of rotator cuff tears.

STUDY DESIGN: Controlled laboratory study.

METHODS: Supraspinatus tears (25 mm) were created in 20 fresh-frozen, human cadaveric shoulders, which were randomized to TOE or AT repair (10 in each group, paired experimental design). Biomechanical testing was performed with an initial preload, cyclic loading, and load to failure. Optical markers were used to monitor gap formation in 3 planes, and the failure mode was recorded. Paired t tests were used to make comparisons of biomechanical parameters between the groups. Multinomial logistic regression was used to compare failure modes between the groups. Significance was set to .05.

RESULTS: The TOE group had a significantly higher mean (±SD) ultimate failure load (578.5 ± 123.8 N) than the AT group (468.7 ± 150.9 N) ( P = .034). The TOE group also had a significantly less mean first-cycle excursion (2.97 ± 1.97 mm) than the AT group (4.70 ± 2.04 mm) ( P = .046). There were no significant differences between the groups in cyclic elongation or linear stiffness during cyclic loading. Primary modes of failure were a type 2 tendon tear with medial tendon disruption in the TOE group (7/10) and a type 1 tendon tear with lateral tendon disruption in the AT group (6/10).

CONCLUSION: TOE repair resulted in a significantly higher mean failure load compared with AT repair in a cadaveric model. The most common modes of failure were a type 2 tendon tear in the TOE group and a type 1 tendon tear in the AT group.

CLINICAL RELEVANCE: A higher mean failure load in TOE versus AT constructs may come at the cost of a less favorable failure mode adjacent to medial anchors at the musculotendinous junction, potentially making revision difficult.