CORA ABSTRACT #V - 1

CYCLIC LOADING OF ROTATOR CUFF REPAIRS: AN IN VITRO BIOMECHANICAL COMPARISON OF BIOABSORBABLE ANCHORS WITH TRANSOSSEOUS SUTURES

R.T. Bicknell

J.C. Harwood

L. Ferreria

D.G. Chess

G.J.W. King

J.A. Johnson

D. Drosdowech

The objective of this study was to compare rotator cuff repair strength after physiologically simulated cyclic loading of a bioabsorbable anchor and traditional transosseous sutures and to correlate the results with bone mineral density, age and sex. This study utilized eight paired cadaveric proximal humeri with intact rotator cuff tendons. A standardized full-thickness defect (20 mm x 10 mm) was created in each supraspinatus tendon. One specimen from each pair was then randomized and repaired with bioabsorbable nonsuture-based anchors (BioTwist, Linvatec). The paired specimen was repaired using transosseous sutures. Each specimen was then subjected to a physiological stepwise cyclic loading protocol. Repair site migration was measured using machine vision measurement methods. Mode of failure, number of cycles and load to failure were measured and recorded for 50% (5 mm) and 100% (10 mm) loss of repair. These results were correlated with bone mineral density, age and sex. The anchors failed more often at the anchor-tendon interface, whereas the sutures tended to fail through the sutures. The number of cycles and load to failure for 50% loss of repair were significantly higher for the anchors compared to sutures (p<0.05). However, the corresponding values for 100% loss of repair were significantly higher for the sutures (p<0.05). These results did not correlate with bone mineral density, age or sex. Therefore, this study has described a new high resolution method of measuring tendon repair strength. As well, we have demonstrated that these anchors provide improved initial fixation, but eventually fail sooner, in comparison to a traditional suture-based repair.