[In-vitro stability of rotator cuff repair techniques]

Rotator cuff repair techniques were examined in vitro. First, the mechanical properties of nine different tendon-grasping techniques were compared using 159 normal infraspinatus sheep tendons. The clinically most frequently used simple stitch and mattress suture failed at low-to-moderate loads (two stitches, 184 N and 269 N) with the sutures pulling out of the tendons. A modification of the Mason-Allen grasping technique improved the ultimate tensile strength to 359 N (two stitches) without allowing relevant gap formation. Augmentation with synthetic materials did not improve the mechanical properties of the tendon-grasping techniques tested. The mechanical properties of different anchoring techniques to bone were assessed using osteoporotic bone specimens with mechanical properties comparable to those of proximal humeri with long-standing cuff defects. Single as well as double transosseous suture fixation (139 N and 146 N) and suture anchor fixation (142 N) were weak. Tying the knots over a plate-like cortical bone augmentation device improved the failure strength to 329 N. Some of these data were presented in the English literature in 1994. Considering the excellent preliminary experience in the clinical application of the modified Mason-Allen grasping technique and cortical augmentation, it seemed appropriate to present them in German as well.