[Primary strength of conventional and alternative suture techniques of the rotator cuff. A biomechanical study]

The aim of this biomechanical study was to evaluate rotator cuff repair strength using different suture anchor techniques compared to conventional repair, taking into consideration the native strength of the supraspinatus tendon. Therefore, a defined defect of the supraspinatus was created in 50 freshly frozen cadaver specimen (group size n = 10; median age at death: 56 years). Five methods were employed for cuff repair: standard transosseous suture, modified transosseous suture with patch augmentation and three suture anchors (Acufex Wedge TAG, Acufex Rod TAG und Mitek GII). The maximum tensile load of the five techniques was: standard transosseous suture, 410 N; modified transosseous suture, 552 N; Wedge TAG, 207 N; Rod TAG, 217 N; Mitek GII, 186 N. The difference between the suture anchor and standard techniques were highly significant (P < 0.001). In this series, the Mitek Gll anchor showed the lowest anchor dislocation rate at 3% (n = 1). The Wedge TAG system had a dislocation rate of 27% (n = 8) and the Rod TAG system 43% (n = 13). Suture anchor techniques revealed about 20%, the standard technique 34% and its modification 60% of the hypothetically calculated native tendon strength. Compared to conventional transosseous suture techniques, the use of the suture anchors tested in this series does not significantly increase the primary fixation strength of rotator cuff repair. The metallic implant with two barbs (Mitek GII) seems to be superior to the polyacetal anchors when inserted into the spongiform bone of the greater tubercle. The considerably weaker repair strength needs to be taken into consideration in postoperative patient rehabilitation, especially after the use of suture anchors.