LOSS OF ANCHOR FIXATION AFTER ARTHROSCOPIC ROTATOR CUFF REPAIR

Abstract

Aim: Review causes of anchor fixation failures in patients who underwent arthroscopic rotator cuff repair.

Methods: Between 2003 and 2006, 650 arthroscopic rotator cuff repairs were performed by the senior author. Of these, anchor fixation failure occurred in fifteen patients. A retrospective review was undertaken to find out the reasons for their failure.

Results: There were ten women and five men, age range 46–84 (mean age 64). Thirteen underwent repair with metallic knotless anchors (Arthrocare), and two with 5.5mm biodegradable screw anchors (Arthrotek). Knotless anchors were used to repair six massive, one large, three medium and three small tears. The two patients with biodegradable anchor repair had only small tears, each held with a single anchor. All but one failure was apparent at six weeks. One metallic anchor failed at four months. Twelve knotless anchors failed through pull-out and one broke. Both biodegradable anchors broke at the eyelet.

Discussion: The increasing strength of suture material has shifted the weak point away from the suture-tendon interface towards the anchor-bone interface. Arthroscopic techniques permit a wider age range of patients suitable for surgery, each with varying degrees of osteoporosis in the proximal humerus, increasing risk of anchor pull-out. Multiple anchor insertions to reduce stiff, retracted tears may also lead to weakening of the bone table in the footprint area of the greater tuberosity. Incomplete anchor deployment, commonly at the curved cortical bone edge of greater tuberosity can also lead to failure.

Conclusion: Anchors failed if tension in the repair exceeds the bones capacity to retain the anchor, if the anchor is incompletely deployed or if one anchor is stressed beyond its tension capability. We recommend that consideration is given to spreading the tension of the tissue repair amongst the anchors placed in the greater tuberosity.