Discussion
Protrusion and migration of suture anchors in shoulder surgery has been documented extensively.3,4 Zuckerman and Matsen4 divided these complications into 4 groups: (1) incorrect placement, (2) migration after placement, (3) loosening, and (4) device breakage. These complications may be frequently related to surgical technique, and all these studies describe backward migration of the anchor out of the drill hole. In the current case, the anchor tip penetrated the articular surface of the humeral head, not because of anchor migration but because the anchor was inserted too far. To the authors’ knowledge, there is only 1 reported case of anchor protrusion through the humeral head; it involved a different type of anchor insertion system.5 In that case, there was only mild cartilage damage to the glenoid, and the patient recovered after removal of the anchors.
Several factors contributed to the improper insertion of the anchor in the current patient. First, repairing a high-grade articular side defect or partial articular supraspinatus tendon avulsion lesion can be technically challenging because rotator cuff tissue obscures the view when inserting the anchor. Second, the anchor was inserted too medially on the greater tuberosity, which made the distance from the tuberosity to the joint shorter. Wong and colleagues5 performed an analysis of the angle of insertion that would be safe using a PEEK PushLock SP system (Arthrex), but they emphasized that the angle depends on the configuration of the particular insertion system. The current case also shows that the surgeon should be cognizant of the fact that penetration of the humeral head by the anchor can occur if the surgeon is unaware of the distance from the anchor to the laser line on the insertion device or of the distance from the tuberosity to the articular surface of the humeral head.
The current case also shows that the type of anchor and delivery system may contribute to this complication. Double-loaded suture anchors can decrease the number of anchors needed for secure fixation. Bioabsorbable anchors can be used for this purpose, but they may be technically more difficult to use for repairing partial tears of the rotator cuff. Better visualization of the laser line on the anchor may be facilitated by using a probe from an anterior portal to hold the cuff up while the anchor is inserted.
This case has shown the importance of obtaining postoperative radiographic studies in patients who have metal anchors placed during shoulder surgery, especially if they complain of continued pain, new pain, crepitus, or grinding. When conventional radiography is insufficient for locating the anchor or its proximity to the joint line, computed tomography can be helpful.1
Conclusion
Removing failed suture anchors can be challenging, especially when they protrude into the joint on the humeral side.1,6 The best way to prevent this complication is through careful technique. The anchors should not be inserted beyond the depth of the laser line on the anchors, and every attempt should be made to make sure the laser line is visible at the time of anchor insertion. Postoperative radiographs should be considered for patients with metal anchors in the shoulder, especially if the patient continues to have symptoms or develops new symptoms in the shoulder after surgery.