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| IMAGE QUIZ ARCHIVE | ||||||
| Image Quiz | ||
| Mechanical Shoulder Pain in a Seventeen-Year-Old Girl Nine Months Following Arthroscopic Bankart Repair (continued) | ||
| Answer: Loose suture-anchor fragments in the left axillary recess | ||
 Fig. 3-A |
 Fig. 3_B |
For larger view, click on image |
| Fig. 3-A Transaxial fat-suppressed T1-weighted magnetic resonance imaging-arthrogram of the left shoulder, demonstrating an intact glenoid labrum and rotator cuff with no signs of degenerative change. At the level of the anterior glenoid, there is a small radiolucency (arrow) representing the remaining portion of the suture anchor attached to the glenoid rim. Fig. 3-B Coronal fat-suppressed T1-weighted magnetic resonance imaging-arthrogram of the left shoulder, showing a 4 × 2 mm disc-shaped fragment (arrow) present within the axillary recess. |
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| The patient underwent arthroscopically aided removal of a suture-anchor fragment that was located in the axillary pouch (Figs. 4 and 5). | ||
 Fig. 4 |
Fig. 4 Arthroscopic view of the left shoulder, demonstrating the drilled glenoid hole (arrow) from which the bioabsorbable suture-anchor fragments became dislodged. For larger view, click on image |
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 Fig. 5 |
Fig. 5 Arthroscopic view of the left shoulder, showing the loose suture-anchor fragment (arrow) present within the axillary recess. For larger view, click on image |
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| Arthroscopic examination revealed that the patient had an intact biceps tendon and rotator cuff. She had a normal humeral head and glenoid without any evidence of scuffing or degeneration. The anterior-inferior glenohumeral ligament and labral complex were intact and well healed. Furthermore, there was no evidence of stretching or attenuation of the reconstructed glenohumeral ligament complex. Upon further evaluation of the glenohumeral joint, a second loosened anchor fragment was found superficially embedded in the glenoid rim at the 7:30 o'clock position. This anchor fragment was also removed arthroscopically. Six days following the surgery, the patient began a home-based physical therapy program with pendulum and wall-climbing exercises. Two weeks postoperatively, the patient had regained full range of motion of the left shoulder and had no further pain. | ||
| Discussion | ||
| During the evaluation of a patient with postoperative mechanical shoulder pain following this procedure, the differential diagnosis should include (1) dislodged/loose suture anchor, (2) recurrent shoulder instability and/or (3) labral tear. A mechanical clicking sensation is often associated with pain. Because of the similarities in clinical presentation among these entities, the examiner should utilize both physical examination and diagnostic imaging to make an accurate diagnosis. In the case of suspected shoulder instability, the examiner may use the load-and-shift test2 to reproduce any symptoms of instability; however, diagnostic imaging is essential to determine the cause of the instability. Magnetic resonance imaging is useful in the evaluation because it specifically highlights any soft-tissue injury or loose bodies. In this case, the patient presented with mechanical shoulder pain associated with activity but had no symptoms of instability, thereby pointing to a possible labral tear and/or dislodged suture anchor. Ultimately, we acquired a magnetic resonance imaging-arthrogram to further elucidate the shoulder joint and we found a loose anchor lying in the axillary recess. It is important to note that magnetic resonance arthrographic imaging must be obtained if a loose anchor is suspected, as bioabsorbable suture anchors cannot be detected on standard radiographs. | ||
| Several reports have discussed the general complications associated with arthroscopic shoulder surgery3-6. However, since the advent in 1991 of arthroscopic modified Bankart repair that makes use of suture anchors, there have been relatively few reports of complications directly attributable to the use of the suture anchors themselves7. Meyer and Gerber8 were recently the first to report two cases in which failure of Bankart repair that made use of bioabsorbable anchors was attributable to the eyelet cutouts of the anchors. In both cases, on repeat arthroscopic inspection, it was discovered that repair sutures were intact and knotted around avulsed labrum; however, the anchors were not displaced and remained fixed to the glenoid rim. Although the authors did not directly observe that the suture eyelets had broken or degraded, their findings led them to conclude that the anchor eyelet was the site of failure. The shoulder of each patient was subsequently repaired with use of new suture anchors, and the postoperative course for each was without further incident. In our patient, we found that the labrum was sufficiently healed to the glenoid rim; therefore, we did not believe that it was necessary to replace the dislodged suture anchor. | ||
| Richmond et al. reported that among a group of twenty-six patients, three metallic anchors had dislodged from bone and appeared in the soft tissue around the shoulder. However, these patients continued to have stable shoulders and were asymptomatic7. Snyder also reported complications associated with the use of suture anchors, including postoperative suture anchor migration and suture anchor dislodgment at the time of glenohumeral arthroscopic insertion10. According to Snyder, such events can be avoided by following specific manufacturer guidelines. These include using drill guides to localize and control proper drilling position and to avoid overdrilling the glenoid, inserting the anchor through an appropriate cannula to avoid snagging the soft tissue during insertion, and utilizing a safety suture that attaches the anchor to the insertion tool to prevent the anchor from becoming loose in the joint if dislodgment does occur during insertion10. Further recommendations for the avoidance of complications include careful attention to the proper placement of suture anchors within the glenoid9,11, orientation of the anchors away from the glenoid articular surface7,9,11,12, and stressing of the anchors at the time of placement to ensure proper fixation in the bone7,9. | ||
| In our patient, one of the suture anchors used for anterior-inferior capsular labral reconstruction dislodged late postoperatively and migrated to the axillary pouch. The patient subsequently had a popping sensation with activity in the left shoulder. Antonogiannakis et al.13, who utilized three knotless metallic suture anchors for an arthroscopic Bankart repair, reported a similar complication. We believe that dislodged bioabsorbable suture anchors need not be surgically removed if the patient is asymptomatic. However, many surgeons continue to use steel anchors, and as these anchors are not bioabsorbable, we believe that removal should be considered, especially if there are signs of shoulder instability. | ||
| One of the most likely explanations for the disengagement of the suture anchor in our patient was an inflammatory response to the bioabsorbable anchor. Soft-tissue complications of bioabsorbable anchors include sterile sinus formation, hypertrophic fibrous encapsulation, synovitis, and osteolysis14. Most symptomatic foreign-body reactions have been associated with the use of rapidly resorbed materials containing polyglycolic acid14-16. Foreign-body response to polyglycolic acid has been observed as early as three to six weeks postoperatively14,17. However, reactions to poly-L-lactic acid, which is the material that our suture anchors were made of, have been observed as well14,18. Bostman and Pihlajamaki reported on a foreign-body reaction in a patient in whom a poly-L-lactic acid screw was placed for ankle-fracture fixation four years postoperatively18. | ||
| We surmise that an inflammatory reaction to the anchor may have weakened the bone around the original repair, thereby allowing migration of the anchor into the axillary pouch. The postoperative radiographs that were taken when the patient initially presented with mechanical pain demonstrated an apparent widening of the glenoid drill-hole made in the anterior glenoid rim for anchor insertion, implicating an inflammatory response as the cause of disengagement of the suture anchor. | ||
| The complication that occurred in our patient illustrates the importance of considering migration of suture anchors as part of the differential diagnosis in patients who present with mechanical symptoms postoperatively. Appropriate imaging of the involved joint is necessary to confirm the diagnosis. Bioabsorbable anchors, which are undetectable on standard radiographs, can be visualized on magnetic resonance images. | ||
| *The authors did not receive grants or outside funding in support of their research for or preparation of this manuscript. They did not receive payments or other benefits or a commitment or agreement to provide such benefits from a commercial entity. No commercial entity paid or directed, or agreed to pay or direct, any benefits to any research fund, foundation, educational institution, or other charitable or nonprofit organization with which the authors are affiliated or associated. | ||
| References | ||
1. McFarland EG, Neira CA, Gutierrez MI, Cosgarea AJ, Magee M. Clinical significance of the arthroscopic drive-through sign in shoulder surgery. Arthroscopy. 2001;17:38-43. |
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