Arthroscopic Repair of a Posterior Midcapsular Rupture Causing Posterior Shoulder Instability

Abstract

Background:

Gross posterior instability is rare and when found likely has an injury or deficiency to the posterior static restraints of shoulder associated with it. Traditionally, injuries to the posterior capsule have been difficult to diagnose and visualize with magnetic resonance imaging preoperatively, and very little literature regarding arthroscopic repair of posterior capsular tears exists currently.

Indications:

We present a repair of a posterior midcapsular and posterior labral tear in a 26-year-old man with recurrent left posterior shoulder instability using a novel all–arthroscopic technique.

Technique Description:

We performed a shoulder arthroscopy in a lateral decubitus position with the arm at 45° of abduction using standard posterior viewing and anterior working portals. Diagnostic arthroscopy revealed a large posterior midcapsular rupture approximately 2 cm lateral to the glenoid with an associated posterior labral tear. We created an accessory posterolateral portal with needle localization that was outside the capsular defect yet allowed access to the posterior labrum. Anatomic closure of the capsular tear was achieved arthroscopically with 3 interrupted No. 2 nonabsorbable sutures in a side–to–side fashion. Posterior labral repair and capsular shift were done to further address the instability using 2 knotless all–suture anchors percutaneously placed at the 7 o'clock and 9 o'clock position. We closed the posterior portal with a combination of curved and penetrating suture passers. Incisions were closed with interrupted 4-0 nylon. Postoperatively, the patient was placed in an ultra–sling for 4 weeks before physical therapy. We allowed light strengthening at 8 weeks, full strengthening at 12 weeks, and estimated return to sport at 4 months.

Results:

At 6 months postoperatively, the patient has regained symmetric motion, full strength, and has no residual pain or instability.

Conclusion:

Gross posterior instability is a rare and difficult condition to diagnose and manage. If no significant labral injuries are identified, injury to the posterior capsule must be considered and full assessment should be done when visualizing from the anterior portal. Repair of the posterior capsule is necessary and can be achieved all arthroscopically with this technique.

Graphical Abstract

This is a visual representation of the abstract.

VIDEO TRANSCRIPT

We present a case of arthroscopic repair of a posterior midcapsular rupture causing posterior shoulder instability.

We will start with the case presentation followed by a technique presentation of our arthroscopic posterior midcapsular repair and posterior labral repair followed by our postoperative protocol, a brief literature review, and finally pearls and pitfalls to the procedure and management of posterior shoulder instability.

We present a case of a 26-year-old man with recurrent left posterior shoulder instability. The patient initially suffered a traumatic posterior dislocation 6 years ago in a motorcycle accident and underwent successful closed reduction in the emergency department. Despite conservative treatment, the patient continued to have pain and instability during the last 6 years. The patient recently suffered a second frank left posterior shoulder dislocation after an altercation and again underwent closed reduction in the emergency department.

He finally presented to our clinic for definitive management.

On examination, he has reduced active but full passive range of motion, pain and instability with crossbody adduction, and a positive posterior load and shift test with significant apprehension.

Radiographs in our clinic show an anatomically reduced glenohumeral joint without obvious bony deformity. Magnetic resonance imaging (MRI) shows a small reverse Hill-Sachs lesion, and a small posterior labral tear. A computed tomography was obtained further delineating the reverse Hill-Sachs lesion and also demonstrating blunting of the posterior glenoid.

Given the patients chronic recurrent and symptomatic left posterior shoulder instability, we elected to proceed with operative management. Our plan is to perform a diagnostic left shoulder arthroscopy with posterior labral repair and consideration for a McLaughlin procedure based on intraoperative findings.

Our preference is to perform shoulder arthroscopy in a lateral decubitus position with the arm at 45° abduction in an arm holder. We use standard posterior viewing and anterior working portals and in the case of posterior shoulder instability, will make an accessory posterior lateral portal under needle localization ensuring access to the posterior labrum.

Diagnostic arthroscopy through the posterior portal did not reveal any pathology in the cartilage, the anterior superior labrum, the biceps tendon, or the rotator cuff. We did identify a small nonengaging reverse Hill-Sachs lesion, as well as fraying in the posterior labrum. The arthroscope was then placed in the anterior portal to visualize the posterior structures. At this time, we identified a large posterior midcapsular rupture extending from the 6 o'clock to the 10 o'clock position approximately 2 cm lateral to the glenoid.

There is also a posterior labral tear that extended from the 9 o'clock to 6 o'clock position. We typically perform a posterior labral repair through a standard posterior portal and an accessory portal; however, our standard portal was noted to be within the capsular defect. Because we elected to close this defect first, we made an accessory posterior lateral portal using needle localization approximately 2 cm distal to the acromion and lateral to the capsular defect, and we used this accessory portal to close the capsular rent.

We placed an 8.25-mm screw–in–cannula into this modified posterior portal, which was positioned outside the defect and would allow us to perform an arthroscopic all–inside repair of the posterior midcapsular rupture. A curved suture passer was used to pass a polydioxanone suture (PDS) shuttle stitch across the capsular defect.

We prefer to use a passer with multiple attachments due to the added versatility, but any curved passer can be used. We then shuttle a No. 2 Fiberwire across the defect for a side–to–side repair. The No. 2 Fiberwire can now be seen traversing the capsular defect. As they are passed, these sutures are tensioned and tied. You can see a suture has been placed inferiorly to close the defect. This process was repeated a total of 3 times during the capsular repair.

At this point, we proceeded with posterior labral repair. We prefer to use a technique described by Lacheta et al using an all–suture anchor tensionable repair as these allow for multiple bailout options, a knotless repair, excellent pull–out strength, and sequential tensioning of the anchors. A curved suture passer is used to pass a PDS shuttle stitch through the posterior labrum.

Given this patient's frank posterior shoulder instability, we did elect to incorporate the posterior capsule as part of a capsular shift to complete his labral repair. A spherical rasp is used along the posterior glenoid to encourage healing. Once the suture anchors are placed, the PDS is used to shuttle the repair stitch for labral repair. A second knotless suture anchor is placed percutaneously at the 9 o'clock position. The PDS suture was used to shuttle the repair stitch through the labrum and the portion of the capsule that we had incorporated into the repair. The looped shuttling limb is then used to shuttle the repair stitch back through the anchor so that tension can be applied and secure the labrum.

A grasper is used to reduce the labrum, and the knotless anchors are sequentially tensioned while the labrum is held reduced. The excess sutures are then retrieved through the cannula and cut. The final repair is visually inspected. Three stitches were necessary to achieve appropriate closure of the capsular tear. Two anchors can be seen positioned at the 7 o'clock and 9 o'clock position for the labral repair.

For the final part of the procedure, a capsular closure of the posterior portal was performed. The cannula was placed in an extracapsular position. A combination of curved and penetrating suture passers was used to pass sutures to close the rent made for the posterior portal. The cannula was then backed out, and the sutures were tied allowing for closure of the capsule. All incisions were closed with interrupted 4-0 nylon suture.

The patient was placed in an ultra–sling for 4 weeks before physical therapy. We allowed light strengthening at 8 weeks, full strengthening at 12 weeks, and estimated return to sport at 4 months. Traditionally, patients treated surgically for posterior instability have done well with success rates and return to play around 90%. We do think it is critical to address all pathology contributing to posterior instability, and in this case, the posterior capsule would be included. In addressing this pathology, we believe the results should be consistent with prior literature on posterior instability and success rates at 6 months should approach 90%.

Deficiency of the posterior capsule has been shown to contribute to posterior instability. Several authors have implicated isolated posterior capsular laxity as a contributor to posterior instability and their cases were treated with posterior capsular plication. Bokor et al have reported on the largest case series of reverse humeral avulsion of the glenohumeral ligament (HAGL) lesions, and in their series of posterior instability, 14% were found to have reverse HAGL lesions; however, only 50% were identified on MRI. The authors did note that the posterior capsule can only be fully visualized using the anterior portal.

Traditionally, injury to the posterior capsule, such as reverse HAGL lesion, has been managed with open repair. We presented a novel technique for an all–arthroscopic repair of posterior midcapsular tears. There is very little literature to assist in management of these injuries. The only similar case we found in the literature is by Shah et al reporting on a 20-year-old football player with pain during blocking. Similarly, the MRI did not reveal capsular injury. The posterior capsule was visualized from the anterior portal and repaired. At 5 months postoperatively, the patient had regained symmetric motion, full strength, and had no instability.

In summation, gross posterior instability is rare and when found likely has an injury or deficit to the posterior static restraints to shoulder. If no significant labral injury is identified, make sure to consider posterior capsular injury as a contributor to posterior instability. Remember the full assessment of the posterior capsule can only be done when visualizing from the anterior portal and that when found, repair of the posterior capsule is necessary and can be achieved arthroscopically with the use of an accessory posterior lateral portal. Addressing the posterior capsular defect first can help prevent unnecessary fluid extravasation during the case. And finally, ensuring the availability of appropriate suture passers, including curved and penetrating passers, will make the capsular repair much easier.