Arthroscopic Repair of a “Floating” Posterior Inferior Glenohumeral Ligament

Abstract

Background:

Combined posterior glenoid labrum lesions with posterior humeral avulsion of the glenohumeral ligament, also known as the “floating” posterior inferior glenohumeral ligament (PIGL), occur infrequently. These combined lesions are frequently missed on magnetic resonance imaging in the workup of posterior shoulder instability. Correct identification of the “floating” PIGL lesion allows for appropriate preoperative planning and treatment to decrease the risk of recurrent posterior shoulder instability.

Indications:

A “floating” PIGL lesion is a cause of posterior shoulder instability and demonstrates increased translation when compared with isolated labral lesions. Surgical repair of an acute “floating” PIGL lesion with concomitant superior labral tear is described.

Technique Description:

The patient is placed in the lateral decubitus position. Standard posterior and anterior portals are created. In this case, a superior labral tear with anterior labral tear extension was also identified and repaired. The posterior labrum was repaired prior to the posterior humeral avulsion of the glenohumeral ligament (HAGL). The torn posterior labrum is mobilized and glenoid bony bed prepared. Short, 2.9-mm biocomposite knotless suture anchors loaded with suture tape are used for labral fixation. A 70° arthroscope is used to visualize the posterior HAGL from the anterior cannula and an additional posterior inferior portal established. The footprint of PIGL on the humerus is identified, debrided, and two 3.0-mm anchors loaded with suture placed. The sutures are passed through the capsule and PIGL and tied in a mattress pattern external to the capsule and ligament. The posterior portals are closed with nonabsorbable suture.

Results:

While few outcomes are described in the literature for the “floating” PIGL, the literature suggests good outcomes following surgical repair.

Conclusion:

The “floating” PIGL lesion is a rare cause of posterior shoulder instability. It is important to perform a thorough evaluation for concomitant pathology in patients with posterior shoulder instability as multiple structures can be injured. Arthroscopic repair of the posterior labrum and posterior humeral avulsion of the glenohumeral ligament can be performed to restore posterior stability to the shoulder in the setting of a “floating” PIGL.

Graphical Abstract

This is a visual representation of the abstract.

Video Transcript

This video demonstrates our technique for arthroscopic repair of a “floating” posterior inferior glenohumeral ligament (PIGL).

These are our disclosures.

Here is an overview of the presentation.

Posterior shoulder instability occurs in approximately 2% to 10% of patients with traumatic shoulder instability. The spectrum of injury in posterior shoulder instability includes injury to the posterior labrum, midsubstance of the PIGL, and a posterior humeral avulsion of the glenohumeral ligament (HAGL). The “floating” PIGL lesion occurs when a posterior labrum tear and a posterior HAGL occur in combination.

The “floating” PIGL injury is a relatively rare injury pattern, with predominantly case reports in the literature.

The rarity of the “floating” PIGL can further be seen in this case series of combined anterior and posterior HAGLs. Only 7% of cases were posterior HAGL lesions, while 4% demonstrated a “floating” PIGL.

Ames et al describe a classification scheme for the “floating” PIGL. This classification scheme separates all soft tissue injuries from bony avulsions at the glenoid and/or the humerus.

The impact of the “floating” PIGL on the shoulder has been evaluated in a biomechanical cadaveric model. In this model, the “floating” PIGL lesion resulted in greater posterior and inferior translation of the humerus on testing when compared with an isolated posterior labral lesion from the glenoid.

Now on to the case: A 15-year-old right–hand–dominant male football player presented to clinic after sustaining an injury in a football game approximately 1 month prior. He described pain in the shoulder with inability to block and do pushups. Examination demonstrated full, symmetric range of motion and strength. A positive O’Brien test and tenderness along the bicipital groove were noted. There was no anterior apprehension. Posterior load and shift was graded at 2+.

A magnetic resonance arthrogram of the right shoulder was obtained. Here are the axial images. These demonstrate a posterior labral tear as well as a posterior HAGL. The coronal slices are shown here. These images demonstrate tear extension into the superior labrum.

To summarize, this is a 15-year-old male contact athlete with posterior shoulder instability. There is a “floating” PIGL lesion with labral tearing extending to the superior labrum.

A lateral decubitus position was planned. Planned portals included standard anterior and posterior portals with a percutaneous lateral portal and accessory inferior posterior portal. Both 30° and 70° arthroscopes were planned for use; 2.9-mm short biocomposite knotless anchors loaded with suture tape were planned for use for the posterior labrum repair, while 3.0-mm anchors were planned for the repair of the posterior HAGL. The repair sequence plan was to start with the superior labrum, and then proceed to the posterior labrum, and finally repair the posterior HAGL.

Examination under anesthesia demonstrated a 2+ posterior load and shift with an obvious clunk. Posterior load and shift is an important examination maneuver for posterior shoulder instability and is performed having the shoulder abducted approximately 90° with a posteriorly directed axial load.

Here is the room set up for lateral decubitus positioning with a commercially available arm holder. Fifteen pounds of traction was applied in this case.

Anatomic landmarks were identified and marked. The anticipated portal sites can be seen with 2 posterior portals, a lateral percutaneous portal, and an anterior portal. The superior posterior portal is established approximately 2 cm distal to the anterolateral edge of the acromion, aiming toward the coracoid, and is superior and lateral in order to allow for appropriate trajectory of drilling into the glenoid at the articular margin. The inferior posterior portal is established 1 to 2 cm distal and in line with the superior posterior portal and will be localized with a spinal needle in order to allow for work on the posterior HAGL repair.

After making a standard posterior portal, a diagnostic arthroscopy was performed with a 30° arthroscope. Tear extension into the anterior labrum was noted, along with anticipated findings of superior labrum tearing. The “floating” PIGL was identified with the posterior labrum tear and posterior HAGL. An anterior portal was established above the subscapularis using outside–in technique ensuring appropriate trajectory for placement of anchors onto the articular margin of the glenoid. Probing through an 8.25-mm cannula demonstrates superior labrum tearing with anterior extension to the 3-o’clock position.

An elevator is used to mobilize the anterior and superior labrum from the glenoid surface. The glenoid was then prepared with a combination of a ball point rasp and a shaver adjacent to the articular cartilage. A lasso is used to penetrate the capsule at a more inferior position for capsulorrhaphy to tighten the anterior capsule, and the wire passed around the labrum. The wire is then taken out of the anterior portal and a suture tape is shuttled. Next the drill guide is inserted through the anterior cannula and the anterior glenoid drilled. The anchor is then placed, ensuring appropriate tension. The suture tails are then cut. The process is then repeated moving closer toward the biceps anchor. The drill guide is placed through the anterior cannula. The anchor is then placed. It is important not to over–tension the repair at this location. Here the anchor is past–pointed and the anchor subsequently inserted to avoid over–constraint of the biceps anchor. The sutures are then cut.

Moving posterior to the biceps anchor, a lasso is used through the anterior cannula to pass a wire around the labrum. The wire is then retrieved out of the anterior cannula and a suture tape passed. A lateral percutaneous portal is then established directly lateral to the acromion edge and medial to the rotator cuff cable, after localization with a spinal needle. This ensures an appropriate drilling angle for anchor placement. After drilling the glenoid through the percutaneous portal, a suture anchor is placed, again avoiding excessive tensioning. We then proceed more posterior and drill the glenoid through the percutaneous cannula. The lasso is used from the anterior cannula to pass a wire around the labrum. A suture tape is then shuttled through the percutaneous cannula. The anchor is again placed with appropriate tensioning.

The camera is then moved to the anterior cannula and the posterior superior portal is established. The position of the portal is checked to ensure an adequate angle for drilling and anchor placement on the articular margin of the posterior glenoid, particularly inferiorly. An elevator and ball point rasp is used through an 8.25-mm cannula to prepare the labrum and glenoid for repair. A lasso is then used to pass a wire through the PIGL and the capsule. The wire is retrieved out of the posterior portal and a suture tape is shuttled. The glenoid is then drilled through the posterior portal. Next an anchor is inserted. It is important not to capture an excessive amount of tissue at this point, as over–tensioning could result when repairing the ligament on the humeral side. The repair process proceeded superiorly. Suture anchors were ultimately placed along the posterior labrum at the 7-o’clock, 8-o’clock, and 9-o’clock positions. Anchor placement for the superior labrum included anchors at the 10-o’clock, 11-o’clock, and 1-o’clock position, with again the anchor at the 3-o’clock position anteriorly. This concluded our glenoid based fixation.

A 70° arthroscope was then placed through the anterior cannula to visualize the posterior HAGL. Using outside–in technique with spinal needle localization aimed at the PIGL insertion on the humerus, particularly for suture anchor placement, an inferior posterior portal is established approximately 2 cm distal to the superior posterior cannula. A ball point rasp is then used to debride the insertion of the posterior HAGL adjacent to the articular margin through the 8.25-mm cannula. A shaver is also used to debride the bony surface. A drill guide is then placed through the posterior inferior cannula at the region of the inferior insertion site of the PIGL, and a 3.0-mm anchor inserted into the humerus. The sutures from the anchor are then grasped and retrieved from the superior posterior cannula. A lasso is then used from the posterior inferior cannula to penetrate the posterior capsule and PIGL. The wire from the lasso is then grasped and retrieved out of the posterior superior cannula. One limb of suture is then shuttled back out the posterior inferior cannula. The process is then repeated with a lasso penetrating the PIGL tissue and capsule, and the wire retrieved out of the superior posterior portal. The other limb of the suture is then shuttled to perform a mattress type of repair. The sutures are then tied using an arthroscopic knot pusher through the posterior inferior portal. This anchor repair restored the inferior anatomy of the PIGL. The sutures are then cut.

An anchor is then placed in the more superior aspect of the humerus at the insertion site of the PIGL, this time placing the guide through the posterior superior cannula. Again, a suture lasso is used to penetrate the capsule as well as the PIGL tissue, and one limb is shuttled out the posterior inferior cannula. This process is then repeated for the second limb. A lasso is used and the wire retrieved out of the posterior superior cannula. The second limb of suture is then shuttled through the posterior inferior portal. The sutures are then tied, nicely reconstituting the PIGL as it inserts on the humerus. Both posterior portals were then closed using a wire to shuttle a non–absorbable suture.

Here is the final repair of the “floating” PIGL which extended into the superior labrum.

Postoperatively, the patient was placed in a sling for 6 weeks. Passive shoulder range of motion began with physical therapy at that 6–week point. No internal rotation past the abdomen or cross body adduction was allowed for a total of 8 weeks. Active shoulder range of motion started at 8 weeks with physical therapy, with shoulder strengthening beginning at 12 weeks. Return to sport testing and ultimately return to sport was estimated at 5 months.

When evaluating posterior shoulder instability, a thorough assessment of concomitant pathology is necessary, as one study demonstrated that only 50% of posterior HAGL lesions were correctly identified by a radiologist on magnetic resonance imaging (MRI). Moreover, in the setting of a posterior HAGL, 93% of cases had concomitant glenohumeral pathology in one series, 58% had an associated posterior labral tear while 32% had a SLAP tear in a second series, and in a third series, it was demonstrated that only one–third of cases had an isolated posterior HAGL lesion. Therefore, a thorough physical examination of the entire shoulder, including maneuvers for anterior labral pathology, superior labral tears, and rotator cuff pathology, should be performed. A critical evaluation of imaging, which should include radiographs and MRI, should also be performed.

In terms of outcomes, there is limited evidence in the literature for the “floating” PIGL lesion.

In a series of 9 cases of posterior HAGL lesions, in which only one–third were isolated injuries, the Constant score was 80 at a mean final follow–up of 34 months, while all patients returned to sport without symptoms or limitation.

Thank you for your attention.