Arthroscopically Assisted Anterior Bone Block for Shoulder Instability

Abstract

Background:

Shoulder instability is a common complaint, with treatment depending on the severity of the bony defect. Advancements in arthroscopic techniques have allowed for a less invasive surgery with decreased postoperative pain, improved graft placement, and better visualization.

Indications:

Large bony defects of the glenoid require bone block augmentation to reduce recurrent instability. In this presentation, arthroscopically assisted anterior bone block was performed with a distal tibial allograft to address recurrent anterior shoulder instability with a large glenoid defect.

Technique Description:

The patient is placed in a lateral decubitus position. Standard arthroscopic portals are made. The bone block is fashioned from a distal tibial allograft. Using a guide, drill holes are placed in the bone block. The guide is inserted from the posterior portal and placed parallel to the joint surface. Using drill sleeves, superior and inferior screw holes are drilled and a metal cannula is left in place to allow for shuttling of suture. Two anchors are placed on the glenoid to allow for capsule labral junction to be brought up to the graft once the graft is in place. The bone block is delivered through a dilated anterior portal and reduced. The sutures are tensioned. A button is placed on each set of looped sutures, a Nice knot is placed into each, and a tensioning device is tensioned. Once compression is achieved, knots are tied to perform final fixation over the buttons. A suture passing device is used to grab inferior capsule and labrum to the priorly placed anchor on the inferior glenoid and tied.

Results:

Arthroscopically assisted anterior bone block for shoulder instability has been demonstrated to have similar clinical and radiographic outcomes when compared with open treatment. However, arthroscopically assisted Latarjet has been shown to have decreased soft tissue disruption and possible improvements in graft placement.

Discussion/Conclusion:

Arthroscopically assisted anterior bone block is a technically demanding surgery but has been shown to have similar outcomes when compared with open treatment. In this video, we demonstrate an arthroscopically assisted anterior bone block for recurrent anterior shoulder instability.

Patient Consent Disclosure Statement:

The author(s) attests that consent has been obtained from any patient(s) appearing in this publication. If the individual may be identifiable, the author(s) has included a statement of release or other written form of approval from the patient(s) with this submission for publication.

Graphical Abstract

This is a visual representation of the abstract.

Video Transcript

We will be describing our surgical technique for arthroscopically assisted anterior bone block augmentation for recurrent anterior shoulder instability.

Disclosures can be found on the AAOS website.

Here is a brief outline for the presentation.

Shoulder instability is a common shoulder problem with treatments ranging from nonoperative management focused on physical therapy to surgical interventions that includes soft tissue procedures, including labral repair and remplissage or bony procedures such as Latarjet dependent on the severity of bone loss. ⁷

When there is a large bony defect of the glenoid, it requires bony block augmentation to reduce the recurrent instability. Waterman et al demonstrated that bone block augmentation has been associated with high rates of complications including recurrent instability despite addressing the bony defect. ¹³ Galvin et al noticed increasing trends in incorporating bony procedures as recognition of the importance and indications for bony augmentations. ⁴

There have been recent advancements in arthroscopic techniques that have allowed for bony block procedures to be performed arthroscopically. This has been shown in the literature to have improvements in graft placements, less soft tissue disruption, better visualization during the surgery, as well as decreased postoperative pain.^4,6,8 Latarjet and distal tibial allografts are both acceptable treatments for reconstruction.

Latarjet provides the benefit of being an autograft and reduces costs associated with allografts.

Distal tibial allografts allow the graft to be fashioned uniquely to the patient’s defect and more accurately matches the anatomic curvature of the glenoid, but it does have drawbacks of being an allograft with graft-associated costs and risk of disease transmission.

Our current indications for bone augmentation are patient specific. At our institution, we will typically perform a bone augmentation procedure when bone loss is approximately 13.5%, as measured by the best-fit circle technique. ⁹ In this presented case, the patient had 25% bone loss. In this surgical technical presentation, we will demonstrate arthroscopically assisted anterior bone block which is performed for anterior shoulder instability with a distal tibial allograft.

The case presented here is of a 28-year-old right-hand-dominant woman who presented to our clinic with a 3-year history of recurrent right shoulder instability. She was having dislocations with overhead activities with monthly episodes. On examination, she had 170° of forward flexion and preserved full strength throughout her rotator cuff. She did have positive instability signs including anterior apprehension.

Radiographs show a large posterior and superior Hill-Sachs lesion of the humeral head as well as an anterior deformity of the glenoid. On 3-dimensional (3D) reconstructions from a computed tomography (CT) scan, you can visualize a large anterior bony defect of the glenoid. Given the large bony defect of the glenoid and her recurrent instability, we recommended proceeding with a bony block procedure for her recurrent anterior shoulder instability and elected to proceed with an arthroscopically assisted procedure.

The patient was placed in a lateral decubitus position with the aid of a beanbag. The posterior portal was established, and then 2 anterior portals were established via an outside-in technique using a spinal needle for localization. Diagnostic scope was performed. An arthroscopic shaver was introduced, the defect was identified, and gentle debridement of the frayed labrum was performed as well as using a shaver to take down the malunited bony Bankart.

We then fashioned our bone block from the distal tibial allograft, and 2 drill holes were placed using the guide. The optimal spacing between drill holes in the graft is 1 cm, which is the set distance based on the guide. Sutures were then passed through the drill holes with buttons on the end. Final dimensions of the graft were 2 cm in the superior-inferior direction, 1 cm in the anterior-posterior direction, and 1 cm in the medial-lateral direction.

Here, you can see our final product.

We then inserted a skid and switching stick through the posterior portal to allow for introduction of devices. Next, viewing from the anterior-superior portal, the posterior portal was enlarged to allow for passage of the drilling guide for suspensory fixation of the bone block. The guide was placed, and then the hook was placed in the midpoint of the glenoid, ensuring that it was parallel to the joint surface. The drill sleeves were ratcheted down, and the drill was brought through both the inferior and superior screw holes, leaving a metal cannula for shuttling sutures in place. A suture passing device was then inserted through each cannula to place a passing suture with the looped ends pulled through the anterior glenoid to allow retrieval of the final fixation suture from the distal tibial allograft.

Next, anchors were placed at the inferior position of the graft on the glenoid face to allow for the capsular-labral junction to be brought back up to the graft once the graft was in place. The sutures were then shuttled through the corresponding drill holes on the native glenoid and out the posterior portal. The distal allograft was then delivered through the rotator interval portal which had been widened digitally to allow for passage through the soft tissues. The bone block was then reduced to the anterior glenoid, demonstrating an anatomic fit in congruence with the native glenoid. When placing the graft, the goal is to have the chondral surface be perfectly flush, as opposed to slightly medial in Latarjet.

At this point, tension was brought along the sutures to ensure that the block sat flush and had good compression. Once we were happy with the position of the graft, it was then held in place with a switching stick via the posterior portal, and a button was placed on each set of looped sutures corresponding to the superior and inferior sutures. A Nice knot was then placed into each and using a tensioning device was then tensioned to 100 N.

Once adequate compression was achieved, knots were then tied to perform final fixation over the posterior buttons.

Using a suture passing device, we then grabbed the inferior capsule and labrum that was remaining up to the priorly placed anchor locations on the inferior glenoid. This was tied to provide a nice bumper of tissue at the inferior chondro-labral graft junction.

Here, you can see postoperative radiographs which demonstrate anatomic placement of the bone graft as well as final fixation with the buttons.

Postoperatively, the operative extremity is immobilized in a sling, and the extremity is made nonweight-bearing. Postoperative medications follow a standardized, multimodal pain control management, and the patient is started in rehabilitation to follow an arthroscopic anterior shoulder instability protocol. The patient will wear the sling for the first 4 to 6 weeks, including while sleeping. At week 4, the patient can start active range of motion. By weeks 7 to 12, the patient will start to begin to increase strength and endurance and increase functional activities. By the end of week 12, the goal is to increase passive range of motion to within normal limits in all planes. From weeks 12 to 20, the goal is to normalize strength, endurance, and power, eventually returning to recreational activities. The patient can consider returning to sport from weeks 16 to 20 if they continue to progress with rehabilitation. To return to sport, the muscular strength must be no less than 80% of the contralateral side and have complete rotator cuff strength.

Buckup et al had a minimum of 2-year follow-up on 47 patients who had arthroscopic Latarjet. ³ Of these patients, 89.4% were able to perform their preferred sport by an average of 4.6 months. Overhead athletes and athletes who participated in martial arts had lower return to sport compared with non-collision or non-overhead athletes. In those patients who had previously failed open or arthroscopic Bankart repair, there was no difference; 4.1% of patients had traumatic recurrent instability.

Suture button and screw fixation both provide reliable methods for glenoid fixation. ⁸ Both types of fixation have similar mechanical properties with no significant difference in ultimately load to failure or strain at failure. Screw fixation can fail at the bone block drill holes, while the most common point of failure for suture fixation is at the clamp-muscle interface. Suture button fixation also has lower rates of hardware removal. ²

In terms of patient outcomes, Hurley et al have demonstrated that both open and arthroscopically assisted Latarjet have improvements in patient function and outcome scores. ⁷ They both have similar rates of total recurrent instability, revision procedures, and total complications. Open Latarjet did have a lower rate of persistent apprehension, and there is a steep learning curve that is associated with arthroscopically assisted Latarjet, quoted as having to require 20 cases to have similar operating room times. Outcomes with suture button fixation have a low instability recurrence rate and excellent return to pre-injury activity, similar to screw fixation. ²

Ali et al, ¹ published in Arthroscopy that, again, both open and arthroscopic Latarjet had good functional results; however, arthroscopic Latarjet did have a significant Western Ontario Shoulder Instability score when compared with open Latarjet. They both had similar radiographic parameters and no difference in graft resorption. Open Latarjet did have a 20% nonunion rate on CT scan, and arthroscopic Latarjet had a quoted 15% rate of overall complication.

Pearls and pitfalls to note regarding this surgical technique include staying parallel to the glenoid with the guide. This is to ensure that there is no penetration of the joint when using the drill. When passing the bone block, use markings on the graft to keep appropriate orientation. Finally, suture management is critical to avoid knots while passing sutures.

Here is a list of our references.

We want to thank you for your time and watching our video. We hope that you have found it educational on the technique of arthroscopically assisted anterior bone block for recurrent anterior shoulder instability.

Thank you.