Humeral Head Osteochondral Allograft Reconstruction for Chronic Locked Posterior Glenohumeral Dislocation With Large Reverse Hill–Sachs Defect

Abstract

Background:

Locked posterior glenohumeral dislocations are a rare but often missed injury when it occurs. In these dislocations, patients may have a reverse Hill–Sachs lesion, which are associated with high rates of recurrent posterior glenohumeral instability. Open reduction with allograft reconstruction to reconstruct the defect can be used to treat chronic locked posterior glenohumeral dislocations.

Indications:

Osteochondral allograft reconstruction is indicated when patients have a large defect affecting less than 50% of the articular surface and if the humeral head has been dislocated for less than 6 months.

Technique Description:

With the patient in beach chair position, exposure is obtained through deltopectoral approach. An open reduction is performed, and the defect is debrided down to healthy bleeding bone. The defect is templated, and the allograft is harvested and prepared. The allograft is securely fixed using cannulated cancellous screws. The patient undergoes a postoperative rehabilitation protocol.

Results:

There have been several case series following allograft reconstruction for locked posterior dislocations that have demonstrated good results. Riff et al found favorable results in his series of 20 patients with isolated humeral head lesions, with significant improvement in patient-outcome measures. There are several potential complications though. A systematic review by Saltzman et al found allograft resorption to occur in 36% and glenohumeral arthritic changes to occur in 35% with frozen allografts. These rates appear to be improved with fresh allografts.

Discussion/Conclusion:

In conclusion, osteochondral allograft is an effective surgical treatment for large Hill–Sachs defects in chronic locked posterior dislocations.

Graphical Abstract.

This is a visual representation of the abstract.

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DOI: 10.1177/26350254221102460.M1

Video Transcript

This video will describe our technique for the treatment of a reverse Hill–Sachs defect from a chronic locked posterior glenohumeral dislocation with humoral head osteochondral allograft.

Our disclosures are listed here.

In this video, we will discuss the patient’s history, physical exam, and imaging; preoperative planning; our surgical technique in detail; postoperative management and rehabilitation; and finally, our pearls and pitfalls to avoid regarding surgical outcomes and complications.

Locked posterior glenohumeral dislocations are a rare but commonly missed injury when it occurs. With these dislocations, patients may have a reverse Hill–Sachs lesion. This is an impaction injury to the anterior humeral head. These lesions are associated with high rates of recurrent posterior glenohumeral instability. Treatments for chronic locked posterior shoulder dislocations include open reduction with one of the following procedures: lesser tuberosity transfer, osteochondral allograft reconstruction to fill the defect, and arthroplasty. Arthroplasty is considered in cases where 50% or more of the articular surface is affected or if the humeral head has been dislocated for more than 6 months.

Our patient is a 38-year-old man with history of seizure disorder who presented with inability to raise his left arm overhead and rotate externally. He initially sustained a proximal humerus fracture 5 months prior to his presentation. He was treated conservatively for the fracture by a different physician. Three months after his initial injury, he suffered a seizure and subsequently had increased pain and decreased mobility. Despite increased complaints, continued nonoperative treatment was recommended. He presented for a second opinion. He had recently been evaluated by his neurologist, and his seizures were now controlled. On physical examination, he had limited active range of motion, with external rotation 10°. He had full strength in all planes. He was able to fire his deltoid, and his axillary sensation was intact. The remainder of his distal extremity was neurovascularly intact.

Preoperative radiographs showed a posteriorly dislocated humeral head with a large reverse Hill–Sachs defect. Preoperative computed tomography (CT) scan showed the humeral head perched on the posterior glenoid with a large reverse Hill–Sachs lesion. Our patient had a subacute locked posterior dislocation with reverse Hill–Sachs defect involving approximately 30% of the humeral head with no glenoid bone loss. We used the method described by Cho et al, that is, measure the width of the defect on the axial and coronal scans, as compared with the diameter of a circle drawn on the articular surface. Given the size of the defect and the timeline of his injury, we recommended open reduction with osteochondral allograft reconstruction.

For preoperative planning, the first step is to ensure that the patient is appropriately optimized. His seizures need to be under control to prevent further risk of injury. As far as technical considerations, either a humoral head allograft or femoral head allograft can be used. To prepare the defect, a burr, curettes, and rongeur can be used. A microsagittal saw is useful for harvesting the allograft. For fixation of the graft, either headless compression screws or countersunk cancellous screws can be used. We prefer beach chair for positioning with a limb positioner. Ensure that the patient’s arm can be adequately externally rotated during the procedure.

The key steps in the procedure are exposure, preparation of the recipient site, templating the defect, graft harvest, graft implantation and fixation, and finally closure. Our patient is in beach chair position. Our incision is drawn along the deltopectoral interval. Incision is made through the skin. Subcutaneous tissues are dissected down to the deltopectoral interval. The interval is developed with blunt dissection, and cephalic vein is taken laterally. The clavipectoral fascia is incised, and the biceps tendon is sharply resected from the superior labrum and tagged with a #1 vicryl suture.

The subscapularis tendon is sharply incised using a “peel” technique off the lesser tuberosity and tagged with a #2 fiberwire suture for later repair. Of note, the anatomy can be distorted due to the posterior dislocation of the humoral head. The joint is now exposed. An open reduction is performed. This can be done manually or with the assistance of a Cobb elevator. Once reduced, the defect is then exposed by externally rotating the arm to approximately 90°. Blunt Hohmanns can assist with exposure. The defect is debrided down to a healthy bleeding bone bed with the use of a burr, curettes, and rongeur.

A ruler is then used to measure the anterior to posterior distance of the defect at the superior middle and inferior aspects. The depth at these 3 locations is also measured. Ensuring that the allograft is positioned appropriately, the measurements are drawn out with a surgical marker. A micro sagittal saw is then used to excise the predetermined allograft in a lemon wedge shape. The graft can then be removed with the use of an osteotome and mallet. The graft is soaked to remove preservatives. The shape is then fine-tuned with the rongeur to meet our predetermined measurements. Once the graft is implanted in appropriate position, the surgeon needs to ensure that there is an appropriate contour of the humeral head with no stepoffs. Once again, fine tune adjustments can be made. When the contour is appropriate, the graft is pinned in a place with Kirshner wires. The wire is then over drilled and countersunk. Depth is measured, and the cannulated cancellous screw is placed. These steps are repeated for the second screw. Once the graft is appropriately fixed, it is important to take the shoulder through a range of motion to ensure there is no hardware prominence or mechanical blocks with range of motion.

After completion of graft fixation, repair of the subscapularis tendon is performed. We prefer to use 2 double-loaded suture anchors and repair the subscapularis tendon in a Mason–Allen configuration. When placing these anchors, be mindful of the trajectory to avoid conversion with the allograft. A soft tissue tenodesis of the previously tenotomized biceps tendon is performed to the subscapularis. The deltopectoral interval is marked. Subcutaneous tissue and skin is closed. The patient is placed in a dressing and a gunslinger brace. Our postoperative radiographs demonstrate a well contoured osteochondral allograft with fixation in appropriate positioning. The glenohumeral joint is well reduced.

Although there is not an abundance of literature regarding humeral head reconstruction with osteochondral allograft, there have been several case series that have demonstrated good results. Riff et al found favorable results in his series of 20 patients with isolated humeral head lesions, with significant improvement in patient-outcome measures. There are several potential complications though. A systematic review by Saltzman et al found allograft resorption to occur in 36% and glenohumeral arthritic changes to occur in 35% with frozen allografts. These rates appear to be improved with fresh allografts. To minimize the complications and to ensure appropriate graft contour and healing, special care should be taken with debridement of recipient site down to bleeding healthy bone, fine tuning the allograft to match the patient’s defect, and ensuring secure fixation to allow early range of motion.

Postoperative rehabilitation includes sling immobilization for 6 weeks. At 4 weeks, passive range of motion is initiated. At 6 weeks, active assisted range of motion is initiated. Beginning at 8 weeks, independent active range of motion is allowed, transitioning into a strengthening program at 12 weeks. Return to full activities is expected around 6 to 9 months.

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