Posterior dislocations of shoulder are uncommon, constituting only 2–4% of glenohumeral dislocations and are often missed [1, 2]. About 50% of these occur with an impaction fracture of the anteromedial aspect of the humeral head (reverse Hill-Sachs lesion or McLaughlin lesion) [3, 4]. These bony defects in the humeral head can lead to refractory glenohumeral instability. Increasing sizes of defect are increasingly challenging to manage [5, 6].
Treatment options for smaller lesions include transfer of the subscapularis tendon alone (McLaughlin) or with the lesser tuberosity along with the anterior capsular attachments (modified McLaughlin), to fill the bony defects ^[7]. For large, engaging reverse Hill-Sachs lesions involving more than 40% of the humeral head, hemiarthroplasty can be used in suitable patients ^[8].
Larger lesions up to 40% of the humeral head articular surface, especially in younger patients, can fall between the groups described above, leaving surgeons with some uncertainty about optimal management. However, in this group, reconstruction with osteochondral allograft is a promising operative solution ^[9]. The allograft can be from femoral head, humeral head, or talus [10, 11]. It is challenging to restore the sphericity of native humeral head with this allograft of variable source and dimensions. We present our surgical technique in fashioning the allograft in a way that best restores the native humeral head.

A physical examination of the shoulder is performed preoperatively. Apprehension in abduction is suggestive of a bony lesion. A comprehensive radiographic evaluation using X-ray, CT (Fig. 1), and MRI is conducted preoperatively to accurately evaluate the presence, volume, and orientation of the reverse Hill-Sachs lesion.

Our patients are given a general anesthetic, then placed in the beach chair position. An examination under anesthetic is performed to establish range of motion, the degree of instability, and the point of engagement of the reverse Hill-Sachs lesion. The shoulder is prepared and draped in a sterile fashion. A deltopectoral approach is used, through a 7 cm incision from the coracoid process extended distally. This is followed by dissection through subcutaneous tissue then fascia.
Establishment of the deltopectoral interval is facilitated by identification of the cephalic vein, coracoid, and the conjoint tendon. Tracing the conjoint tendon distally reveals an inverted V-shaped interval between pectoralis major and deltoid. The interval between the deltoid and pectoralis is then developed by blunt dissection. The distal attachment of pectoralis major is divided in its upper one-third.
The superior one-third to one-half of the subscapularis tendon is identified and reflected off the bone. It is then then tagged with a 2 Vicryl suture to facilitate repair when closing. Finally, a T-shaped capsulotomy is performed to expose the humeral head and to visualize and evaluate the defect. Evaluation of the Hill-Sachs lesion (Fig. 2) is facilitated by placement of the shoulder in abduction and external rotation.
Once fully assessed, the lesion is outlined and an oscillating saw is used to create uniform edges – a regular “orange slice”-shaped defect. The prepared defect size is measured with a ruler, including width, length, and depth. In our case example, the width, length, and depth of the lesion measured 17 mm × 38 mm × 12 mm, respectively. Calcium phosphate cement is used to fill the defect and form a mold that represents the dimensions of allograft required to recreate the native sphericity of the humeral head (Fig. 3).
This mold then acts as a reference when fashioning the osteochondral femoral allograft (Fig. 4, 5) to make sure this fits the defect anatomically. Once the graft is prepared, it is placed into the defect in the correct orientation and fixed in situ using headless screws (Fig. 6). Optimal care should be taken to verify that the screws are countersunk into the subchondral bone to avoid damage to the cartilage surface. This is also necessary to avoid any damage to the glenoid.
The goal of reconstruction is to recreate a smooth articular surface and fill the reverse Hill-Sachs defect. Once fixation is complete, leveling between the graft and native humeral head is verified to ensure complete anatomic restoration throughout shoulder range of motion. Internal and external rotation of the shoulder is performed to confirm optimal positioning of the graft. The partially detached subscapularis tendon is identified by the tagging stitch, and the subscapularis is repaired through use of a double-row technique along with anterior capsule (Fig. 7).
CT scan was done for patient at 6 months following the procedure, showing a near full incorporation of the allograft. The patients were followed up at 2 weeks after surgery for wound review, then at 6 weeks, 3 months, 6 months, and 18 months to assess their progress throughout the process of rehabilitation. We used the following physiotherapy protocol for our patients –
First 2 weeks: Only elbow and wrist exercise
2nd–6th weeks: Passive assisted flexion to 90° and external rotation up to 30°
After 6 weeks: Full gradual range of movements (active assisted)
No loading with weights for 6 months following surgery.

In cases of recurrent posterior dislocations, humeral bone loss and reverse Hill-Sachs lesions can result in refractory glenohumeral instability that is difficult to treat ^[12]. Yamamoto et al. ^[13] introduced the concept of the glenoid track. Through this concept, engagement is associated with recurrent instability. The surgical treatment goal for Hill-Sachs lesions is to prevent engagement of the lesion ^[14].
Surgical options to correct an engaging reverse HS lesion can be largely categorized into non-anatomic and anatomic reconstruction. Non-anatomic options include the McLaughlin and modified McLaughlin procedures ^[15]. Anatomic procedures have been described in the literature for larger lesions, aiming to restore the normal contour of the humeral articular cartilages [16, 17]. There were initially attempts to elevate the areas of anterior impaction in reverse Hill-Sachs lesions. However, due to the loss of integrity in the subchondral bone and persistent damage to the articular cartilage with these techniques, many have begun to favor anatomic reconstruction with osteochondral allograft 12, 13].
In our technique, the use of calcium phosphate cement provides us with a mold, which is exactly the same shape as the prepared defect. When the mold is used as a reference to fashion the allograft, the final graft will have the same three-dimensional measurements as the defect. This anatomical reconstruction restores the congruity and sphericity of the humeral head, at the same time providing viable cartilage. On regular follow-up, our patients had good clinical outcome at 18 months after surgery (Fig. 9a, b, c).

We recommend the use of a calcium phosphate cement mold and fresh frozen osteochondral femoral allograft to fill the humeral head defect accurately (<40%) in young patients with reverse Hill-Sachs lesions. This technique has proven beneficial in providing an anatomical reconstruction and good functional outcome in our patients (Fig. 9a, b, c).

The authors believe that our described technique of using cement mold to fashion the allograft and fill the humeral head is promising. This will help the surgeon obtain a congruent humeral head and hence treat the posterior glenohumeral instability.