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abstractFull article available online at Healio.com/Orthopedics. Search: 20120426-33

Glenoid and humeral head bone loss is the most common cause of failure after surgi-cal shoulder instability stabilization. Large Hill-Sachs lesions involving .30% of the articular surface of the humeral head typically occur after neglected or locked shoul-der dislocations. Such large lesions may require osteochondral allograft reconstruction or prosthetic replacement to regain shoulder stability and function.

Previous reports of osteochondral allograft reconstruction have focused on adults. This article describes a case of a 16-year-old autistic boy who sustained an anterior disloca-tion of the right shoulder following a seizure episode. The dislocation was diagnosed 12 days later as a progressive deformity, and his parents noticed his inability to use his upper extremity. The patient had a large (30%) humeral head Hill-Sachs lesion and persistent anterior shoulder instability after initial closed reduction. He underwent an open osteochondral allograft reconstruction for the restoration of the humeral head articular surface. The sizing of the defect, matching harvest of the allograft, and perfect fit of the allograft to the defect are critical steps to ensure congruent restoration of the humeral head. The allograft was stabilized in the defect of the humeral head using cancellous screws placed from below the articular surface. Radiographs 20 months postoperatively showed complete incorporation of the osteochondral allograft. At 30 months postoperatively, his shoulder was stable and functional.

Drs Nathan and Parikh are from the Division of Orthopaedic Surgery, Cincinnati Children’s Hospital Medical Center, Cincinnati, Ohio.

Drs Nathan and Parikh have no relevant financial relationships to disclose.Correspondence should be addressed to: Shital N. Parikh, MD, Division of Orthopaedic Surgery,

Cincinnati Children’s Hospital Medical Center, Cincinnati, OH 45229-3039 (shital.parikh@cchmc.org).doi: 10.3928/01477447-20120426-33

Osteoarticular Allograft Reconstruction for Hill-Sachs Lesion in an AdolescentSenthil t. nathan, MD; Shital n. Parikh, MD

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Figure: Anteroposterior radiograph 18 months postoperatively showing allograft incorporation.

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In 1940, Hill and Sachs1 described an impaction fracture of the posterolat-eral humeral head following traumatic

anterior shoulder dislocation. Since then, studies have shown such lesions to ex-ist in 80% of acute shoulder dislocations and almost 100% of recurrent shoulder dislocations.2-5 Although smaller Hill-Sachs lesions can be ignored during the management of anterior shoulder disloca-tion, larger lesions should be addressed to prevent recurrent shoulder instability.5-7

Larger Hill-Sachs lesions typically exist after neglected, missed, or recurrent an-terior shoulder dislocation.8,9 Large lesion reconstruction using humeral head osteo-articular allografts has been reported in adults10,11 but has not been reported in an adolescent patient.

Case RepoRtA 16-year-old autistic boy presented to

the emergency department with his parents for an increasing deformity over his right dominant shoulder and restricted right upper extremity use following a seizure episode approximately 12 days previous-ly. Physical examination showed obvious shoulder deformity, anterior position of the humeral head on palpation, and restricted upper limb mobility. Neurovascular ex-amination of the right upper extremity was normal. Radiographs revealed an anterior dislocation of the humeral head and a Hill-Sachs lesion. Due to the inability to reduce the shoulder in the emergency department, he underwent closed reduction under anes-thesia (Figure 1).

Intraoperatively, the shoulder was unstable and dislocated in 30° to 40° of external rotation with the arm in adduc-tion. Postreduction magnetic resonance arthrogram revealed a large Hill-Sachs lesion affecting approximately 30% of the articular surface of the humeral head (Figures 2A, B). Other findings included an intra-articular loose body in the poste-rior aspect of the humeral head, a partial tear of the biceps tendon, and injury to the anterior capsulolabral structures. The gle-

noid showed no significant bony erosion on the anterior aspect. The patient under-went elective reconstruction for the right shoulder based on the availability of fresh osteochondral humeral head allograft.

The standard deltopectoral approach to the shoulder was performed under general anesthesia in the beach chair position. The subscapularis tendon and underlying cap-sule was cut approximately 5 mm from its insertion on the lesser tuberosity. The humeral head was dislocated anteriorly, and the posterolateral impaction frac-ture defect was visualized (Figure 3A). Because initial attempts at osteoplasty failed, osteoarticular allograft reconstruc-tion was performed. The articular-arc deficit was approximately 30%, and the humeral head was dislocated in approxi-mately 30° to 40° of external rotation. The posterolateral defect was prepared with a

microsagittal saw to have straight sides and a wedge shape for adequate allograft placement. The defect size, including its length, width, and depth, were measured with a ruler, and a suture pack (foil) was used as a template to estimate the shape of the defect. The shape and dimensions were marked on the fresh osteoarticular humeral head allograft corresponding with the site and area of the defect.

A wedge was harvested using a saw ap-proximately 2 mm larger than the measured size (Figure 3B). The wedge was trimmed to press-fit into the defect (Figure 3C). Three 4.0-mm partially threaded cancellous screws were inserted from below the lesser tuberos-ity into the osteoarticular wedge to achieve adequate graft fixation (Figure 3D). Once the humeral head was restored, joint stabil-ity was satisfactory in all planes of motion. The anterior capsulolabral structures were

Figure 1: Prereduction anteroposterior (A) and scapular (B) radiographs showing anteroinferior shoulder dislocation with a posterolateral Hill-Sachs defect of the humeral head. Fluoroscopic image postreduction showing the humeral head defect (C).

Figure 2: Axial magnetic resonance arthrogram section used to quantify the Hill-Sachs defect. If the humeral head articular surface is considered 180°, the humeral head defect would be 55/180530% (A). If the humeral head defect is calculated based on the diameter,14 then line ‘a’ corresponds with 12.5%, line ‘b’ corresponds with 25%, and line ‘c’ corresponds with 50% humeral head loss. The 12.3-mm line is the measured depth loss, which corresponds with approximately 50% of the humeral head radius (B).15

1A 1B 1C

2A 2B

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then repaired using 3-0-mm Bio-FASTak suture anchors (Arthrex, Naples, Florida) inserted at the 3-o’clock and 5-o’clock po-sitions. The humeral head was kept moist throughout the procedure. The subscapular-is tendon was repaired, with the arm held in approximately 15° of abduction and 15° of external rotation. Routine closure was per-formed over a drain, which was removed on postoperative day 3.

Postoperatively, the patient’s arm was placed in a sling for approximately 3 weeks, followed by gradual progressive range of motion exercises and shoulder strengthening. Physical therapy contin-ued for 6 months. Radiographs and clini-cal follow-up 20 months postoperatively showed complete osteochondral allograft incorporation and a functional, stable shoulder. Thirty months postoperatively, the patient’s family was contacted over the phone, and they reported that the pa-tient’s shoulder had satisfactory function.

DisCussionOpen or arthroscopic anterior capsulo-

labral repair stabilizes the shoulder in most patients with anterior shoulder instability, despite the presence of a Hill-Sachs le-sion. However, Hill-Sachs lesions have caused recurrent instability in patients who have had a failed anterior capsulolabral re-pair.12,13 In patients with chronic, locked, or neglected dislocations (eg, those related to seizures), the risk of recurrent disloca-tion and the presence of large Hill-Sachs

lesions are higher.8 Quantifying humeral head bone loss

in Hill-Sachs lesions is important in the management of shoulder instability. Biomechanical studies suggest that hu-meral head lesions as small as 12.5% and 25% affect shoulder stability.14 Burkhart and Danaceau7 introduced the concept of articular-arc deficit and identified the mis-match between the articular arc length of the humeral head and the glenoid in the presence of bone defects, thus causing the sensation of subluxation or dislocation. The concept depends on the size of the de-fect and its location in the arc. Hill-Sachs lesions that engage the anterior glenoid with the shoulder in a functional position of 90° of abduction and external rotation are termed engaging Hill-Sachs lesions. They are in contrast to nonengaging le-sions, which cause symptoms in nonfunc-tional shoulder positions, such as extension or ,90° of abduction.

In a recent study, Kaar et al15 modeled the humeral head as a circle when shown on an axial magnetic resonance imaging (MRI) or a computed tomography (CT) scan, and the humeral head articular sur-face to be approximately 180°. Based on their study, a defect of five-eighths of the radius of humeral head, which would cor-respond with a defect of approximately 38% of humeral head, would affect gleno-humeral stability. In the current study, the patient’s MRI revealed a defect of approxi-mately 30% of the articular surface (Figure

2A), which corresponded with a defect of three- to five-eighths of the radius of the humeral head (Figure 2B).

Various operative procedures have been described in the literature for the manage-ment of Hill-Sachs lesions based on the percentage of the articular surface defect and the presence of engaging Hill-Sachs le-sions. For humeral head defects ,20% of the articular surface, arthroscopic Bankart repair has been effective, with no need to address the humeral defect.16 Various op-tions exist for humeral defects that are 20% to 30% of the articular surface with an en-gaging Hill-Sachs lesion. Remplisssage is the open or arthroscopic transposition of the infraspinatus tendon into the humeral head defect.17-18 Humeral head osteoplasty has also been reported, but this method

Figure 3: Intraoperative photographs showing the defect of the posterolateral aspect of the humeral head (A). The osteoarticular allograft is marked on its cor-responding posterolateral aspect, and the initial cut is made about 2 mm larger than the measured dimension (B). The graft is then trimmed and secured to the humeral head using nonarticular screws (C), as seen on fluoroscopic image (D).

Figure 4: Anteroposterior radiograph 18 months postoperatively showing allograft incorporation.

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3A 3B 3C 3D

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cannot be used in large humeral head de-fects or patients with osteopenia who lack subchondral bone support.

Sekiya et al14 used a bone tamp percu-taneously to elevate the Hill-Sachs defect through an anterior cortical window, which they termed as percutaneous humeroplasty. Based on cadaveric studies, they concluded that large defects, could only be reduced into smaller defects and complete correc-tion of the defect was not possible. In 1954, Latarjet19 described the coracoid process transfer to the anterior glenoid, thereby extending the glenoid arch such that it prevents engagement of the Hill-Sachs le-sion on the glenoid surface. Although the precise mechanism by which the Laterjet procedure provides stability is unknown, disadvantages include loss of external rota-tion, coracoid graft osteolysis, and a higher incidence of glenohumeral arthritis.

For humeral head defects .30%, the op-tions include humeral rotational osteotomy, osteochondral bone graft, and arthroplasty.13 In 1984, Weber et al20 described the rota-tional osteotomy of the proximal humeral shaft, which increases the retroversion of the proximal humerus and reduces the like-lihood of recurrent instability by redirecting the defect more posteriorly. However, the risk exists of redislocation, hardware failure, nonunion, malunion, and internal rotation deficit. Shoulder arthroplasty and osteo-chondral humeral head allograft reconstruc-tion have been described to treat adults with large head defects. Their use in an adoles-cent patient has not been described.

Miniaci and Gish11 reported the use of osteochondral allografts in Hill-Sachs le-sion reconstructions in adults. At 2-year follow-up, no recurrent instability existed, but 2 patients underwent hardware removal due to partial graft collapse. Hart and Kelly4 reported improved clinical outcomes af-ter humeral head osteochondral allograft reconstruction 18 months postoperatively in 7 patients with no associated complica-tions. Advantages include restoration of the near congruent articular surface, a biome-chanically stable joint without alteration of

the joint kinematics, and the possibility of future prosthetic replacement with no bone stock compromise.

ConClusionIn the current study, considering the pa-

tient’s age, history of uncontrolled seizures, and defect size, the authors performed a fresh osteochondral allograft for humeral head re-construction rather than prosthetic replace-ment. Compared with the surgical technique described in the literature,11 the allograft was press-fit into the defect, and further fix-ation was achieved by using screws directed into the allograft from the nonarticular hu-meral head surface. This technical modi-fication prevents articular surface damage during screw insertion, as well as articular surface damage due to screw prominence in case of cartilage resorption or graft collapse. Radiographs at 20-month follow-up showed good bony graft integration and a congruent articular surface (Figure 4). Osteochondral allograft reconstruction is a viable option for humeral head defect restoration in ado-lescent patients.

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