Teaching Case

A 12-year-old male tennis player presented with complaints of chronic right shoulder pain for one year exacerbated during playing. On examination, no restriction of movements was noted, and imaging was performed to evaluate the cause of pain.

MRI shows a focal defect in the articular surface of the right humeral head involving the subchondral bone plate, with mild oedema of overlying articular cartilage. Mild marginal sclerosis is noted. No surrounding marrow oedema is seen, which suggests a chronic/stable lesion. Rest of the articulating surfaces, muscles, tendons and ligaments appear normal. CT also shows focal cortical irregularity in the articular surface of the humeral head.

A. Background:

Osteochondral lesions can be acute or chronic localized abnormalities of the articular cartilage or subchondral bone plate. Osteochondral defect occurs due to acute osteochondral fracture, subchondral insufficiency fracture, avascular necrosis, osteochondritis dissecans and osteoarthritis [1]. A number of possible etiologies have been proposed, including repetitive microtrauma and ischemia or ossification abnormalities, of which repetitive trauma is considered to be the primary insult in most cases [2]

Osteochondral lesion rarely involves the shoulder; however, cases have been reported affecting males on the dominant side [3], with pitching reported to be a causative factor. Most frequently affected site of shoulder is the anterosuperior aspect of humeral head, followed by the superior and posterosuperior aspects, or the glenoid. Osteochondral lesions usually involve the articular cartilage, subchondral bone plate and subchondral bone marrow [4].

B. Clinical Perspective:

Acute lesions like osteochondral and subchondral insufficiency fractures (SIF) present as acute onset of severe pain. Chronic lesions like avascular necrosis (AVN) and osteochondritis dissecans (OCD) present as chronic pain exacerbated by collapse. Pediatric athletic shoulder injuries include fractures of the proximal humeral physis, coracoid process, acromial apophyseolysis and little Leaguer's shoulder [5].

C. Imaging Perspective:

Osteochondral injury staging system for MRI (6) includes

Stage I: Injury limited to articular cartilage with subchondral oedema.

Stage II: Articular cartilage injury associated with subchondral fracture but without detachment.

Stage III: High signal around osteochondral fracture (Rim sign) but without displaced fragment.

Stage IV: Displaced osteochondral fragment.

Stage V: Secondary degenerative changes.

SIF has a hypointense line that is irregular, sometimes discontinuous, or open-ended in the subarticular marrow at a variable distance from the epiphyseal surface. AVN has a necrotic marrow rim of sclerosis separating necrotic and viable bone producing the typical double-line sign. OCD usually occurs in childhood to middle age, assessing whether associated instability is present is the important aspect of imaging.

In cases of OCD involving knee and talus, the size of OCD lesion is noted to be significantly larger in patients with associated bone marrow oedema, than in patients without bone marrow oedema [7]. Few case reports suggesting osteochondral lesions in the shoulder joint involving the humeral head [8] and glenoid [9] have been documented; however, no widespread studies have been performed.

D. Outcome:

The patient underwent conservative management of the osteochondral defect with rest and immobilization and recovered well in two months.

Treatment for osteochondral lesions includes both surgical and non-surgical options. Nonsurgical options are rest, cast immobilization and use of NSAIDs. Surgical treatment includes surgical excision, excision and curettage, excision combined with curettage and microfracturing, or filling of the defect with cancellous bone grafts (10).

E. Take-Home Message / Teaching Points:

Osteochondral lesions are seen commonly in the talus and knee joint. Osteochondral lesions occurring in the humeral head are very rare. We present this case of osteochondral lesion in the humeral head owing to its rarity.