Title: Osteonecrosis of the Humeral Head
Reference: Loebenberg, Mark, Plate, A.M, Zuckerman, J.D., AAOS ICL Volume 48, Chapter 42
Most people present late with this disease because of the non-weightbearing nature of the shoulder. The treatment options are limited, and hemiarthroplasty remains the mainstay of treatment of advanced osteonecrosis. The key is to identify it early (although one wonders if we truly have the ability to affect the natural history…)
Points of Interest
– The humeral head is the second most common site of osteonecrosis, after the femoral head.
– Matson: 4.6% of GH arthritis patients are 2o to osteonecrosis.
– Etiology: corticosteroids (most common), sickle cell disease (plus other hemoglobinopathies) trauma, Gaucher’s disease, alcoholism, tobacco use. Trauma is the big non-systemic cause.
– Prosthetic replacement in sickle cell is associated with a high rate of loosening.
– Risk of osteonecrosis after 3 and 4 part fractures ranges from 26 to 75%.
– Pathology: bone necrosis – vascular ingrowth with osteoprogenitor cells at the periphery that proliferate into fibroblasts – macrophages in the fibrous layer resorb dead bone while osteoblasts lay down new bone on the dead trabeculae, resulting in thickened, radiodense bone within an area of relative osteopenia. Restoration fails to keep up with resorption and the resulting weak bone collapses.
– Classification: Cruess, CORR, 1978. X-ray classification
– I: before changes (can be seen on MRI)
– II: sclerosis in superior central portion of the head
– III: crescent sign – caused by subchondral bone collapse; may have mild flattening
– IV: significant collapse of humeral articular surface.
– V: degenerative joint disease.
– Natural History: sickle cell patients tend not to progress. Corticosteroid patients tend to get symptomatic and progress. Those with stage III disease or worse tend to do poorly.
– Presentation: shoulder pain comes far before significant ROM loss. Sleeping discomfort. Difficulty with overhead activities in particular. The area of the head in contact with the glenoid at 60% of forward elevation corresponds to the region of the humeral head most often affected by flattening and collapse.
– MRI has a 91% sensitivity at identifying lesions early.
– Treatment: Has anything been shown to change the natural history? – not really
– analgesia, physio – to maintain full passive range, restricting overhead activities (these increase joint reaction force)
– core decompression – if early. Not really very promising.
– arthroscopic debridement if clearly mechanical loose body symptoms
– hemiarthroplasty – the authors clearly favor this vs total shoulder
– total shoulder – discouraged by the authors, primarily because of the age of the patients that present. Hawkins probably puts in the glenoid.
Thoughts…. The natural history may not be affected by anything we do!