Acromegaly has multiple effects on bone and soft-tissues. The anabolic effects of excess growth hormone can cause marked proliferation of bone, cartilage, synovium, and other soft-tissues. Rheumatic symptoms are common in acromegaly and frequently predate recognition of the underlying disorder. The progression of acromegaly is insidious and, therefore, attention to the rheumatic manifestations may point to the diagnosis before advanced disease becomes evident.
- Progressive degenerative arthropathy that may be monoarticular or polyarticular.
- May affect a variety of joints.
Initially, cartilage overgrowth leads to joint space widening, but this overgrowth involves haphazard deposition of matrix, resulting in its fissuring and degeneration. In addition, overgrowth and hypertrophy of joint capsules can cause progressive ligamentous laxity and hypermobility. Premature osteoarthritis ensues, particularly involving the weight-bearing joints, and invariably results in marked joint-space narrowing and osteophytosis characteristic of all forms of degenerative joint disease. In addition, acromegaly has been linked to calcium pyrophosphate dihydrate deposition disease, a process that can further exacerbate any ongoing degenerative changes.
Up to 50% of patients with acromegaly have back pain. Patients can have widened disk spaces, large osteophytes, kyphosis or loss of lordosis, and ligamentous laxity of the spine. In one series of patients, duration of disease correlated with the height of vertebral bodies and intervertebral spaces, and concomitant DISH was diagnosed in 20% of patients. The degenerative changes in the spine can lead to radiculopathies, and bony overgrowth can impinge on the spinal canal.
Acromegaly should be suspected when precocious degenerative joint disease occurs. Particular attention should be paid to those patients who demonstrate excessive hypermobility or laxity of their joints, a finding that would appear to be in contradiction to the degree of degenerative disease encountered.
Early in disease, radiographs of the hands demonstrate increased soft-tissue of the hands, joint space widening, and spade-like deformities of the distal phalangeal tufts. Later, the changes observed radiologically resemble those seen in most forms of advanced osteoarthritis.
If treated early enough, most of the rheumatic manifestations of acromegaly respond to removal of the pituitary adenoma or pharmacologic suppression of growth hormone secretion. However, once advanced degenerative changes have taken place, symptomatic relief is usually provided through conservative measures, including nonsteroidal anti-inflammatory medications. Severe disease may be amenable to surgical correction once the underlying metabolic abnormality has been successfully corrected.
Acromegalic patients often have coarsely enlarged fingers and hands characteristic of the soft-tissue, bone, and fibrous proliferation associated with excess growth hormone secretion. As a result of this tissue overgrowth, crowding of the carpal tunnel occurs, leading to carpal tunnel syndrome. This condition is often bilateral and can be the initial clue to the diagnosis of acromegaly.
A painless, proximal myopathy has been reported in patients with acromegaly. Serum muscle enzyme levels are usually normal in this disorder.