What is hypertrophic osteoarthropathy?
Hypertrophic osteoarthropathy is a disease of the joints and bones. It is characterised by clubbing of the fingers and toes, enlargement of the extremities, and painful and swollen joints. The disease falls into 2 categories:
- Primary hypertrophic osteoarthropathy
- Secondary hypertrophic osteoarthropathy.
Primary hypertrophic osteoarthropathy is a rare inherited condition. In most cases it develops over a period of time and is essentially symptomless. Initial visits to doctors are usually for minor pains in the shoulders and hands.
Patients with secondary hypertrophic osteoarthropathy usually complain of pain and swelling in joints and long bones, and clubbing of fingers. The symptoms occur suddenly and progress rapidly. Approximately 90% of these cases have an underlying malignancy; the remainder have non-malignant chronic diseases of the lungs, liver or heart.
Features of secondary hypertrophic osteoarthropathy include:
- Clubbing – skin surrounding nails may be red and tender
- Thickening of the skin
- Thickening of tubular bones
- Periostosis (this is the abnormal deposition of bone around the outside of a bone), that may be symptomless or may cause severe burning and deep-seated pain of the extremities
- Swelling of large joints causing pain and limited movement
Who gets it and what is the cause of hypertrophic osteoarthropathy?
Primary hypertrophic osteoarthropathy is a rare hereditary condition.
Secondary hypertrophic osteoarthropathy is most often associated with an internal malignancy or chronic disease. Peripheral non-small cell lung cancer is the most commonly associated malignancy in patients with secondary hypertrophic osteoarthropathy. The underlying malignancy or disease usually appears first, although in some cases the symptoms of hypertrophic osteoarthropathy have preceded the underlying disorder by more than one year.
The actual cause of hypertrophic osteoarthropathy remains unclear. Oestrogens, circulating factors, neurogenic factors and growth hormone are all thought to play a role.
Diseases associated with clubbing
Clubbing can also be seen as an isolated abnormality in patients with lung and/or heart disease, and rarely gastrointestinal disease, hyperthyroidism and other diseases. Examples include:
- Lung/heart diseases (80–90%): cancer, abscess, interstitial pulmonary fibrosis, sarcoidosis, congenital heart disease, beryllium poisoning, pulmonary arteriovenous fistula, subacute bacterial endocarditis, infected arterial grafts, aortic aneurysm
- Gastrointestinal disease (5%): inflammatory bowel disease, sprue, cancer, liver cirrhosis, achalasia
- Hyperthyroidism (1%, known as thyroid acropachy), thyroid cancer
- Palmoplantar keratoderma
How is clubbing recognised?
To determine if clubbing is present, flex the fingers of both hands. Bring the index fingers together until the distal phalanxes are touching. A diamond space between them (Schamroth's window) means the nails are not clubbed (Schamroth's sign).
Clubbing is associated with:
- Soft, spongy nail bed
- Reduction or loss of Lovibond angle between the nail bed and nail fold
- Increase in nail fold convexity
- Thickening of the end of the finger
How is hypertrophic osteoarthropathy diagnosed?
Hypertrophic osteoarthropathy is diagnosed by the presence of nail clubbing in associated with typical radiological signs on plain X-ray.
What is the treatment for hypertrophic osteoarthropathy and clubbing?
The main aim of treatment for secondary hypertrophic osteoarthropathy is treatment of the underlying malignancy or chronic disease. Removal of the underlying tumour usually results in spontaneous improvement of bone and joint symptoms within 2-4 weeks. Clubbing is unlikely to be reversed if substantial chronic tissue changes, including increased collagen deposition, have occurred. Nonsteroidal anti-inflammatory drugs may be helpful for relieving painful osteoarthropathy.
Treatment of isolated clubbing is of the underlying cause.