Hypertrophic Osteoarthropathy

Hypertrophic osteoarthropathy (HOA) is a syndrome of digital clubbing, periostosis of long bones, and arthropathy.

• Primary (pachydermoperiostosis): rare autosomal dominant or recessive (HPGD, SLCO2A1 mutations), onset in adolescence, thickened skin, coarse facial features.

• Secondary (95%): intrathoracic disease (non-small cell lung cancer, mesothelioma, bronchiectasis, cystic fibrosis, lung abscess, pulmonary fibrosis), cardiac (cyanotic congenital heart disease, endocarditis), gastrointestinal (IBD, cirrhosis, coeliac disease, oesophageal cancer), others.

• Pathogenesis: platelet-derived growth factor and VEGF release from megakaryocyte fragments bypassing lung capillaries, or prostaglandin E2 excess.

• Painful periosteal new bone formation of distal tibia, fibula, radius, ulna.

• Digital clubbing (loss of Lovibond angle, increased nail curvature, spongy nail bed), burning deep bone pain in limbs, worse with dependency and relieved by elevation.

• Symmetric arthralgia, effusions (wrists, knees, ankles), warm swollen distal limbs.

• Skin changes in primary form (thick skin, seborrhoea, hyperhidrosis).

• Features of the underlying disease (cough, weight loss, haemoptysis).

• Chest radiograph and CT thorax first (searching for lung cancer, infection); echocardiography; investigate liver, bowel.

• Radiographs: symmetrical linear periosteal thickening ("double contour") of distal long bones; bone scan: "tram-track" sign along cortices.

• Inflammatory markers mildly raised; alkaline phosphatase raised; synovial fluid non-inflammatory.

• Genetic testing and urinary prostaglandin E2 in primary HOA.

• Exclude inflammatory arthritis, venous insufficiency, thyroid acropachy, osteomyelitis.

• Treat the underlying disease: resection of lung tumour, drainage of abscess, endocarditis therapy, control of IBD; symptoms often improve dramatically within days.

• NSAIDs (naproxen 500 mg twice daily, etoricoxib 60 to 90 mg) and paracetamol for bone pain.

• Bisphosphonates: pamidronate 60 mg IV or zoledronic acid 4 mg for refractory pain; octreotide 100 to 200 micrograms SC three times daily or long acting 20 to 30 mg monthly in refractory cases (reduces VEGF).

• Vagotomy or radiotherapy for palliation in unresectable cancer.

• Primary HOA: NSAIDs, COX-2 inhibitor (etoricoxib reduces PGE2 effect), colchicine 0.5 mg twice daily, intra-articular steroids, cosmetic surgery for skin changes.

• Monitor underlying disease; clubbing may persist.