Intended for healthcare professionals


Synovitis induced by alendronic acid can present as acute carpal tunnel syndrome

BMJ 2005; 330 doi: (Published 06 January 2005) Cite this as: BMJ 2005;330:74
  1. David Gwynne Jones, consultant orthopaedic surgeon (David.gwynne-jones{at},
  2. Ruth Savage, senior research fellow2,
  3. John Highton, associate professor of rheumatology2
  1. 1 Department of Orthopaedic Surgery, Dunedin Hospital, Great King Street, Dunedin, 9001, New Zealand
  2. 2 Department of Rheumatology, Dunedin Hospital Centre for Adverse Reactions Monitoring, New Zealand Pharmacovigilance Centre, PO Box 913, Dunedin
  1. Correspondence to: D Gwynne Jones


Alendronic acid (Fosamax, Merck) is a potent oral bisphosphonate licensed for prevention (5 mg daily) and treatment of postmenopausal osteoporosis (70 mg weekly or 10 mg daily).1

A 69 year old woman had been treated for osteoporosis with disodium etidronate (Didronel, Procter & Gamble) for four years. She had a history of asthma but was not taking prednisolone. She started taking 70 mg alendronic acid a week but within 24 hours of her first dose developed synovitis in her right wrist and within 72 hours developed acute carpal tunnel syndrome. Fluid was found in the carpal tunnel when it was decompressed. No organisms or crystals were seen. Laboratory tests have included a consistently normal C reactive protein and erythrocyte sedimentation rate, calcium 2.41 mmol/l, ferritin 39 μg/l, uric acid 0.3 mmol/l, antinuclear antibodies 1/80, and negative extractable nuclear antigens, double stranded DNA, and rheumatoid factor. Nerve conduction studies showed a marked axonal lesion in the sensory median nerve. Alendronic acid was restarted at 10 mg daily five months later, but she developed pain in multiple joints after three days. The symptoms recurred on rechallenge at 10 mg on alternate days. She recovered fully when alendronic acid was discontinued.


Synovitis is a well recognised cause of carpal tunnel syndrome. This patient had no previous history of carpal tunnel syndrome or evidence of inflammatory arthritis. Rechallenge led to symptoms in multiple joints.

Alendronic acid can cause musculoskeletal pain.2 The New Zealand Pharmacovigilance Centre ( holds three other reports of synovitis occurring in patients taking alendronic acid, one of whom developed a wrist effusion. Synovitis recurred when alendronic acid was re-administered after the normal dose interval of seven days in two patients and at a reduced dose after 11 days in the third. Alendronic acid should be considered a cause of synovitis or polyarthritis in the absence of any other pathology.


  • Contributors DGJ identified and managed the case surgically, and JH investigated and managed the patient medically. DGJ and RS searched the literature, and RS collated and summarised other adverse reactions. DGJ is guarantor.

  • Funding None.

  • Competing interests None declared.


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