Table 1

Study inclusion and exclusion criteria

Inclusion criteria
Diagnosis	Knee osteoarthritis based on American College of Rheumatology clinical criteria26 and confirmed by radiographic findings
Age	Over 50 years
Pain duration	Knee pain for at least 6 months
Severity	Average pain over past week rated as moderate or severe by the patient
Medication	Willing to abstain from simple analgaesics, NSAIDs, weak opioids or medications that combine these, for 24 h prior to testing
Consent	Willing and able to give full consent
Exclusion criteria
Pathology	Lumbar or cervical radiculopathy, systematic inflammatory disease, positive screen for diabetic neuropathy, neuropathic pain
Past medical history	Previous surgery or disease of the peripheral or central nervous system, sensory loss secondary to chemotherapy or radiotherapy, fibromyalgia, chronic fatigue syndrome
Cognitive ability	Cognitive or psychiatric disorder interfering with ability to fully consent or cooperate with assessment
Other treatment	Injection or physiotherapy treatment for knee joint within previous 3 months
Medication	Taking antidepressant or anticonvulsant medication, strong opioids