Table 1 Eligibility criteria

Age above 40 years

Member of a Health Insurance Company that participates in the "Model Project"

Signed informed consent

Chronic pain in at least one knee joint during the last six months as minimum according to the ACR-criteria [26]

Radiological signs of a gonarthrosis in the same knee (Kellgren 2 or 3) [27]

WOMAC ≥ 3 points (on a scale of 0–10)

Von Korff Chronic Pain Score ≥ 1

Exclusion criteria

A systemic disease of the musculosceletal system

Bone tumour, bone tumour like lesions or metastasis

Bone fracture in the lower extremities during the last three months

Acute infection or osteonecrosis in the knee joint

Surgery of the afflicted extremity during the last six months or planned surgery

Radiological signs of a severe gonarthrosis of a Kellgren grade 4

Other pain conditions which compels the patient to take analgesics for more than three days during the last four weeks

Addiction to analgesics, opiate or other drugs

Acupuncture treatment in the past 12 months

Acupuncture treatment of gonarthrosis.

Ongoing cortico-steroid therapy or cortisone injections in the past six weeks

Dermatological disease within the acupuncture area impairing acupuncture treatment

Medical diseases causing an impairment of physical capacity (NYHA > II)

Severe Coagulopathy

Ischialgia or other neurological diseases

History of epilepsy and psychiatric diseases

Pregnant or breast-feeding patients

Inability to follow instructions (insufficient command of language, dementia)

Participation in another clinical study

Ongoing legal proceedings concerning pension entitlement