2.1 Arthritis refers to inflammation of a joint, and is a leading cause of pain and disability in the UK. Arthritis can have many causes, the most common of which is osteoarthritis (defined by a loss of cartilage within the joint and related changes in the associated bone). Estimates suggest that up to 8.5 million people in the UK are affected by joint pain that may be attributed to osteoarthritis. The second most common cause is rheumatoid arthritis (an autoimmune inflammatory disease that affects the synovial lining of joints). Around 400,000 people in the UK have rheumatoid arthritis.
2.2 Symptoms of hip arthritis include pain and stiffness that limit daily activities such as walking, climbing stairs and performing household tasks. The diagnosis of arthritis of the hip is usually based on individual patient history and clinical examination assessing joint pain, deformity and reduced range of movement. Osteoarthritis: Care and management in adults (NICE clinical guideline 177) states that clinicians should first offer patients non-surgical treatments including exercise, physical therapy and analgesics, and should consider referring patients for joint replacement surgery if they have ongoing pain, joint stiffness, reduced function and a poor quality of life. People having elective primary surgery to relieve pain and disability caused by arthritis of the hip may receive either a total replacement of the damaged hip (total hip replacement) or a hip resurfacing arthroplasty.
2.3 The National Joint Registry was set up by the Department of Health and Welsh Assembly Government for the mandatory collection of information on all hip, knee, ankle, elbow and shoulder replacement operations from NHS organisations and private practice, and to monitor the performance of joint replacement prostheses. Since 2009, all NHS patients who are having hip replacement surgery are invited to fill in Patient Reported Outcome Measures (PROMs) questionnaires about their health and quality of life before and after their surgery.
2.4 Following publication of Guidance on the selection of prostheses for primary total hip replacement (NICE technology appraisal guidance 2), the National Health Purchasing and Supply Agency (PASA) was given the task of monitoring adherence to the technology appraisal recommendation. PASA set up a panel of experts known as the Orthopaedic Data Evaluation Panel (ODEP). PASA was subsequently replaced by NHS Supply Chain, which still manages and provides administrative support to ODEP. ODEP provides the NHS with an approved list of prostheses that meet the revision rate standard at 10 years set out in NICE guidance and which are suitable for use in primary hip replacement (see section 3.6). ODEP provides separate ratings for the 2 components of hip replacement prostheses (that is, stems and cups; see section 3.1). For hip prostheses with less than 10 years of clinical data, there are currently 3 entry standards expressed by ODEP as failure rate: 3% or less at 3 years; 5% or less at 5 years; and 7% or less at 7 years, which are considered to be consistent with the 10-year standard.