Osteoarthritis (OA) is the most prevalent joint disease in the uk. it is a common cause of pain and disability and the main reason for hip and knee replacement. Three million GP consultations for OA took place in the UK in 2000,¹ and with the ageing population this figure is set to increase.

OA is a syndrome of joint pain and stiffness with associated inability to participate in usual activities; consequently, it has a major impact on quality of life. It is associated with structural joint pathology; hyaline cartilage loss; meniscal damage and extrusion; and changes within the bone underneath the cartilage, including bony outgrowths or attempts at repair called osteophytes. There is often inflammation within the synovial lining of the joint and weakness of the supporting ligaments and muscles.²

In most patients, the aetiology of OA is unknown, although there are several risk factors for its development, see box 1, attached. Prevalence increases with age, and the condition is more common in women.

Many patients will have had symptoms for months before they seek medical help, and often patients never seek help, perhaps reflecting a negative community outlook on OA treatment.³ However, OA is not a necessary association of ageing and often does not deteriorate over time.

Diagnosis

The knee, hip, hand and first metatarsophalangeal joint are the most common peripheral joints affected by OA. The most frequently affected joints in the hands are the distal interphalangeal (DIP) joints and proximal interphalangeal (PIP) joints.

The involvement of the metacarpophalangeal (MCP) joints is less common. However, modern imaging studies suggest that OA may affect these joints more frequently than is detected by plain X-ray.

See box 2,attached, for the criteria for hand and knee OA.

Symptoms

The most common symptom of OA is joint pain, usually when the patient is weight bearing through the joint. Patients often feel worse at the end of the day, with symptoms worsening after repetitive weight bearing, for example after a walk or using stairs.

Patients may have early morning stiffness. However, it is uncommon for it to last more than 10 minutes, and prolonged early morning stiffness (more than 30 minutes) may indicate inflammatory arthritis. Patients with OA may complain of 'gelling', which is stiffness of a joint with disuse (for example after sitting in one position for a prolonged period). This is often mistaken for joint locking.

Pain from the hip joint is usually felt in the groin or deep buttock. Pain on the outer thigh usually indicates trochanteric bursitis. This can be associated with underlying hip OA, but is more commonly associated with poor quadriceps strength, which can be caused by knee OA. Patients with bursitis often have a history of pain when lying on their side in bed.

An assessment of joint pain should include:

• The number of joints involved and the pattern of joints affected (OA commonly involves multiple joints in the over 50s)

• The effects on participation in important daily activities and work

• Any associated sleep and mood disturbance.

Excluding an inflammatory arthritis

Symmetrical joint pain, especially associated with prolonged early morning stiffness and raised inflammatory markers, should raise suspicion of inflammatory arthritis and warrants early referral to a rheumatologist. GPs should ask patients about diseases associated with inflammatory arthritis, such as diarrhoeal illnesses, STIs, inflammatory bowel disease and psoriasis.

Patients should be referred to a rheumatologist if:

• There is a suspicion of an inflammatory arthritis

• There is diagnostic uncertainty and the patient or clinician is concerned

• There is substantial impact of joint symptoms on quality of life.

Examination

On examination, a joint with OA will have:

• Tenderness (most marked over the joint line)

• Swelling (synovial or bony)

• Crepitus

• Reduced range of movement

• Reduced muscle strength.

Hands

The hands may have bony swelling at the DIP joints (Heberden's nodes) or PIP joints (Bouchard's nodes), see box 2, attached. There may be tenderness in the base of the thumb (anatomical snuff box) or marked squaring of the thumb base. Associated poor grip strength and weakness of the forearm muscles is common.

Hip

In early hip OA there is normally loss of internal rotation when the patient lies on their back and flexes the knee to 90 degrees. Active or passive movement of the hip joint will often reproduce the patient's symptoms.

Tenderness over the trochanteric bursa region may indicate bursitis rather than hip OA.

Knee

Patients with knee OA may have a varus (bow-legged) or valgus (knock-kneed) deformity, bony enlargement or tenderness and crepitus. It is important to check for ligament stability. Patients may have a flexion deformity, which may be reversible early in the disease and can be fixed in later stages. Joint effusion may be present (see box 2, attached).

Investigations

Diagnosis of OA is usually based on history and clinical examination. Conventional X-rays are not required as they rarely change management. However, X-rays are useful if there is diagnostic uncertainty or to assess the structural severity of OA if joint replacement is being considered.

Inflammatory markers are usually normal in OA. Patients should only have CRP, ESR or rheumatoid factor measured if inflammatory arthritis is suspected.

Treatment

All current treatments for OA are directed at symptom control, and at present no widely accepted structure modifying drugs are available.

All recent OA guidelines agree that patient education is crucial and a holistic approach should be used, taking into account the patient's occupation, quality of life, function and mood. A combination of non-pharmacological and pharmacological management is recommended.

Two evidence-based guidelines, from NICE⁴ and the Osteoarthritis Research Society International (OARSI),⁵ have recently been published. The main difference between these guidelines is that NICE includes a health economic analysis relevant to the UK. The NICE guideline also includes a treatment algorithm.

The initial management should include:

• Patient education, advice and information

• Strengthening exercises and aerobic fitness training

• Weight loss if overweight/obese.

Initially, patients should be encouraged to use self-help and patient-driven treatments. Patient education should include the objectives of treatment and the need for changes in lifestyle, exercise and weight reduction to unload their damaged joints.

Exercise is essential for people with OA, regardless of comorbidity or age. Pain should not be a barrier to exercise. Patients should be encouraged to undertake and continue regular aerobic, muscle strengthening and range of motion exercises, for example quadriceps-strengthening exercises for knee OA and forearm-strengthening exercises for hand OA. Patients with symptomatic OA require referral to a physiotherapist for appropriate exercises to reduce pain and improve function.

Pharmacological treatments

Paracetamol and/or topical NSAIDs are the treatments of choice if additional analgesia is required. Topical NSAIDs may require multiple daily applications to be effective, which can reduce compliance.

NSAIDs or COX-2 inhibitors should be considered if paracetamol and/or topical NSAIDS fail to provide sufficient pain relief. They should be used at the lowest effective dose for the shortest possible time period, and their potential gastrointestinal, liver and cardio-renal toxicity must be taken into account when prescribing. Patients prescribed these drugs should be reviewed at least yearly.

NICE recommends that all patients with OA on NSAIDs and COX-2 inhibitors should be prescribed a proton pump inhibitor.

Topical capsaicin can be an effective analgesic for knee or hand OA. It can be applied up to four times a day, but local redness or irritation can occur in 40% of patients.⁵

Intra-articular corticosteroid injections can be used for the relief of moderate to severe pain in patients with knee and base of thumb OA. Usually, no more than three injections per year are recommended. Around 70% of patients receiving an intra-articular steroid injection to the knee will show a modest but short-term improvement (usually 2-4 weeks),6 during which muscle-strengthening exercises can be promoted.

The data on the analgesic efficacy of various hyaluronan preparations are mixed and they are not recommended by NICE. Like many OA therapies, there is unfortunately no good evidence to select OA subgroups that may have a better response to this therapy.

Opioid analgesics are a useful option in OA but generally have more effect on pain than function.

There may be a high incidence of side-effects (especially confusion and constipation), which may be more debilitating in the elderly.

The use of glucosamine and/or chondroitin remains somewhat controversial. There is now one licensed preparation of glucosamine hydrochloride available in the UK, but results from previous trials have not suggested benefits. However, there is some evidence that glucosamine sulphate at a dose of 1.5g daily can provide symptomatic relief of knee OA5 and a three-month trial can be considered, although this preparation is not licensed in the UK.

Non-pharmacological treatments

GPs should advise patients with knee/hip OA on appropriate footwear, which should be shock absorbing with arch support. Referral to a podiatrist for insoles, which may reduce pain and improve mobility, should be considered. Walking aids can reduce pain in knee or hip OA when used in the contralateral hand.

A knee brace can reduce pain and the risk of falls in knee OA and mild/moderate valgus or varus instability. However, this is not a substitute for quadriceps exercises for most people with OA.

TENS therapy may give additional short-term pain relief. Local cold or heat application can also reduce symptoms, although supporting evidence is limited.

The use of acupuncture remains somewhat controversial because of heterogeneous analgesic trial results, and different regimens and types of acupuncture interventions. There is some evidence for short-term (2-6 weeks) symptomatic relief for knee OA.⁵

Surgical options

Surgical options for the treatment of OA include:

• Total joint replacement

• Unicompartmental knee replacement, eg for OA restricted to a single compartment

• Osteotomy and joint-preserving procedures, eg for young adults with deformity, although these procedures are performed relatively infrequently.

These options will vary with individual cases and surgical advice.

Patients with knee OA who have a clear history of mechanical locking (not gelling, 'giving way' or X-ray evidence of loose bodies) should be referred for arthroscopy.

Patients with OA with inadequate pain relief and functional improvement from a combination of the above treatments should be considered for joint replacement. These patients should be referred before there is prolonged and established functional limitation and severe pain.