Osteoarthritis

Osteoarthritis (OA) is the most common form of arthritis. It is a degenerative disease affecting the whole joint. Pathologically, there are focal areas of damage to load-bearing articular cartilage, new bone formation at the joint margins (osteophytosis), changes in the subchondral bone (sclerosis), inflammation of the synovium (synovitis) and thickening of the joint capsule.

It can affect any joint, but most commonly the knees, hips, hands, neck and low back. One joint may be affected but it is more common for OA to affect multiple joints.

It can lead to significant problems with mobility and is the most common cause of disability in elderly people in the developed world.¹ 85% of all knee and hip replacements are carried out because of osteoarthritis.²

NICE guidelines on the care and management of adults with osteoarthritis are due to be published in January 2008.

Prevalence rises with age. About 6% of adults aged 30 have frequent knee pain and radiographic evidence of osteoarthritis.³ Symptomatic knee OA affects 12% of people over the age of 65.⁴

• Increasing age
• Female sex (for knee disease)
• Family history (several chromosomal loci and gene variations have been identified as putting someone at increased risk for OA)⁵
• Previous joint injury including infection, intra-articular fracture and ligament tear causing joint instability
• Joint malalignment problems such as Perthes' disease, slipped upper femoral epiphysis, congenital dislocation of the hip
• Obesity
• Occupational (knee OA in elite athletes, elbow OA in people working with pneumatic drills)⁶
• Ethnic origin (more common in white Europeans)

Symptoms

• Joint pain that is exacerbated by exercise and relieved by rest. Rest and night pain can occur in advanced disease. Knee pain due to OA is usually bilateral and felt in and around the knee. Hip pain due to OA is felt in the groin and anterior or lateral thigh.⁶ Hip OA pain can also be referred to knee and, in males, to the testicle on the affected side.
• Joint stiffness in the morning or after rest.

Signs

• Reduced range of joint movement
• Pain on movement of joint or at extremes of joint movement
• Joint swelling/synovitis (warmth, effusion, synovial thickening)
• Periarticular tenderness
• Crepitus
• Absence of systemic features such as fever, rash
• Bony swelling and deformity due to osteophytes - in the fingers this presents as swelling at the distal interphalangeal joints (Heberden's nodes, as seen in the picture below) or swelling at the proximal interphalangeal joints (Bouchard's nodes)
  
  
  
  
  
  
• Joint instability
• Muscle weakness/wasting around affected joint

• Knee OA: Bursitis; referred pain from the hip or spine.
• Hip OA: Bursitis; referred pain from the knee or spine.
• OA of any joint: Pseudogout; psoriatic arthritis; septic arthritis; viral arthritis; reactive arthritis such as reiter's syndrome; rheumatoid arthritis; gout; connective tissue disease; seronegative arthritis such as ankylosing spondylitis; referred pain; medical conditions presenting with arthropathy such as sarcoidosis and infective endocarditis.

• Clinical examination: The diagnosis is usually based on clinical examination.
• Plain X-rays: When disease is advanced it can be seen on plain xrays. The diagnostic features that can be seen on xray are shown below:
  
  
  
  
  
  
• Body weight and body mass index: This should be recorded.
• MRI: This may be useful to distinguish other causes of joint pain.
• Blood tests: These are normal. Consider checking baseline fbc, creatinine and lfts before starting a patient on NSAIDs.
• Joint aspiration: This may be considered for swollen joints to exclude other causes such as septic arthritis and gout. The synovial fluid in osteoarthritis is non-inflammatory (leucocyte count <2000/mm³, clear and viscous).²

There is no cure for osteoarthritis. The aim of treatment is to reduce pain and improve joint function. The management strategies below also reflect the EULAR (European League Against Rheumatism) evidence based recommendations for the management of hip and knee osteoarthritis.^7,8

Conservative treatments

• Weight loss: Overweight patients with a BMI > 28 should be advised to lose weight through diet modification and exercise as this will reduce the load on their joints and help to improve pain.
• Exercise: As well as helping weight loss, exercise itself will help to build muscle strength and endurance and can lead to reduced pain and improved joint function. Non-weight bearing exercise such as swimming is ideal.⁹
• Physiotherapy: This can also help build muscle strength (e.g. quadriceps muscle strengthening exercises for knee OA) and improve joint movement.
• Knee braces and orthotics: These can help to shift joint load and can relieve pain and stiffness and improve function.^10,11
• Walking stick: A stick held in the hand of the unaffected side can relieve the load through the affected joint and help pain relief as well as improve function.
• TENS machine: This has been shown to provide pain relief in knee OA.¹²
• Acupuncture: A recent systematic review and meta-analysis has shown significant effects of acupuncture for pain control in patients with peripheral joint OA. It also has a favourable safety profile.¹³
• Patellar taping of the knee: This may also be used for OA knee as a method of pain relief.¹⁴
• Occupational therapy: A referral may be required if modification and/or aids are needed in the home.

Pharmacological treatments

• Analgesia
  • Paracetamol is the treatment of choice for mild to moderate pain. It is efficacious and safe.
  • Oral NSAIDs: ibuprofen, diclofenac, naproxen can be added or substituted if paracetamol is not effective but they do have toxic side effects including an increased risk of gastrointestinal bleeding, particularly in the elderly. COX 2 selective inhibitors have also been associated with an increased risk of cardiovascular disease. If a COX 2 inhibitor is prescribed, celecoxib should be used. Do not give celecoxib to those with established ischaemic heart disease, cerebrovascular disease, peripheral arterial disease or heart failure due to the increased risk of thrombotic events. Gastroprotection, in the form of a PPI or misoprostol, should be added to a non-selective NSAID if there is thought to be increased gastrointestinal bleeding risk.
  • Topical NSAIDs may be helpful in an acute flare-up or as an alternative to oral NSAIDs if gastroprotection is required.
  • Topical capsaicin may be tried if topical NSAIDs are not effective.
  • Opioids There is no evidence that low-dose opioids combined with paracetamol (co-codamol 8/500, co-dydramol 10/500) have any increased benefit over paracetamol alone.¹⁵ Higher dose codeine (60mg) has been shown to provide good analgesic effect when given with 1g paracetamol.¹⁶ Caution should be used if stronger opioids are prescribed due to the risk of dependency. Moderate/strong opioids may be necessary for those awaiting joint surgery, for those in whom other treatments have not controlled their pain, or those unsuitable for surgery.
• Glucosamine is found naturally in the body and is one of the building blocks of cartilage. It is thought that supplements may help prevent cartilage breakdown and help re-build cartilage. It may be purchased over the counter by the patient. 1500mg daily may provide some symptom relief in OA of the knee.^17,18,19 There are shellfish-derived formulations so patients should be warned. Also, it may possibly potentiate the effect of warfarin.
• Chondroitin is not licensed for the treatment of OA. A recent meta-analysis has shown that the symptomatic benefit of chondroitin is minimal or non-existent and concluded that its use in clinical practice should be discouraged.²⁰
• Intra-articular steroids may be useful if there is acute pain and joint effusion as long as inflammatory, septic and other forms of arthritis have been excluded. In primary care, intra-articular steroid hip injections should only be given by specialized GPs in a suitable environment. Long-term outcome after intra-articular steroids does not seem to show any difference when compared to other treatments.²¹
• Intra-articular hyaluronan has controversy associated with its use. It is sometimes used, particularly in private care, for those who have not responded to, or cannot tolerate intra-articular steroids, or for those awaiting joint replacement. It is thought to increase the natural hyaluronic acid in the synovial fluid returning the elasticity and viscosity of the synovial fluid to normal but there is limited evidence to support this.⁶

Surgical treatments

This should only be used if other treatments have failed. Surgery should be considered if there is severe daily pain and significant loss of function that has not responded to other therapy as well as x-ray evidence of joint space narrowing.^8,7

• Arthroscopic debridement and lavage: Arthroscopic knee washout with debridement is supported by NICE as a treatment for OA knee. Washout expels any loose debris from the knee joint and debridement removes damaged cartilage or bone. Patients with large effusions and early osteoarthritic changes are more likely to benefit.²²
• Osteotomy: This can improve pain and function, especially in young adults, and may delay the need for total joint replacement for 5-10 years.²³ For example, in hip OA, osteotomies of the pelvis and/or femoral osteotomies can alter force transmission through the hip joint and therefore have an impact on pain and function.
• Joint replacement: The joint lasts for 15 years in 95% of cases.²⁴ Hip and knee replacements are most common but trapeziometacarpal joint replacement is also supported by NICE for the treatment of end-stage OA in the hand.²⁵ Ankle and shoulder joint replacements are also carried out for OA.

These can include reduced mobility which can lead to problems with self care and loss of employment.

Most people affected by OA do not become severely disabled. Knee OA seems to have the worst prognosis with most cases deteriorating over a 10 year period. Hand OA has the best. A recent study has shown that generalised OA is associated with the radiological progression of knee OA. Knee pain, baseline radiological severity, sex, quadriceps strength, knee injury and regular sport activities did not seem to be related to the progression of OA in the knee.²⁶

• Weight control
• Increasing physical activity
• Avoiding injury
• Improving education about osteoarthritis including increased use of expert patient programmes
• Optimal management of symptoms by GPs to reduce the prevalence of disability due to OA