Osteoarthritis in focus

Evidence-based management of osteoarthritis needs to address the underutilisation of core
recommended treatments and over-reliance on surgery and pharmacological agents

Osteoarthritis is a chronic degenerative joint disorder characterised by cartilage loss. It is a leading cause of pain and disability, affecting 3.3-to-3.6 per cent of the global population and is the most common form of arthritis worldwide.Oste oarthritis affects approximately 400,000 Irish people and is the most common joint disease in Ireland.

Osteoarthritis presents with joint pain and loss of function; however, the disease is widely variable and can present from an asymptomatic incidental finding to a permanently disabling disorder. Osteoarthritis is a heterogeneous disease caused by multiple factors. Risk factors for developing osteoarthritis include increasing age, female gender, obesity, anatomical factors, muscle weakness and joint injury, particularly from occupational and sports activities.

The prevalence and incidence of osteoarthritis increase with age, with a majority of individuals over the age of 65 affected. The occurrence of osteoarthritis is progressively rising due to increased life expectancy and population ageing together with a rise in obesity. Excess weight compounds the problem by putting extra strain on damaged joints. Osteoarthritis is more common and often more severe in women, especially in the knees and hands. It often starts after the menopause. Certain occupations can place excessive loads on the joints resulting in osteoarthritis in later years.

Occupations with repetitive knee-bending can result in knee osteoarthritis, while heavy manual labour may predispose to hip osteoarthritis. Although complex, the genetic contribution to osteoarthritis is significant. The roles of genes and signalling pathways in osteoarthritis pathogenesis have been demonstrated by ex vivo studies using tissues derived from osteoarthritis patients and in vivo studies using surgically-induced osteoarthritis animal models and genetic mouse models.

Nodal osteoarthritis is one common form of osteoarthritis that runs strongly in families and particularly affects the hands of middle-aged women. In other common forms of osteoarthritis, heredity plays a small part compared with obesity, ageing and joint injury. There are some very rare forms of osteoarthritis that start at a young age and run in families and these are linked with single genes that affect collagen, which is an essential component of cartilage. Osteoarthritis is a disease of the entire joint and is recognised as a low-grade inflammatory disease involving cartilage degradation, bone remodelling, osteophytes and synovitis.

The chronic low-grade inflammation found in osteoarthritis contributes to disease development and progression. During osteoarthritis progression, the entire synovial joint, including cartilage, subchondral bone, and synovium, are involved in the inflammation process. Osteoarthritis can be classified into two categories: Primary osteoarthritis and secondary osteoarthritis. Primary osteoarthritis is the most common subset and is diagnosed in the absence of predisposing trauma or disease. Primary osteoarthritis can be localised or generalised, the latter more commonly
found in postmenopausal women, with development of Heberden’s nodes.

Secondary osteoarthritis occurs with a pre-existing joint abnormality. Predisposing conditions include trauma or injury, congenital joint disorders, inflammatory arthritis, avascular necrosis, infectious arthritis, Paget disease, osteopetrosis, osteochondritis dissecans, metabolic disorders, hemoglobinopathy, Ehlers-Danlos syndrome or Marfan syndrome.

Symptoms

The presentation and progression of osteoarthritis varies greatly from person to person. The triad of symptoms are joint pain, stiffness and locomotor restriction. Patients can also present with muscle weakness and problems with balance. Pain is usually related to activity and resolves with rest. For patients in whom the disease progresses, pain is more continuous and affects activities of daily living, eventually causing severe limitations in function.

Patients may also experience bony swelling, joint deformity and instability. Osteoarthritis typically affects proximal and distal interphalangeal joints, first carpometacarpal joints, hips, knees, first metatarsophalangeal joints and joints of the lower cervical and lumbar spine, and can be mono or poly articular in presentation. Shoulder and elbow joints are also susceptible to osteoarthritis although this is much rarer.

Joints can be at different stages of disease progression. Typical exam findings include bony enlargement, crepitus, effusions, and a limited range of motions. Tenderness may be present at joint lines, and there may be pain upon passive motion. Classic physical exam findings in hand osteoarthritis include Heberden’s nodes, Bouchard’s nodes and ‘squaring’ at the base of the thumb.

Diagnosis

A thorough history and physical examination with a focused musculoskeletal exam should be carried out. Differential diagnosis can include rheumatoid arthritis, psoriatic arthritis, crystalline arthritis, haemochromatosis, bursitis, avascular necrosis, tendinitis, radiculopathy, among other soft tissue abnormalities. There are no specific blood tests for diagnosing osteoarthritis, however, blood tests including FBC, ESR, rheumatoid factor and anti-nuclear antibodies can be ordered to rule out inflammatory arthritis.

X-rays of the affected joint can show findings consistent with osteoarthritis, such as marginal osteophytes, joint space narrowing, subchondral sclerosis, and cysts, however, radiographic findings do not correlate to the severity of condition and may not be present early in the disease. MRI is not routinely indicated for osteoarthritis workup; however, it can detect osteoarthritis at earlier stages than normal radiographs. Ultrasound can also identify synovial inflammation, effusion, and osteophytes, which can be related to osteoarthritis.

Treatments

Current therapeutic options are aimed at keeping the associated pain, inflammation, and degeneration of synovial joint tissues manageable in order to minimise the structural and symptomatic progression of osteoarthritis. Management of the disease involves both pharmacological and non-pharmacological therapies.

Pharmacotherapy involves oral, topical, and/or intra-articular options. Paracetamol and oral NSAIDs are usually the initial choice of pharmacological treatment. Topical NSAIDs are less effective than their oral counterparts, but have fewer gastrointestinal and other systemic side-effects. A proton pump inhibitor (PPI) may also be prescribed at the same time as oral NSAIDs to reduce the risk of damage to the stomach lining. Capsaicin cream may also be prescribed for osteoarthritis of the hands or knees, if topical NSAIDs have not been effective in easing pain. Capsaicin cream works by blocking the nerves that transmit pain in the treated area.

Intra-articular joint injections can be an effective treatment for osteoarthritis. Glucocorticoid injections have a variable
response, however, and there is ongoing controversy regarding repeated injections. Although corticosteroid injections can ease osteoarthritis symptoms, they have limitations. They cannot repair damaged cartilage or slow the progression of osteoarthritis and relief is only temporary. There are also some risks involved with glucocorticoid joint injections including; injury to the joint tissues, mainly with repeated injections; thinning of cartilage; weakening of the ligaments of the joint; inflammation in the joint caused by a corticosteroid that has crystallised; irritation of the nerves; infection; and whitening or thinning of the skin at the injection site.

Non-pharmacologic therapy includes avoidance of activities that exacerbate pain, exercise to improve strength, weight loss if applicable, wearing suitable footwear and occupational therapy for unloading joints. Malalignment of joints should be corrected via mechanical means such as realignment knee brace or orthotics. Weight loss is an important intervention in patients who are overweight and obese. Regular exercise that keeps a person active, builds up muscle and strengthens the joints usually helps to improve symptoms. Patients should, however, be advised to avoid exercise that puts strain on joints and forces them to bear an excessive load, such as running and weight training.

Activities such as swimming and cycling, where strain on joints is more controlled, are advisable. In addition to lifestyle changes and pharmacology, patients may benefit from a number of supportive treatments that can help reduce pain and make everyday tasks easier. Not using joints can cause muscles to waste and increase the stiffness caused by osteoarthritis. Manual therapy is a technique where a physiotherapist uses their hands to stretch, mobilise and massage the body tissues to keep a patient’s joints supple and flexible. Applying hot or cold packs to the affected joints can also help relieve the pain and symptoms of osteoarthritis in some people.

Transcutaneous electrical nerve stimulation (TENS) if advised by a doctor or healthcare professional may help ease the pain caused by osteoarthritis, by numbing the nerve endings in the spinal cord which control pain. For osteoarthritis in the lower limbs, such as hips, knees or feet special footwear or insoles for shoes may be helpful. Footwear with shock-absorbing soles can help relieve some of the pressure on the leg joints when walking, and special insoles may help spread weight more evenly. Leg braces and supports also work in the same way.

For osteoarthritis in the hip or knee that affects mobility, the use of a walking aid, such as a stick or cane, may be beneficial. Occupational therapists can provide help and advice about using assistive devices in the home or workplace. Osteoarthritis can affect any joint in the body, but the most common areas affected are the knees, hips and small joints in the hands. For patients with knee or hip osteoarthritis for whom pharmacological and non-pharmacological treatments have failed, joint replacement surgery/arthroplasty is the next option.

Failure rates for both knee and hip replacements are quite low, and joint replacement can provide pain relief and increased functionality. The timing of surgery is important. Poor functional status and considerable muscle weakness may not lead to improved postoperative functional status versus those undergoing surgery earlier in the disease course. Most patients who undergo joint replacement tend to have a good prognosis with success rates of over 80 per cent. However, most prosthetic joints wear out in 10-to-15 years, and repeat surgery is required.

A newer type of joint replacement surgery called resurfacing uses only metal components and may be more suitable for younger patients. If a joint replacement is not a suitable option, an operation to fuse the joint in a permanent position known as an arthrodesis, may be carried out. The joint will be stronger and less painful; however, the patient will no longer be able to move it. For patients with osteoarthritis of the knees but who are unsuitable for knee replacement surgery, an osteotomy may be performed. This involves adding or removing a small section of bone either above or below the knee joint. This helps realign the knee so weight is no longer focused on the damaged part of the knee. An osteotomy can relieve symptoms of osteoarthritis, although the patient may still need knee replacement surgery in the future.

Outlook

The prognosis for osteoarthritis patients depends on the joint involved, how many joints are affected, and the severity of the disease. There is currently no cure for osteoarthritis, and all available treatments are directed towards reducing symptoms. Although significant research has been carried out and progress made in recent years, the molecular mechanisms of osteoarthritis initiation and progression is still not fully understood. The last decade has seen significant advances however, in understanding the processes that contribute to osteoarthritis and over the coming years these new insights will hopefully lead to better treatment options.

Further research and a better understanding of the molecular mechanisms could accelerate the development of novel therapeutic strategies for osteoarthritis.

Traditional osteoarthritis management approaches often result in varying treatments, evidence practice gaps and delayed treatment due to over demand and long waiting lists. Despite the considerable societal, economic and personal burden associated with osteoarthritis, the condition is often overlooked in healthcare strategic plans for chronic disease management. A shift is needed to promote evidence-based management of osteoarthritis and address the underutilisation of core recommended treatments and over-reliance on surgery and pharmacological agents.

Model of Care ‒ ENACt Project

Osteoarthritis does not feature alongside other chronic diseases such as asthma or diabetes and there is currently no specific model of care for osteoarthritis in primary care in Ireland. The ENACt research project (2020-2024), led by researchers at the RCSI hopes to change that, and is in the process of developing a model of care for osteoarthritis in primary care to deliver best practice nationwide. The ENACt project is developing a model of care for osteoarthritis specifically tailored to the Irish healthcare system, with the goal of implementing and evaluating it on a large scale national level.

The research, to be carried out in three work packages over four years, aims to identify current primary care management of osteoarthritis in Ireland and develop a model of care focusing on core interventions, education, exercise and weight loss.