Osteoarthritis of the knee – more than wear and tear

Dr. Tony Tom, Specialist Physician (Geriatrics Medicine) at Melomed Tokai Hospital
MBCHB (UFS) FCP (SA) MMED (UFS)

Knee osteoarthritis is the most frequently diagnosed arthritis, with an ever-growing number and increasing cause of disability. Long characterized as the "wear and tear" condition of the knee, but now understood as a complex interplay and cascade of degeneration of the knee joint structure (cartilage and meniscus degeneration, bone remodelling, joint inflammation, formation of osteophytes, and loss of normal joint function).

An estimated 240 million people worldwide are affected by symptomatic (e.g., pain, stiffness, and deformity) and activity-limiting knee osteoarthritis, with women slightly more affected than men. With the aging of the population, an increasing presentation of knee osteoarthritis is noted, with 40% of people over 70 years of age having symptomatic knee osteoarthritis. Also of interest is the increasing number of people with knee osteoarthritis with associated lifestyle diseases. About 30% of people with knee osteoarthritis have uncontrolled blood pressure (hypertension) and blood sugar levels (diabetes mellitus). The lifetime risk of symptomatic knee osteoarthritis is also increased in overweight individuals.

Individuals with knee osteoarthritis usually complain of long-term persistent knee pain, stiffness, and deformity with limitations in daily activities. The knee pain is usually activity related when standing or walking, and the stiffness is worse in the morning and after sitting for a long time. With a prolonged illness, patients develop deformities, in the form of bowed or knock knees.

What should I do if I think I might be suffering from arthritis?

The first step would be to consult your local doctor. The consultation with the doctor will focus on making the clinical diagnosis and distinguishing between age-related/ idiopathic (primary) and secondary osteoarthritis (usually after an injury, rheumatoid arthritis, or gout). The doctor may request X-rays of the knee that might show any of the following: osteophytes, asymmetric joint space narrowing, and subchondral changes (see images).

What are the treatment options?
Once the diagnosis is confirmed, the doctor will suggest a treatment program, which begins with lifestyle modification and physical therapy. There is a recommendation for patients to participate in self-management programs aimed at weight loss and the management of high blood sugar and high blood pressure. Physical therapy employs a knee-focused exercise program with a controlled supervised range of motion and functional training. High-impact exercises such as running on firm ground and jumping should be avoided, instead, low-impact activities such as swimming and cycling should be encouraged.

In addition to lifestyle modification and physical therapy, the doctor will prescribe medication to control the pain. A combination of medications will be prescribed to effectively manage the pain. These medications may include paracetamol, anti-inflammatories (e.g., Celebrex, naproxen), and weak opioids (e.g., tramadol). The non-steroidal anti-inflammatory medication is considered the firstline medication, which can be offered as oral and topical preparations. Selection should be based on patient acceptability, effectiveness, cost, and side effect profile.

What about surgery?
In individual cases where the patient has exhausted non-surgical treatment options (lifestyle modification, physical therapy, and medication) and continues to experience severe knee pain, or patients who present with severe illness (e.g., severely bent legs or bruised knees), we recommend that the patient be referred to an orthopaedic surgeon.

Importantly, the orthopaedic surgeon would reassess the patient to determine the severity of the knee osteoarthritis (x-ray staging). In some cases, advanced imaging (e.g., MRI scan) can narrow the diagnosis, especially in cases of a degenerative meniscal tear with minimal articular cartilage damage.

Knee osteoarthritis treatment focuses on paineradication, preventing disease progression, and restoring normal function. Depending on the severity of the disease, a shared decision between the doctor and patient will be made to perform a joint-sparing or joint-replacement procedure. Joint-sparing surgery is offered for mild and moderate disease severity, with the procedure aimed at preserving the original knee joint and removing what has been found to be causing the pain (pain generator). The effectiveness is that this procedure is limited in severe cases, as there may be multiple pain generators and not all of them can be addressed. In the severe form of knee osteoarthritis, joint replacement surgery is recommended. This directly addresses all pain generators, removing the diseased joint and replacing it with a durable metal prosthesis. This procedure is considered one of the most successful surgeries in the new era as it relieves joint pain with the restoration of function.

Take home message
• Knee osteoarthritis is a multifactorial disease, influenced by age, weight, and daily activities.
• Knee osteoarthritis is a leading cause of global disability and loss of productivity.

Early orthopaedic referral is always recommended for early disease staging and initiating non-invasivetreatment modalities.
• Self-management programs such as education, weight loss programs, and lifestyle modification (e.g., healthy diet, cessation of smoking, not excessive alcohol use) result in improved pain scores.
• When medication is started, the first line remains the nonsteroidal anti-inflammatories with the addition of paracetamol and a weak opioid (e.g., tramadol).
• Where a surgical procedure is recommended, in the young patient, joint preserving techniques yield better results, and in the older patient with severe disease, total knee replacement has shown favourable outcomes with low complication rates.