Knee pain in the old age due to Osteoarthritis

All you want to know

Osteoarthritis (OA) is one of the leading causes for knee pain and thus disability in the elderly. In India prevalence of osteoarthritis has been reported between 22% and 39% in various studies. The prevalence of OA increases with age and it affects more women than men. Nearly 70% people over 65 years age have X ray features of OA and up to 45% have knee pain.

What happens with age:

Age-related changes in the articular cartilage (which layer the joint) include: Decreased number of chondrocytes (cartilage cells), decreased water content, decreased proteoglycan content (a protein of intercellular matrix).

Osteoarthritic knee pain: what is the treatment?

Treatment of knee pain due to osteoarthritis depends upon the severity of articular cartilage damage (grading of joint damage). To grade the joint damage a weight bearing standing X ray is required. When we see the normal weight bearing X ray a gap is seen between the thigh and leg bones. Actually this gap is articular cartilage which is not seen in the X ray (marked in red in X ray below).

If this is gap is reduced in weight bearing standing X ray, it indicates wear and tear of joint cartilage. In the initial stages of joint damage this gap is reduced but with progressive damage, this gap is completely lost.

Mild to moderate osteoarthritis:

In the early stages of osteoarthritis most effective treatment consists of thigh muscle building exercises (quadriceps exercises), pain killers like diclofenec, paracetamol etc. Lifestyle modification includes avoiding climbing stairs and sitting cross-legged and squatting to off load the joint from excessive forces. Weight reduction and use of walking aids also assists in the process. Quadriceps strengthening and aerobic exercises are advised to improve muscle strength around the joints. Hot fomentation and TENS(transcutaneous electric nerve stimulation, a sort of electrotherapy) may provide pain relief.

Corticosteroids and hyaluronic acid are two most common knee injections used for osteoarthritic knee pain. Injection hyaluronic acid is relatively safer and more commonly used. It takes 5-6 weeks to show its maximum effects. Corticosteroid injections produce significant relief within a few days. However, while the effects of hyaluronic acid last for longer time (6 months or more) pain relief from corticosteroids injection diminishes within a few weeks. However multiple uses of corticosteroids are not recommended as it may cause cartilage to break down and pain may worsen. Many other drugs are commonly used but effects remain uncertain and latest guidelines of American orthopedic association don’t recommend these drugs for treatment of osteoarthritis. These include rosehip extract, collagen preparation, boswellia serrata extract etc.

Intraarticular injections of platelet rich plasma, which contains many growth factors has also emerged as a promising potential treatment for OA knee. PRP stimulates proliferation and synthesis of collagen.

Severe osteoarthritis causes marked narrowing of joint space and significant disability. X ray shows reduction of joint space, some cystic and sclerotic changes in the cartilage and bone below it, and new bone (osteophytes) formation. While osteoarthritis prominently reduces inner compartment of the joint rheumatoid arthritis usually involve outer or both compartments of the joint.

Rheumatoid arthritis causes reduction of both compartments (inner and outer) of the joint

Osteoarthritis usually involve only outer compartment.

Small joints of the hands are other common joints to be involved by the osteoarthritis.

Treatment of severe osteoarthritis is essentially surgical and includes partial (unicondylar) or total knee replacement. In the initial stages when only one compartment of the joint is involved some surgical procedures like high tibial osteotomy, proximal fibular osteotomy may provide pain relief.