OSTEOARTHRITIS OF THE KNEE- KNEE PAIN

KNEE OSTEOARTHRITIS
Osteoarthritis(OA) is the most common type of arthritis in adults.

About 35% of adults 60 years and above, have radiological evidence of knee osteoarthritis.

Osteoarthritis is the commonest cause of disability in persons over 65 years of age.

Osteoarthritis may involve any joint, but it usually affects the hands, hips, knees, and joints in the neck and low back spine.

PATHOPHYSIOLOGY.
Multiple mechanisms are involved and these include:

a. Joints Trauma(s) (single, repeated or insignificant multiple trauma), lead to production of inflammatory cytokines.

b. fat cells do produce the proinflammatory hormone: adipocytokines (1).

, These pro-inflammatory cytokines, through a cascade of biologic mechanisms, eventually lead to production of matrix metalloproteinases(MMP), the group of catabolic enzymes that eat away joint cartilage.

(The cartilages are slippery firm tissues at the ends of bones, that allow friction-free motion in the joints.)

It has been observed, that high levels of adipocytokines in the serum, especially leptin, and adipsin, correlate with knee cartilage volume loss and that, very high levels may predict the need for eventual knee replacement surgery (2)

The bones in the affected joints react, by producing poorly organized bony materials, in attempt, to replace the lost cartilage.

RISK FACTORS FOR KNEE OSTEOARTHRITIS:
Advance age: Risk of OA increases with age
Female gender: older women are more prone to developing OA.

Obesity: more burden/stress on weight bearing joints as well as adipocytokines production.

Family history: Genetic tendency to develop OA

Joint mal-alignment, lax ligaments may increase risk for OA

Ligamentous injury.
The lifetime risk for knee osteoarthritis is 45%, and this percentage, increases with obesity and knee injuries.

SIGN AND SYMPTOMS OF KNEE OSTEOARTHRITIS.
. Knee Joint stiffness (especially after a period of inactivity or on waking up in the morning) that improves within 20-30 minutes after using the joints.

. Knee Joint pain, usually experienced on moving the knee, that get better with rest.

. Crepitus: grating, creaking, grinding sensation on moving the joint.

. Decreased knee flexibility or limited range of joint movement.

. Knee Swelling: due to hard bony lumps and or, occasional joint fluid accumulation.

. In severe case, bowed and bent knees
. The muscles around the knee joint look thin and wasted

COMPLICATIONS
As a degenerative disease, OA worsens with time. The stiffness and pain eventually lead to disability, due to the gradual impairment of daily tasks. In general, OA is the most common cause of disability in the elderly population.

DIAGNOSIS :
Plain X-rays of the Knees:
X-ray changes do occur before patients experience pain and stiffness.

X-ray shows asymmetric narrowing of joint spaces. (due to loss of cartilage volume)

There may be bony projections (spurs) around a joint.

MANAGEMENT.
LIFESTYLE CHANGES
Exercise and achieving a healthy weight are the 2 most important ways to control OA pain and OA disease progression.

In the obese, weight loss is the most effective way to improve the pain. Weight loss eases the stress on the knee joint. Weight loss include switching to vegetable based and minimally processed foods, avoiding simple sugars and meat. Adults do not need red meat and chicken. Fish is okay.

Exercise: Any exercise that involves the use of the knee: climbing stairs, biking, Walking, swimming, improve the knee joint musculature, and ease the stress on the knee.

A combination of weight loss and exercise is key to arresting OA progression.

MEDICATIONS:
Paracetamol/Acetaminophen, is the initial choice for mild to moderate pain.

NSAIDs: naproxen, ibuprofen (if acetaminophen provides inadequate pain relief).

Tramadol, when acetaminophen, NSAIDs are ineffective.

Duloxetine (antidepressant) may be used with acetaminophen, NSAIDs, or used alone, for chronic O.A pain.

Glucosamine/chondroitin sulfates are ineffective and not recommended.

For severe pain
3 monthly glucocorticoid injection into the joint space eases pain within days to weeks

Knee replacement surgery, reduces pain, improves function and quality of life.

Reference:
1.) https://www.ncbi.nlm.nih.gov/pmc/articles/pmc3291123

2.) https://academic.oup.com/rheumatology/article/55/4/680/1833361

Rheumatology volume 55, issue 4 1 April 2016, pages 680-688.