Arthritis of the knee is typically a particularly debilitating form of arthritis. The knee may become affected by almost any form of arthritis. The word ''arthritis'' refers to inflammation of the joints. Types of arthritis include those related to wear and tear of

cartilage Cartilage is a resilient and smooth type of connective tissue. Semi-transparent and non-porous, it is usually covered by a tough and fibrous membrane called perichondrium. In tetrapods, it covers and protects the ends of long bones at the joints ...

, such as

osteoarthritis Osteoarthritis is a type of degenerative joint disease that results from breakdown of articular cartilage, joint cartilage and underlying bone. A form of arthritis, it is believed to be the fourth leading cause of disability in the world, affect ...

, to those associated with

inflammation Inflammation (from ) is part of the biological response of body tissues to harmful stimuli, such as pathogens, damaged cells, or irritants. The five cardinal signs are heat, pain, redness, swelling, and loss of function (Latin ''calor'', '' ...

resulting from an overactive

immune system The immune system is a network of biological systems that protects an organism from diseases. It detects and responds to a wide variety of pathogens, from viruses to bacteria, as well as Tumor immunology, cancer cells, Parasitic worm, parasitic ...

(such as

rheumatoid arthritis Rheumatoid arthritis (RA) is a long-term autoimmune disorder that primarily affects synovial joint, joints. It typically results in warm, swollen, and painful joints. Pain and stiffness often worsen following rest. Most commonly, the wrist and h ...

).Arthritis Causes, Symptoms, Diagnosis and Treatment Information on MedicineNet.com
Retrieved on 2010-01-22.

Causes

It is not always certain why arthritis of the knee develops. The knee may become affected by almost any form of arthritis, including those related to mechanical damage of the structures of the knee (

, and post-traumatic arthritis), various autoimmune forms of arthritis (including; rheumatoid arthritis,

juvenile arthritis Childhood arthritis (juvenile arthritis or pediatric rheumatic disease) is an umbrella term used to describe any rheumatic disease or chronic arthritis-related condition which affects individuals under the age of 16. There are several subtypes tha ...

, and SLE-related arthritis,

psoriatic arthritis Psoriatic arthritis (PsA) is a long-term inflammatory arthritis that may occur in some people affected by the autoimmune disease psoriasis. The classic features of psoriatic arthritis include dactylitis (sausage-like swelling of the fingers ...

, and

ankylosing spondylitis Ankylosing spondylitis (AS) is a type of arthritis from the disease spectrum of axial spondyloarthritis. It is characterized by long-term inflammation of the joints of the spine, typically where the spine joins the pelvis. With AS, eye and bow ...

), arthritis due to infectious causes (including

Lyme disease Lyme disease, also known as Lyme borreliosis, is a tick-borne disease caused by species of ''Borrelia'' bacteria, Disease vector, transmitted by blood-feeding ticks in the genus ''Ixodes''. It is the most common disease spread by ticks in th ...

-related arthritis),

gout Gout ( ) is a form of inflammatory arthritis characterized by recurrent attacks of pain in a red, tender, hot, and Joint effusion, swollen joint, caused by the deposition of needle-like crystals of uric acid known as monosodium urate crysta ...

y arthritis, or

reactive arthritis Reactive arthritis, previously known as Reiter's syndrome, is a form of inflammatory arthritis that develops in response to an infection in another part of the body (cross-reactivity). Coming into contact with bacteria and developing an infect ...

Osteoarthritis of the knee

The knee is one of the joints most commonly affected by osteoarthritis. Cartilage in the knee may begin to break down after sustained stress, leaving the bones of the knee rubbing against each other and resulting in osteoarthritis. Nearly a third of US citizens are affected by osteoarthritis of the knee by age 70.

Obesity Obesity is a medical condition, considered by multiple organizations to be a disease, in which excess Adipose tissue, body fat has accumulated to such an extent that it can potentially have negative effects on health. People are classifi ...

is a known and very significant risk factor for the development of osteoarthritis. Risk increases proportionally to body weight. Obesity contributes to OA development, not only by increasing the mechanical stress exerted upon the knees when standing, but also leads to increased production of compounds that may cause joint inflammation. Parity is associated with an increased risk of knee OA and likelihood of knee replacement. The risk increases in proportion to the number of children the woman has birthed. This may be due to weight gain after pregnancy, or increased body weight and consequent joint stress during pregnancy.

Flat feet Flat feet, also called pes planus or fallen arches, is a Posture (psychology), postural deformity in which the arches of the foot collapse, with the entire sole (foot), sole of the foot coming into complete or near-complete contact with the gro ...

are a significant risk factor for the development of osteoarthritis. Additionally, structural deformities, advanced age, female sex, past joint trauma, genetic predisposition, and certain at-risk occupations may all contribute to the development of osteoarthritis in general.

Lyme disease-related arthritis of the knee

The knee is often the first joint affected in Lyme disease.

Systemic lupus erythematosus

Arthritis is a common symptom of SLE. Arthritis is often symmetric and more often involves small joints. Though almost any joint may be affected, the knees and joints of the hands are most often involved in SLE. In larger joints (including the knee),

avascular necrosis Avascular necrosis (AVN), also called osteonecrosis or bone infarction, is death of bone tissue due to interruption of the blood supply. Early on, there may be no symptoms. Gradually joint pain may develop, which may limit the person's abilit ...

is a possible complication, leading to further pain and disability.

Reactive arthritis

Reactive arthritis often presents with lower limb oligoarthritis, including that of the knee.

Gout

Arthritis of a single joint of the lower extremities with rapid onset is highly suggestive of gouty arthritis. The knee may sometimes be affected. In cases of gouty arthritis of the knee, skin symptoms occur less often, however pain and swelling may be particularly intense.

Rheumatoid arthritis

RA most often first manifests as inflammation of particular finger or toe joints, however, pain and swelling of larger joints, including the knees, may also be the first sign.

Diagnosis

Osteoarthritis of the knee

Diagnosis of knee osteoarthritis often entails a physical examination, assessment of symptoms and the patient's medical history, but may also involve medical imaging and blood tests. Persistent knee pain, limited morning stiffness and reduced function, crepitus, restricted movement, and bony enlargement appear to be the most useful indications of knee osteoarthritis for diagnosis. Standardized medical questionnaires like the Knee injury and Osteoarthritis Outcome Score (KOOS) or the Western Ontario and McMaster Universities Osteoarthritis Index (WOMAC) can also be used to diagnose and monitor progression of knee osteoarthritis.

Management

A physician will recommend a treatment regimen based upon the severity of symptoms. General recommendations for the management of knee arthritis may include avoiding activities that aggravate the condition, and applying cold or warm packs and using ointments and creams to relieve symptoms.

Pharmaceutical

Pharmaceutical management is usually dependent upon the nature of the underlying condition causing arthritis. Over-the-counter medications like acetaminophen (paracetamol), and ibuprofen, naproxen, and other NSAIDs are often used as first-line medical treatments for pain relief and/or managing inflammation. Corticosteroids may be injected directly into the joint cavity to provide more significant relief from inflammation, swelling, and pain. Other medications used in management of arthritis of the knee include;

disease-modifying antirheumatic drug Disease-modifying antirheumatic drugs (DMARDs) comprise a category of otherwise unrelated disease-modifying drugs defined by their use in rheumatoid arthritis to slow down disease progression. The term is often used in contrast to nonsteroida ...

biopharmaceutical A biopharmaceutical, also known as a biological medical product, or biologic, is any pharmaceutical drug product manufactured in, extracted from, or semisynthesized from biological sources. Different from totally synthesized pharmaceuticals, t ...

s, viscosupplementation (including hyaluronic acid injections), and glucosamine and chondroitin sulphate.

Hyaluronic acid Hyaluronic acid (; abbreviated HA; conjugate base hyaluronate), also called hyaluronan, is an anionic, nonsulfated glycosaminoglycan distributed widely throughout connective, epithelial, and neural tissues. It is unique among glycosaminog ...

is normally present in joints (including the knee), acting as lubricant and providing shock absorption, among other functions. In osteoarthritis, there is a loss of articular hyaluronic acid activity, likely contributing to pain and stiffness associated with the condition. Hyaluronic acid injections are an FDA-approved treatment for osteoarthritis of the knee, and are sometimes also used for other joints. However, the merits of HA injections are still disputed. HA injections are indicated when other medications fail to offer adequate symptom relief. Symptom relief associated with HA injections may last up to 2 years after an injection. HA injections appear to offer significant pain relief to some patients, while others may see no benefits at all. In severe osteoarthritis without much cartilage, the benefits of hyaluronic are not observed.

Orthotics

Supportive devices like knee braces can be used for symptom relief in osteoarthritis of the knee. Knee braces may however result in discomfort, skin irritation, swelling, and may not provide benefits to all. Using a cane, shock-absorbent footwear and inserts, elastic bandages, and knee sleeves may also be helpful for managing arthritis symptoms. Braces may be especially effective when only one knee is affected. Shoe insoles that are fitted to correct flat feet provide significant relief to those with severely flat feet. However, it has been found that insoles used to correct medial knee osteoarthritis (the more common form) may not offer much pain relief.

Lifestyle

Body weight

Obesity is a known and very significant risk factor for the development of osteoarthritis. Furthermore, losing weight reduces mechanical stress acting upon the knees when standing, possibly reducing pain and improving function in knee osteoarthritis. However, it is necessary to ascertain whether the patient is actually overweight before committing to weight loss as a management technique.

Exercise

Exercises can help increase range of motion and flexibility as well as help strengthen the muscles in the leg.Arthritis of the Knee - American Academy of Orthopaetic Surgeons
Retrieved on 2010-01-22.

Physical therapy Physical therapy (PT), also known as physiotherapy, is a healthcare profession, as well as the care provided by physical therapists who promote, maintain, or restore health through patient education, physical intervention, disease preventio ...

and exercise are often effective in reducing pain and improving function. Compared to the patient-education program, pain and function showed improvement after eight weeks of aquatic exercise, and after twelve weeks it showed improvement in the function actiites. Inclusion of isokinetic quadriceps and hamstring strengthening exercises into the rehabilitation packages for the patients with knee osteoarthritis may also enhance the high-quality of life and make a contribution to the decreased hazard of fall. land-based exercises that focus on hip abductor shows improvement related to performance and function in women with symptomatic knee osteoarthritis. A Cochrane review could not conclude whether high-intensity exercises provide better results than low-intensity exercises.

Surgical

Surgical intervention may be undertaken if no other management technique yields adequate relief. Surgical procedures may entail an arthroscopy (seldom used for sole osteoarthritis),

osteotomy An osteotomy is a surgical operation whereby a bone is cut to shorten or lengthen it or to change its alignment. It is sometimes performed to correct a hallux valgus, or to straighten a bone that has healed crookedly following a fracture. It i ...

(performed only for unilateral early-stage osteoarthritis), or

arthroplasty Arthroplasty (literally " e-orming of joint") is an orthopedic surgical procedure where the articular surface of a musculoskeletal joint is replaced, remodeled, or realigned by osteotomy or some other procedure. It is an elective procedure that ...

. Knee replacement is the most definitive treatment for osteoarthritis-related symptoms and disability. It is a type of

, and may involve either a partial or total replacement with a prosthesis.

Alternative medicine

Alternative medicine interventions undertaken for pain relief in arthritis of the knee include acupuncture, and magnetic pulse therapy.

Notes

{{Inflammation Aging-associated diseases Inflammations Rheumatology Skeletal disorders Knee injuries and disorders