The knee is one of the joints most commonly affected by osteoarthritis.[2] 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.[7] Nearly a third of US citizens are affected by osteoarthritis of the knee by age 70.[8]
Obesity is a known and very significant risk factor for the development of osteoarthritis.[9] 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.[7]
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.[10]
Flat feet are a significant risk factor for the development of osteoarthritis.[11] 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.[7]
Lyme disease-related arthritis of the knee
The knee is often the first joint affected in Lyme disease.[2]
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 is a possible complication, leading to further pain and disability.[12]
Reactive arthritis
Reactive arthritis often presents with lower limb oligoarthritis, including that of the knee.[13]
Gout
Arthritis of a single joint of the lower extremities with rapid onset is highly suggestive of gouty arthritis.[14] 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.[15]
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.[16]
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.[1] 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.[17]
Standardized medical questionnaires like the Knee injury and Osteoarthritis Outcome Score (KOOS)[18] and short form KOOS JR.[19] or the Western Ontario and McMaster Universities Osteoarthritis Index (WOMAC)[20] 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.[1]
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 drugs, biopharmaceuticals, viscosupplementation (including hyaluronic acid injections), and glucosamine and chondroitin sulphate.[1]
Hyaluronic acid 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.[21][22][23][24] 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.[25][26] Knee braces may however result in discomfort, skin irritation, swelling, and may not provide benefits to all.[26] 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.[1] Shoe insoles that are fitted to correct flat feet provide significant relief to those with severely flat feet.[27] However, it has been found that insoles used to correct medial knee osteoarthritis (the more common form) may not offer much pain relief.[28][29]
Lifestyle
Body weight
Obesity is a known and very significant risk factor for the development of osteoarthritis.[9] Furthermore, losing weight reduces mechanical stress acting upon the knees when standing, possibly reducing pain and improving function in knee osteoarthritis.[26][1] However, it is necessary to ascertain whether the patient is actually overweight before committing to weight loss as a management technique.[9]
Exercise
Exercises can help increase range of motion and flexibility as well as help strengthen the muscles in the leg.[30]Physical therapy 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.[31] 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.[32] land-based exercises that focus on hip abductor shows improvement related to performance and function in women with symptomatic knee osteoarthritis.[33] A Cochrane review could not conclude whether high-intensity exercises provide better results than low-intensity exercises.[34]
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 (performed only for unilateral early-stage osteoarthritis), or arthroplasty.[1]
Knee replacement is the most definitive treatment for osteoarthritis-related symptoms and disability.[10][7] It is a type of arthroplasty, and may involve either a partial or total replacement with a prosthesis.[1]
Alternative medicine
Alternative medicine interventions undertaken for pain relief in arthritis of the knee include acupuncture, and magnetic pulse therapy.[1]
↑ Taglietti, Marcelo; Facci, Ligia Maria; Trelha, Celita Salmaso; de Melo, Fernanda Cristiane; da Silva, Daniela Wosiack; Sawczuk, Geovane; Ruivo, Thamires Marques; de Souza, Thaisley Barbosa; Sforza, Chiarella; Cardoso, Jefferson Rosa (June 2018). "Effectiveness of aquatic exercises compared to patient-education on health status in individuals with knee osteoarthritis: a randomized controlled trial". Clinical Rehabilitation. 32 (6): 766–776. doi:10.1177/0269215517754240. hdl:2434/548022. ISSN1477-0873. PMID29417831. S2CID3431729.
Arthritis is a term often used to mean any disorder that affects joints. Symptoms generally include joint pain and stiffness. Other symptoms may include redness, warmth, swelling, and decreased range of motion of the affected joints. In some types of arthritis, other organs are also affected. Onset can be gradual or sudden.
Rheumatoid arthritis (RA) is a long-term autoimmune disorder that primarily affects joints. It typically results in warm, swollen, and painful joints. Pain and stiffness often worsen following rest. Most commonly, the wrist and hands are involved, with the same joints typically involved on both sides of the body. The disease may also affect other parts of the body, including skin, eyes, lungs, heart, nerves and blood. This may result in a low red blood cell count, inflammation around the lungs, and inflammation around the heart. Fever and low energy may also be present. Often, symptoms come on gradually over weeks to months.
Osteoarthritis (OA) is a type of degenerative joint disease that results from breakdown of joint cartilage and underlying bone which affects 1 in 7 adults in the United States. It is believed to be the fourth leading cause of disability in the world. The most common symptoms are joint pain and stiffness. Usually the symptoms progress slowly over years. Other symptoms may include joint swelling, decreased range of motion, and, when the back is affected, weakness or numbness of the arms and legs. The most commonly involved joints are the two near the ends of the fingers and the joint at the base of the thumbs, the knee and hip joints, and the joints of the neck and lower back. The symptoms can interfere with work and normal daily activities. Unlike some other types of arthritis, only the joints, not internal organs, are affected.
Psoriatic arthritis (PsA) is a long-term inflammatory arthritis that occurs in people affected by the autoimmune disease psoriasis. The classic feature of psoriatic arthritis is swelling of entire fingers and toes with a sausage-like appearance. This often happens in association with changes to the nails such as small depressions in the nail (pitting), thickening of the nails, and detachment of the nail from the nailbed. Skin changes consistent with psoriasis frequently occur before the onset of psoriatic arthritis but psoriatic arthritis can precede the rash in 15% of affected individuals. It is classified as a type of seronegative spondyloarthropathy.
A Baker's cyst, also known as a popliteal cyst, is a type of fluid collection behind the knee. Often there are no symptoms. If symptoms do occur these may include swelling and pain behind the knee, or knee stiffness. If the cyst breaks open, pain may significantly increase with swelling of the calf. Rarely complications such as deep vein thrombosis, peripheral neuropathy, ischemia, or compartment syndrome may occur.
In medicine, a joint injection is a procedure used in the treatment of inflammatory joint conditions, such as rheumatoid arthritis, psoriatic arthritis, gout, tendinitis, bursitis, Carpal Tunnel Syndrome, and occasionally osteoarthritis. A hypodermic needle is injected into the affected joint where it delivers a dose of any one of many anti-inflammatory agents, the most common of which are corticosteroids. Hyaluronic acid, because of its high viscosity, is sometimes used to replace bursa fluids. The technique may be used to also withdraw excess fluid from the joint.
Prolotherapy, also called proliferation therapy, is an injection-based treatment used in chronic musculoskeletal conditions. It has been characterised as an alternative medicine practice.
Chondromalacia patellae is an inflammation of the underside of the patella and softening of the cartilage.
Calcium pyrophosphate dihydrate (CPPD) crystal deposition disease, also known as pseudogout and pyrophosphate arthropathy, is a rheumatologic disease which is thought to be secondary to abnormal accumulation of calcium pyrophosphate dihydrate crystals within joint soft tissues. The knee joint is most commonly affected. The disease is metabolic in origin and its treatment remains symptomatic.
Synovitis is the medical term for inflammation of the synovial membrane. This membrane lines joints that possess cavities, known as synovial joints. The condition is usually painful, particularly when the joint is moved. The joint usually swells due to synovial fluid collection.
Sacroiliitis is inflammation within the sacroiliac joint. It is a feature of spondyloarthropathies, such as axial spondyloarthritis, psoriatic arthritis, reactive arthritis or arthritis related to inflammatory bowel diseases, including ulcerative colitis or Crohn's disease. It is also the most common presentation of arthritis from brucellosis.
Articular cartilage, most notably that which is found in the knee joint, is generally characterized by very low friction, high wear resistance, and poor regenerative qualities. It is responsible for much of the compressive resistance and load bearing qualities of the knee joint and, without it, walking is painful to impossible. Osteoarthritis is a common condition of cartilage failure that can lead to limited range of motion, bone damage and invariably, pain. Due to a combination of acute stress and chronic fatigue, osteoarthritis directly manifests itself in a wearing away of the articular surface and, in extreme cases, bone can be exposed in the joint. Some additional examples of cartilage failure mechanisms include cellular matrix linkage rupture, chondrocyte protein synthesis inhibition, and chondrocyte apoptosis. There are several different repair options available for cartilage damage or failure.
A tear of a meniscus is a rupturing of one or more of the fibrocartilage strips in the knee called menisci. When doctors and patients refer to "torn cartilage" in the knee, they actually may be referring to an injury to a meniscus at the top of one of the tibiae. Menisci can be torn during innocuous activities such as walking or squatting. They can also be torn by traumatic force encountered in sports or other forms of physical exertion. The traumatic action is most often a twisting movement at the knee while the leg is bent. In older adults, the meniscus can be damaged following prolonged 'wear and tear'. Especially acute injuries can lead to displaced tears which can cause mechanical symptoms such as clicking, catching, or locking during motion of the joint. The joint will be in pain when in use, but when there is no load, the pain goes away.
Autologous chondrocyte implantation is a biomedical treatment that repairs damages in articular cartilage. ACI provides pain relief while at the same time slowing down the progression or considerably delaying partial or total joint replacement surgery. The goal of ACI is to allow people suffering from articular cartilage damage to return to their old lifestyle; regaining mobility, going back to work and even practicing sports again.
Sodium hyaluronate is the sodium salt of hyaluronic acid, a glycosaminoglycan found in various connective tissue of humans.
Gene therapy for osteoarthritis is the application of gene therapy to treat osteoarthritis (OA). Unlike pharmacological treatments which are administered locally or systemically as a series of interventions, gene therapy aims to establish sustained therapeutic effect after a single, local injection.
Polysulfated glycosaminoglycan (PSGAG), sold under the brand name Adequan, is an injectable drug for dogs and horses that is used to alleviate the limpness, pain, and lowered range of motion caused by arthritis. It is made of repeat disaccharide units (comprising hexosamine and hexuronic acid), and is similar to glycosaminoglycans already present in the cartilage; PSGAG thus easily integrates itself there. In vitro studies have shown it to inhibit the enzymes that degrade cartilage and bone, as well as suppress inflammation and stimulate the synthesis of replacement cartilage. While it can cause an increased risk of bleeding, it is relatively safe and has a high LD50. PSGAG is one of the most widely prescribed joint treatments for horses.
Post-traumatic arthritis (PTA) is a form of osteoarthritis following an injury to a joint.
A disease-modifying osteoarthritis drug (DMOAD) is a disease-modifying drug that would inhibit or even reverse the progression of osteoarthritis. Since the main hallmark of osteoarthritis is cartilage loss, a typical DMOAD would prevent the loss of cartilage and potentially regenerate it. Other DMOADs may attempt to help repair adjacent tissues by reducing inflammation. A successful DMOAD would be expected to show an improvement in patient pain and function with an improvement of the health of the joint tissues.
An antiarthritic is any drug used to relieve or prevent arthritic symptoms, such as joint pain or joint stiffness. Depending on the antiarthritic drug class, it is used for managing pain, reducing inflammation or acting as an immunosuppressant. These drugs are typically given orally, topically or through administration by injection. The choice of antiarthritic medication is often determined by the nature of arthritis, the severity of symptoms as well as other factors, such as the tolerability of side effects.
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