Knee pain is

pain Pain is a distressing feeling often caused by intense or damaging stimuli. The International Association for the Study of Pain defines pain as "an unpleasant sensory and emotional experience associated with, or resembling that associated with, ...

in or around the

knee In humans and other primates, the knee joins the thigh with the leg and consists of two joints: one between the femur and tibia (tibiofemoral joint), and one between the femur and patella (patellofemoral joint). It is the largest joint in the ...

. The

joint consists of an articulation between four bones: the

femur The femur (; ), or thigh bone, is the proximal bone of the hindlimb in tetrapod vertebrates. The head of the femur articulates with the acetabulum in the pelvic bone forming the hip joint, while the distal part of the femur articulates ...

tibia The tibia (; ), also known as the shinbone or shankbone, is the larger, stronger, and anterior (frontal) of the two bones in the leg below the knee in vertebrates (the other being the fibula, behind and to the outside of the tibia); it conn ...

fibula The fibula or calf bone is a leg bone on the lateral side of the tibia, to which it is connected above and below. It is the smaller of the two bones and, in proportion to its length, the most slender of all the long bones. Its upper extremity ...

and

patella The patella, also known as the kneecap, is a flat, rounded triangular bone which articulates with the femur (thigh bone) and covers and protects the anterior articular surface of the knee joint. The patella is found in many tetrapods, such as ...

. There are four compartments to the knee. These are the medial and lateral tibiofemoral compartments, the patellofemoral compartment and the superior tibiofibular joint. The components of each of these compartments can experience repetitive strain, injury or disease. Running long distance can cause pain to the knee joint, as it is a high-impact exercise.

Causes

Injuries

Some common injuries based on the location include: *

Sprain A sprain, also known as a torn ligament, is an acute soft tissue injury of the ligaments within a joint, often caused by a sudden movement abruptly forcing the joint to exceed its functional range of motion. Ligaments are tough, inelastic fiber ...

(Ligament sprain) **

Medial collateral ligament The medial collateral ligament (MCL), or tibial collateral ligament (TCL), is one of the four major ligaments of the knee. It is on the medial (inner) side of the knee joint in humans and other primates. Its primary function is to resist outwar ...

** Lateral collateral ligament **

Anterior cruciate ligament The anterior cruciate ligament (ACL) is one of a pair of cruciate ligaments (the other being the posterior cruciate ligament) in the human knee. The two ligaments are also called "cruciform" ligaments, as they are arranged in a crossed formati ...

Posterior cruciate ligament The posterior cruciate ligament (PCL) is a ligament in each knee of humans and various other animals. It works as a counterpart to the anterior cruciate ligament (ACL). It connects the posterior intercondylar area of the tibia to the medial cond ...

Tear of meniscus 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 ...

** Medial meniscus **

Lateral meniscus The lateral meniscus (external semilunar fibrocartilage) is a fibrocartilaginous band that spans the lateral side of the interior of the knee joint. It is one of two menisci of the knee, the other being the medial meniscus. It is nearly circular ...

Strain Strain may refer to: Science and technology * Strain (biology), variants of plants, viruses or bacteria; or an inbred animal used for experimental purposes * Strain (chemistry), a chemical stress of a molecule * Strain (injury), an injury to a mu ...

(Muscle strain) **

Quadriceps muscles The quadriceps femoris muscle (, also called the quadriceps extensor, quadriceps or quads) is a large muscle group that includes the four prevailing muscles on the front of the thigh. It is the sole extensor muscle of the knee, forming a large ...

Hamstring muscles In human anatomy, a hamstring () is any one of the three posterior thigh muscles in between the hip and the knee (from medial to lateral: semimembranosus, semitendinosus and biceps femoris). The hamstrings are susceptible to injury. In quadrupeds, ...

** Popliteal muscle **

Patellar tendon The patellar tendon is the distal portion of the common tendon of the quadriceps femoris, which is continued from the patella to the tibial tuberosity. It is also sometimes called the patellar ligament as it forms a bone to bone connection when ...

**Hamstring tendon **Popliteal tendon *

Hemarthrosis Hemarthrosis is a bleeding into joint spaces. It is a common feature of hemophilia. Causes It usually follows injury but occurs mainly in patients with a predisposition to hemorrhage such as those being treated with warfarin (or other anticoagulan ...

– Hemarthrosis tends to develop over a relatively short period after injury, from several minutes to a few hours.

Fractures

Femoral fracture A femoral fracture is a bone fracture that involves the femur. They are typically sustained in high-impact trauma, such as car crashes, due to the large amount of force needed to break the bone. Fractures of the diaphysis, or middle of the fem ...

Tibial fracture The human leg, in the general word sense, is the entire lower limb of the human body, including the foot, thigh or sometimes even the hip or gluteal region. However, the definition in human anatomy refers only to the section of the lower lim ...

Patella fracture A patella fracture is a break of the kneecap. Symptoms include pain, swelling, and bruising to the front of the knee. A person may also be unable to walk. Complications may include injury to the tibia, femur, or knee ligaments. It typically res ...

Diseases

Some of the diseases of cause of knee pain include the following: *

Knee osteoarthritis 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 w ...

Chondromalacia patella Chondromalacia patellae (also known as CMP) is an inflammation of the underside of the patella and softening of the cartilage. The cartilage under the kneecap is a natural shock absorber, and overuse, injury, and many other factors can cause i ...

Baker's cyst 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 ...

Meniscal cyst {{no footnotes, date=January 2017 Meniscal cyst is a well-defined cystic lesion located along the peripheral margin of the meniscus, a part of the knee, nearly always associated with horizontal meniscal tears. Signs and symptoms Pain and swelli ...

Discoid meniscus Discoid meniscus is a rare human anatomic variant that usually affects the lateral meniscus of the knee. Usually a person with this anomaly has no complaints; however, it may present as pain, swelling, or a snapping sound heard from the affected k ...

* Osgood-Schlatter disease * Larsen-Johansson disease *Knee

rheumatoid arthritis 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 inv ...

Osteochondritis dissecans Osteochondritis dissecans (OCD or OD) is a joint disorder primarily of the subchondral bone in which cracks form in the articular cartilage and the underlying subchondral bone. OCD usually causes pain during and after sports. In later stages ...

disease *

Synovial chondromatosis Synovial chondromatosis is a locally aggressive bone tumor of the cartilaginous type. It consists of several hyaline cartilaginous nodules and has the potential of becoming cancerous. Signs and symptoms People usually complain of pain in one j ...

disease * Tumors *

Ankylosing spondylitis Ankylosing spondylitis (AS) is a type of arthritis characterized by long-term inflammation of the joints of the spine typically where the spine joins the pelvis. Occasionally areas affected may include other joints such as the shoulders or hi ...

Reactive arthritis Reactive arthritis, also 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 infection can t ...

* Tuberculosis arthritis *

Septic arthritis Acute septic arthritis, infectious arthritis, suppurative arthritis, osteomyelitis, or joint infection is the invasion of a joint by an infectious agent resulting in joint inflammation. Generally speaking, symptoms typically include redness, h ...

(''Pyogenic arthritis'') *

Osteomyelitis Osteomyelitis (OM) is an infection of bone. Symptoms may include pain in a specific bone with overlying redness, fever, and weakness. The long bones of the arms and legs are most commonly involved in children e.g. the femur and humerus, while the ...

* Hemophilic arthritis *

Gout Gout ( ) is a form of inflammatory arthritis characterized by recurrent attacks of a red, tender, hot and swollen joint, caused by deposition of monosodium urate monohydrate crystals. Pain typically comes on rapidly, reaching maximal intens ...

(Gouty arthritis) *

Neuroma A neuroma (; plural: neuromata or neuromas) is a growth or tumor of nerve tissue. Neuromas tend to be benign (i.e. not cancerous); many nerve tumors, including those that are commonly malignant, are nowadays referred to by other terms. Neuro ...

Inflammations

Bursitis Bursitis is the inflammation of one or more bursae (fluid filled sacs) of synovial fluid in the body. They are lined with a synovial membrane that secretes a lubricating synovial fluid. There are more than 150 bursae in the human body. The bursae ...

of the knee **

Prepatellar bursitis Prepatellar bursitis is an inflammation of the prepatellar bursa at the front of the knee. It is marked by swelling at the knee, which can be tender to the touch and which generally does not restrict the knee's range of motion. It can be extreme ...

- Housemaid's knee (most common) ** Infrapatellar bursitis - Clergyman's knee (''Superficial infrapatellar bursitis'' and ''Deep infrapatellar bursitis'') **Semimembranosus bursitis *

Tendinitis Tendinopathy, a type of tendon disorder that results in pain, swelling, and impaired function. The pain is typically worse with movement. It most commonly occurs around the shoulder (rotator cuff tendinitis, biceps tendinitis), elbow (tennis elbo ...

Patellar tendinitis Patellar tendinitis, also known as jumper's knee, is an overuse injury of the tendon that straightens the knee. Symptoms include pain in the front of the knee. Typically the pain and tenderness is at the lower part of the kneecap, though the upp ...

(''Jumper's knee'') **

Hamstring In human anatomy, a hamstring () is any one of the three posterior thigh muscles in between the hip and the knee (from medial to lateral: semimembranosus, semitendinosus and biceps femoris). The hamstrings are susceptible to injury. In quadrupe ...

tendinitis **Popliteal tendinitis * Synovitis of the knee

Deformities

Common deformities of the knee include: *

Bipartite patella Bipartite patella is a condition where the patella, or kneecap, is composed of two separate bones. Instead of fusing together as normally occurs in early childhood, the bones of the patella remain separated. The condition occurs in approximatel ...

(two-part kneecap) *

Genu varum Genu varum (also called bow-leggedness, bandiness, bandy-leg, and tibia vara) is a varus deformity marked by (outward) bowing at the knee, which means that the lower leg is angled inward ( medially) in relation to the thigh's axis, giving th ...

(bow legs) *

Genu valgum Genu, a Latin word for "knee," may refer to: * Genu of internal capsule * Genu of the corpus callosum * Genu recurvatum * Genu valgum * Genu varum Genu varum (also called bow-leggedness, bandiness, bandy-leg, and tibia vara) is a varus def ...

(knock-knees) * Genu recurvatum ( Knee hyperextension) * Knee flexion deformity

Syndromes

Patellofemoral pain syndrome Patellofemoral pain syndrome (PFPS; not to be confused with jumper's knee) is knee pain as a result of problems between the kneecap and the femur. The pain is generally in the front of the knee and comes on gradually. Pain may worsen with sittin ...

Plica syndrome Plica syndrome is a condition that occurs when a ''plica'' (a vestigial extension of the protective synovial capsule of usually the knee) becomes irritated, enlarged, or inflamed. Cause This inflammation is typically caused by the plica being ca ...

Iliotibial band syndrome Iliotibial band syndrome (ITBS) is the second most common knee injury, and is caused by inflammation located on the lateral aspect of the knee due to friction between the iliotibial band and the lateral epicondyle of the femur. Pain is felt mos ...

* Hoffa's syndrome *

Joint hypermobility syndrome Hypermobility spectrum disorder (HSD), related to earlier diagnoses such as hypermobility syndrome (HMS), and joint hypermobility syndrome (JHS) is a heritable connective tissue disorder that affects joints and ligaments. Different forms and sub ...

Dislocations

* Patella dislocation * Knee joint dislocation (''Tibiofemoral joint dislocation'')

Cold temperature

Knee pain is more common among people working in the cold than in those in normal temperature. Cold-induced knee pain may also be due to

tenosynovitis Tenosynovitis is the inflammation of the fluid-filled sheath (called the synovium) that surrounds a tendon, typically leading to joint pain, swelling, and stiffness. Tenosynovitis can be either infectious or noninfectious. Common clinical manifest ...

of the

tendon A tendon or sinew is a tough, high-tensile-strength band of dense fibrous connective tissue that connects muscle to bone. It is able to transmit the mechanical forces of muscle contraction to the skeletal system without sacrificing its ability ...

s around the knee, in which cold exposure has a specific role, either as a causative or a contributing factor. Frank

arthritis 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 som ...

has been reported in children due to

frostbite Frostbite is a skin injury that occurs when exposed to extreme low temperatures, causing the freezing of the skin or other tissues, commonly affecting the fingers, toes, nose, ears, cheeks and chin areas. Most often, frostbite occurs in t ...

from extreme cold causing direct

chondrocyte Chondrocytes (, from Greek χόνδρος, ''chondros'' = cartilage + κύτος, ''kytos'' = cell) are the only cells found in healthy cartilage. They produce and maintain the cartilaginous matrix, which consists mainly of collagen and prote ...

injury. There is also a

hereditary disease A genetic disorder is a health problem caused by one or more abnormalities in the genome. It can be caused by a mutation in a single gene (monogenic) or multiple genes (polygenic) or by a chromosomal abnormality. Although polygenic disorders ...

familial cold autoinflammatory syndrome Cold urticaria (essentially meaning cold hives) is a disorder in large red welts called hives (''urticaria'') form on the skin after exposure to a cold stimulus. The hives are usually itchy and often the hands and feet will become itchy and swolle ...

(FCAS), which often features knee pain, in addition to hives, fever and pain in other joints, following general exposure to cold.

Knee pain due to less physical movement

A lower level of physical activity and a work environment where one is required to sit in a chair during the work day is one reason for developing knee joint pain, as the lower degree of physical movement tends to weaken the knee muscles. Blood vessels also can be affected, leading to development of painful conditions. Working on building strength through a full range of motion is crucial for rebuilding strength and getting rid of knee pain. As age progresses the movement of the knee joint involves higher friction with adjacent tissue and cartilages.

Other causes

Ligamentous laxity Ligamentous laxity, or ligament laxity, is a cause of chronic body pain characterized by loose ligaments. When this condition affects joints in the entire body, it is called ''generalized joint hypermobility'', which occurs in about ten percent ...

* Fat pad impingement *

Knee effusion Knee effusion, informally known as water on the knee, occurs when excess synovial fluid accumulates in or around the knee joint. It has many common causes, including arthritis, injury to the ligaments or meniscus, or fluid collecting in the burs ...

Deep vein thrombosis Deep vein thrombosis (DVT) is a type of venous thrombosis involving the formation of a blood clot in a deep vein, most commonly in the legs or pelvis. A minority of DVTs occur in the arms. Symptoms can include pain, swelling, redness, and enla ...

Peripheral vascular disease Peripheral artery disease (PAD) is an abnormal narrowing of arteries other than those that supply the heart or brain. When narrowing occurs in the heart, it is called coronary artery disease, and in the brain, it is called cerebrovascular dise ...

Exostosis An exostosis, also known as bone spur, is the formation of new bone on the surface of a bone. Exostoses can cause chronic pain ranging from mild to debilitatingly severe, depending on the shape, size, and location of the lesion. It is most commonl ...

Referred knee pain

Referred pain is that pain perceived at a site different from its point of origin but innervated by the same spinal segment. Sometimes knee pain may be related to another area from body. For example, knee pain can come from ankle, foot, hip joints or

lumbar spine The lumbar vertebrae are, in human anatomy, the five vertebrae between the rib cage and the pelvis. They are the largest segments of the vertebral column and are characterized by the absence of the foramen transversarium within the transverse p ...

Diagnosis

Knee MRIs should be avoided for knee pain without symptoms or

effusion In physics and chemistry, effusion is the process in which a gas escapes from a container through a hole of diameter considerably smaller than the mean free path of the molecules. Such a hole is often described as a ''pinhole'' and the escap ...

, unless there are non-successful results from a functional rehabilitation program. * * * * * In some diagnosis, such as in knee osteoarthritis, magnetic resonance imaging does not prove to be clear for its determination.

Management

Although surgery has a role in repairing traumatic injuries and broken bones, surgeries such as

arthroscopic lavage Arthroscopic lavage is the washing out or cleaning out the contents (blood, fluid or loose debris) inside a joint space. Lavage is a general term referring to the therapeutic washing, cleaning or rinsing. Medical uses Excessive growth of irritated ...

do not provide significant or lasting improvements to either pain or function to people with knee pain, and therefore should almost never be performed. Knee pain is pain caused by wear and tear, such as

osteoarthritis 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 ...

or a meniscal tear. Effective treatments for knee pain include

physical therapy Physical therapy (PT), also known as physiotherapy, is one of the allied health professions. It is provided by physical therapists who promote, maintain, or restore health through physical examination, diagnosis, management, prognosis, pat ...

exercises, pain-reducing drugs such as

ibuprofen Ibuprofen is a nonsteroidal anti-inflammatory drug (NSAID) that is used for treating pain, fever, and inflammation. This includes painful menstrual periods, migraines, and rheumatoid arthritis. It may also be used to close a patent ductus ar ...

, joint stretching,

knee replacement Knee replacement, also known as knee arthroplasty, is a surgical procedure to replace the weight-bearing surfaces of the knee joint to relieve pain and disability, most commonly offered when joint pain is not diminished by conservative sources ...

surgery, and weight loss in people who are overweight. Overall, a combination of interventions seems to be the best choice when treating knee pain. Interventions such as exercises that target both the knee and the hip, foot bracing, and patellar taping are all recommended for use with patients who have knee pain. Current evidence suggests that psychological factors are elevated in individuals with patellofemoral pain. Non-physical factors such as anxiety, depression, fear of movement, and catastrophizing are thought to have a linear correlation with increased pain experience and decreased physical function. Catastrophizing is defined as imagining the worst possible outcome of an action or event. The psychosocial factors may have either a positive or negative impact on adherence to rehabilitation programs for managing knee pain. Furthermore, studies have found knee pain to be negatively associated with health-related quality of life, and an increase in knee pain to be associated with a reduction in patient-reported quality of life, as compared to those with no or stable knee pain, even in the relatively younger middle-aged population.

Epidemiology

About 25% of people over the age of 50 experience knee pain from degenerative knee diseases.

Society and culture

In the United States, more than US$3 billion is spent each year on arthroscopic knee surgeries that are known to be ineffective in people with degenerative knee pain.

References

External links

{{Medical resources , ICD10 = , ICD9 = , ICDO = , OMIM = , DiseasesDB = , MedlinePlus = 003187 , eMedicineSubj = , eMedicineTopic = , MeshID = Musculoskeletal disorders Rheumatology Orthopedic problems

Pain Pain is a distressing feeling often caused by intense or damaging stimuli. The International Association for the Study of Pain defines pain as "an unpleasant sensory and emotional experience associated with, or resembling that associated with, ...