What Is Knee Pain?
Table of Contents
The knee joint is also attached to various muscles, via tendons. These muscles include the quadriceps and the muscles commonly known as the hamstrings (which is also the common name for the tendon that attaches these to the joint). The knee joint is reinforced by thick layers of cartilage from within. This material helps to keep the femur and the tibia of the lower leg apart, and protect the knee from stresses and shocks. The knee is also surrounded by synovial fluid, which is contained in sacs called bursae. Pain in the knee joint may be associated with any of the structures mentioned above.
Must Watch Video – What is Knee Pain?
The anterior cruciate ligament (or ACL) can be found under the femur. It is an important ligament that connects this bone with the tibia. This ligament is attached to a point toward the front of the upper tibia, and then crosses the interior of the knee joint to attach to a point to the rear of the lower femur. Conversely, the posterior cruciate ligament (PCL) is attached to the rear of the tibia and more to the front of the femur. The cross-like shape this forms supports the knee joint, and ensures that the bones stay apart. This contributes to the free and optimal movement of the joint. The ACL and PCL are surrounded by the meniscus, which protects and supports these ligaments to a certain extent. The medial and lateral collateral ligaments connect the tibia and femur on either sides of the joint.
These tissues may be subject to degeneration, or wear and tear. This may result from everyday activity or from more extensive exertion such as athletic activity. This degeneration may be related to a case of knee pain. Pain may also be associated with many variables or risk factors. These may include trauma, as a result of accidental injury, or infections in the joint. Events such as these may be a source of acute (or sudden-onset and usually temporary) pain, but may also increase the risk of chronic (persistent and possibly long-term) knee pain in the future. An exact cause of knee pain may be difficult to detect, as some types of pain may be a symptom of many different conditions and disorders that affect this joint.
Knee Pain PrevalenceSome research suggests that the number of new knee pain complaints in women have doubled over 20 years, and that the complaints in men have tripled over the same length of time. Most of these male patients were non-Hispanic Caucasian or of Mexican origin. The majority of the female patients were of African or Mexican origin. These statistics were not affected by age or body mass index. Other estimates suggest that episodic or chronic knee pain resulting in impaired joint stability and motion and decreased life quality is present in approximately 25% of all adults.
The condition most commonly associated with knee pain in patients of 50 years or more is osteoarthritis. This may be associated with relative reductions in activity in this age group. Athletes may be at higher risk of knee pain resulting from trauma (i.e. due to accidents or other injuries). Damage to cartilage and fascia may result from activities such as running, cycling, aerobics, and general sporting activity. Dislocations of the kneecap are prevalent among teenage girls of 13 to 18 years, which may also be associated with athletic activity.
Those (particularly males) of ten to 15 years may be susceptible to osteochondrosis of the knee, which can also result in pain.
The incidence of knee replacement surgery, particularly in those aged 65 or more, has also gone up recently.
These procedures are performed to address chronic knee pain or dysfunction of the joint. These surgeries are also occasionally required in younger patients. Estimates indicate that approximately four million U.S. adults have needed total knee replacement. Approximately 37.5% of these are in the 50-69 year age bracket.
Causes Of Knee PainPain in the knee as a result of trauma is typically related to adverse events such as:
- Blunt force
- Sprains or strains (i.e. twisting or other abnormal stress acting on tendons or ligaments)
- Falling onto the knee joint
- Atypical motions, such as excessive twisting or bending of the joint
Inadvertent excessive rotations or twisting of the knee joint increases the risk of damage to the meniscus. Knee injuries may also be associated with occupational hazards, e.g. injuries at work.
More severe types of trauma include kneecap fractures, or fractures in the bones of the leg (i.e. the tibia, fibula or femur), as they meet to form the joint.
Damage to these bones may also result from the adverse events as listed above. These injuries can result in acute pain and damage to the nerves or blood vessels found in the knee. This may result in neurological abnormalities such as loss of sensation in the joint. Kneecap dislocation may be associated with intense pain.
This injury can result in the formation of small shards of bone, which may migrate within the joint, resulting in further pain. Dislocation of the kneecap should be addressed with acute medical care.
Other conditions associated with knee pain may result from over-use of the joint caused by repetitive movements or behaviors. These include climbing stairs, jumping, running, and cycling. Conditions that are associated with these activities include:
- ACL damage
- Iliotibial band syndrome
- Patellofemoral pain syndrome
- Synovial plica syndrome
Damage to the ACL is also a prevalent concern of sportspeople and athletes. Some reports suggest that this accounts for approximately half of all ligament injuries.
This is commonly sustained in the course of repetitive motions, atypical knee movements, or accidental injury. It may also be susceptible to damage resulting from additional forces or loading related to the training and conditioning of one muscle group at the expense of another (e.g. the hamstring or quadriceps). This is a common feature of many sports, disciplines, and activities such as martial arts. The risk of ACL damage may also be influenced by gender.
Some research suggests that women are more susceptible to the injuries than men.
It can also be due to abrupt changes in the surface trained or competed on, increased knee joint weaknesses, and excessive flexing of the ankle.
ACL injuries may have a considerable impact on the performance and form of athletic individuals unless treated.
Bursitis is a condition in which the bursa (or the sac containing synovial fluid) becomes inflamed, which may be associated with chronic pain.
Tendinitis is a similar condition affecting the tendons of the knee, whereas tendinosis is a condition in which minor fissures appear in these tissues. Patellofemoral pain syndrome is a condition in which pain is felt in the kneecap or in the front of the joint, and is associated with excessive weight or force acting on this bone. Synovial plica syndrome is the abnormal folding or impingement of the edges of the synovial capsule. This may cause the kneecap to become directly connected to the femur, as opposed to its normal single attachment via the tendon of the quadriceps.
The iliotibial band is a thick band of fascia (another form of tissue that connects muscles to other structures in the body) that runs roughly from the hip region to the back of the knee. Iliotibial band syndrome is a condition in which this fascia becomes inflamed, tightened, or swollen. This disorder is (again) associated with overuse of the joint. This may result in knee pain that intensifies in response to movement. Iliotibial band syndrome is common in athletes and sportspeople who participate in activities requiring a high volume of repetitive knee motions.
Knee pain may also be associated with medical conditions, particularly those associated with the release of inflammation into the tissues of this joint. These include osteoarthritis. This condition affects the cartilage of the joint. Specifically, osteoarthritis is the progressive degeneration, or loss, of cartilage from the joint over time. The risk of this condition may be influenced by pre-existing injury or other trauma. Severe advanced cases of osteoarthritis may lead to direct bone-on-bone contact, which is associated with possible chronic pain.
Other forms of arthritis include rheumatoid arthritis, in which the tissues of the knee joint are attacked by components of the immune system, resulting in inflammation and pain.
Untreated rheumatoid arthritis may result in the degeneration of many types of tissue in the joint, and may also spread to other parts of the body. Systematic lupus erythromatosis is a similar condition, in which the immune system also attacks the body’s own tissues.
This disorder is associated with chronic pain, swelling, and degeneration in many joints, including the knee.
Knee joint effusion is the accumulation of fluid in the joint, which is also associated with inflammation.
This may be associated with moderate to severe pain in the knee.
Other sources of knee pain include the development of cysts in the joint. Pain may also be related to damage to important nervous tissue in the spine, leg, or hip that are associated with the sensory functions of the joint.This may result in chronic pain, despite the lack of direct damage to the joint.
Gout (or hyperuricemia) is a condition in which excess uric acid circulates in the bloodstream. This results in the accumulation of uric acid crystals in joints, including the knee. The symptoms of gout include pain (which may result in the impairment of normal function and activity), swelling, and redness in affected joint.
Septic arthritis is a condition that mimics other forms of arthritis, but is associated with infections within the knee. A number of other infectious conditions such as Lyme disease, influenza, and hepatitis have also been linked to cases of knee pain.
Osteochondrosis, or Schlatter’s disease, is prevalent in male children and young adolescents, as mentioned above. This condition involves damage to the growing tibia in the joint, and may also be associated with inflammation. Schlatter’s disease can also be accompanied by necrosis in the affected bone, which may contribute greatly to pain if present. Osteochondritis dissecans is a similar disorder in which a part of the bone or cartilage becomes starved of blood and undergoes necrosis.
Some of these factors may be associated with immediate, acute pain or result in pain that gradually intensifies over time. The severity of this pain will vary from patient to patient.
Symptoms Of Knee PainThe nature of pain associated with a specific knee injury or disorder may not be constant for every patient. Some describe their pain as a dull ache or throbbing felt in parts of or the entire knee region, whereas others may perceive theirs as a highly specific, concentrated sensation in one point. Knee pain may be accompanied by other symptoms, largely depending on the exact cause.
- Stiffness or swelling in the joint
- Changes in the color of the skin around the knee joint, i.e. to a paler shade, blue, or red
- Perceptions of coldness, numbness, or tingling in the joint
- Increased instability or weakness in the joint
- Audible or palpable snapping, grinding, or popping emanating from the joint that occurs in response to movement
- Reduced movement or flexibility in the joint
Acute snapping in the knee may indicate a sprain, or more specifically that a ligament has been severely damaged.
This may be followed shortly by impaired knee movement or swelling.
Serious ligament tears may be visible as an anomaly through the skin. These symptoms also occur in response to tendon or ligament strain.
Knee dislocations or fractures may be indicated by intense pain, bruising, swelling, increased instability, impaired movement, the inability to flex or relax the joint, impaired walking or standing, and visible anatomical disturbances. These may appear as abnormal twists or shifts in position of the joint.
If these symptoms arise, it is recommended that medical care is sought as soon as possible.
Repetitive stress-related injuries (e.g. tendinitis) is associated with inflammation (which may be perceived as swelling and increased temperature in the affected joint) and pain that intensifies in response to pressure.
This may also be accompanied by the build-up of fluid around tissues experiencing frequent stress.
Conditions including iliotibial band syndrome and patellofemoral pain syndrome may be associated with pain that occurs while attempting maneuvers such as squatting, sitting, climbing stairs, or jumping. Other symptoms include popping, grinding, and increased weakness.
Osteoarthritis may result in pain in the affected joint(s) that radiate toward other areas such as the feet. This pain may increase in response to activity or over the course of a day. Patients with advanced osteoarthritis may find that resting results in minimal relief from symptoms. However, decreased activity will also result in increased stiffness for these patients, particularly at the start of a day. Osteoarthritis may also present with increased swelling, fluid build-up, and tenderness over time.
Less common symptoms may be an indication of serious infective or physiological disorders. These are rare, but their appearance should be reported to a physician if they do occur. These include:
- Fever that can not be explained by common diseases such as flu
- Unexpected decreases in bodyweight equivalent to at least ten pounds
- Very intense pain in the knee accompanied by additional unusual symptoms
- Pain that persists for three days or more that has a deleterious effect on everyday activity or the ability to sleep
Risk Factors For Knee PainThe probability of knee pain development may be influenced by some environmental or behavioral variables. These are known as risk factors.
Examples of risk factors in knee pain include:
- Body mass index (BMI): Some studies indicate an association between increased bodyweight and knee pain. A higher BMI may influence the probability of mechanical knee damage and increases in inflammation. Carrying additional weight may increase the risk of repetitive strain injuries in response to even moderate levels of activity. Osteoarthritis of the knee is associated with increases in both age and BMI. However, there is some evidence that bodyweight may play more of a role in the degeneration of cartilage. Some research suggests that increased BMI is associated with reductions in life quality in patients aged 50 to 84. In addition, obesity may be strongly associated with the incidence of total knee replacement surgeries.
- Anatomical defects: Structural abnormalities that result in features such as knee misalignment, flat feet, or one leg longer than the other may increase the risks of knee damage and pain. Muscle defects resulting in impaired strength or increased stiffness can result in increased instability or weakness in the knee joint, which may in turn increase the probability of pain. These issues can be managed or avoided by wearing footwear with appreciable arch support and other forms of joint stress reduction.
- Athletic activity: Training or sporting activities increase the risk of certain knee conditions, as outlined above. These include many sports, athletic disciplines, and recreational activities, particularly those that involve repeated, complex, or atypical knee motions. This risk may be intensified by the consistent probability of injury or blunt-force trauma to the joint.
- Pre-existing trauma: A history of prior knee injury may increase the risk of recurring trauma or chronic pain.
- Smoking: Habitual smoking is associated with impaired healing, circulation, and tissue regeneration. These may adversely affect recovery from a knee injury or disorder.
Diagnosis Of Knee PainThis type of pain may be associated with a plethora of illnesses and variables, as outlined above. This can hamper the diagnosis of a specific cause in a case of knee pain.
A pain specialist or physician starts the process by asking detailed questions about the nature, severity, and duration of the pain. The patient may also be asked for details that determine the presence of one or more risk factors.
A family history of conditions such as osteoarthritis is also useful. The appearance of other symptoms, as above, (e.g. popping, swelling, etc.) may also contribute to a diagnosis.
The region of the knee affected may also correspond to the underlying condition; for example, pain in the kneecap may be indicative of patellofemoral pain syndrome.
Visible abnormalities, if not associated with a fracture or dislocation, may increase the probability of a diagnosis of a sprain or strain.
A report of the circumstances surrounding an accident can also aid a doctor when diagnosing knee pain.
Imaging techniques also contribute to the detection of conditions or injuries affecting the knee joint. These include:
- Computerized tomography (CT)
- Magnetic resonance imaging (MRI)
- X-ray imaging
X-ray images can detect or confirm a fracture or other injury. CT may contribute to the visualization of weaknesses or instability in a knee joint. MRI or ultrasound-based imaging may be superior in terms of detecting ligament, cartilage, or tendon damage.
Conditions such as gout may be diagnosed through laboratory analysis of samples such as blood or synovial fluid. The fluid in the joint can also be analyzed using a procedure called arthrocentesis.
Treatments For Knee PainThere are many options available to manage and reduce knee pain. A pain specialist or doctor may start by advising the patient to try conventional remedies for joint pain treatment that is prepared or performed at home. These include applying ice packs or hot compresses. These are made from everyday materials or are available as commercial products.
Other commonly available products marketed to treat pain include over-the-counter painkillers or braces. Braces restrict or stabilize joint movement to reduce pain associated with repetitive or specific stresses. Another first-line therapy that may correct the effects of disproportional or repetitive stress is physical therapy. This treatment uses a regimen of specific exercises and stretches to condition the muscles, tendons, and ligaments of the knee.
These conventional therapies are normally best suited to conditions in which mild injury or additional stress are factors. They should not be applied to events such as fractures. Optimal use of these treatments involve:
- Immediate application of ice or cold packs to the source of pain. This may help to treat swelling and restore some normal function. This should take ten to 20 minutes, if possible, approximately three times per day.
- Rest and immobilize the injured joint, using a brace if necessary. This is particularly relevant to pain that increases in response to movement, such as strains or sprains.
- Avoid bathing in hot water or applying heat to the site of pain for 48 hours after acute trauma.
- If an injury responds positively to heat and mild activity after 48 hours, alternate the application of heated and cold packs to the affected area.
- Using a compression bandage may aid recovery in some cases, but may not function to retain stability in the joint as a brace would.
- Try to keep the affected leg elevated while resting.
- Mild exercise and stretching may help retain flexibility, but strenuous activity can increase the severity of the damage or injury.
- Consult your pain specialist or physician if the pain does not respond to these measures, intensifies, or changes in nature
These home therapies require adaptation and specific measures depending on the condition or damage associated with the pain. These include:
- Torn meniscus: First-line therapies for this condition are those that retain as much joint mobility as possible. These include the alternation of heat and cold, over-the-counter drugs, bandaging, and physical therapy. These therapies may also be recommended in recovery following surgical reconstruction of the cartilage.
- ACL damage: Mild to moderate ACL injuries can be managed with physical therapy. This may involve specific conditioning and stretching with the goals of reducing the effects of the original injury and of preventing their recurrence in the future. ACL damage that does not respond to this strategy requires corrective surgery.
- Bursitis: This can be addressed using ice packs, immobilization, and the reduction of strenuous or repeated motions. An increase in temperature in conjunction with bursitis may require immediate attention from a healthcare professional.
- Patellofemoral pain syndrome: The symptoms of this condition can be reduced by avoiding joint motions that increase the forces or stresses on the kneecap. Home therapy also includes conventional painkillers, cold packs, and rest. Physical therapy or bracing may also be of benefit in these cases. Severe or advanced cases of atellofemoral pain syndrome may require surgery.
- Iliotibial band syndrome: This disorder may respond to conventional medications, rest, or physical therapy. Injections of steroid drugs (see below) have also demonstrated some positive effects for this condition.
Specific treatment options for knee pain include commonly available drugs, as mentioned above. Conventional painkillers are associated with effective pain relief and improvements in function and movement for many patients. These include non-steroidal anti-inflammatory drugs (NSAIDs). These include popular painkillers such as aspirin, naproxen, and ibuprofen. These drugs act by inhibiting the production of inflammatory molecules in the body, thus reducing the associated pain. These are alternatives to oral steroids, which also reduce inflammation through other physiological pathways. Steroids are also recommended for cases of knee pain associated with arthritis.
NSAIDs may be counterindicated in some instances of knee pain related to an injury occurring 24 hours or less previous to the onset of pain. This is due to their inhibitory effects on blood clotting. This may have a negative effect on recovery from bruises and on blood clotting in the course of healing.
The drugs as outlined above are effective for many patients affected by conditions such as rheumatoid arthritis. However, in some cases, they may fail to relieve chronic pain. These patients and their physician/specialist may consider opioid medications. These are a class of drugs that act on the pain receptors in the central nervous system directly. This may render them more effective than over-the-counter drugs. A doctor should generally recommend opioid therapy in the short term only, as these drugs are associated with rapid tolerance and high levels of dependence. This may include the risks of adverse effects such as addiction, abuse, and unpleasant withdrawal symptoms.
Patients subject to chronic knee pain that does not respond to conventional drug therapy may consider alternative routes in pharmacotherapy instead. These include the injection of steroids directly into an affected joint. These are available at many reputable pain clinics and physician’s practices. Joint injections deliver steroids into the joint to treat disorders such as rheumatoid arthritis. These also include local anesthetics, for short- to medium-term pain relief. Some patients respond positively and quickly to a single injection. However, others may require multiple injections over time for a similar result. Joint injections have been associated with significant decreases in pain and improved life quality in some studies.
Another procedure using injections of local anesthetics or steroids are nerve blocks. These procedures are also associated with significant effects on pain in conditions such as knee osteoarthritis. These may include spinal nerve blocks, targeting major nervous tissue connecting the knee joint to the brain. This procedure involves the injection of the drugs as above into the periphery of the spine, for safe yet efficacious delivery to these nerves. This can result in pain relief that lasts for a number of weeks or months.
Other Treatments Options Related To Knee PainPatients who find that these drug-based therapies are ineffective in their case can consider alternative forms of pain management. This may include forms of neuromodulation, including spinal cord stimulation (SCS). Neuromodulation is a method of pain correction that is based on the emission of tiny electrical signals similar to normal nervous-system transmission. This overrides abnormal or disproportionate pain signals associated with damaged or dysfunctional nerve tissue. If this tissue is located in a certain area of the spine, it may result in indirect chronic knee pain as referred to above. SCS is a form of neuromodulation delivered by small electrode-like devices, implanted in similar locations to the targets as some spinal nerve blocks. These are connected to external leads and a switch that the patient can carry and use to activate the SCS device in response to the onset of pain. This may effectively reduce signals that are perceived as pain in the knee joint.
SCS is a safe, effective procedure that may result in satisfactory pain management. Patients considering this form of treatment will generally undergo a procedure to implant a temporary device, so that they may assess its effect on pain in their case. An adequately positive response, in the absence of any side effects or adverse events, may lead to the implantation of a permanent set of electrodes. The main disadvantage of this treatment option is that it involves a more invasive procedure. In addition, SCS is associated with some risks and adverse effects. These include the failure of the implant to override pain signals, migration (or slipping) of the electrodes from their ideal location, neurological complications, and infections in the skin through which the leads must pass.
Damage to ligaments such as the ACL may be repaired using surgical techniques. These involve the removal of severely torn or damaged ligaments and their total or partial replacement with grafts. These grafts are typically sourced from other ligaments or tendons from the patient (e.g. patellar tendon autografts). Grafts from other donors are also possible. Ligament reconstruction is often preferred by competitive athletes who wish to regain their full performance or condition prior to injury. These procedures may result in this return to form in many cases. Recovery from these surgeries typically includes a program of rehabilitative physical therapy. This may contribute to the return of full stability, strength, and rotation of the knee joint following a ligament injury.
The final resort in cases of pain associated with advanced osteoarthritis or other conditions is often arthroplasty (i.e. knee replacement). This may effectively reduce chronic pain and functional decline associated with long-term disorders involving cartilage degeneration or inflammation. Early-stage osteoarthritis can be managed with conventional therapies, but this may not prevent the progressive loss of cartilage or other tissues. Some reports indicate that patients receiving successful total knee arthroplasty may experience the approximate equivalent of five or six years of life quality as a result compared to the duration of life quality in patients with similar symptoms who have not undergone these procedures. Arthroplasty is associated with some risks and adverse effects, however. These include the failure of a prosthesis (which replaces the damaged or worn surfaces of the bone) to integrate with the rest of the bone. This is known as implant failure or slippage, and may result in further pain. Other complications include the development of infection around an implant and inadvertent nerve damage incurred during surgery.
Prevention Of Knee PainMany sporting and athletic organizations currently promote education and information on measures to reduce the onset or recurrence of knee pain in those involved in competitive activities and training. These include techniques in various sports (e.g. soccer, American football, and basketball) that minimize the chances of knee pain resulting from atypical movements. Prevention of this pain may also be enhanced by ensuring adequate warming-up, stretching, and warming-down of muscles, tendons, and ligaments before, during, and after training. Failure to take these precautions may also result in ACL damage, strains, and tendinitis.
ConclusionPain in the knee joint is a relatively prevalent form of pain. It is associated with many conditions and factors that affect one or more structures in this joint. Knee pain may also be related to mechanical damage to these tissues.
These include fractures, dislocations, strains, or sprains. Some injuries may result from repetitive strain in ligaments, tendons, or muscles, such as those normally encountered in occupational life or athletic activities. Risk factors that influence the onset or development of knee pain include increased bodyweight, age, anatomical anomalies, smoking, and prior knee damage.
Specific disorders associated with knee pain include gout, osteochondrosis, and osteoarthritis.
Osteoarthritis is strongly associated with advancing age, and is prevalent in both men and women. Younger people may be at more risk of knee pain related to injuries such as dislocations and conditions such as osteochondrosis.
There is a range of treatment options available that are effective for many patients with knee pain.
A choice between first-line or conventional therapy may be defined by the injury or condition found to be associated with each individual case.
Pain that does not respond to these options may require re-evaluation by the pain specialist or physician.
Injuries such as sprains can be managed using home treatments such as the application of ice and compression.
However, more serious forms of damage such as fractures require advanced medical treatment.
Patients who suffer from intense pain associated with conditions such as osteoarthritis can consider treatments such as joint injections or nerve blocks in the absence of a response to conventional painkillers.
Those whose knee pain is related to spinal nerve damage may also benefit from neuromodulation-based treatments such as spinal cord stimulation. These options are available at many competent pain clinics, which may also offer information and further consultation concerning these choices for cases of chronic knee pain.
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