At some stage in their lives, nearly everyone will suffer some sort of knee pain or discomfort. In many cases this will be little more than a brief twinge caused by a bump, fall, sprain or other injury that rights itself within a few days or weeks at most. For some, knee pain will be an ongoing issue that will plague them for the rest of their lives.
The knees are some of the most important joints in the body as they are responsible for a great deal of mobility and carry a great deal of load. The knee is also a very complex joint, encompassing four bones (the fibula, tibia and femur and kneecap or patella), knee cartilage (meniscus) as well as ligaments and tendons.
Damage or aggravation to any of these structures may cause issues, making knee pain a very common problem for people of all ages.
The most common causes of knee pain can be divided into the following categories; Injury, Biomechanical issues and Arthritis.
- Anterior Cruciate Ligament (ACL) Injury - the ACL is one of the four ligaments that connect the thigh bone (femur) to the shin bone (tibia), lending support and structure to the knee. Injuries to the ACL most often occur during activities that involve sudden changes in direction or stops and starts, such as sports like basketball, netball, soccer or rugby. The ACL is also highly innervated, and is responsible for telling the brain where the leg is in space, (a phenomena known as proprioception).
Symptoms of an ACL tear may include a popping sound or sensation when the injury first takes place, severe, immediate pain, a marked reduction in range of motion, rapid inflammation and an inability to bear weight on the affected knee, although this can resolve quickly. The sensation of giving way is also very common following ACL injury. Recovery from ACL surgical reconstruction typically requires a great deal of physical rehabilitation.
- Fractures - any of the bones that make up the knee; the tibia, fibula, femur and kneecap (patella) may be fractured through impact, accident or weakness and degradation caused by a disease like osteoarthritis.
- Torn Meniscus - each knee contains two menisci, crescent shaped pads of tough cartilage that work as cushions or shock absorbers between the thigh bone (femur) and shin bone (tibia). Meniscal tears are a common knee injury caused by twisting or rotating on the knee while it is bearing weight, but can also occur as a process of degeneration as we age.
Typical symptoms of a torn meniscus include a popping sensation, immediate, severe pain, inflammation, difficulty straightening or bending the knee, and an inability to bear weight on the knee.
- Bursitis - bursae are small, fluid-filled sacs that help reduce friction and help cushion pressure points between bones, tendons and ligaments in joints. Bursitis is Inflammation of the bursae.
Knee bursitis most commonly occurs over the patella or towards the inside edge of your knee. Bursitis in the knee may cause pain and a reduction in range of motion. The constant pressure on the knees that comes from kneeling is a common cause of knee bursitis. As a result the condition is sometimes known as preacher’s knee or housemaid’s knee.
- Tendinopathy - refers to the degeneration of a tendon due to overload, microtears and micro-traumas. The cause of tendinopathy is typically overload or repeated microtrauma to a tendon or group of tendons (running on hard surfaces or uneven ground, jumping, bearing excess weight, etc), or training error, (doing too much too soon, or without appropriate recovery).
The two most important tendons in the knee are the quadriceps tendon that connects the quadriceps muscle at the front of the thigh to the patella (kneecap), and the patellar tendon (technically a ligament as it connects two bones) that connects the patella and the tibia (shin bone). Injury to this tendon is commonly known as Jumper’s Knee.
- Sprain - a sprain is a stretched, twisted or torn ligament. They are typically caused by a joint being stressed by a fall, impact or rotation and the ligament being stretched or torn as a result. Sprained knees are common in many sports.
Take care of your knees and schedule an appointment with a physiotherapist
Biomechanics is the science of investigating and measuring the forces acting on and generated within the musculoskeletal system and the effects of load on the body. Load is the amount of physical stress exerted on the body through different means, such as motion, vibration, force or temperature.
Biomechanical disorders are abnormalities resulting from the effects of load.
- Loose Bone or Cartilage - injury or degeneration to the bones or cartilage of the knee may cause small pieces to break off. While these floating pieces of material aren’t necessarily dangerous, they may become lodged in the joint, resulting in inflammation, pain and limited range of motion.
- Dislocation - the patella is a triangular shaped bone that sits at the front of the knee and glides through a groove in the joint as it bends or straightens. A blow to the knee or a sudden rotation or change in direction can cause the patella to dislocate from this groove, injuring the surrounding tissue.
In some cases the patellar dislocation may be momentary, with the patella popping back into place by itself, while in others the patella may remain dislocated (typically to the outside edge of the knee).
Symptoms of a dislocated patella include sudden, severe pain, an inability to straighten the leg, an inability to bear weight on the knee and inflammation.
- Iliotibial Band Syndrome - also known as ITB Syndrome or Iliotibial Compression Syndrome is one of the most common knee issues with runners. The iliotibial band is a long strip of fascia (a thin connective tissue that surrounds every muscle and organ in the body) that connects the outside of the leg from hip to knee to shin and helps stabilise and control the movement of the hip as well as protecting the thigh and helping to stabilise the knee.
The ITB is attached to the femoral condyle, a bony lump on the side of the knee. The fascia slides across and around the connection as the knee moves. Compression from the ITB at the knee can cause pain, and an adventitious bursa to develop, which can then become inflamed and irritated during running.
- Gait Issues - a change in the way a person walks can drastically affect the joints in the legs due to different distribution of weight, impact and rotation. Common gait disorders, or abnormal gaits are typically categorised in five ways due to their symptoms. These categories are Propulsive, Scissor, Spastic, Steppage and Waddling. In addition to these five common categories, gait disorders may also be classified as Painful, Hyperkinetic or Stomping.
Changes in gait may be caused by a large range of factors, from injury, musculoskeletal disorders, disease, neurological impairment, substance abuse and more.
- Repetitive Strain Injury - sometimes known as a repetitive stress injury, this type of musculoskeletal disorder is caused by the gradual buildup of damage caused by repetitive motions or activities, often exacerbated by improper technique or conditions. Sitting for long periods or having improper posture can also cause repetitive strain. Examples of knee RSI include bursitis (housemaid’s knee).
- Ergonomic Injury - an ergonomic injury is often caused by small, repeated traumas to muscles, tendons, ligaments, blood vessels or nerves due to the workplace or environment not being suitable for the task at hand.
Repetitive strain injury may be a form of ergonomic injury. As an example, before OH&S changes were implemented in Australian industrial bakeries, many bakers experienced degeneration of the patella, bursitis and other knee issues due to using their knees to shut oven doors.
- Baker’s Cyst - also known as a popliteal cyst, a Baker’s cyst often results from arthritis, a torn meniscus or other damage to the knee. This damage causes the knee to produce too much synovial fluid (typically used to lubricate the knee and reduce friction in the joint). This fluid builds up and may lead to swelling, typically either behind the knee or in the lower leg.
The swelling may result in pain or discomfort as well as restricted range of movement. Treating a baker’s cyst typically involves treating the underlying condition that caused the cyst in addition to draining the cyst itself.
- Chondromalacia patellae - (colloquially known as “runner’s knee”), chondromalacia patellae is a degeneration of the cartilage on the back of the patella (kneecap). This smooth layer of cartilage typically helps the patella glide over the joint, but misalignment may cause the patella to rub and the tissue to become irritated.
Running or other high impact activity is only one potential cause of chondromalacia patellae. An imbalance between muscles on the inner and outer thighs, weakness in gluteal muscles, arthritis, gait issues and injury may all lead to the development of runner’s knee. Symptoms include a grinding sensation when moving the knee and pain that often gets worse both during activity or after long periods of inactivity.
Runner’s knee is often found in young, healthy and athletic individuals. Young people who have not finished growing are at risk of developing runner’s knee with rapid growth leading to muscle imbalances and change of gait. Women are far more at risk of developing runner’s knee than men, due to women, on average having less muscle mass than men, as well as hips wider than their knees causing muscle imbalance or weakness.
There are hundreds of forms of arthritis that may affect any joint in the body. The following include the most likely to affect the knees.
- Osteoarthritis - osteoarthritis is the most common form of arthritis and occurs when wear and tear causes the protective cartilage at the end of bones to degenerate and wear away. This degeneration may lead to pain and stiffness in the joint, inflammation, a loss of flexibility in the joint, and an unpleasant grating sensation in the joint.
The degeneration of the cartilage may be caused by acute or chronic trauma, disease, carrying extra weight (obesity), biomechanical issues, previous significant ligament injury, or simply growing older.
- Rheumatoid Arthritis - rheumatoid arthritis (RA) is a chronic autoimmune disease that causes inflammation and pain in the joints. The presentation of rheumatoid arthritis is typically bilateral, so if you have RA in one knee you will most likely have it in the other as well.
Symptoms of RA include, pain, inflammation, joint stiffness and reduced range of motion. Even though rheumatoid arthritis is an incurable, chronic (long term) condition, that does not mean the symptoms are always severe or even present. RA goes through periods of flare or exacerbation as well as pain-free periods of remission.
Flares and exacerbations may be triggered by certain foods, stress, medication, mood, exposure to chemicals, physical activity, infection, injury or nothing identifiable.
- Septic Arthritis - inflammation and pain in the knee caused by infection.
- Gout - a form of arthritis that occurs in people with elevated uric acid levels. The body produces uric acid when breaking down purines, an organic compound found naturally in the body as well as a number of foods. Typically uric acid is filtered out of the blood by the kidneys and excreted in urine or faeces.
If the kidneys don’t filter enough uric acid from the blood, or for some other reason the body processes too many purines, this leads to a condition known as hyperuricemia (high levels of uric acid in the blood). In some people, this leads to the uric acid becoming deposited in joints and forming sharp, needle-like crystal deposits in the joints or surrounding tissue leading to inflammation and intense pain.
The crystals may build up in any joint in the body, with the most common being the big toe, ankles and knees. The pain of gout is often described as sudden and intense. It is one of, if not the most common form of inflammatory arthritis. Men are around three times more likely to develop gout than women, with men over 40 and women post menopause being the most at risk groups.
- Pseudogout - also known as false gout or calcium pyrophosphate deposition disease (CPPD), pseudogout is in most respects similar to gout in terms of onset and presentation, but this form of arthritis is caused by a buildup of calcium pyrophosphate crystals rather than uric acid crystals.
Calcium pyrophosphate is a naturally occurring substance in the body and the crystals become more common with age. Nearly half of all people over 85 have deposits of calcium pyrophosphate crystals, but only a small fraction go on to develop CPPD.
- Osteosarcoma - osteosarcoma is a form of bone cancer that grows in the long bones of the body. Although the tumours may grow in the bones of the arms, they are far more common in the legs, typically forming just above or below the knee.
Osteosarcomas are most commonly found in teenagers and young adults but may sometimes be found in children or older adults. Symptoms include inflammation, bone or joint pain and bones that may break or otherwise injure easily.
If you’re experiencing knee pain, don’t ignore it and hope it will go away. Damage to the knees can worsen over time and severely limit your quality of life. Take care of your knees and schedule a consult with your GP . The fastest and easiest way to search for and book healthcare appointments online, any time of the day or night is through MyHealth1st.