The following are the common causes of knee pain:
Injury
The bones of the knee can be broken as a result of trauma (eg. road traffic accident) or falls. People who have fragile bones due to osteoporosis may sustain a knee fracture by simply tripping or stepping wrong.
Ligament injury.
ACL injury may occur as a result of a sudden change in direction or twisting of the knee, most commonly when playing sports such as basketball or football. PCL injury occurs from direct impact to the front of the knee, classically when the knee hits against the dashboard in a car accident.
Meniscal injury.
The menisci can tear when the knee undergoes a twisting motion while it is bent. Meniscal tears tend to also occur when playing sport, and may happen together with ligament injuries.
Tendon injury.
Repetitive stress and overworking of the tendons can lead to tendon injuries such as tendinitis (inflammation of the tendon) or rupture.
Bursitis.
Inflammation of the bursae, which are small fluid-filled sacs that aid in cushioning pressure points and reducing friction between the bones and ligaments or tendons, can result from frequent or prolonged kneeling. Gardeners and plumbers, or people who play sports such as volleyball, are at increased risk of this condition.
Osgood-Schlatter Disease (OSD).
OSD occurs mostly in preteen or teenage boys undergoing growth spurts, and especially if also participating actively in sport. OSD is caused by inflammation of the patella tendon.
Mechanical issues
Loose body.
Occasionally, knee injuries can cause small fragments of bone or soft tissue to break off into the joint space. These loose bodies may interfere with joint movement and cause pain.
Iliotibial band (ITB) syndrome.
The ITB is a band of fibrous tissue that extends from the outer hip to the outer knee. Repeated stress, especially from long distance running, can cause the ITB to rub directly against the outer part of the femur, resulting in sharp, severe knee pain.
Patella dislocation.
An injury to the knee can cause the kneecap to slip out of place, leading to intense pain on movement.
Abnormal gait.
People with conditions such as leg-length discrepancy, or pain in the other joints of the lower limb, often make modifications to their gait in order to compensate for the pain. Over time, increased stress to the knee joint leads to pain.
Arthritis and other diseases
The most common form of arthritis, this is a chronic degenerative condition characterised by wear and tear of the cartilage and menisci. In the late stage, the bones of the knee joint start rubbing directly against each other, leading to severe pain, stiffness and deformity.
Rheumatoid arthritis.
This is a chronic autoimmune condition, in which the immune system mistakenly attacks the synovium, the thin membrane that lines our joints. This leads to joint pain, damage, deformity and debilitation. This condition affects almost any joint in the body, including the knees.
This is a condition caused by excessive buildup of uric acid crystals in the affected joint, leading to intense pain and swelling. Repeated attacks to the same joint over time eventually leads to joint erosion.
Septic arthritis.
Also known as infectious arthritis, this is caused usually by the spread of bacteria from the bloodstream into the joint. Patients usually present with high fever, and the pain is excruciating. Urgent treatment is required for this condition.
Lupus is a chronic autoimmune disease,
whereby the body’s immune system mistakenly creates antibodies to attack healthy tissues. In addition to the knee and other joints, lupus affects many other organs in the body.
Others
Patellofemoral Pain Syndrome (PFPS).
PFPS, also known as runner’s knee, is frequently seen in the younger population, especially athletes who engage in sports like running, hiking and cycling. The pain is located around and behind the patella, and is usually brought on by recent changes in the individual’s training regimen or intensity.
