The knee is a hinge-joint formed between the tibia (lower bone) and femur (upper bone), also called Tibiofemoral joint, which is dived into medial and lateral compartment. The patella glides over the front of femoral condyles to form a patellofemoral joint. In addition, there is superior tibiofibular joint between the tibia and the head of fibula (outer leg bone).
The knee joint is particularly susceptible to traumatic injury because it depends more on the ligaments due to less musculature around it for its strength and stability. The space between the tibia and femur is partially filled by two menisci (inner and outer sides) that are attached to add congruency. They aid in lubrication and nutrition of the joint and act as shock absorbers.
NOTE: It must also be remembered that the lumbar spine (lower back), hip, and ankle may refer pain to the knee, and these joints must be assessed if it appears that joints other than the knee may be involved.
Chondromalacia patella: Irritation of the cartilage on the underside of the kneecap (patella), causing knee pain. This is a common cause of knee pain in young people.
Knee osteoarthritis: Osteoarthritis is the most common form of arthritis, and often affects the knees. Caused by aging and wear and tear of cartilage, osteoarthritis symptoms may include knee pain, stiffness, and swelling.
Knee effusion: Fluid buildup inside the knee, usually from inflammation. Any form of arthritis or injury may cause a knee effusion.
Meniscal tear: Damage to a meniscus, the cartilage that cushions the knee, often occurs with twisting the knee. Large tears may cause the knee to lock.
ACL (Anterior Cruciate Ligament) strain or tear: The ACL is responsible for a large part of the knee’s stability. An ACL tear often leads to the knee “giving out,” and may require surgical repair.
PCL (Posterior Cruciate Ligament) strain or tear: PCL tears can cause pain, swelling, and knee instability. These injuries are less common than ACL tears, and physiotherapy (rather than surgery) is usually the best option.
MCL (Medial Collateral Ligament) strain or tear: This injury may cause pain and possible instability to the inner side of the knee.
Patellar subluxation/ Dislocation: The kneecap slides abnormally or dislocates along the thigh bone during activity as a result patient complains of Knee pain and inability to walk.
Patellar tendonitis: Inflammation of the tendon connecting the kneecap (patella) to the shin bone. This occurs mostly in athletes from repeated jumping.