Anterior Cruciate Ligament (ACL) Tears
The anterior cruciate ligament, or ACL, is one of the major ligaments of the knee that is located in the middle of the knee and runs from the femur (thighbone) to the tibia (shinbone). It prevents the tibia from sliding out in front of the femur. Together with posterior cruciate ligament (PCL), it provides rotational stability to the knee.
An ACL injury is a sports-related injury that occur when the knee is forcefully twisted or hyperextended. An ACL tear usually occurs with an abrupt directional change with the foot fixed on the ground or when the deceleration force crosses the knee. Changing direction rapidly, stopping suddenly, slowing down while running, landing from a jump incorrectly, and direct contact or collision, such as a football tackle can all cause injury to the ACL.
What is a meniscal tear?
The meniscus is a specialised cartilage that helps cushion the knee (“shock absorbers”) and protects the cartilage lining the joint (i.e. the articular cartilage). It can tear as a result of an injury or fall, which can cause significant knee pain and other mechanical symptoms. Meniscal tears are commonly associated with other injuries such as ACL rupture. Unfortunately, meniscal tears do not heal. As the meniscus is an important structure, damage can lead to osteoarthritis of the knee in the long term.
Knee pain is the predominant symptom usually followed by swelling within 24 hours. It may be difficult to walk for several days. These acute symptoms eventually resolve spontaneously.
Osteoarthritis, also called degenerative joint disease, is the most common form of arthritis. It occurs most often in older people. This disease affects the tissue covering the ends of bones in a joint (cartilage). In a person with osteoarthritis, the cartilage becomes damaged and worn out, causing pain, swelling, stiffness and restricted movement in the affected joint. This condition most commonly affects the joints in knees. Rarely, the disease may affect the shoulders, wrists and feet.
Causes and risk factors
Osteoarthritis is caused by the wearing-out of the cartilage covering the bone ends in a joint. This may be due to being overweight, excessive strain over prolonged periods of time, previous fracture, growth abnormalities, joint diseases, injury or deformity.
Some people have congenital abnormalities of the joints that cause early degeneration and subsequently cause osteoarthritis.
The patella (knee cap) is a small piece of bone in front of the knee that slides up and down the femoral groove (groove in the femur bone) during bending and stretching movements of the leg. The ligaments on the inner and outer sides of the patella hold it in the femoral groove and avoid dislocation of the patella from the groove. Patellar instability results from one or more dislocations or partial dislocations (subluxations). Patellar dislocation is a condition that occurs when the kneecap or the patella completely shifts out of the groove towards the outside of the knee joint.
Normally, the kneecap fits in the groove, but an uneven groove can cause the kneecap to slide off, resulting in partial or complete dislocation of the kneecap.