The knee is a gathering place for 4 bones — the femur (thigh bone), tibia (shinbone), fibula (calf bone), and patella (kneecap). It requires a number of ligaments to maintain these bones in place and keep its capacity to flex and bend.
The knee joint capsule, also called the articular capsule of the knee, is a vital structural element. Like many different joints within the physique, the knee has a dense, fibrous, connective tissue that seals the joint house between the bones. Within the knee, these bones are the femur and tibia. The patella sits outdoors the capsule.
Inside this capsule are pads that cushion the joint. A kind of pads isa bursa, a sac full of a gelatinous liquid that helps forestall friction between bones within the joint. When the fluid turns into irritated or contaminated, it is named bursitis, a situation that may make joint motion painful and stiff within the morning.
Additionally between the heads of the femur and tibia are the menisci. These are the medial meniscus and lateral meniscus. These are horseshoe-shaped pads of cartilage, a form of robust, versatile tissue. They lie reverse one another on the inside (medial) and outer (lateral) edges of the tibia. They act as shock absorbers within the knee and assist with weight distribution among the many bones.
The menisci are liable to harm from trauma — mostly in athletes when the knee is twisted whereas in a flexed place— and degeneration (arthritis), resembling in older folks. Injury to this cartilage typically creates ache and tenderness within the joint together with clicking within the joint. Extreme harm typically requires surgical procedure.
Ligaments are robust bands of fibrous tissue that join bones. Within the knee and different joints, they take in stress from twisting, influence, and different probably dangerous actions to make sure the bones keep in place.
There are 4 main ligaments of the knee. Two are situated outdoors the knee joint capsule. They’re:
- Medial collateral ligament (MCL): This broad, flat, ligament is on the skin of the knee and connects the pinnacle of the femur to the pinnacle of the tibia. It’s generally injured in sports activities involving influence when the knee is bent, resembling soccer, snowboarding, or skateboarding.
- Lateral collateral ligament (LCL): The LCL connects the pinnacle of the tibia to the top of the femur. It will be significant in holding the knee joint intact when the knee is injured from the within. The LCL is mostly injured in sports activities that contain many fast stops, resembling soccer and basketball, or high-impact sports activities, resembling soccer and ice hockey.
The 2 ligaments which are situated contained in the knee joint capsule are the cruciate ligaments. They type a cross in the course of the knee, contained in the knee joint capsule. These ligaments are:
- Anterior cruciate ligament (ACL): The ACL stretches from the entrance of the pinnacle of the tibia to the again of the pinnacle of the femur to forestall the tibia from shifting ahead. Damage to the ACL is widespread in twisting actions, resembling freestyle rollerblading. ACL tears additionally generally consequence from high-impact sports activities, resembling soccer and basketball. A torn ACL typically requires reconstructive surgical procedure and in depth bodily rehabilitation.
- Posterior cruciate ligament (PCL): This ligament wraps across the ACL because it travels from the again of the pinnacle of the tibia to the again of the pinnacle of the femur. It’s mostly injured by direct influence when the knee is flexed, resembling putting a dashboard in a automotive accident.
- The knee additionally comprises the patellar ligament, which helps maintain the kneecap in place. This robust, flat ligament connects the kneecap to the pinnacle of the tibia under it. On the high of the kneecap, the tendon of the quadriceps femoris muscle rises above the kneecap. As a result of the underside of the kneecap is linked to bone and the highest to a muscle, the knee has larger flexibility than if it have been linked to bone on each ends.