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 potential to flex and bend.
The knee joint capsule, often known as 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 type of pads isa bursa, a sac crammed with a gelatinous liquid that helps stop 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 sort of sturdy, versatile tissue. They lie reverse one another on the internal (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), akin to in older folks. Harm to this cartilage usually creates ache and tenderness within the joint together with clicking within the joint. Extreme harm usually requires surgical procedure.
Ligaments are robust bands of fibrous tissue that join bones. Within the knee and different joints, they soak up stress from twisting, affect, 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 surface of the knee and connects the pinnacle of the femur to the pinnacle of the tibia. It’s generally injured in sports activities involving affect when the knee is bent, akin to soccer, snowboarding, or skateboarding.
- Lateral collateral ligament (LCL): The LCL connects the pinnacle of the tibia to the tip of the femur. It will be important in preserving 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, akin to soccer and basketball, or high-impact sports activities, akin to soccer and ice hockey.
The 2 ligaments which can be situated contained in the knee joint capsule are the cruciate ligaments. They kind a cross in the midst 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. Harm to the ACL is frequent in twisting actions, akin to freestyle rollerblading. ACL tears additionally generally end result from high-impact sports activities, akin to soccer and basketball. A torn ACL usually requires reconstructive surgical procedure and intensive 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 affect when the knee is flexed, akin to placing 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 related to bone and the highest to a muscle, the knee has larger flexibility than if it have been related to bone on each ends.