A Healthy Knee
What Does a Healthy Knee Look Like?
The knee is a hinge type of joint which is made up of three bones joined together by bands of ligaments and tendons which make up the hinge. Joints allow movement between the bones and to absorb shock from movements like walking or repetitive motions.
The three bones that make up the knee joint are:
The femur (thigh bone or upper leg bone)
The tibia (shin bone or larger bone of the lower leg)
The patella (kneecap). The patella sits over the other bones at the front of the knee joint and slides when the knee moves. It protects the knee and gives leverage to muscles
Within the knee joints are important structures which facilitate function, smooth movement and stability and these are:
Cartilage: A hard but slippery coating on the end of each bone which facilitates smooth movement between the bones and protects the underlying bones from damage.
Joint capsule: A tough membrane sac that encloses all the bones and contains fluid that lubricates the joint
Synovial fluid: A fluid that lubricates the joint and keeps the cartilage smooth and healthy.
Important structures surrounding the knee joint
Ligaments, tendons, and muscles are tissues that surround the bones and joints and allow the joints to bend and move.
Ligaments are tough, cord-like tissues that connect the bones to each other and give stability and strength to the joint
Tendons are elastic tissues made up of collagen which connect muscles to bone and help stabilise the knee
Muscles are bundles of specialised cells which help keep the knee well aligned, stable and moving. The two main muscles associated with the knee are the quadriceps and the hamstrings. The quadriceps are made of four muscles and are situated in the front of the thigh and are responsible for straightening the knee from a bent position. The hamstrings are behind the thigh and provide the opposite motion, bending the knee from a straight position.
The quadriceps tendon connects the quadriceps muscle to the patella and provides the power to straighten the knee. In the graphic, you can see that four ligaments connect the femur and tibia and give the joint strength and stability.
Menisci are pads of connective tissue which act like shock absorbers , cushioning the lower part of the leg, which allow range of motion in the joint and acts as a stabiliser. They also help improve balance and weight distribution.
Muscles
There are two groups of muscles at the knee. The four quadriceps muscles on the front of the thigh work to straighten the knee from a bent position. The hamstring muscles, which run along the back of the thigh from the hip to just below the knee, help to bend the knee.
References:
“Handout on Health: Osteoarthritis.” National Institute of Arthritis and Musculoskeletal and Skin Diseases, U.S. Department of Health and Human Services,[link](https://www.niams.nih.gov/health-topics/osteoarthritis). Accessed 28 Apr. 2017.
“Questions and Answers about Knee Problems.” National Institute of Arthritis and Musculoskeletal and Skin Diseases, U.S. Department of Health and Human Services,[link](https://www.niams.nih.gov/health-topics/knee-problems). Accessed 28 Apr. 2017.