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Glossary of Medical Terminology

26th January 2017

Having a basic understanding of medical terms relating to a specific condition can be useful for those suffering from that condition, helping them to better understand their condition and the treatment options available to them. This glossary should help anyone affected by common knee or leg disorders, such as osteoarthritis.

Cartilage: Cartilage is the rubbery, flexible tissue which acts as a shock absorber at the joints. It coats the joint ends of the bones and cushions them because it can change shape under pressure.

Cervical spine: This term refers to the first seven vertebrae at the top of the spine, which connect the head to the thoracic spine or upper back. In other words, the spinal bones of the neck.

Extensor mechanism: The extensor mechanism refers to the entire complex of muscles, ligaments, tendons and bones which work together to provide the contraction which results in the straightening function of the knee. The system extends from the hip to the tibia.

Fat pad: Behind the patella, filling the space between the kneecap itself, the patellar tendon and the cruciate ligaments, is a vital piece of fatty tissue. This is crucial to the anatomy and effective functioning of the knee. A common cause of knee pain is when the fat pad becomes inflamed after injury.

Femur: The femur is the thigh bone. It articulates (joins) with the hip at the top, and with the tibia at the knee joint. The femur terminates with two round lumps which are known as condyles. The space between the condyles is called the femoral notch or inter-condylar notch, and it is joined by knee ligaments to the top of the tibia. Under the patella, the femur forms a v-shaped space, known as the femoral groove. The patella slots into this like a jigsaw piece. The end of the femur is covered with cartilage.

Joint: This is any junction between two bones. The knee contains two joints, the patellofemoral, which is the meeting of the kneecap and the femur or thigh bone, and the tibiofemoral which is the joint between the femur and the tibia. The movement of two bones via a joint is called an articulation.

Kneecap dislocation: Some people have recurring abnormalities within the kneecap structure itself, such as a misshapen kneecap or femoral trochlea. This can result in conditions like patella alta, where the kneecap rides higher on the femur than is normal. Surgery is often used to correct kneecap dislocations.

Ligaments: Strips or bands of fibrous connective tissue which serve to provide strength and support in the musculoskeletal system. Ligaments are distinct from tendons because ligaments connect bone to bone. Tendons connect muscle to bone. Ligaments are central to the structure and functionality of the knee. Knees contain five main ligaments. The anterior and posterior cruciate ligaments, the lateral and medial collateral ligaments and the confusingly named patellar tendons are all ligaments in the knee.

Lumbar region: The term lumbar is derived from the Latin for lion, because the lower back region which the term refers to bears the whole weight of the torso, and therefore has to be incredibly strong. The lumbar region starts at about 5 inches below the shoulder blades, spanning the thoracic spine at the top and the sacral spine at the bottom.

Occiput: This is simply the medical term for the back of the head.

Orthosis: An orthosis is an external orthopaedic appliance which corrects or aids alignment and functionality of musculoskeletal structures. Braces or splints are common forms of orthoses.

Osteoarthritis: Can be a result of ageing, obesity or injury. It is known as the "wear and tear" form of arthritis, and results when cartilage within weight-bearing joints breaks down, leading to pain and inflammation. Osteoarthritis causes cartilage to stiffen and lose its cushioning properties. This results in friction and swelling at the joints, and eventually bones can even come into contact with each other, seriously limiting joint mobility.

Patella: The medical name for the kneecap. The patella is what is technically called a sesamoid bone, which is a bone situated within the tendons of a muscle. The patella is actually part of the tendons of the quadriceps muscle group. Because the quadriceps muscle contains the patella, any alteration within the quads affects it. A strong quadriceps complex is essential for optimum patellar function. The patella sits within a v-shaped groove (trochlea) in the femur and is free to move up and down but not side to side.

Patellar tendon: This is the length of fibrous tissue which joins the kneecap to the tibia at an area known as the tibial tubercle. Technically it is a ligament, not a tendon, because it joins two bones.

Patellofemoral joint: This is the junction of the underside of the kneecap with the femur.

Patellofemoral syndrome: This is a collection of symptoms which relate to kneecap pain deriving from problems with the relationship between the patella and the femoral groove or trochlea.

Quadriceps: This is the group of muscles which form the front of your thighs. The name quadriceps means "four heads", and this refers to the four muscles which form the group. These are called the rectus femoris (in the middle), the vastus lateralis (on the outside of the leg), the vastus medialis (on the inside of the leg) and the vastus intermedius (under the rectus femoris).

Quadriceps tendons: These are the tendons which connect the kneecap to the quadriceps group of muscles.

Spinal stenosis: This is the narrowing of the bone channels formed by the spine, and the consequent pressure on nerve roots within the spinal cord. This can occur anywhere in the spine but is most common within the lumbar region. Neck or cervical stenosis can lead to serious consequences such as paralysis, but lumbar spinal stenosis usually leads to pain when walking (claudication). This is often a result of the ageing process and can be aided by orthotics.

Spinal disc herniation: This is the correct terminology for what is commonly referred to as a "slipped disc". The fibrous outer layer of tissue which forms part of the intervertebral disc can tear, resulting in a painful protrusion of the inner soft tissue.

Spondylolisthesis: This is a condition where one of your vertebrae slips out of place. There may be no obvious symptoms, or you may feel pain during movement, sciatica, or tight hamstring muscles. Spondylolisthesis can be caused by a birth defect, trauma, repetitive injury, ageing or disease.

Spondylolysis: Is an abnormality within the facet joint of a vertebra. It is commonly linked to spondylolisthesis and is normally caused by trauma.

Tendons: These are the fibrous ends of muscles, which connect your muscles to your bones.

Tibia: The tibia is the scientific name for the shin bone. The tibia is the supporting bone of the lower leg. The fibula is the outer bone and bears much less weight. However, although it does not form part of the knee joint, it nevertheless acts as an important anchor for various different muscles and tendons.

Tibial tubercle: This is the spot where the patellar tendon attaches to the tibia.

Transfemoral amputation: This is when a leg has been amputated through the femur or thigh bone. Because the limb has been amputated above the knee, the patient will need to adapt to having both the knee joint and the ankle joint replaced by prostheses.

Transtibial amputation: Transtibial amputation is when the amputation occurs below the knee, normally in the area between the knee and the ankle. This is most often performed to eliminate foot and ankle problems.


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