E
Extension
Extension means 'straightening'. Knee extension is to straighten the knee by actively contracting the extensor muscles or by positioning the body to allow passive extension. Page updated June 2024 by Dr Sheila Strover (Clinical Editor)
Extensor mechanism
The extensor mechanism consists of a chain of anatomical structures including the quads muscle and kneecap that work together to straighten the knee.
External fixator
An external fixator is a metal apparatus to hold together the broken ends of a bone via rods drilled through the skin into the bone.
Extraarticular
Extraarticular means outside of the joint cavity and its capsule.
Extracellular matrix
The extracellular matrix is a 3-dimensional network of large molecules outside of the cells (eg collagen) that provide them with structural and biochemical support.
F
Fabella
A fabella is a little bone which sometimes forms at the back of the knee, within the tendon of the gastrocnemius muscle, like a tiny kneecap at the back of the knee.
Fabella syndrome
The fabella syndrome is a set of symptoms relating to the fabella, with pain on the outer back part of the knee where the fabella can rub on the femoral condyle (knuckle of the thighbone).
Facet
A facet is one of the flat surfaces at the back of the kneecap (patella).
Facetectomy
Facetectomy is an operation to remove one of the facets (flat surfaces) at the back of the kneecap (patella), usually to remove an area of arthritis.
Fascia
Fascia is net-like fibrous tissue that anatomically either binds structures together or separates structures into different layers.