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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.