Atrophy versus Inhibition
Atrophy must be compared with 'inhibition', which often occurs soon after a knee insult, such as surgery. In inhibition the muscle is not wasted, but a reflex action prevents the muscle from firing properly. Unlike atrophy, it usually reverses relatively easily.
Quadriceps atrophy in the anterior cruciate insufficient knee. Baugher WH, Warren RF, Marshall JL and Joseph A. Am J Sports Med. 1984 May-Jun;12(3):192-5.