Wiktionary
acromioplasty
n. Surgical removal of all or part of the acromion bone.
Wikipedia
Acromioplasty
Acromioplasty is an arthroscopic surgical procedure of the acromion.
Generally, it implies removal of a small piece of the surface of the bone ( acromion) that is in contact with a tendon causing, by friction, damage to the tendon.