Impingement Syndrome - In the beginning was the Word
Authors: Joseph Bernstein
References: Exerpt from JBJSA 88:442-445. 2006
The term impingement syndrome was first used by Neer  in 1972 to describe a condition of shoulder pain associated with chronic bursitis and partial tearing of the rotator cuff. Impingement comes from a Latin root impingo, which means "to strike against." Neer explicitly stated that in this pathological state, the anterior acromion was striking against (and damaging) the underlying rotator cuff. He described the anterior acromion as "the rough surface on which the supraspinatus tendon is rubbing."
Neer further described the lateral acromion as "an innocent part," and recommended removing only the anterior edge. But what if all of the acromion is "innocent"? McCallister et al. were able to show good results of rotator cuff repair performed without acromioplasty, and Budoff et al. noted that débridement of partial-thickness tears of the rotator cuff without acromioplasty is clinically beneficial as well.
In his recent commentary on Neer , Zarins stated: "Neer believed that impingement causes rotator cuff tears. This hypothesis does not appear to have withstood the test of time. It is more likely that rotator cuff dysfunction results in upward displacement of the humeral head and causes impingement of the humeral head against the acromion with shoulder use rather than the reverse.
To call rotator cuff tendinopathy "impingement syndrome" is to explicitly blame extrinsic tendon compression and to implicitly discount a vast body of evidence that cites intrinsic factors such as avascularity, aging, and overuse. Neer himself described operating on only fifty shoulders over a five-year period, demonstrating his great discretion regarding the removal of "impinging" bone. Surgeons who perform fifty acromioplasty procedures in a season or two may be taking this phrase perhaps too literally. "
1 - Neer CS 2nd. Anterior acromioplasty for the chronic impingement syndrome in the shoulder: a preliminary report.J Bone Joint Surg Am .1972; 54:41 -50
2 - McCallister WV, Parsons IM, Titelman RM, Matsen FA 3rd. Open rotator cuff repair without acromioplasty. J Bone Joint Surg Am. 2005;87:1278 -83.
3 - Budoff JE, Nirschl RP, Guidi EJ. Débridement of partial-thickness tears of the rotator cuff without acromioplasty. Long-term follow-up and review of the literature. J Bone Joint Surg Am. 1998;80:733 -48.
4 - Neer CS 2nd. Anterior acromioplasty for the chronic impingement syndrome in the shoulder. 1972. J Bone Joint Surg Am. 2005;87:1399.