To determine if an acromioplasty is impairing, an evaluator must know shoulder anatomy, the diagnosis or diagnoses, what treatment was provided, and the patient's present status. Over time, the earlier classification of shoulder impingement has been modified, and the current classification was adopted in 1994. At present, acromioplasty often is not the primary surgery but rather is one component of subacromial decompression with or without concomitant rotator cuff and/or intra-articular shoulder surgery. Until the sixth edition, the AMA Guides to the Evaluation of Permanent Impairment (AMA Guides) did not address the question whether acromioplasty itself constitutes an impairment. In the fourth and fifth editions of the AMA Guides, although open or arthroscopic acromioplasty commonly results in temporary shoulder pain, stiffness, and weakness, the surgical procedure itself, barring complication, results in no permanent impairment. According to the AMA Guides, Sixth Edition, if an acromioplasty eliminated impingement and resulted in no pain or significant objective findings at maximal medical impairment, no impairment occurred. Diagnosis-based impairment is considered the rating method of choice, but range of motion is used primarily in the physical examination adjustment grid. Further, surgical error and/or complications may result in ratable motion and/or strength deficits. The AMA Guides, Fourth and Fifth Editions, also provide a means to rate impairment due to any concomitant distal clavicular resection.