title: Internal impingement in the etiology of rotator cuff tendinosis revisited.
abstract: OBJECTIVE
  The theory of internal impingement holds that, in overhead athletes, repeated contact between the undersurface of the rotator cuff and the posterosuperior glenoid rim leads to articular-sided partial-thickness rotator cuff tears and superior labral lesions. However, we have noted this same constellation of lesions in our general patient population. These recreational athletic patients do not routinely assume the position of extreme abduction and external rotation, and thus are unlikely to experience significant internal impingement forces. The goal of this study was to document the prevalence of superior labral lesions in patients being treated for partial-thickness undersurface rotator cuff tears.
  
  
  METHODS
  Retrospective case series.
  
  
  METHODS
  We retrospectively reviewed the records of 75 shoulders arthroscopically treated for partial-thickness articular-sided rotator cuff tears. With the exception of one professional tennis player, no patients were playing sports at a professional or major college level. No professional or collegiate throwing athletes were included. The prevalence of these lesions and their association with recreational athletics was noted.
  
  
  RESULTS
  We found that 55 of 75 (73.3%) shoulders with articular-sided partial-thickness rotator cuff tears also had superior labral lesions. A statistically significant increased prevalence of superior labral lesions in the dominant shoulder was seen (P =.03). In addition, our patients who engaged in overhand throwing had significantly fewer superior labral lesions in the dominant shoulders than did nonthrowers (P =.017).
  
  
  CONCLUSIONS
  The "kissing lesions" of undersurface rotator cuff tears and posterosuperior labral damage may be explained by mechanisms other than "internal impingement."
authors.affiliation: Department of Orthopaedic Surgery, Baylor College of Medicine, and the Houston VAMC, Houston, Texas, USA. Jbudoff@mysurgeon.com <Jbudoff@mysurgeon.com>
authors.forename: Jeffrey E
authors.initials: JE
authors.lastname: Budoff
authors.forename: Robert P
authors.initials: RP
authors.lastname: Nirschl
authors.forename: Omer A
authors.initials: OA
authors.lastname: Ilahi
authors.forename: Dennis M
authors.initials: DM
authors.lastname: Rodin
mesh_terms: D000293:Adolescent; D000328:Adult; D000368:Aged; D000369:Aged, 80 and over; D001182:Arthroscopy; D001265:Athletic Injuries / Q000503:physiopathology; D002358:Cartilage, Articular / Q000293:injuries / Q000473:pathology; D012090:Cumulative Trauma Disorders / Q000150:complications* / Q000503:physiopathology; D006801:Humans; D008875:Middle Aged; D012189:Retrospective Studies; D017006:Rotator Cuff / Q000473:pathology / Q000601:surgery; D000070636:Rotator Cuff Injuries; D019534:Shoulder Impingement Syndrome / Q000209:etiology* / Q000503:physiopathology / Q000601:surgery; D052256:Tendinopathy / Q000209:etiology* / Q000503:physiopathology; D016896:Treatment Outcome