title: The prevalence of a large Hill-Sachs lesion that needs to be treated.
abstract: BACKGROUND
  A large Hill-Sachs lesion has been considered a risk factor for postoperative recurrence of shoulder instability. However, there are few reports describing the prevalence of Hill-Sachs lesions that engage with the glenoid. The purpose of this study was to clarify the prevalence of engaging Hill-Sachs lesions using the concept of the glenoid track.
  
  
  METHODS
  The computed tomography images of 100 consecutive patients with unilateral recurrent anterior shoulder dislocations were assessed. An image in the plane perpendicular to the rotator cuff attachment was reconstructed from the DICOM (Digital Imaging and Communications in Medicine) data, and the maximum distance from the medial margin of the Hill-Sachs lesion to the medial margin of the rotator cuff footprint was measured. The location of the Hill-Sachs lesion in the glenoid track was assessed, and when the Hill-Sachs lesion extended medially over the glenoid track, it was defined as an "engaging Hill-Sachs lesion."
  
  
  RESULTS
  Engaging Hill-Sachs lesions were observed in 7 of 100 cases (7%). There were 2 types of Hill-Sachs lesions: a large and wide type (3 cases) and a narrow but medially located type (4 cases). All cases with an engaging Hill-Sachs lesion had a large bony defect of the glenoid at the same time.
  
  
  CONCLUSIONS
  In our series of consecutive 100 cases, the prevalence of engaging Hill-Sachs lesions was 7%. There were 2 types of Hill-Sachs lesions: a wide and large type and a narrow but medially located type.
authors: Department of Orthopaedic Surgery, Tohoku University School of Medicine, Sendai, Japan.
authors: Daisuke
authors: D
authors: Kurokawa
authors: Nobuyuki
authors: N
authors: Yamamoto
authors: Hideaki
authors: H
authors: Nagamoto
authors: Yasushi
authors: Y
authors: Omori
authors: Minoru
authors: M
authors: Tanaka
authors: Hirotaka
authors: H
authors: Sano
authors: Eiji
authors: E
authors: Itoi
mesh_terms: D000293:Adolescent; D000328:Adult; D000368:Aged; D001837:Body Weights and Measures; D015331:Cohort Studies; D005260:Female; D061165:Glenoid Cavity / Q000473:pathology; D006801:Humans; D058430:Humeral Head / Q000473:pathology* / Q000601:surgery; D007593:Joint Instability / Q000209:etiology* / Q000473:pathology / Q000628:therapy; D008297:Male; D008875:Middle Aged; D015995:Prevalence; D012008:Recurrence; D012783:Shoulder Dislocation / Q000209:etiology* / Q000473:pathology / Q000628:therapy; D012785:Shoulder Joint; D014057:Tomography, X-Ray Computed; D055815:Young Adult
keywords: Anatomic Study; Anterior shoulder instability; Basic Science; Hill-Sachs lesion; Imaging; engaging Hill-Sachs lesion; glenoid bony defect; glenoid track