title: Hill-sachs lesions in shoulders with traumatic anterior instability: evaluation using computed tomography with 3-dimensional reconstruction.
abstract: BACKGROUND
  In patients with traumatic anterior shoulder instability, a large Hill-Sachs lesion is a risk factor for postoperative recurrence. However, there is no consensus regarding the occurrence and enlargement of Hill-Sachs lesions.
  
  
  OBJECTIVE
  To investigate the influence of the number of dislocations and subluxations on the prevalence and size of Hill-Sachs lesions evaluated by computed tomography (CT) with 3-dimensional reconstruction.
  
  
  METHODS
  Cohort study (diagnosis); Level of evidence, 2.
  
  
  METHODS
  The prevalence and size of Hill-Sachs lesions were evaluated preoperatively by CT in 142 shoulders (30 with primary instability and 112 with recurrent instability) before arthroscopic Bankart repair. First, the prevalence of Hill-Sachs lesions was compared with the arthroscopic findings. Then, the size of Hill-Sachs lesions confirmed by arthroscopy was remeasured using the previous CT data. In addition, the relationship of Hill-Sachs lesions with the number of dislocations and subluxations was investigated.
  
  
  RESULTS
  Hill-Sachs lesions were detected in 90 shoulders by initial CT evaluation and were found in 118 shoulders at arthroscopy. The Hill-Sachs lesions missed by initial CT were 15 chondral lesions and 13 osseous lesions. However, all 103 osseous Hill-Sachs lesions were detected by reviewing the CT data. In patients with primary subluxation, the prevalence of Hill-Sachs lesions was 26.7%, and the mean length, width, and depth of the lesions (calculated as a percentage of the diameter of the humeral head) were 9.0%, 5.3%, and 2.1%, respectively, while the corresponding numbers for primary dislocation were 73.3%, 27.7%, 14.8%, and 7.0%, all showing statistically significant differences. Among all 142 shoulders, the corresponding numbers were, respectively, 56.3%, 20.7%, 11.2%, and 4.8% in patients who had subluxations but never a dislocation; 83.3%, 33.4%, 19.1%, and 7.6% in patients with 1 episode of dislocation; and 87.5%, 46.8%, 22.2%, and 10.2% in patients with ≥2 episodes, all showing statistically significant differences. There were no differences in lesion measurements in relation to the number of subluxations.
  
  
  CONCLUSIONS
  Computed tomography is a useful imaging modality for evaluating Hill-Sachs lesions except for purely cartilaginous lesions. Hill-Sachs lesions were more frequent and larger when the primary episode was dislocation than when it was subluxation. Among patients with recurrent episodes of complete dislocation, the prevalence of Hill-Sachs lesions is increased, and the lesions are larger.
authors.affiliation: Department of Orthopaedic Surgery, Toyonaka Municipal Hospital, Osaka, Japan.
authors.forename: Ritsuro
authors.initials: R
authors.lastname: Ozaki
authors.affiliation: Department of Orthopaedic Sports Medicine, Yukioka Hospital, Osaka, Japan nakagawa@yukioka.or.jp.
authors.forename: Shigeto
authors.initials: S
authors.lastname: Nakagawa
authors.affiliation: Department of Orthopaedic Surgery, Toyonaka Municipal Hospital, Osaka, Japan.
authors.forename: Naoko
authors.initials: N
authors.lastname: Mizuno
authors.affiliation: Department of Orthopaedic Surgery, Graduate School of Medicine, Osaka University, Osaka, Japan.
authors.forename: Tatsuo
authors.initials: T
authors.lastname: Mae
authors.affiliation: Arthroscopy and Sports Medicine Center, Nakanoshima Iwaki Hospital, Osaka, Japan.
authors.forename: Minoru
authors.initials: M
authors.lastname: Yoneda
mesh_terms: D000293:Adolescent; D000328:Adult; D000368:Aged; D001182:Arthroscopy; D002648:Child; D005260:Female; D050815:Fractures, Compression / Q000000981:diagnostic imaging* / Q000453:epidemiology* / Q000209:etiology; D006801:Humans; D058430:Humeral Head / Q000000981:diagnostic imaging* / Q000293:injuries*; D021621:Imaging, Three-Dimensional; D007593:Joint Instability / Q000209:etiology / Q000601:surgery; D008297:Male; D008875:Middle Aged; D015995:Prevalence; D012008:Recurrence; D012189:Retrospective Studies; D012782:Shoulder / Q000601:surgery; D012783:Shoulder Dislocation / Q000150:complications*; D000070599:Shoulder Injuries; D012785:Shoulder Joint / Q000000981:diagnostic imaging* / Q000601:surgery; D014057:Tomography, X-Ray Computed; D055815:Young Adult
keywords: 3-dimensional reconstructed computed tomography; Hill-Sachs lesion; dislocation; traumatic anterior shoulder instability