title: In vivo analysis of acromioclavicular joint motion after hook plate fixation using three-dimensional computed tomography.
abstract: BACKGROUND
  The clavicle hook plate can be used to treat acromioclavicular and coracoclavicular ligament injury or distal clavicular fracture with comminution. However, the hook plate can induce subacromial impingement, resulting in discomfort from the hardware.
  
  
  METHODS
  Our inclusion criteria were (1) men and women aged older than 20 years and (2) the presence of comminuted distal clavicular fractures (Neer type IIB) fixed with a hook plate (Synthes, Oberdorf, Switzerland). Three-dimensional computed tomography was obtained before removal of the hook plate. Seven patients were enrolled prospectively. The mean age was 42 years (range, 24-60 years). Zero degree images and abduction images were obtained. The sagittal cut surface was obtained 5 mm medial from the distal clavicle. The equator of the cut surface of the clavicle was compared with the full abduction model to analyze rotation. The center of the cut surface of the clavicle was compared with the full abduction model to analyze translation.
  
  
  RESULTS
  The average difference in rotation of the distal clavicle between both shoulders was 16° (range, 3°-22°; P = .001). The mean difference in anterior translation of the distal clavicle was 2.2 mm (range, -0.7 to 5.6 mm; P = .030).
  
  
  CONCLUSIONS
  Hook plate fixation at the acromioclavicular joint causes decreased internal rotation and increased anterior translation of the distal clavicle with respect to the medial acromion, indicating that the scapula relative to the thorax has decreased posterior tilting and increased external rotation in shoulders fixed using a hook plate.
authors.affiliation: School of Computer Science and Engineering, Korea University of Technology and Education, Cheonan, Chungnam, South Korea.
authors.forename: Yoon Sang
authors.initials: YS
authors.lastname: Kim
authors.affiliation: Department of Orthopedic Surgery, Hallym University, Dongtan, South Korea.
authors.forename: Yon-Sik
authors.initials: YS
authors.lastname: Yoo
authors.affiliation: School of Computer Science and Engineering, Korea University of Technology and Education, Cheonan, Chungnam, South Korea.
authors.forename: Seong Wook
authors.initials: SW
authors.lastname: Jang
authors.affiliation: Department of Orthopedic Surgery, Hallym University, Dongtan, South Korea.
authors.forename: Ayyappan Vijayachandran
authors.initials: AV
authors.lastname: Nair
authors.affiliation: Department of Orthopedic Surgery, St. Paul's Hospital, College of Medicine, The Catholic University of Korea, Seoul, South Korea.
authors.forename: Hyonki
authors.initials: H
authors.lastname: Jin
authors.affiliation: Department of Orthopedic Surgery, St. Paul's Hospital, College of Medicine, The Catholic University of Korea, Seoul, South Korea. Electronic address: hssongmd@yahoo.com.
authors.forename: Hyun-Seok
authors.initials: HS
authors.lastname: Song
mesh_terms: D000173:Acromioclavicular Joint / Q000000981:diagnostic imaging* / Q000293:injuries / Q000601:surgery; D000328:Adult; D000368:Aged; D001860:Bone Plates; D002968:Clavicle / Q000000981:diagnostic imaging / Q000293:injuries / Q000601:surgery*; D005260:Female; D005593:Fracture Fixation, Internal; D050723:Fractures, Bone / Q000000981:diagnostic imaging / Q000601:surgery*; D018460:Fractures, Comminuted / Q000000981:diagnostic imaging / Q000601:surgery*; D006801:Humans; D021621:Imaging, Three-Dimensional; D008297:Male; D008875:Middle Aged; D009068:Movement; D011446:Prospective Studies; D014057:Tomography, X-Ray Computed / Q000295:instrumentation; D055815:Young Adult
keywords: 3D-CT; Hook plate; acromioclavicular joint; distal clavicular fracture; range of motion