title: A new alternative to quantify finger rotation: angles between the axis of flexed fingers and the axis of third metacarpal bone.
abstract: OBJECTIVE
  To determine whether the proposed angle, formed between the axis of middle and distal phalanges of each of flexed fingers and the axis of the third metacarpal bone was symmetrical between both hands in adult population.
  
  
  METHODS
  Thirty-one volunteers (12 males and 19 females) having normal and uninjured hands with an average age of 38 years underwent a fluoroscopic examination of their hands. All volunteers put their hands in a special positioning device that passively held the metacarpophalangeal and proximal interphalangeal joints in full flexion with distal interphalangeal joint in full extension. Fluoroscopic images were then taken and angles were digitally measured.
  
  
  RESULTS
  Mean angles of the flexed index, middle, ring and small fingers compared to the third metacarpal bone were -4.07 (SEM = 1.041), 5.22 (SEM = 0.889), 12.91 (SEM = 1.009) and 23.11 (SEM = 1.370) degrees, respectively. The angles were statistically symmetrical between both hands (p = 0.838, 0.546, 0.620 and 0.641, respectively). The genders had no effect on the symmetry (p > 0.3). The differences between angle of each finger and the angle of the middle finger were also found to be statistically symmetrical.
  
  
  CONCLUSIONS
  Side-to-side comparison of the angle formed between the axis of flexed fingers and the third metacarpal bone measured from radiographic images can be used as an additional alternative to determine the finger rotation. The angular relationship between each finger with respect to the middle finger can also be used to purposefully reduce x-ray beam projection variation.
authors.affiliation: Division of Hand and Microsurgery, Department of Orthopaedics, Phramongkutklao Hospital, Bangkok, Thailand. chatchanin@hotmail.com
authors.forename: Chatchanin
authors.initials: C
authors.lastname: Mayurasakorn
authors.forename: Suriya
authors.initials: S
authors.lastname: Luenam
authors.forename: Arkaphat
authors.initials: A
authors.lastname: Kosiyatrakul
authors.forename: Kanista
authors.initials: K
authors.lastname: Luenam
authors.forename: Sanya
authors.initials: S
authors.lastname: Prachaporn
mesh_terms: D000328:Adult; D005260:Female; D005385:Fingers / Q000033:anatomy & histology* / Q000000981:diagnostic imaging / Q000502:physiology; D006801:Humans; D008297:Male; D050279:Metacarpal Bones / Q000033:anatomy & histology* / Q000000981:diagnostic imaging / Q000502:physiology; D008875:Middle Aged; D011859:Radiography; D016059:Range of Motion, Articular; D055815:Young Adult