title: The influence of gravity on the unstable elbow.
abstract: BACKGROUND
  Safely permitting early range of motion after a destabilizing injury to the elbow is believed to optimize return of function. However, the range-of-motion exercises must be balanced against the risk of re-dislocation or subluxation. The goal of this study was to describe the position of the upper limb that permitted the greatest motion while minimizing the risk of re-dislocation or subluxation.
  
  
  METHODS
  Seven cadaveric elbows were affixed with a 3-dimensional motion capture system. Ulnohumeral distraction was recorded at flexion angles from 10° to 90° for intact, approach only (sham procedure), and LCL-sectioned. Ulnohumeral separation was recorded in 3 distinct positions of the upper limb that are frequently used in a clinical setting: 1) trunk seated upright with arm at the side; 2) trunk seated upright with elbow in hinged-brace; and 3) trunk supine with shoulder flexed and internally rotated - "gravity-assisted overhead motion" protocol.
  
  
  RESULTS
  A significant ulnohumeral distraction difference was found between the supine and the upright protocols. Upon direct comparison, 104% more displacement occurred across the ulnohumeral joint in the upright LCL-sectioned condition compared to the supine LCL-sectioned condition (P = .001). The greatest ulnohumeral distraction occurred in the seated upright range of motion with a hinged elbow brace (range, 2.5-5.6 mm).
  
  
  CONCLUSIONS
  The overhead motion protocol is a safe protocol for unstable elbows. The supine position results in the least amount of ulnohumeral distraction across flexion angles from 10° to 90°. The upright protocols, especially with the hinged elbow brace, exhibited ulnohumeral distraction that may result in dislocation.
authors.affiliation: Hand and Upper Extremity Surgery Department, Hospital for Special Surgery, New York, NY 10021, USA.
authors.forename: Arthur T
authors.initials: AT
authors.lastname: Lee
authors.forename: Mark A
authors.initials: MA
authors.lastname: Schrumpf
authors.forename: Daniel
authors.initials: D
authors.lastname: Choi
authors.forename: Kathleen N
authors.initials: KN
authors.lastname: Meyers
authors.forename: Ronak
authors.initials: R
authors.lastname: Patel
authors.forename: Timothy M
authors.initials: TM
authors.lastname: Wright
authors.forename: Robert N
authors.initials: RN
authors.lastname: Hotchkiss
authors.forename: Aaron
authors.initials: A
authors.lastname: Daluiski
mesh_terms: D000368:Aged; D000369:Aged, 80 and over; D002102:Cadaver; D005260:Female; D006112:Gravitation; D006801:Humans; D004204:Joint Dislocations / Q000209:etiology*; D007593:Joint Instability / Q000209:etiology*; D008297:Male; D008875:Middle Aged; D016059:Range of Motion, Articular; D000092464:Elbow Injuries