Biomechanical analysis of cervical distraction.
A biomechanical analysis of cervical distraction is presented, and a model comparing closed reduction of cervical spine dislocations to spring mechanics is developed. Behavior of a spring may be described as F = k delta x where F = distraction force; delta x = elongation of the spring; and k = spring constant. The records and roentgenograms of 24 cervical spine dislocations were reviewed retrospectively. Evaluation of cervical distraction vs traction weight indicates that Ftraction = kneck delta x; where F = traction weight and x = distraction at the injured level. The constant, kneck, is different for bilateral and unilateral dislocations (P less than .001) and is a function of magnitude of injury and neck morphology. As determined in this study, traction weight needed for reduction of facet dislocations may be estimated using the formulae: Ftx = 107.1 lbs/cm (x) unilateral, and Ftx = 76.4 lbs/cm (x) bilateral.
Miller
L S
LS
Jefferson Medical College, Thomas Jefferson University, Philadelphia, Pennsylvania.
Cotler
H B
HB
De Lucia
F A
FA
Cotler
J M
JM
Hume
E L
EL
D000328:Adult; D001696:Biomechanical Phenomena; D002574:Cervical Vertebrae / Q000293:injuries* / Q000503:physiopathology / Q000601:surgery; D006801:Humans; D004204:Joint Dislocations / Q000503:physiopathology*; D008297:Male