The statics of cervical traction.
The statics of a sliding body was used to study the distribution of forces during the application of cervical traction in supine patients. This theoretical analysis was completed using a dynamometer to determine the static friction between bed surface and patient head. Therefore, we measured the head weight in 12 inpatients and the minimum force that causes impending motion of the head on the bed surface. The static friction coefficient was calculated from the ratio of the two quantities. The forces acting on the cervical spine were determined by inserting the former data into a specifically designed algorithm that forecasted a progressively increasing traction angle. The coefficient of static friction was 0.62, whereas the maximum available force acting on the cervical spine was obtained with a 35 degrees traction inclination. In contrast, the forces dissipated by the plane progressively decreased with larger angles.
Pio
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Clinica Ortopedica e Traumatologica, Università Degli Studi di Pavia, Policlinico S. Matteo I.R.C.C.S., Italia.
Rendina
M
M
Benazzo
F
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Castelli
C
C
Paparella
F
F
D000368:Aged; D000465:Algorithms; D004548:Elasticity; D005260:Female; D017276:Friction; D006257:Head; D006801:Humans; D008022:Ligaments / Q000502:physiology; D008297:Male; D008875:Middle Aged; D009038:Motion; D009333:Neck; D009334:Neck Muscles / Q000502:physiology; D009929:Organ Size; D013314:Stress, Mechanical; D016683:Supine Position; D014143:Traction; D014783:Viscosity