The Journal of Japanese Society of Lumbar Spine Disorders
Online ISSN : 1882-1863
Print ISSN : 1345-9074
ISSN-L : 1345-9074
Different pressure in lumbar spine in sitting position with or without back rest
Shigeru MASUYAMA[in Japanese][in Japanese][in Japanese][in Japanese][in Japanese]
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2004 Volume 10 Issue 1 Pages 90-94

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Abstract

Since the report by Nachemson (1976) concerning pressure on L3 from various positions, it is believed that sitting in a semi-upright position is contraindicatory after lumbar spine surgery. Nachemson's report indicated that there was twice the amount of pressure or more sitting in a semi-upright position than in an upright one. In this paper, a logical investigation on disc load with regards to action and reaction was performed. When W means body weight and α inclination of the body axis, disc pressure is equal to W (sinα+√3 cosα) in a semi-upright position without back rest. This trigonometric function draws a curve whose peak is 2W at 30 degree and W at 90 degree. These results support the report by Nachemson. On the other hand, disc pressure is equal to W sinα in a semi-upright position with back rest, because reaction is caused by the back rest. As a result, sitting in a semi-upright position with back rest after lumbar spine surgery is a reasonable posture to adopt.

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© 2004 The Japanese Society of Lumbar Spine Disorders
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