Hi Sana,

I dont have anything specific for you right now in terms of studies but I will give you my professional understanding of the whole acute, then subacute, lumbar spine pain.....

I do agree that a bulge will not always cause an issue. In fact... I am not sure why X-Rays and Wikipedia reference-linkMRI's of the lumbar spine are done at all if the disks have been continously compressed and torqued throughout the day. Degenerative disk disease is such a layman diagnosis and shows either the lack of experience or lack of knowledge that the professional employed to make that diagnosis (oooops... rant). Maybe I'll start a different thread on this subject.....:eek

Any insult in the lumbar spine will cause protective splinting to protect it from further insults. One must remember what force is going through the lumbar (and cervical) spine.

This is where things get a little complicated so I will define the major forces. Compression ("squishing" together) which bones resist quite well, Tension (pulling away) which muscles resist fantastically, and Shear (force that is parallel to the surface) which collagen fibers are supposed to be able to resist with some degree of success.

Bones loaded in Bending are subject to compression on one side (which it resists easily) and tension on the other (which it cannot withstand and fractures). Bones loaded in Torsion develop inner shear stress with the maximal stress in the periphery and the least/no stress in the centre.

Muscles are viscoelastic (which means it is extensable and elastic over time) and irritable ( :lol it's a long night) because it can respond to stimulus. Now that stimulus is either electrochemical (ie action potential) or mechanical. If the stimulus is strong enough the muscle responds by developing tension. When a stimulated muscle develops a tension, the amount of tension present is the same throughout the muscle and tendon and at the site of the tendon attachment to bone. So, if a muscle is a kilometer long and develops tension, the tension is the same the ENTIRE kilometer. Even if the cause is limited to a small area.

So... I am sure the pieces are coming together now. When the lumbar spine is under tension (a very unnatural position and potentially very dangerous in terms of resisting force) the brain freaks out and tries to prevent it by developing tension in the muscles with attachments in the area stimulated. This is why there is a brief moment of tension before the patient regains control of the muscles and relaxes. If the brain freaks out and the patient can not reassert control then a painful splint occurs where the muscle prevents further tension.

Why would the brain freak out? Shear is a very scary force that the lumbar spine NEVER wants to experience. If there is compression and shear at the same time, the force is almost to much for the body. Add torsion and we are looking at a surgery date. What does this have to do with putting the lumbar spine in traction. If a joint is unstable due to acute inflammation and it is put into traction, the muscles that are protecting it from further forces are placed into a stretch. Since a muscle is viscoelastic, it will become more stretched and more loose and less protective of the joint if stretched over time and it will not have the necessary tension to contract forcefully and quickly enough to counteract unforseen forces. That's why it freaks out... it knows the joint will be unstable and vulnerable to more serious injury.

When the joint inflammation settles down and enters the subacute phase then the joint becomes slightly more stable but the muscles continue to splint to prevent a relapse. Pain that is felt now by the patient is now mainly coming from the muscles as opposed to the joint and referral pain is more common. As blood flow is restricted by the contracted muscle, it feels cramped and becomes more vulnerable to strain. Trigger points develop because of the lack of oxygen to sustain ATP production and muscle fibers are stuck in contraction. Trigger points shorten muscle fibers which puts them in a position of possible strain injury. A muscle will shorten in order to keep itself comfortable and not put a strain on the trigger points. So, again, when the lumbar spine is put into traction, the muscle will then contract to protect itself from strain which will put added forces on the spine.

This is just forces acting on the spine... god forbid if there is a pain/spasm cycle going on... But since I am sure your eyes are tired and carpal tunnel is settling into my wrists, I'll save it for later. 8o

Hope I did not bore ya
Adamo