Lumbar traction

I'm using mechanical traction for quite a few different lumbar conditions. I tend to use forces between 12 and 18 kilogram. Just started work in a different practice where one of the guys is using a minimum of 30 kg as he read in some research that that would be the minimum force required to distract the vertebras'
Can anyone point to further research or do you have any ideas opinions on this subject? I'd like to hear them

[Eyean]

I haven't got any references for you, but the Level I orthopaedic curriculum in Canada teaches that distraction of vertebrae is not necessary to achieve therapeutic effects. CLinically, this explains why manual traction can produce benefits even though I'm pretty sure we're not using 30kg of force. What do ya think about that?

[NARSTR]

In Australia, the aim is to stretch only soft tissue. Something like 3-400 lbs is required for vertebral distraction and no-one knows why we would want to achieve this distraction anyway. Interestingly, relief from muscle tightness using a heat pack may be just as effiecient. We simply do not know.