The old "Dem dry bones" song.
"The Association Between Low Back Pain and Osteoarthritis of the Hip and Knee: A Population-Based Cohort Study"- Stupar et al; Journal of Manipulative and Physiological Therapeutics 6-10.
The authors studied the relationship of hip & knee osteoarthritis to low back pain. There was a strong correlation between hip OA & low back pain. The lumbar spine is stuck between two trouble makers- the hips and the T-Spine. If the pain is lower lumbar, always take a look at that those hips. The modified Thomas test is a good, quick screen.