Low back pain is very common, with 80% of people experiencing back pain at least once in their lifetimes. The good news is that a thorough physical examination can often determine the best course of management and whether you require imaging (X ray, MRI, CT scans, etc) to rule out a serious problem. Read full article (PDF) 
Perspectives for Patients – Low Back Pain from the Journal of Orthopaedic & Sports Physical Therapy.
