Induced pain referral from posterior lumbar elements in normal subjects.

Patterns of pain referral, induced from the posterior elements, have been studied in normal volunteer subjects. A series of intracapsular and pericapsular injections were performed at the L1-2 and L4-5 levels. The areas of pain referral indicate overlap between the upper and lower lumbar spine. It is also shown that the pericapsular and intrafacetal pain referral areas are similar and that the upper lumbar spine is more sensitive than the lower.