What is the basic meaning when mri shows bilateral l5 pars interarticularis defects without subluxation? this incurred after a multiple car accident.

Low back pain: Subluxation means partial dislocation of a bone, something luckily you do not have although you appear to have some damage to the L-5 spinal; bone but no fracture. Continue to see your orthopedic surgeon and/or family physician for followup for pain relief and physiotherapy

Don't worry too much: Pars defects are not uncommon and can be developmental and also traumatic. If the MRI was done within 6 weeks of the accident the MRI might show edema and findings of an acute pars defect. When there is no subluxation (slippage) then you are less likely to get symptoms. Back and abdominal strengthening exercises are helpful as well as intermittent use OTC NSAIDS would be helpful.

Spondylolysis: Spondylosysis, or pars interarticularis defect, is essentially a stress fracture of the narrow bridge of bone between vertebral body and the spinous process of the vertebrae. This is not an uncommon condition following repetitive trauma (seen also in gymnasts and football players). Subluxation occurs if the fracture separates from normal position and becomes displaced.