Hi, Nina's Mom,
Spondylitis means "inflammation of the spine" (AS, for example).
Spondylosis means "disease of the spine" and is often synonymous with osteoarthritis of the spine. Meaning, then, it is not an autoimmune arthritis (not a spondyloarthropathy).
Any arthritis of the spine is terrible. It just means the treatment will be different from your daughter with AS as the root cause is different.
I just recently researched this because my mom has OA of the spine also and has tremendous pain in her back, hips and knees. I'm sorry you have this, too, and pray you can find a treatment that relieves your pain.
You indicated you have a pars defect. This is different than what my mom has. A pars defect means there is disease in a specific part of the vertebra, called the pars interarticularis, often caused by trauma or repetitive motion.
Pars-related spondylolysis often involves treatment directed towards reducing the back pain with NSAIDs and stretching and strengthening exercises for the back and abdominal muscles. In more severe cases, one website explains that a lumbosacral support and physical therapy may be ordered.
In the most severe cases where there is severe trauma and muscle spasm, the website I found says that a nuclear bone scan may be done to check if the pars defect is indeed a fracture. If so, it may be necessary to use a rigid lumbosacral orthosis or even a body cast. Physical activities will be curtailed for three months to allow time for healing.
This is the website I was referencing to above:http://www.orthoseek.com/articles/spondyl.html
I certainly hope yours is not so severe! What has your doctor said? Have you had a bone scan?