_:vb50950720 . _:vb50950720 "A bone structure disease that involves a defect located_in lumbar vertebral column."^^ . _:vb50950720 "url:http://orthoinfo.aaos.org/topic.cfm?topic=a00053"^^ . _:vb50950720 . _:vb50950720 . _:vb50950720 . _:vb50950720 . _:vb50950720 "url:http://www.umm.edu/spinecenter/education/spondylolysis_spondylolisthesis.htm"^^ . _:vb50950720 "url:http://en.wikipedia.org/wiki/Spondylolysis"^^ . _:vb50950720 "url:http://my.clevelandclinic.org/disorders/back_pain/hic_spondylolysis.aspx"^^ .