May-Thurner syndrome (MTS) is a rare condition in which patients develop iliofemoral deep venous thrombosis due to an anatomical variant in which the right common iliac artery overlies and compresses the left common iliac vein against the lumbar spine. We report a case of variant MTS, where vascular distortion secondary to spontaneous spinal arthrodesis of degenerative lumbar spondylolisthesis resulted in left common iliac vein compression and iliofemoral deep vein thrombosis. While the common complications of degenerative spondylolisthesis, such as spinal stenosis, are well described; the potential for pelvic vascular distortion secondary to anterior translation of the lumbar spine is not well recognized. The purpose in presenting this case is to describe the mechanism by which this variant of MTS occurs and highlight the need for vigilance for this unusual clinical entity.