Time frame: preoperatively, at 3-4 months postoperatively and at approximately 12 and 24 months postoperatively
Clinical Results measured by Oswestry Disability Index (ODI). ODI contains ten topics concerning intensity of pain, lifting, ability to care for oneself, ability to walk, ability to sit, sexual function, ability to stand, social life, sleep quality, and ability to travel, each topic category is followed by 6 statements describing different potential scenarios in the patient's life relating to the topic. Each question is scored on a scale of 0 (indicating the least amount of disability) to 5 5 (indicating most severe disability). The scores for all questions answered are summed, then multiplied by two to obtain the index (range 0 to 100). Zero is equated with no disability and 100 is the maximum disability possible.