Radiographic and Clinical Outcomes Following Unilateral or Bilateral Posterior Fixation in MI-TLIF

The purpose of this study is to compare the healing of the patients spine at 24-months following surgery and screw placement among 3 groups. The doctor will also compare clinical outcomes and the immediate and delayed medical and surgical complications among the 3 study groups. The goal of this study is to determine if treating patients with one of the 3 groups is better than the others.

Patient must be between 18 and 80 years old and have problems with the bones in there lower back (lumbar disease) for which Cautious management over at least 3 months has not brought relief from back and/or leg pain. Patients will be scheduled to undergo surgery to treat there lumbar disease. The surgery will be followed by placement of screws in the back of the bones of there lower back. This includes placing solid metal rods that are connected and secured to adjacent vertebrae (bones of the back) using screws. The screws are used to hold the spine together. Everyone who takes part in this study will be assigned to one of the following 3 study groups: 1) One-sided screw placement into the bones above and below the area where the nerve is being surgically relieved of its pinching; 2) Same as group 1 but with an additional stand alone screw which crosses the spinal joint placed into the joint on the other side; 3) Screw placement on both sides into the bones above and below the area where the nerve is being surgically relieved of its pinching.

Eligibility Criteria:
Inclusion Criteria:

* Age 18-80 years.
* Symptomatic single-level lumbar disease including lumbosacral junction.
* Unilateral leg-dominant pain non-responsive to conservative management with concordant imaging findings. These include degenerative spondylolisthesis (grade 1 or 2), facet arthropathy +/- lateral disc herniation, recurrent disc herniation, or large central disc herniation.
* Back pain of confirmed discogenic origin (single level disease only).
* Failed conservative management for a minimum of 3 months.
* Negative serum pregnancy test (for women of childbearing potential)

Exclusion Criteria:

* Severe bilateral leg symptoms.
* Prior instrumented arthrodesis at any lumbar level.
* History of osteoporosis.
* Co-morbidities requiring medication that may interfere with bone or soft tissue healing (i.e., oral or parenteral glucocorticoids, immunosuppressive agent, methotrexate).
* Severe co-morbidities (e.g., heart, respiratory, or renal disease).
* Recent (\<3 yrs) Co-incident spinal tumor or infection.
* Greater than single level symptomatic involvement.
* Associated thoracolumbar kyphotic or scoliotic deformity (\>10).
* Morbid obesity (BMI \> 40).
* History of metal sensitivity/foreign body sensitivity.
* Concurrent involvement in another investigational drug or device study that could confound study data.
* History of substance abuse (recreational drugs, prescription drugs, or alcohol) that could interfere with protocol assessments and/or with the subject's ability to complete the protocol required follow-up.
* Subjects who are pregnant or plan to become pregnant in the next 24 months.
* Prisoner.