Lumbar spinal fusion was introduced approximately 70 years ago and has evolved as a treatment option for symptomatic spinal instability, spinal stenosis, spondylolisthesis, and degenerative scoliosis.

Many techniques evolved since then, from wiring, rods, pedicle screws, and recently inter-spinous fixation devices like the Aspen. Along its evolutionary trail, various methods for achieving circumferential fusion have arisen. Distinct from staged anterior/posterior fusion techniques, two methods of achieving an interbody fusion from a posterior approach have emerged: posterior lumbar interbody fusion (PLIF) and transforaminal lumbar interbody fusion (TLIF). Recently, the lateral approach for interbody fusion (XLIF) has became a more common technique, requiring in some cases, complemental posterior fixation with pedicle screws, facet screws or interspinous fixation devices like the Aspen device.

In this study, we address the clinical and radiological outcome of a novel technique using standard PLIF interbody fusion and insertion of the Aspen device via posterior lumbar approach.

Inclusion Criteria:

• Oswestry Disability Index score >30%
• Diagnosis of low back pain and/or radicular pain associated to spinal instability
• Diagnosis of low back pain and/or radicular pain associated to degenerative disc disease
• Elective single level surgery
• Signed informed consent form

Exclusion Criteria:

• Previous surgery with complete laminectomy, pars defect, etc
• Patients that during the surgery requires complete laminectomy at level of the surgery
• Structural lesion to facet joints
• Osteoporosis
• Systemic or local infection
• Pregnant or planning to become pregnant

Patients 40 years and older with clinical and radiological signs of low back pain and spinal instability or degenerative disc disease requiring single level decompression and fusion.