• Chronic (>1 year) low back pain with degenerative disc disease:
Spinal fusion with bone graft: this is the most common surgery. Fusion can be done with or without instrumentation (plates, screws, cages) that serve as internal splints. Bone morphogenic proteins are frequently used to improve fusion. Unfortunately, there is little evidence that this improves pain more than conservative nonsurgical therapy.
Lumbar artificial disc replacement: theoretic advantage over fusion is that the prosthetic disc will help preserve ROM and lessen the chance for progressive degeneration of discs above and below a fusion. There is little evidence that an artificial disc is any better than fusion. Patients who are candidates are aged <60 years, have disease limited to one disc space, and have no back deformities or neurologic deficits.
• Lumbar disc prolapse meeting criteria for surgery (see Question 35):
Open discectomy: standard technique. Frequently involves a laminectomy.
Microdiscectomy: most common procedure performed. Smaller incision. Involves a hemilaminectomy and removal of disc material.
Minimally invasive techniques to remove/vaporize the disc: tubular or trocar discectomy, percutaneous manual nucleotomy, laser discectomy, endoscopic discectomy, coblation nucleoplasty, disc DeKompressor, others. Smaller incisions and quicker recovery times.
• Spinal stenosis:
Decompressive laminectomy: most common surgery. Fusion with or without instrumentation is also done especially for multilevel laminectomy and for degenerative spondylolisthesis causing stenosis. Instrumentation and bone morphogenic proteins improve chance of fusion but not clinical outcomes.
Interspinous spacer implantation (X-STOP): titanium implant placed between two spinous processes. Patients who may be candidates for this procedure are aged over 50 years, have no spondylolisthesis, suffer from intermittent claudication/leg pain which is exacerbated by back extension and relieved by sitting forward, and have only one or at most two lumbar levels involved. Certain deformities and severe osteoporosis are contraindications.
Spondylolysis and isthmic spondylolisthesis: spondylolysis, seen in 6% of the population, is a lytic defect of the pars interarticularis. Isthmic spondylolisthesis is much less common and is attributable to lytic defects in the pars interarticularis bilaterally with anterior subluxation occurring most commonly (90%) at L5 on S1. This differs from degenerative spondylolisthesis which occurs most commonly with L4 disc degeneration leading to posterior subluxation of L4 vertebrae causing spinal stenosis.
Posterolateral fusion is the procedure of choice for isthmic spondylolisthesis.