Percutaneous lumbar discectomy techniques hold significant promise; however, at the present time, lumbar microdiscectomy remains the gold standard for the surgical treatment of lumbar disc protrusion with radiculopathy.Intradiscal electrothermal therapy (IDET) is emerging as a useful option for selected patients with intractable mechanical back pain, whose only other option has historically been a spinal fusion. Percutaneous fusion techniques are in their infancy, and may also prove to be of benefit for these patients. Although not a minimally invasive procedure, disc arthroplasty (‘artificial disc’) was approved by the US Food and Drug Administration (FDA) in 2004, and may be appropriate for selected patients with mechanical back pain.

Percutaneous vertebral augmentation, including vertebroplasty and kyphoplasty, has become the treatment of choice for many patients with intractable back pain secondary to vertebral insufficiency fractures in the elderly. This article chronicles the evolution and current status of several minimally invasive spinal procedures and provides a comparison with conventional treatments.

Pe rcutaneous Discectomy
Over the last 40 years, numerous percutaneous techniques have been developed for the treatment of radiculopathy secondary to lumbar disc herniation. The effectiveness of these methods must be considered in the context of the conventional procedure – lumbar microdiscectomy.

Lumbar Microdiscectomy
Lumbar discectomy as a treatment for herniated lumbar intervertebral discs was first reported by Dandy in 1929,¹ and subsequently described in greater detail by Mixter and Barr in 1934.² After initial modifications, the procedure was basically unchanged until the operating microscope was introduced as a technical adjunct in 1978. This resulted in better illumination and magnification of the operative field. The operation came to be known as lumbar microdiscectomy or microsurgical discectomy, which is carried out through a smaller incision with less dissection than a standard discectomy. Microdiscectomy is generally regarded as a technical modification of standard discectomy, rather than a distinctly different procedure. Currently, the procedure is carried out through a small posterior incision, which is centered over the disc space. Most surgeons use some form of magnified vision, either loupes or an operating microscope. Variable amounts of laminar bone, ligamentum flavum, and medial facet are removed as needed to provide access to the disc herniation, which is then removed. The remaining disc nucleus is removed to varying degrees based on surgeon preference. The open surgical approach permits exploration for sequestered disc fragments and decompression of bony foraminal stenosis. In some centers, the procedure is now carried out through tube retractors of various sizes to limit dissection of paraspinal tissues.

Surgical outcomes are generally excellent. Success rates as high as 95% have been reported in single surgeon series. Results obtained in routine clinical practice are not as robust, but are still excellent. In a prospective study of 219 patients undergoing lumbar discectomy performed by multiple surgeons in community hospitals, with one-year minimum follow-up, Atlas reported that sciatica was improved in 81.3% of patients, and that 86.5% of patients would choose surgery again.³

These results serve as an important benchmark when analyzing outcomes with percutaneous approaches.