Modern Back Surgery

In a previous section a retrospective synopsis of approaches to the management of pain in the back was provided. In this section the focus is on significant medical innovations associated with the surgical management of spine trauma, disorders and diseases that are in current use:

The surgeon’s credo: Primum non noncore…First, do no harm

Imaging Technology

Imaging technology allows the surgeon to see inside the body without cutting through the skin. Included under the general term ‘medical image technology’ are (1) the x-ray, (2) fluoroscopy, (3) ultrasound, (4) computed tomography (CT), and (5) magnetic resonance imaging (MRI). Each of these imaging formats can be used by the surgeon as a diagnostic tool and as a guide for interventional procedures.

• X-Ray: The accidental discovery of electromagnetic radiation by Wilhelm Roentgen near the end of the nineteenth century to see into the human body led to the development of x-ray radiography. It was found that beams of electromagnetic radiation passing through the body could provide a detailed, two dimensional, static image of the dense materials in the body, i.e., bones and metal. Less dense objects, such as organs, muscles, circulatory system and soft tissue, cannot be effectively visualized since the radiation passes right through them. To compensate for this situation, liquids (contrast media) that absorb x-rays better than surrounding tissue are injected into the patient. The most commonly used contrast mediums for enhancing x-ray based imaging methods are iodine (for the circulatory system) and barium (for the digestive system). At the Kraus Back and Neck Institute x-rays of the cervical vertebrae and lumbosacral vertebrae generally outnumber those of the thoracic spine vertebrae and the five fused bones at the bottom of the spine (sacrum) and the four small bones that make up the tail bone (coccyx).
• A continuing issue associated with the use of traditional x-ray technology is the fact that prolonged exposure to the ionizing radiation created by the x-ray machine can cause radiation poisoning in the doctor, technicians and the patient. Careful measures are taken to prevent this from happening. Multiple uses of the x-ray such as dental x-rays, security applications, weld integrity inspections, etc. will ensure the continued application of this fundamental imaging technology.
• Fluoroscopy: This form of imaging, based on the x-ray platform, was developed around the same time as the x-ray itself. Due to early technological limitations, fluoroscopy languished until the 1950s when it was joined together with the newly developed x-ray image intensifier, which allowed the light produced by the fluorescent screen to be amplified, and video technology. The blending of these technologies, accompanied by the use of contrast media, enabled the physician to view real time images of the shape, size and movement of body’s internal organs. The moving images could then be recorded on video or film. Fluoroscopy shares with the problem of ionizing radiation with the standard x-ray.
• Ultrasound Imaging (sonography): This non-invasive, imaging technology uses ultra-high frequency sound waves that are beamed into the body to diagnose and treat various conditions. The echoes that are returned from the beams “bouncing off” internal structures are used to visualize in real time what is beneath the skin. Unlike the two dimensional images created by x-ray and fluoroscopy, ultrasound imaging can produce three dimensional images, as well as 3-D images in motion. With ultrasound, there are no harmful risks to patients. However, because tissue attenuates sound waves, the technology is not as effective when used on large patients. Ultrasound may have limited use as a diagnostic tool in spinal surgery as it has not been found to be more advantageous or has a greater diagnostic accuracy than established procedures such as computed tomography (CT) or magnetic resonance imaging (MRI). However, it has recently been reported that ultrasound can be used to effectively guide the insertion of pedicle screws during scoliosis surgery. In addition, therapeutic deep tissue ultrasound can relieve pain in the back due to muscle strain or spasm.
• Computed Tomography (CT): The early 1970s saw the application of the computer to technologies in every sector of the economy. The results in many instances were absolutely mind-boggling. No where was this more evident that in field of medicine. The development of the CAT-scan, brought about by the melding of the computer with the x-ray, gave surgeons a precise, three dimensional image of the organs, bones and systems of the body that not only supplemented, but surpassed those of 2-dimensional x-rays and ultrasonography. As with x-rays and ultrasound, intravenous contrast material served to sharpen image quality.
• Magnetic Resonance Imaging (MRI): This imaging technology was introduced at the beginning of the 1980s. Unlike the previous imaging systems which relied on ionizing radiology, the MRI uses magnetic and radio waves to produce precise images of structures and organs in the body. The MRI produces images that are superior to those produced by the x-ray, fluoroscope, ultrasound or computed tomography. The spine surgeon can use the MRI to precisely evaluate such conditions as spinal stenosis, vertebral fractures, scoliosis, lordosis, spinal tumors, disc herniations, etc. before the surgery begins. The MRI also uses a gadolinium-based intravenous contrast agents to further sharpen the images of the central nervous system (spine, brain and spinal nerves).

It should be noted that despite the remarkable advances in imaging science and tchnology the diagnosis and treatment of spinal disorders remains a challenging undertaking.

Surgical Procedures

• Discectomy: A discectomy is the surgical removal of herniated disc material that is causing pain due to pressure on the spinal cord and/or nerve root compression. The first discectomy was performed by neurosurgeon W. J. Mixter and orthopaedic surgeon Joseph Barr on the lumbar spine in 1937. In the intervening years the procedure has undergone extensive refinement to improve patient outcomes. Although discectomy surgery can be performed in each region of the spine, the great majority take place in the cervical and lumbar regions. Each year more than 800,000 discectomies take place around the world, with more than 200,000 performed by neurosurgeons and orthopaedic surgeons in the United States. Surgeons now have at their disposal improved instrumentation (fixation devices, pedicle screws, titanium rods and plates, etc.) to stabilize the spine as well as improved fusion techniques using bone grafts and bone substitutes. In recent years the use of the laser to remove disc fragments without damaging adjacent tissue and a minimally invasive, microsurgical approach to disc removal has been introduced that avoids cutting muscle surrounding the vertebrae, thereby reducing complications and accelerating patient recovery.
• Perhaps the most recent innovation in discectomy surgery has been the introduction of genetic engineering technology to create substances that stimulates bone formation in spinal fusions (arthrodesis). One of these applications, the production of bone morphogenic proteins (BMP), is reported to stimulate progenitor cells in the patient’s cellular tissue to enhance the bone formation necessary for successful spinal fusion.
• Microsurgery: Two disparate innovations combined to make microsurgery a reality. The first was the development of electrocautery devices for hemorrhage control that provided the surgeon with a drier operating field. The second was the introduction of the operating microscope. The use of the microscope as an adjunct for surgical procedures began in the 1920s when a monocular microscope was used for ear surgery. This type of device had major shortcomings: the lack of a light source and image distortion and vibration with increased magnification. The introduction of the binocular microscope soon followed. This device is credited with making major improvements in the surgical techniques in many medical fields. This was particularly true in the field of neurosurgery when the Zeiss microscope, accompanied by innovations in microsurgical instruments and suture materials, became the standard of care for brain and spine surgery.
• Continued improvements in the operating microscope led to the development of superb optics that eliminate aberrations, device stability that did not limit operational flexibility and low heat light sources. This will allow bone spur removal, correction of multi-level cervical stenosis (corpectomy), more aggressive surgical decompression, spinal tumor resection and correction of severe spinal deformities. Recent innovations associated with the operating microscope  include viewing ports for the physicians assisting the primary surgeon conducting the surgery and the use of video cameras to record surgical procedures.
• Endoscopic Surgery: Endoscopic surgery refers to the use of miniaturized video cameras and instruments which are passed through small incisions to perform various spine surgeries. Among the benefits of this type of surgery are smaller incisions, less post-operative pain, less damage to surrounding tissues, reduced blood loss, cosmetically satisfying incisional scars and faster recovery times.
  
  Endoscopic surgery has proved effective in neuro-surgeries treating:
  • Spinal Arthritis
  • Bone Spurs
  • Bulging Discs
  • Degenerative Disc Disease
  • Facet Syndrome
  • Foraminal Stenosis
  • Herniated Disc
  • Sacroiliac Pain
  • Sciatica
  • Spinal Stenosis
  • Synovial Cysts
• Gamma Knife Stereotactic Radiosurgery (Non-invasive brain surgery): Gamma Knife stereotactic radiosurgery is a non-invasive method of brain surgery introduced in 1967. The Gamma Knife was designed to arrest brain tumor growth while preserving neurologic function. The device uses 201 cobalt 60 radiation emitters placed in a circular array in a heavily shielded steel collimator helmet. A light-weight stereotactic frame secured to the patient’s head focuses the beams of radiation so precisely that healthy tissue less than 2 millimeters from the target is unaffected. After the stereotactic frame is attached to the patient, a remote-controlled positioning system moves the patient into a shielded enclosure and the 201 beams of gamma radiation are delivered. The radiation causes tumor cell destruction by destroying the DNA intracellularly without causing an inflammatory response.
  
  The advantages of Gamma Knife stereotactic radiosurgery include:
• The absence of an incision minimizes the risk of hemorrhage, infection, and adverse reaction to anesthesia
• Gamma Knife treatments take approximately 12 to 25 seconds. Convalescent time is extremely short. There is no post-operative pain and post-operative rehabilitation is not required, and hair is not shaved from the head
• The cost of a Gamma Knife procedure is up to 35% less than conventional neurosurgery and is usually performed on an out-patient basis. Patients can resume their previous activities in a day or two

Dr. Kraus has directed the operation of Gamma Knife facilities for more than ten years and has performed over 2000 Gamma Knife surgeries.

• Computer-guided Spine and Brain Surgery: Dr. Kraus uses computer technology combined with advanced imaging technology and the surgical microscope to enable him to perform minimally invasive spine and brain surgery for the precise removal of lesions. By creating three dimensional models of the spine or brain, Dr. Kraus can manipulate the model to determine the best approach to a lesion. This “navigation” can then be performed through a minimal skin or cranial opening thereby allowing for minimal manipulation of normal tissue and/or the precise placement of spinal instrumentation. The result is a reduced risk of injury to the spinal cord and peripheral nerves,  and in the case of the brain, a reduction in the amount of brain tissue needed to be removed.
• Artificial Disc Replacement: It is generally agreed that a healthy, natural disc is superior to any prosthetic replacement available today. Research is currently being conducted to create an artificial, failsafe, prosthetic disc from biocompatible material that mimics normal disc geometry, endurance, and kinetic dynamics while ensuring positive fixation of the prosthesis to the vertebral bone. One approach that is currently being evaluated in animal test subjects is the use of a prosthetic disc to replace a portion of the natural disc. The concerns for biocompatibility of the artificial material, diffusion of nutrition and other problems continue to be studied.

Instrumentation

The traditional approach to the closure of wounds and surgical incisions has been to use sutures, either surgical gut or nylon. Today sutures come in different sizes (requiring different size needles) within two basic formats: non- absorbable sutures that must be removed after the wound heals and absorbable sutures that are dissolved by the body. In either instance after the incision is closed there remains the chance that the wound may develop swelling, redness and drainage that can lead to pain and infection. Healing of the wound can be affected by the age of the patient, nutrition, metabolic disorders such as diabetes mellitus and uremia, infections, etc.

In recent years alternatives to sutures to close incisions have been developed. They include metal staples, skin adhesives/tape and surgical glues (cyanoacrylate tissue adhesives and human fibrin glue).

Surgical Closure Systems

The use of spinal instrumentation (screws, plates, rods, hooks, wire, interbody cages, etc.) was first introduced in the late 1950s when surgeons attempted to correct the spinal deformities caused by polio. The successful use of instrumentation limited the need for external bracing. When instrumentation is used today in spinal fusion surgery exceptional stability of the spine can be achieved. Innovative procedures and materials continue to be developed to limit the risk of instrument fatigue. However, since all instrumentation hardware is subject to metal fatigue, emphasis is placed on the need for the fusion to heal properly. Surgeons are keenly aware that smoking and osteoporosis can severely limit the success of spinal fusion with instrumentation.

Today researchers and surgeons such as Dr. Kraus are making patent-pending improvements in the biomechanics and construction of spinal instrumentation that allows for smaller devices that can be employed in minimally invasive procedures. Another area of interest is the development of instrumentation made from bioabsorbable materials that will dissolve once successful fusion is accomplished.

Pain Management (neurostimulation systems)

The introduction of neurostimulation devices to assist in the management of chronic spinal pain occurred in the 1970s. The first such devices were transcutaneous electrical neurostimulators (TENS) that were worn by the patient. TENS proved effective for managing pain associated with various nerve pathologies (e.g., low back pain), osteoarthritis, chronic musculoskeletal pain and postoperative pain. The TENS device operated on the premise that the spinal cord can only handle a limited number of sensory inputs. By producing an excessive number of inputs the TENS unit could limit the ability of the spinal cord to send pain messages to the brain.

At present there are two types of neurostimulation systems available: transcutaneous systems with an external power source and fully implantable, self-contained systems. The latter includes a radio-wave transceiver (for adjustment of signal strength), a long-life battery and a miniature computer. The implantable system has proved effective for chronic back pain caused by failed back syndrome (FBS), radicular pain syndrome, unsuccessful disk surgery, post-laminectomy pain, degenerative disk disease, epidural fibrosis, reflex sympathetic dystrophy, lumbar adhesive arachnoiditis, etc.