Imaging

• Use magnetic resonance imaging as a screening tool to determine possible levels of involvement
  
• Standing lumbar radiographs with flexion and extension view to assess segmental motion
  
• Computed tomography or bone scan if integrity of pars is questioned
  
• Provocative lumbar discography for concordant confirmation of disease

Choice of Arthroplasty Device

Charité

• U.S. Food and Drug Administration (FDA) approved for single level from L4–S1
  
• Biarticulating mobile core with variable center of rotation
  
• Metal-on-polyethylene: two cobalt-chrome endplates and an ultra-high molecular weight polyethylene core
  
• Spike fixation to endplates

PRODISC-L

• FDA approved for single level from L3–S1
  
• Ball-and-socket configuration with fixed center of rotation
  
• Metal-on-polyethylene: two cobalt-chromium endplates and an ultra-high molecular weight polyethylene core
  
• Center keel fixation to endplates

Maverick

• Awaiting FDA approval for single level from L4–S1
  
• Ball-and-socket configuration with fixed center of rotation
  
• Metal-on-metal: cobalt-chromium-molybdenum
  
• Center keel fixation to endplates

Patient Counseling

• Discuss risks, potential benefits, and possible complications
  
• Discuss motion-sparing technology versus fusion
  
• Make patient aware of risk of adjacent segment disease
  
• Inform patient of radiographic imaging difficulties with arthroplasty

Operating Room Set-up

• Intraoperative fluoroscopy

Anesthetic Issues

Positioning and Exposure

• The patient is placed in a supine position or in the French position with the legs spread (with the surgeon standing between the patient legs for direct anterior access to the lumbar spine).
  
• The lumbar spine may be approached through either a transperitoneal or retroperitoneal exposure. The amount of great vessel release and retraction should be limited to that required for insertion of the instruments and constructs.
  
• At L4–L5, the iliolumbar and segmental vessels should be identified and ligated to facilitate mobilization of the vena cava.
  
• At L5–S1, the middle sacral artery and vein are ligated and divided. Minimize cautery use along the anterior aspect of the spine to avoid injury to the presacral sympathetic plexus.
  
• A lateral fluoroscopic image is used to confirm the targeted lumbar level.
  
• An anteroposterior fluoroscopic image with Ferguson projection is used to identify midline.
  
• Mark the centerline location of the vertebral bodies above and below the operative level (with cautery, a chisel, or with a center-marking pin for the Maverick).

Discectomy and Endplate Preparation

• Identify and mark the lateral margins of the discectomy.
  
• Incise the annulus sharply.
  
• Use a Cobb elevator to elevate the cartilaginous endplate.
  
• Use the pituitary rongeurs to remove the nucleus pulposus.
  
• The discectomy should clear the disc space all the way to the posterior ligament.
  
• Endplates may be prepared using a high-speed burr or decorticated with a ring curette.

Disc – Space Distraction

• Using blunt-nose scrapers, release any ligamentous adhesions to allow the operative level to move naturally.
  
• Up-and-down-angled Kerrison rongeurs may be used to remove osteophytes from the posterior margin of the disc.
  
• Tension the disc spreader while fluoroscopically watching the motion of the vertebrae to evaluate whether the operative level is moving properly.

Sizing and Placement of the Artificial Disc