ACDF

Operation: Anterior cervical discectomy and fusion

  • Introduction- The anterior cervical discectomy and fusion (ACDF) is the most commonly performed cervical operation and one of the most common operations that neurosurgeons perform. The ACDF is one of the workhorse operations of neurosurgery in that it can be utilized for a myriad of pathologic process. ACDF can play a role in cervical radiculopathy, stenosis, myelopathy, trauma, infections, etc. But, patient success is largely determined by the realizing the advantages and limitations of this approach.
  • Preoperative considerations
    • Is the patient a candidate for the operation?
    • Will the patient tolerate the operation?
    • Do we need to take special precautions to best prepare the patient for an operation? For instance, is the patient myelopathic and do they need an arterial line for blood pressure support?
  • Positioning- The goal of any decompression and fusion operation is to position the patient in such a way to allow for easy surgical access, to maintain the natural sagittal balance and to allow for adequate decompression of the neural elements. The ACDF requires that chin/head be held in extension (with tape) and that neck be supported to maintain sagittal balance throughout the operation.
    • Supine, flat table, top of the head 4-5inches from the head of the bed to allow for adequate extension, head neutral to slightly turned to left
    • Chin tapped to put head in extension
    • Neck bolstered posteriorly with blue towels
    • Both arms tucked and padded
  • Prep and Landmarks
    • Identify: Depends largely on the level but it is important to identify the SCM, carotid pulsation, cricoid/thyroid cartilage, hyoid, etc
    • Anatomic landmarks for level: Hyoid C2-3, Top of thyroid cartilage C3, C5- Cricoid cartilage
  • Incision and approach
    • Incision: Horizontal incision within a skin crease at the appropriate level. It is easier for a right-handed surgeon on the patients right to work inferiorly so place your incision slightly superior to where you think you need to end up. Note: This never made sense to me because it seems like it is easier to work superiorly but the visualize is better when you are working inferiorly. At C3-4 this may be due to the shape of thyroid cartilage
    • Skin- Incise the skin in one fluid motion for an approximately 3 fingerbreadth incision
    • Platysma- open the platysma (Bovie on cut will help you delineate the planes more effectively) and find the medial border of the SCM. Undermining the platysma will afford greater exposure and is worth the additional time at the beginning of the operation
    • The subplatysmal areolar layer is undermined and allows visualized of the SCM
    • Follow the loose areolar layer between SCM and infrahyoid muscles (depending on the level). At this point feel for the carotid pulsation
    • You want to dissect just medial to the carotid down to the vertebral body
    • Your finger as well as mets can be used to develop the plain to gain access down to the vertebral body
    • Use Kittner swab to sweep the overlying soft tissue off of the longus coli muscles. Use a non-lipped cloward handheld retractor at this point
    • Check with fluoro that you are at the right level
    • Once you identify the vertebral body you will need to use the bovie to remove the overlying longus colli as well as the ALL. If you are doing a multiple level ACDF then go ahead and clean the anterior surface of all the segments you will be working with. Be sure to clean off the bone superiorly, inferiorly, and far enough laterally. Note: The peaks are the disc spaces and the valleys are the vertebral bodies.
    • Pitfalls:
      • Superior laryngeal nerve injury- increased risk C3-4
      • Recurrent laryngeal nerve injury- increased risk below C5-6. Have anesthesia pull back the esophageal temperature probe. Also some literature indicates that deflating the ET cuff temporarily while placing the retractors decreases the instance rate of injury
      • Omohyoid- often requires retraction/sectioning at C5/6
  • Operative details
    • Once you have achieved adequate exposure, place your retraction system (Medtronic trimline)
    • Distraction screw- place a 14mm screw in the center of the adjacent vertebral bodies. Tap with a malate. The screw needs to be parallel to the superior endplate at each level and screwed in finger tight (don’t strip). Attach the destractor and Destract.
    • Open the annulus of the disc with either an 11 blade or the bovie and remove the disc with a pituitary, curette, punch, etc
    • To complete the discectomy and assure adequate decompression you must drill the inferior endplate of the superiorly level. Start at the bottom (posterior surface of the vertebral body), remove any osteophyte, and square up the surface as you move up (anteriorly).
    • Prepare the endplates by creating a flat surface for the interbody graft. Use the drill to flatten out the uncovertebral joint (aka Joint of Luschka). Minimal drilling of the superior endplate of the inferiorly level is usually required.
    • With the endplate prepared remove the PLL and remaining disc/osteophytes
    • A nerve hook or small up-biting curette can often be hooked under the PLL and allow a small Kerrison punch to aid in removing the ligament
    • Using a nerve hook assure that the exiting nerve roots are decompressed (also assured by decompressing laterally enough to visualize the uncovertebral joints (ie where the bone turns superiorly at the lateral margins)
    • Place the interbody allograft bone packed with DBX, seat into position using a mallet, Load the graft by releasing the distractors and remove the distraction pins.
    • Place and secure the plate
    • Leave a drain and close platysma with interrupted vicryl
    • Close skin with subcuticular monocryl and dermabond
  • Postop Orders
    • Floor overnight, PRN pain meds, Drain to full compression
  • Notes
    • Law of Wolff- states that bone will not fuse/heal unless placed under a load
Joseph MillerACDF

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