An Introduction to Laparoscopic Anterior Interbody Techniques of the Lumbar Spine For Healthcare Professionals

The Role of Lumbar Laparoscopic Anterior Interbody Techniques


i. To obtain fusion of the symptomatic spinal motion segment

ii. Reconstitution of foraminal volume (decompression)

  • Chen et al. demonstrated a significant increase in neuroforaminal volume using an interbody metal cylinder device.
  • The volumetric increase correlated with increase in posterior disc height
  • The increase in foraminal volume equals 22.9% at L4–5; and 21.5% at L5–S1

iii. Unable to directly decompress the central spinal canal (stenosis or HNP)

iv. To minimize perioperative morbidity (pain, narcotic use, mobility, risks of immobility)

Diagnostic Tools for Laparoscopic Spine Techniques

Plain Radiographs

i. Radiographs are evaluated for disc height, spur formation, spondylolysis / spondylolisthesis, planes (types) of instability.

ii. A degenerative, painful motion segment generally demonstrates more advanced spur formation, disc–space narrowing, and reactive endplate sclerosis on plain x–ray, than does an annular disruption (tear in the ligamentous portion of the disc) due to trauma.

iii. A radiographically degenerative lumbar spine, previously asymptomatic, or minimally symptomatic, may also become symptomatic as a result of trauma.

iv. Instability may be apparent; either forward, backward, lateral, or rotational subluxations (displacements). Additionally, axial instability (compression of the motion segment) may occur.

v. Radiographic findings are solely pieces of information which must be analyzed in the context of the overall clinical picture; i.e., is the abnormality on the x–ray truly from where the pain is arising? Fractures, high–grade subluxations, gross instability, tumors, and infections are the few radiographic findings which alone correlate well with pain/symptoms.

CT Scan

i. Assess spinal canal, vertebral bony anatomy, and/or joint integrity

ii. Of limited use in assessing the mechanical low–back pain patient

MRI

i. Different sequences provide information regarding different aspects of the spine.

  • Herniated nucleus pulposus
  • Broad–based bulging disc
  • Signal intensity of the nucleus pulposis – normally high (white) on T2 imaging, becomes low (dark) in significantly degenerative discs or posttraumatically. This suggests possible sites of discogenic pain – further testing is needed for confirmation.9,30,32
  • High signal–intensity posterior annulus fibrosis abnormality may correlate with annular disruption. Confirmatory testing is recommended (provocative discogram pain study).
  • Vertebral endplate reactive signal changes (modic changes)

Discogram Pain Study

i. Discriminates pain generators from asymptomatic degenerative discs.

ii. This is a study which has been performed for many years. Previously it seemed to be of limited usefulness in terms of correlating with surgical success when used as a decision–making tool. More recently, the manner in which the information provided by this test is analyzed in decision making has changed this to a highly specific and sensitive study. It now is quite useful in patient selection and surgical decision making for these diagnoses.

iii. Pain provocation. Disc pressurization may produce no pain, discordant pain, or concordant pain (pain that reproduces the patients' typical pain pattern). Only reproducibly concordant pain is consistent with the origin of the mechanical LBP. 46

  • Discordant pain is pain (frequently an ache or pressure) different from the pain that bothers the patient.
  • Concordant pain is pain which represents the pain that plagues the patient.
  • The pattern of contrast dispersal (plain x–ray and postdiscogram CT) is useful, though the main emphasis is placed on the pain reproduction.

Current Indications for Laparoscopic Anterior Interbody Techniques – General

i. One or two–level disc disease, L2 to S1

  • Painful degenerative disc disease
  • Traumatic annular tear

ii. Significant disc–space narrowing (the biomechanics of these implants are all designed to work by screwing into the vertebral endplates with the tension of the annulus fibrosus providing a compressive effect due to preoperative narrowing).

iii. Revision of failed posterior fusions

  • Must be particularly careful if pedicle screws are present; make sure the cages can fit around the screws.

iv. Grade I spondylolisthesis (less than 25% offset of one vertebrae to the next)

  • Technically a more difficult procedure
  • In most instances the step–off will reduce with the distraction of the disc space. This may allow the use of a longer cage.
  • It is especially important that the disc space be significantly narrowed in the presence of a spondylolisthesis.

v. Segmental instability

  • Degenerative
  • Posttraumatic
  • Iatrogenic (following an aggressive laminectomy)

Exclusion Criteria for Laparoscopic Anterior Interbody Techniques – General

i. Active infection at the operative site
ii. Active cutaneous, pulmonary, or urologic infection
iii. Metabolic bone disease
iv. Loss of quantity or quality of vertebral bone stock likely to compromise fixation
v. Presence of primarily nonorganic symptoms (i.e., pain out of proportion to the findings on studies of exam)
vi. Additional points of concern:

  • Medical condition interferes with the patient's ability to participate in a postoperative management program (neuromuscular compromise, muscle loss).
  • Circulatory problems (thrombophlebitis, lymphedema, or vascular insufficiency at the implant site
  • Symptomatic cardiac disease
  • Active malignancy
  • Obesity (greater than 40% over ideal for age and height)
  • Greater than Grade I spondylolisthesis at the affected level
  • Pregnancy
  • Multilevel motion–segment pain
  • Three or more of the psychosocial factors: alcoholism/drug dependence, recent or pending divorce, high level of job dissatisfaction, pending litigation, depression, multiple unsuccessful surgeries, smoking one or more packs/day, Waddel test score of three or more (symptom magnification)
  • Metal allergy or intolerance (for metallic devices)
  • Tobacco use
  • Medical condition requiring postoperative medications that interfere with bony healing/fusion, such as nonsteroidal anti–inflammatory drugs and steroids
  • Patient is not a candidate for laparoscopic fusion (laparoscopist consultation).

Part V. Surgical Team

i. Laparoscopic general surgeon
ii. Spine surgeon
iii. Anesthesiologist
iv. Camera operator (often a OR nurse or tech)
v. Scrub nurse/OR technician (familiar with both the laparoscopic and the spinal aspects of the procedure)
vi. Circulating nurse (familiar with both the laparoscopic and the spinal aspects of the procedure)
viii. Radiology technician

TECHNICAL CONSIDERATIONS

Surgical Technique Summary – Threaded Femoral Cortical Dowels

Templating
Use preoperative plain radiographs, MRI, or CT images

laparascopic anterior interbody techniques lumbar spine figure 1 templating heim
Fig.1: Templating

i. Onlay template set

  • Diameter estimated off of adjacent normal disc height
  • Length determined from lateral radiograph
  • Diameter and length estimates verified on MRI/CT axial images – impingement on neuroforamen?

ii. Surgeon orders appropriate threaded cylinder (metal or bone) size when the case is scheduled – he or she should verify appropriate planned and alternate sizes are available at the hospital prior to induction of anesthesia.


iii. Surgical team prepares implant size–specific instrumentation.

 

  • The surgeon verifies the dowel size before it is thawed (if bone dowel is utilized).
  • The surgeon provides the scrub nurse/technician with the likely final distraction plug size in order that the working cannula may be assembled.
  • The surgeon also provides the length for the depth stop on the reamer and tap instruments.

 

General Anesthetic
Anesthesiologist administers anesthetic.

Patient Positioning

i. Trendelenburg position is used.

laparascopic anterior interbody techniques lumbar spine trendelenburg position figure 2 or layout heim
Fig.2: OR Layout

ii. Smoothly contoured, folded surgical blankets are used to elevate the patient's pelvis 3–4 inches from the plane of the OR table.

iii. Arms tucked at the patient's side (with padding)

iv. Pre–procedure lateral fluoroscopy to ensure that the involved spinal segment can be effectively visualized radiographically

v. Pre–procedure AP fluoroscopy to ensure that the spine is not rotated one way or the other

Laparoscopic Portals Established
i.
Supraumbilical laparoscope portal – abdomen insufflated

ii. 10mm right and 5mm left lower–quadrant dissection portals

iii. Gaseous (CO2) insufflation

iv. The spinal working portal is established later. It must be in direct line with the angle of the involved disc space.

 

Posterior Peritoneum Opened – Prevertebral Space
i.
Monopolar cautery is minimized after opening the posterior peritoneum.

  • Extraneous cautery marks may confuse landmarks. (Midline, right and left discal entry sites will ultimately be marked with cautery.)
  • Monopolar cautery in males increases the risk of retrograde ejaculation.

ii. Great vessels mobilized to expose anterior annulus

iii. Radiographic verification of correct level

Iliac Crest Bone Graft Harvesting
i.
Preserve gluteal and iliacus attachments (limits perioperative pain).

ii. Remove superior cortex, harvest cancellous bone with curettes (used with both metal and bone threaded "cages").

Working Portal Established
i.
Long spinal needle passed through anterior abdominal wall a direct laparoscopic visualization.

ii. AP fluoroscopy verifies midline position in anterior annulus – mark with cautery

iii. Lateral fluoroscopy verifies colinear orientation to disc space.

iv. 12 mm working portal is established to be colinear with disc (adjusting from needle entry site if necessary).

Bilateral Discal Entry Sites Established
i.
Starting guide (specific for templated implant size) is placed in the midline mark on the annulus fibrosis

  • This is pushed into the annulus gently by hand.
  • Do not impact the starting guide with a mallet, because the measuring arm may break off.

ii. Disc entry sites are marked with cautery.

  • This leaves three cautery marks on the anterior annulus fibrosus – the midline and the right and the left discal entry sites.
  • Each step should begin with revisualization of each of these three marks to ensure the instrument is truly being placed where desired.

iii. Long K–wire may be used to engage the annulus to prevent migration from true entry site (due to the convexity of the anterior disc space).

iv. Each entry site is opened with trephine placed over K–wire.

  • Select the largest trephine that will fit in the disc space.
  • Start the trephine with a gentle blow with a mallet.
  • Trephine to a depth of 20 mm (monitor laparoscopically and fluoroscopically).
  • Remove disc material with pituitary rongeurs.

 

laparascopic anterior interbody techniques lumbar spine figure 3 portal positions heim
Fig.3: Portal Positions

 

Disc Space Distraction
A series of distraction plugs is provided for each dowel size.

laparascopic anterior interbody techniques lumbar spine small figure 4 disc space distraction heim
Fig.4: Disc Space Distraction

 i. Switch to 18 mm cannula

ii. Distract to where the annulus is "tensioned." (There must be 6 mm or more difference between the distraction plug diameter and implant diameter.)

iii. The working cannula is then inserted (careful visualization and protection of vessels) with the inner sleeve inserted.

Working cannula disc space extensions match distraction plug diameter (i.e., a 12 mm distraction plug size for a 16 mm implant will then use the 16/12 working cannula)

  • Medial and lateral specific disc–space extensions
  • Maintains distraction and alignment with disc space
  • Distraction plug able to be removed

 

Endplate Preparation

laparascopic anterior interbody techniques lumbar spine figure 5 endplate preparation heim
Fig.5: Endplate Preparation

i. Implant size–specific drill

ii. Careful fluoroscopic monitoring – depth of insertion and endplate engagement

  • Adjustable drill stop with implant length markings
  • May be adjusted for slightly deeper drilling permitting implant countersinking

iii. Pituitary rongeurs to remove disc material at the base of the disc sites


 

 

Pack Implants with Cancellous Graft

i. Verify implant size

ii. Implant driver engages implant; surgeon to secure driver to implant

laparascopic anterior interbody techniques lumbar spine figure 6 implant packed with cancellous bone heim
Fig.6: Implant Packed with Cancellous Bone

 

 

Implant Insertion

laparascopic anterior interbody techniques lumbar spine figure 7 implant insertion heim
Fig.7: Implant Insertion

i. Careful fluoroscopic and laparoscopic monitoring

ii. Implant driver reference marks demonstrate flush seating and countersinking in 3 mm increments

iii. AP and lateral fluoroscopic verification of implant positioning


 


Learning Curve in Multicenter Study Using the BAK Device
A significant learning curve was evident in terms of operating time, length of hospitalization, and complications.

Perioperative Nursing Protocol

i. Analgesia

  • PCA may be utilized
  • IM analgesic available in case of postoperative nausea
  • Primary analgesic is P.O. (i.e. Tylenol #3, Vicodin, Lortab, etc.)
  • Valium (5 mg P.O.) can be quite effective in decreasing any graft site muscle spasms.

ii. Prophylactic antibiotics 24–48 hours

iii. DVT prophylaxis

  • Thigh–high TED hose and intermittent compression stockings are applied prior to the procedure, and continued during postoperative hospital course.
  • Early mobilization

iv. Foley catheter – typically discontinued in the recovery room

v. The IV is switched to a heparin lock when P.O. intake is appropriate.

vi. Incentive spirometry

vii. Mobilization

  • On the day of the surgery the patient is usually mobilized to a chair and ambulates with assistance 3–4 times.
  • If the patient returns to the nursing unit by early afternoon, and is recovering well from the anesthesia, PT may be instituted on the day of surgery.

viii. PT/OT for mobilization, body mechanics, and activities of daily living

ix. Brace – surgeon's discretion

Discharge – usually postop day 1, although some patients are discharged on the afternoon of surgery when:

  • Independent in ambulation and ADL's
  • Taking P.O. well
  • Oral analgesics are effective.

Rehabilitation
Walking (goal of 1–2 miles/day at the 2 week postop visit)

ii. Swimming and/or water walking may begin after the 2 week wound check

iii. Abdominal isometrics begin at 6 weeks (unless the surgeon has concerns on the fixation)

iv. The author typically begins the true spinal range of motion and stability exercise rehabilitation at 12 weeks

  • Lumbar ROM and stability exercises 3 times per week for 4 weeks
  • Work hardening usually begins after the first 4 weeks (if indicated by the physical demands of the patient's occupation)
  • The patients are all instructed to maintain their independent lumbar ROM and stability exercise program indefinitely

 

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Updated on: 12/10/09
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