ALIF Anterior lumbar interbody fusion

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Interbody fusion

Pre op

• Document pulse exam pre op

• Pulse oximetry left big toe

• Pt selection
• Skin to spine distance <15
• Abdomen fat
• Prior surgery
• General retroperitoneal procedure
• Radicle pelvic procedure
• Lap inguinal hernia repair
• Pelvic radiation
• Look at sacral slope for L5S1 to make sure it is not angle too low

• Imaging review
• Check arteries and veins location
• Check left sided inferior vena cava
• Venous anomalies
• Horseshoe kidney
• Check if osteophytes flatten out the veins making mobilizing the vessel difficult

Indication

• Lumbar degenerative disc disease

• Isthmic spondylolisthesis (≤ Grade II)

• Degenerative scoliosis

• Pseudarthrosis

• Total disc replacement revision

• Post-laminectomy instability

• Adjacent segment disease

• Sagittal malalignment

• Corpectomy

Contraindications

• Severe osteoporosis

• Previous abdominal surgery

• Collapsed or fused disc space

• General infections

Pros

• Larger surface area for intervertebral graft positioning

• Restoration of segmental lordosis

• High fusion rates compared to the posterior approach

• Less postoperative pain

Cons

• This procedure is less familiar for many spine surgeons

• It generally takes observation of at least 20 cases to learn how to perform this procedure autonomously

• The help of a vascular or general surgeon may be needed for at least the first 20 cases

• A vascular surgeon should be on site in case of any unexpected vascular injuries

Position:

• Supine

• an inflatable bag is placed underneath the lumbar spine to
• exaggerate the lumbar lordosis
• open the anterior disc space.

Incision

• Options
• Midline
• Mr Neil
• Between pubic symphysis and the umbilicus
• try to stay under the arcuate line
• Pros can extend all the way to xiphisternum
• Transverse
• Left transverse skin incision avoids the more prominent right iliac vein that can hinder the deeper dissection.
• A skin incision is carried out from midline to the lateral border of the rectus abdominus.
• Pros
• Better to visualize
• L4-5 level
• Used more commonly for cases of DS since the condition typically affects the L4-5 level.
• L5-S1 level
• better cosmesis
• Paramedian
• Pros
• Better to visualize the higher lumbar levels.
• Require a smaller skin flap
• Less dead-space.

• Location of incision
• L4-5 level
• incision is placed just below the umbilicus
• L5-S1 level
• incision is 2/3 the distance from the umbilicus to the pubic symphysis.

• The incisions are adjusted based on the angle of the target disc space in order to ensure that instruments can be inserted parallel to the disc space.

Superficial Approach

• Blunt dissection through subcutaneous fat to anterior rectus fascia

• Divide linear alba

• Divide transversalis fascia to get into extraperitoneal space

• pull peritoneum medially until retroperitoneal fat visualized

• in left retroperitoneal space blunt dissection down to psoas

• retract medially along with left ureter
• to check for ureter squeeze it with a non tooth forceps and see if there is peristalsis

• move medial and over psoas to anterior spine L5-S1 disc spacc

• iliac artery will be anterior and typically lateral to iliac vein

Deep dissection

• Blunt dissection (Dry swab on a ramplie) is used to develop the retroperitoneal space and visualize the left iliac artery and vein.

• Self-retaining retractors placed

• L5/S1 stay medial to the iliac veins
• cauterize and ligate midsacral vessels during L5-S1 approach

• L4/5 stay lateral to the iliac veins
• move superior and left lateral to the iliac vessels to get to L4-5 disc space
• cauterize and ligate iliolumbar artery during L4-5 approach
• cauterize and ligate left iliolumbar vein during L4-5 approach
• Iliolumbar veins tether the common iliac vein laterally and must be ligated in order for the common iliac vein to be retracted medially.
• variation in anatomy
• single vessel (70%) joins common iliac vein 4cm distal to IVC
• may be double vessels (30%) at 3 and 6cm distal to IVC
• Once the iliolumbar veins are ligated, the iliac artery and vein are mobilized, and any segmental vessels overlying the anterior vertebral body are ligated.

• Nerves
• Genitofemoral nerve injury
• lumbosacral trunk and lumbar plexus lie deep to ILV
• obturator nerve lies superficial to ILV (3cm lateral to where ILV joins CIV)
• The L5 nerve often runs in close proximity to the iliolumbar vein and must be identified.
• Superior hypogastric plexus
• blunt dissect the away from midline
• patient might get varying temperature in leg due to vasodilatory effects of the parasympathetic injury

 

Localisation and Abdominal Frame Setup

• Localise disc level under lateral fluoro
• for L5-S1: especially in Grade 1-2 or higher spondylolisthesis need more caudal incision for disc space angulation

• Set up abdominal retractor system
• Use the Synframe:

• Deep retractors x2 to bluntly dissect to spine

• First place deep retractor medially over edge of anterior body/disc

• Place second retractor laterally over edge of body/disc

• Take care to retract and preserve iliac vein

• Self-retainer first replaces medial deep abdominal retractor

• Attach to frame with arm in-line with direction of pull

• Second self-retainer replaces lateral deep abdominal retractor

• Superior blade is attached last

• Bluntly clear off disc space

Annulotomy and cage implantation

• use spinal needle into disc
• confirm level with lateral x ray

• 15 blade or bovie to perform annulotomy

• remove disc fragments with pituitary

• use Cobb to define endplates clearly

• large curette at anterior part of disc

• microcurettes as disc space collapses down

• pituitary to remove fragments

• burr/kerisons to remove anterior osteophytes and to level endplate

• ring curette to finish endplate preparation

• An AP fluoroscopy image can be used to ensure the annulotomy is midline.

• Enough disc and anterior longitudinal ligament are removed to fit the ALIF spacer
• incomplete discectomy can result in retropulsion of disc fragments into the canal.
• The disc space is distracted, and a trial spacer is placed with the goal of a tight fit at desired distraction.

• A lateral fluoroscopy image is used to confirm the trial placement, with the goal of being just posterior to the anterior vertebral body margin.

• Once the size of the implant is established the final implant is opened, packed with bone graft, and inserted.

Anatomy

• The genitofemoral nerve is located anterior to the psoas muscle.

 

Outcome

• Learning curve for ALIF + percutaneous posterior Mirza 2002
• 30 cases to get a stable Bloods loss of 200mls
• 25 cases to reduce vascular complications to the lowest

• vs TLIF:
• Buell 2021
• ALIF vs TLIF cages were similar in height, but cage lordosis was greater for ALIF: L4-L5 (9°±5° vs 7°±2°, p=0.025) and L5-S1 (14°±9° vs 7°±3°, p<0.001).
• ALIF (vs TLIF) was associated with significantly more L4-S1 segmental lordosis at last follow-up (37°±11° vs 31°±9°, p<0.001) despite similar baseline measurement (32°±15° vs 31°±14°, p=0.705).

• Reoperation rates
• ALIF: McKenna et al. (Eur Spine 2005) – 9.8% re-operation rate.

• Reoperation rates
• 360° fusion (combined anterior–posterior construct): Villavicencio et al. (JSDT 2006) – 14.0% reoperation rate.

Complications

• Most common are approach-related injuries.

• Vascular injuries
• (iliac veins)
• 3%.

• Retrograde ejaculation
• (injury to superior hypogastric plexus)
• 2% of retroperitoneal approaches.

• Bowel injuries are exceedingly rare.

• BMI > 35
• Increased risk of vascular injury
• Increased post op complications
• Increased total surgery time