SpineUniverse Case Study Library

Superior Articular Facet Interbody Reconstruction (SAFIR)

A novel posterior lumbar interbody fusion approach


The patient is a 74-year-old female who presents with 9 months of back and right greater than left leg pain. Four years ago, she underwent anterior lumbar interbody fusion (ALIF) with pedicle screws at L4-S1. Her Oswestry Disability Index (ODI) is 20.

Her past medical history includes borderline diabetes, obesity, and hypertension. She is a nonsmoker.


  • Positive right femoral stretch
  • Trace right quadriceps weakness
  • Diminished right knee reflex

Preoperative Imaging

Lateral herniated nucleus pulposus (HNP) at L3-L4 with disc space collapse; prior L4-S1 ALIF. (Figures 1-4 below)

lateral herniated disc at L3-L4 with disc space collapse; prior L4-S1 ALIFFigure 1

lateral herniated disc at L3-L4 with disc space collapse; prior L4-S1 ALIFFigure 2

lateral herniated disc at L3-L4 with disc space collapse; prior L4-S1 ALIFFigure 3

lateral herniated disc at L3-L4 with disc space collapse; prior L4-S1 ALIFFigure 4

Prior Treatment

A trial of organized physical therapy and selective nerve root injections were not effective.


Lateral HNP at L3-L4 with disc space collapse

Suggest Treatment

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Selected Treatment

Right L3-L4 superior articular facet interbody fusion (SAFIR).

Intraoperative Imaging

Inferior articular process (IAP) and superior articular process (SAP). (Figure 5, below)

inferior and superior articular processesFigure 5

intertransverse membrane; superior articular process removedFigure 6

Disc space and L3 nerve root. (Figures 7-8, below)

disc space and L3 nerve rootFigure 7

disc space and L3 nerve rootFigure 8

Initial height restoration with paddle distractor and maintained with contralateral percutaneous screws; prior to LUNA (Benvenue Medical, Inc., Santa Clara, CA) insertion. (Figures 9-10, below)

medial extent of the bone removal, not entering the spinal canalFigure 9

initial height restoration with paddle distractor; maintained with contralateral percuntaneous screwsFigure 10

Bone graft in LUNA. (Figure 11, below)

Bone graft in LUNA interbody deviceFigure 11

  • Surgical time: 110-minutes
  • Hospital length of stay: 40-hours
  • Estimated blood loss: 45cc


The patient experienced immediate resolution of leg pain (bilaterally), and back pain was much improved by postoperative day 1.

  • ODI preoperatively: 20
  • ODI at 12 weeks postop: 0

pre and postoperative measures: disc and foraminal height, lordosis

Postoperative Images

lateral postoperative imageFigure 12

posterior anterior postoperative imageFigure 13

CT at 12 Weeks Postoperative

12 weeks postoperative CT scanFigure 14

Surgeon's Rationale

Benefits of a "SAFIR" procedure:

  • Avoids intrusion into the spinal canal
  • Permits direct decompression of the ipsilateral neural foramen
  • Indirect decompression of the central canal and contralateral neural forament via height restoration
  • Restoration of lordosis and disc height
  • Familiar anatomy
  • No access surgeon needed
  • Enabled by the use of a unique 3D expanding interbody device (LUNA®, Benvenue Medical, Inc., Santa Clara, CA)

Case Discussion

Doctors Ammerman and Wind illustrate a problem that most experienced spine surgeons experience with monotonous regularity—adjacent segment failure after prior fusion. The authors are to be congratulated on an excellent surgical, radiological and clinical outcome with their targeted MIS approach.

There are many ways to ‘skin this cat’, which includes various posterior or lateral approaches; perhaps anterior or combined with or without interbody fusion, open, mini-open or MIS. No result is better than the other in a definitive fashion. The surgeons in this case report have shown a high level of skill which, in their hands has shown an excellent outcome. Every surgeon will need to find their level of comfort in deciding what works for them.

Community Case Discussion (3 comments)

SpineUniverse invites spine professionals to share their thoughts on this case.

Hello! I just wanted to know how did you took out the previous transpedicular system the patient had....? In the preop X rays we can see transpedicular screws at L4 and S1 and the PO images shows different construct...

The prior L4-S1 screws were removed as follows. Paramedian incisions 1.5 inches in length were opened bilaterally over the screw heads based on fluoroscopy. The fascia was opened and then an expandable MIS retractor (Quadrant, Medtronic) was inserted and expanded to expose the screws and rod. The implants were then removed with standard tools

This is an approach I've been using for about a year and a half now with similar results. I use stab incisions over existing hardware to remove the existing hardware. I then dock a 20 or 22mm tube over the facet joint at an approximately 35-40 degree angle. By removing the superior articular process (removing the inferior articular process may also be necessary for lateral recess decompression and sublaminar/contralateral decompression) you can access the disc space as described.
I concur that average EBL is about 50cc for the index level and average hospital length of stay is 1.5 days. I commend the authors for describing this approach as it a successful, minimally-invasive approach for TLIF, including for adjacent segment breakdown.


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