Bilateral posterior approach for circumferential lumbar arthrodesis with interbody support and pedicle screw fixation | advanced
Surgical Imaging
The trap: Aggressive or prolonged retraction of the thecal sac and traversing root to access the disc space causes ischaemic radiculopathy or cauda equina syndrome.
The fix: Limit retraction time to less than 15 minutes per side. Use a nerve root retractor with a broad blade, release frequently, and alternate sides. If the disc space is narrow, consider a more aggressive facetectomy or convert to TLIF unilaterally to reduce retraction.
Location: The thecal sac is thinnest at the axilla of the traversing root and at the site of prior surgery or severe stenosis.
Risk: Dural tear incidence in PLIF series ranges from 5-15%. Tears occur during initial laminectomy, during retraction, or when instruments slip into the disc space.
Prevention: Wide laminectomy before any retraction, use of cotton patties for protection, and sharp pituitary rongeurs directed away from the dura. Primary repair with 5-0 or 6-0 Prolene or dural substitute is mandatory; watertight closure reduces pseudomeningocele and infection risk.
Location: Central endplate is weakest; the peripheral rim (apophyseal ring) provides the strongest support.
Risk: Over-aggressive endplate removal or oversized cage insertion causes fracture and subsidence, leading to loss of lordosis, foraminal narrowing, and pseudarthrosis.
Fix: Preserve the peripheral 2-3 mm rim. Use curettes and rasps rather than aggressive burrs. Choose cage height that restores disc height without over-distraction (usually 8-12 mm). Confirm fluoroscopically that the cage sits within the apophyseal ring.
Location: Medial wall breach places the screw in the spinal canal or against the traversing nerve root.
Risk: Neurological deficit, radicular pain, or dural injury. Incidence of clinically significant medial breach in freehand technique is 2-5%.
Fix: Use the intersection technique (junction of transverse process and superior articular process). Start slightly lateral and aim medially. Confirm trajectory with lateral fluoroscopy before tapping. If medial breach suspected, redirect the screw more laterally or use navigation.
Location: The exiting nerve root at the foramen and the traversing root in the lateral recess are both at risk when the disc space is distracted or the cage is impacted.
Risk: Direct laceration or stretch injury causing new radiculopathy or foot drop. More common on the side of greater listhesis or severe foraminal stenosis.
Fix: Identify and protect the exiting root at the foramen before disc space work. Use sequential disc space dilators rather than forceful cage impaction. Check root function with intraoperative neuromonitoring (MEP/SSEP) if available.
De Novo symptoms at 12-24 months: Differentiate pseudarthrosis (persistent mechanical pain, no fusion on CT, hardware loosening) from adjacent segment disease (new stenosis or disc degeneration above or below the construct).
Workup: Fine-cut CT with sagittal/coronal reconstructions to assess bridging bone. Flexion-extension radiographs for motion. MRI for adjacent segment pathology. SPECT may help localise pain generator.
Management: Pseudarthrosis without hardware failure may be observed or revised with extension of fusion and bone grafting. Adjacent segment disease may require decompression and extension of the construct.
P.L.I.F.PLIF — Posterior Lumbar Interbody Fusion Steps
D.A.N.G.E.R.DANGER — Neural and Structural Risks in PLIF
F.U.S.I.O.N.FUSION — Factors Affecting Arthrodesis Success
Surgical Indications
Absolute Indications
- Degenerative disc disease with mechanical low back pain refractory to 6 months of conservative care including physiotherapy and injections
- Recurrent disc herniation with predominant leg pain and imaging evidence of instability or significant disc height loss
- Low-grade isthmic or degenerative spondylolisthesis (Meyerding grade I-II) with instability on flexion-extension radiographs
- Foraminal stenosis requiring indirect decompression via disc height restoration when direct decompression alone is insufficient
Relative Indications
- Post-discectomy instability or iatrogenic pars fracture
- Lumbar instability after trauma or tumour resection where anterior column reconstruction is needed
- Multilevel degenerative disease where hybrid constructs (PLIF at index level plus posterolateral fusion) are planned
- Patient preference for single-stage circumferential fusion avoiding an anterior approach
Contraindications
Absolute:
- Active spinal infection or discitis/osteomyelitis (requires debridement and staged reconstruction)
- Severe osteoporosis with inability to achieve screw purchase (consider cement augmentation or alternative approaches)
- High-grade spondylolisthesis (Meyerding III-IV) where reduction and anterior column support may require combined approaches
Relative:
- Previous extensive posterior surgery with scarring that would make safe thecal retraction hazardous — consider TLIF or ALIF
- Smoking or uncontrolled diabetes without willingness to optimise — counsel on elevated pseudarthrosis risk
- Morbid obesity where exposure and retraction are technically challenging
Evidence for PLIF versus Alternatives
Fusion Rates and Clinical Outcomes
- Single-level PLIF with modern cages and posterior fixation achieves fusion rates of 90-96% at 2 years in prospective series
- Clinical success (greater than 50% pain reduction and functional improvement) occurs in 70-85% of patients with degenerative disc disease
- Compared with posterolateral fusion alone, PLIF provides superior disc height restoration and foraminal volume, reducing the need for direct foraminal decompression in selected cases
PLIF versus TLIF
- TLIF requires only unilateral facetectomy and less thecal retraction, resulting in lower dural tear rates (2-8% versus 5-15% for PLIF) and shorter operative times
- PLIF allows symmetric bilateral disc space access and potentially more complete endplate preparation and graft packing
- A meta-analysis of 12 studies (2018) found no significant difference in fusion rate, complication rate, or clinical outcome between PLIF and TLIF when performed by experienced surgeons; choice is often dictated by surgeon training and pathology (bilateral pathology may favour PLIF)
PLIF versus ALIF
- ALIF provides superior lordosis restoration and avoids neural retraction but carries vascular and visceral risks (great vessel injury 1-3%, retrograde ejaculation in males 2-5%)
- PLIF avoids anterior approach morbidity and allows simultaneous posterior decompression and instrumentation
- Combined approaches (ALIF + posterior fixation) are reserved for high-grade listhesis, severe deformity, or revision cases with failed posterior fusion
PLIF versus TLIF versus ALIF — Decision Framework
Key Evidence
Comparison of posterior lumbar interbody fusion and transforaminal lumbar interbody fusion: a meta-analysis
Long-term outcomes of posterior lumbar interbody fusion for degenerative disc disease
Randomised controlled trial of PLIF versus posterolateral fusion for degenerative spondylolisthesis
Clinical Decision Scenarios
Practise clinical reasoning and management decisions out loud
“A 62-year-old man with degenerative disc disease at L4-L5 and Meyerding grade I degenerative spondylolisthesis presents with mechanical low back pain and bilateral L5 radiculopathy. Flexion-extension radiographs show 4 mm of translation. He has failed 9 months of conservative treatment. Discuss your surgical plan and the rationale for choosing PLIF over TLIF or ALIF.”
“During a PLIF at L5-S1 you encounter brisk bleeding from the epidural venous plexus while retracting the thecal sac. The disc space is narrow and the patient has a high-grade listhesis. How do you proceed safely?”
“A 58-year-old woman 18 months after L4-L5 PLIF presents with recurrent mechanical low back pain and new L5 radiculopathy. CT shows no bridging bone, lucency around the L4 screws, and 4 mm cage subsidence. Flexion-extension radiographs show 3 mm of motion. How do you diagnose and manage this?”