What is the step-by-step procedure for oblique lateral interbody fusion (OLIF) and what are the associated caveats?

Step-by-Step OLIF Procedure

OLIF is performed through a retroperitoneal corridor anterior to the psoas muscle, avoiding the lumbar plexus, with the patient in lateral decubitus position, utilizing blunt dissection through abdominal wall musculature to access the disc space from L2 to L5-S1. 1, 2

Preoperative Planning

• Obtain thorough imaging (CT/MRI) to identify vascular anatomy, assess disc space accessibility, and evaluate for osseous obstructions (osteophytes, hypertrophic facets, prominent sacral ala at L5-S1)
• Consider stereotactic navigation planning to minimize radiation exposure and improve accuracy 2
• Identify the retroperitoneal corridor between the aorta/inferior vena cava—this space is devoid of neurovascular structures 2

Patient Positioning

• Standard approach: Lateral decubitus position for L2-L5 1
• L5-S1 access: Maintain lateral position but use oblique approach through iliac bifurcation (typically requires vascular surgeon assistance) 1
• Alternative: Single position prone technique (SPS-P) for selected cases requiring concurrent posterior instrumentation 3

Surgical Approach Steps

1. Skin Incision and Muscle Dissection

• Make oblique incision over the lateral abdomen
• Perform minimally invasive blunt dissection through abdominal wall musculature 1
• Access retroperitoneal space anterior to psoas muscle

2. Retroperitoneal Mobilization

• Mobilize retroperitoneal fat bluntly 1
• Identify and protect the ureter, great vessels, and sympathetic chain
• Critical caveat: Unlike transpsoas (DLIF), surgery is performed anterior to psoas, eliminating need for real-time EMG monitoring 2

3. Disc Space Access

• Expose disc space under direct visualization
• For obstructed L5-S1 or hypertrophic facets: Use 8mm drill to create transfacet corridor with continuous neuromonitoring 4
• Vascular surgeon performs L5-S1 approach through iliac bifurcation when needed 1

4. Discectomy and Endplate Preparation

• Perform complete discectomy to allow height restoration and deformity correction 1
• Prepare endplates meticulously to enhance arthrodesis—this is critical for fusion success 1
• Release disc space completely to enable proper height restoration 1

5. Interbody Cage Placement

• Size implant appropriately based on disc space dimensions 1
• Insert cage at oblique angle (similar to ALIF technique but from lateral position) 1
• Ensure proper positioning to avoid cage subsidence or transverse shifting

6. Posterior Instrumentation (if indicated)

• Two-stage approach: Most commonly, perform posterior pedicle screw fixation through intermuscular space approach 5
• Can be done same-day or staged procedure
• Single position option: Complete posterior instrumentation in prone position if using SPS-P technique 3

Critical Caveats and Complication Prevention

Vascular Injury (3% incidence) 5

• Maintain meticulous dissection technique
• Have vascular surgery backup available, especially for L5-S1
• Reported complications include iliac vein lacerations 6

Nerve Injury (4.7% incidence) 5

• L5 nerve root most vulnerable during L5-S1 approach
• Use continuous neuromonitoring when drilling through facets 4
• Expect transient psoas weakness (3.8%) or quadriceps weakness (1.3%) 5
• Most nerve irritation resolves, though 1.3% may have persistent mild numbness 4

Endplate Damage and Cage Subsidence (9.4% and 7.7% respectively) 5

• Avoid aggressive endplate preparation that creates fractures
• Size cages appropriately—oversized cages increase subsidence risk
• Monitor for cage transverse shifting postoperatively

Vertebral Body Fracture (0.9%) 5

• Use proper technique during cage insertion
• Avoid excessive force during impaction

Other Complications

• Incomplete ileus (0.9%) 5
• Iliac crest pain (1.3%) 5
• Psoas hematoma (0.4%) 5
• Left lower abdominal pain (1.3%)—likely sympathetic nerve irritation 5

Complication Rates by Surgical Extent

Overall complication rate: 32.34% 5

• Single-segment fusion: 30.0%
• Two-segment fusion: 36.4%
• Three-segment fusion: 42.9%
• Four-segment fusion: 46.2%

The complication rate increases significantly with multi-level procedures 5

Stand-Alone vs. Combined Fixation

• Stand-alone OLIF (without posterior instrumentation): 36.3% complication rate 5
• OLIF with posterior fixation: 29.9% complication rate 5
• Stand-alone OLIF is feasible for selected cases but requires careful patient selection 7
• Combined fixation reduces risk of cage migration and provides better stability

Operative Efficiency

• Single-level procedure: 57-61 minutes, blood loss 68-98 ml 7, 4
• Multi-level (3+): 103 minutes, blood loss 146 ml 4
• Hospital stay: 0.4 days (single-level) to 1.6 days (3+ levels) 4

Special Considerations

For degenerative scoliosis with lumbosacral curves: Two-stage OLIF with posterior fixation reduces postoperative coronal decompensation compared to traditional PLIF, requires fewer fusion segments, and causes less blood loss 8

Navigation systems: Stereotactic navigation minimizes radiation exposure and improves accuracy, particularly valuable for complex anatomy 2