Transforaminal Lumbar Interbody Fusion (TLIF) Approach

What it exposes. Transforaminal lumbar interbody fusion (TLIF) is a posterior lumbar fusion technique that accesses the disc space through a unilateral facetectomy and a transforaminal corridor (through the neural foramen), inserting a single interbody cage from ONE side while preserving the CONTRALATERAL facet and the posterior tension band. It was popularised by Harms and Rolinger as a modification of PLIF (posterior lumbar interbody fusion) to reduce neurological morbidity: the transforaminal approach mobilises only ONE nerve root (the exiting root) and avoids the BILATERAL thecal-sac and traversing-root retraction that PLIF demands. The critical anatomic concept — Kambin's triangle. This is the transforaminal "safe working zone", a triangular corridor in the posterolateral foramen bounded by: (1) the exiting nerve root (the superior, oblique hypotenuse — for example the L4 root crossing the upper L4–5 foramen), (2) the traversing nerve root and dural sac (the medial, vertical border — for example the L5 root descending to exit at L5–S1), and (3) the superior endplate of the caudal vertebra (the inferior border or base). A trapezoidal "safe zone" lies immediately superior to the caudal pedicle and is free of nerve roots; this is the target for disc access. Kambin's transforaminal access principle was first described clinically by Kambin and Sampson (1986), and the working-triangle dimensions have since been quantified in cadaveric studies (mean working-triangle area approximately 1.8 cm², largest at L5–S1 — Hardenbrook 2016). Why TLIF over PLIF. (1) Unilateral facetectomy preserves the contralateral facet and posterior tension band, theoretically reducing adjacent-segment stress compared with the bilateral facetectomy of PLIF. (2) Single-root mobilisation — only the exiting root is retracted, rather than the thecal sac and both traversing roots, with a comparative series showing a TREND to fewer durotomies (approximately 9% TLIF vs approximately 17% PLIF) and less iatrogenic nerve-root dysfunction (approximately 2% vs approximately 8%), all transient in that series (Mehta 2010). (3) Equivalent fusion — TLIF and PLIF achieve comparable interbody fusion rates, both higher than instrumented posterolateral fusion alone (Makanji 2018). Indications (consistent across advanced orthopaedic practice): - Degenerative spondylolisthesis (Grade I–II) — the MOST COMMON indication.

• Isthmic spondylolisthesis (Grade I–II) with instability.
• Degenerative disc disease with instability or failed conservative management (more than 6 months of physiotherapy, injections and medication).
• Recurrent disc herniation after prior discectomy (unstable segment).
• Adjacent segment disease after prior fusion.
• Post-laminectomy instability. Relative contraindications. High-grade spondylolisthesis (Grade III–IV), where TLIF access is difficult and ALIF may give better reduction and anterior load-sharing; severe central stenosis requiring extensive bilateral laminectomy (PLIF or decompression alone); severe osteoporosis with high subsidence risk (consider ALIF for better endplate contact or supplemental anterior support); and infection or tumour, which require a different approach. Position. Prone on a Jackson table or Wilson frame with hip flexion 30–45° to open the interlaminar space and reduce lumbar lordosis. Chest and iliac-crest support avoid abdominal compression (this reduces epidural venous pressure and bleeding). Arms on arm boards (shoulder 90°, elbow 90°); face on a horseshoe or mirror headrest with eye checks every 30–60 minutes. General anaesthesia is standard; intraoperative neuromonitoring (somatosensory and motor evoked potentials, and free-running/triggered EMG) is a common adjunct in many centres, though its routine use varies between units and remains an adjunct to — not a substitute for — sound technique. Position fluoroscopy for AP and lateral lumbar views and confirm the level before incision.

Work down through the posterior lumbar layers in the midline, place the pedicle screws first, then perform the defining step of TLIF — a complete unilateral facetectomy that unroofs the foramen and exposes both roots — before entering the disc through Kambin's triangle.

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Structures at risk, by layer

Choosing between posterior interbody techniques

Complications. The principal complications cluster around the exiting root, the dura and the endplate. - Exiting nerve-root injury (1–8%, commonest neurological complication). Presents as intraoperative EMG activity or a post-operative deficit in the exiting-root distribution (for example an L4 injury gives anterior-thigh pain and quadriceps weakness). Mechanism: overzealous facetectomy drilling, a too-lateral/superior upper screw, or aggressive lateral retraction. If the EMG fires, STOP drilling, irrigate, switch to a Kerrison/osteotome, inspect the root (intact vs lacerated), and proceed only if it is intact — most deficits are a recoverable neuropraxia; axonotmesis recovers slowly and incompletely; neurotmesis (transection) does not recover and needs exploration/repair. Prevention is a complete facetectomy exposing the root, controlled bone removal, triggered EMG, and gentle retraction.

• Dural tear / durotomy (3–9%). Managed as above.
• Cage malposition (2–5%). Too posterior (canal/root compression), too anterior (vascular/retroperitoneal risk) or too lateral (foraminal/exiting-root compression). Symptomatic neural compression needs urgent revision; asymptomatic malposition is observed. Prevent with continuous biplanar fluoroscopy and confirming position before closure.
• Epidural haematoma with deficit (2–5%). New or progressive deficit 6–24 hours post-op (foot drop, cauda equina) with wound swelling — obtain URGENT MRI/CT myelogram and re-explore and evacuate; delay greater than 24 hours reduces the chance of recovery. Prevent with meticulous haemostasis, a deep drain, and close neuro checks for the first 24 hours.
• Wound infection (2–5%). Superficial (1–2%) within 2–4 weeks — empirical oral antibiotics covering skin flora (a first-generation cephalosporin, or clindamycin if penicillin-allergic) per local guidance. Deep infection (1–3%) — empirical IV broad-spectrum cover including MRSA (for example vancomycin) plus Gram-negative cover, surgical debridement with hardware retention if fixation is stable, NPWT where appropriate, and a prolonged course guided by infectious diseases. Prevent with pre-operative cefazolin (2 g IV within 1 hour; re-dose every 4 hours if the case exceeds 4 hours), sterile technique, glycaemic control (perioperative glucose less than 180 mg/dL) and minimised operative time.
• DVT/PE (8–12%). Posterior lumbar surgery carries a higher VTE risk than anterior (prolonged immobility, prone positioning, epidural-venous manipulation). Mechanical prophylaxis for all, with chemical prophylaxis (for example LMWH) added per institutional protocol once the bleeding/epidural-haematoma risk is acceptable, and early mobilisation. Timing of chemical prophylaxis after spinal surgery is individualised, and named-society guidance differs.
• Pseudarthrosis (8–15%). Persistent back pain beyond 6 months with no bridging bone on CT at 12 months. Risk factors: smoking (a strong modifiable inhibitor), diabetes, chronic NSAID use, inadequate graft volume, excessive motion. Revision options: revision TLIF with a larger cage and BMP, anterior supplementation (ALIF), or extension of the fusion. Prevent with smoking cessation (delay elective surgery until smoke-free more than 4 weeks), avoiding NSAIDs for more than 3 months post-op, complete graft packing, and bracing.
• Cage subsidence (8–15%). Recurrent back/radicular pain 2–6 months post-op with loss of disc height (cage migration greater than 2 mm into the endplate). Osteoporosis is the strongest risk factor; others are over-aggressive endplate preparation and an oversized cage/over-distraction. Most subsidence is asymptomatic and observed; symptomatic/progressive cases may need revision, preferably anterior supplementation (ALIF) for a larger endplate contact area. Prevent by optimising bone quality pre-operatively, preserving the subchondral endplate, and using the largest cage footprint without over-distraction.
• Adjacent segment disease. New back/radicular pain 2–5 years after fusion as load transfers to adjacent segments. Preserve the contralateral facet and posterior tension band and restore sagittal lordosis at the index fusion; manage conservatively first, reserving revision (extension of fusion) for structural adjacent-level pathology that fails conservative care. Post-operative protocol (general guidance). - Phase 1 (days 0–2): multimodal analgesia (NSAIDs used cautiously given fusion concerns); out of bed to chair on day 1 and walking with assistance days 1–2; continue EMG/SSEP monitoring for the first 2–4 hours; remove the drain when output is less than 50 mL per 8-hour shift; remove the urinary catheter on day 1. Discharge is typically day 3–5 (open) or day 2–3 (MIS).
• Phase 2 (weeks 0–6): LSO brace during upright activities for 6–12 weeks if a single-level TLIF; no bending, lifting greater than 10 lb, or twisting; unlimited walking; driving at 4–6 weeks off opioids; return to sedentary work at 6–8 weeks; AP and lateral X-rays at 2, 6 and 12 weeks.
• Phase 3 (months 3–6): wean the brace if fusion is progressing; CT at 6 months if fusion is questionable on X-ray (CT is the gold standard); core-strengthening physiotherapy once the fusion is solid; return to manual labour at 6–9 months and high-impact activity at 9–12 months after confirmed solid fusion.
• Phase 4 (12+ months): annual X-rays to monitor for adjacent-segment disease; track ODI and VAS; address hardware failure (rare, less than 2% if fusion is solid) and pseudarthrosis. Extensile options. Extend to a second level through the same midline incision for two-level disease. The MIS-TLIF variant (tubular or expandable muscle-sparing retractor via a paramedian incision) reduces blood loss, SSI and length of stay with equivalent fusion, at the cost of greater intraoperative radiation and a learning curve (Phan 2015). For high-grade spondylolisthesis or a failed/osteoporotic TLIF, supplement anteriorly with ALIF for a larger endplate contact area and better anterior load-sharing. Closure: watertight fascia (number 1 absorbable), subcutaneous 2-0 absorbable, skin 3-0 non-absorbable or staples; LSO brace for 6–12 weeks for a single-level TLIF if bone quality is questionable.

• Single- and two-level lumbar fusion for degenerative or isthmic spondylolisthesis (Grade I–II) — the principal use of TLIF.
• Fusion for degenerative disc disease with instability and for recurrent disc herniation with an unstable segment.
• Revision for pseudarthrosis after posterolateral fusion, and for adjacent segment disease or post-laminectomy instability.
• The MIS-TLIF variant for the same indications where a muscle-sparing approach is preferred.