Transforaminal and Posterior Lumbar Interbody Fusion (TLIF and PLIF)

Several fusion techniques are available for lumbar arthrodesis. Fusions in the lumbar spine can be achieved with or without the aid of instrumentation, and can be performed through various anatomic approaches. Each fusion technique offers advantages and disadvantages, allowing the surgeon to customize a patient-specific treatment plan that best suits the patient's unique pathology. Arthrodesis techniques in the lumbar spine include:

• Anterior lumbar interbody fusion (ALIF)
• Lateral lumbar interbody fusion (eponymously known as XLIF, DLIF)
• Posterior lumbar interbody fusion (PLIF)
• Transforaminal lumbar interbody fusion (TLIF), a more popular variant of PLIF
• Posterior Spinal Fusion (PSF), which includes interlaminar/facet fusion and intertransverse fusion

This review article will specifically address the indications and technical aspects related to posterior interbody fusion of the lumbar spine (TLIF and PLIF). Details on other fusion styles are available elsewhere on this website.

Indications

The TLIF and PLIF procedures utilize a familiar posterior approach to the lumbar spine. These procedures incorporate a radical discectomy, endplate preparation, and interbody fusion, typically using supplemental bilateral pedicle screw instrumentation. This allows the surgeon to access all three columns of the spine and address their specific pathologies while accomplishing a circumferential fusion through a single approach. The notable highlights of this versatile technique include:

• Direct neurologic decompression
• Correction of coronal and sagittal plane deformity
• Restoration of foraminal height
• > 90% fusion rate
• Avoids technical issues surrounding ALIF
  • Reduces risk of vascular injury and thromboembolic events
  • Eliminates risk of GU complications in men
  • Avoids logistical issues with an approach, while preserving the anterior approach

TLIF and PLIF procedures can be employed to address various lumbar pathologies including:

• Adult deformity
  • Degenerative scoliosis
  • Mild kyphosis
  • Interbody support at the lumbosacral junction
• Isthmic spondylolisthesis
• Degenerative disc disease
  • Degenerative spondylolisthesis
  • Chronic low back pain after prior discectomy(ies)
  • Discogenic pain syndrome
• High risk for pseudarthrosis
  • Smokers
  • Revision surgery with hypovascular, hypoplastic, and fibrotic posterolateral fusion bed
  • Irradiated fusion bed
  • Patients on chemotherapy or systemic corticosteroids

Contraindications

• Severe osteoporosis
• PLIF should not be attempted at or above the level of the conus medullaris (typically L1-L2); TLIF can be an option at these levels
• Anomalous neural anatomy; ie, conjoined nerve root
• Severe fixed kyphosis; consider an osteotomy or an anterior procedure
• Irreducible high-grade spondylolisthesis

Preoperative Planning

The preoperative workup should include upright and dynamic X-rays to assess for potential deformity and its flexibility, as well as an MRI or a CT-myelogram. The X-rays must be correlated with the MRI before the surgery to scrutinize for transitional levels and identify relevant bony and neural anomalies. This enables the identification of the exact level and location of pathology, allowing the surgeon to determine the need for direct or indirect decompression and unilateral versus bilateral interbody approach and facetectomy. The interbody approach should be performed at the symptomatic side, with maximal neurologic compression. However, in revision surgery with epidural scarring or in the presence of a conjoined nerve root, the contralateral side may need to be accessed instead.

Templating (Utilize MRI or a CT scan)

• Disc space dimensions and lumbar alignment
  • Select optimal interbody implant size and shape
• Pedicle dimensions and trajectories
  • Select appropriate pedicle screws

Positioning

• Prone on a radiolucent Jackson Spine Frame, with hips extended and knees slightly flexed to promote lumbar lordosis and minimize lumbar nerve root tension (Figure 1)
• Abdomen hangs free to decompress the vena cava and minimize venous engorgement
• Consider neurophysiologic monitoring with somatosensory evoked potentials (SSEP) and EMG
• Foley catheter and sequential compression stockings are advised.

Figure 1.

Approach

Traditional Open Surgery

• Standard posterior approach to the lumbar spine centered on the disc space of interest is used for both the TLIF and PLIF procedures (Figure 2, 3).

Figure 2

Figure 3

• Based on surgeon preference and patient factors, the approach should include the exposure of bilateral posterolateral gutters, including the transverse process and the pars interarticularis at the cephalad and caudal levels of the disc space. This allows for optimal placement of pedicle screw instrumentation along with meticulous bone preparation for a true posterolateral arthrodesis (Figure 4).

Figure 4

• If bilateral neural decompression is not needed, then the spinous processes and interspinous ligaments can be left intact. However, the entire lamina and the spinous process can also be removed to facilitate neurologic decompression and provide robust local autograft for interbody and posterolateral fusion.
• Two exposure options are available for the PLIF procedure:
  • Extensive resection, including wide laminectomy and bilateral facetectomies
    • Requires pedicle screw instrumentation for stabilization and to promote arthrodesis in a suitable alignment
  • Limited resection, preserving midline structures, using bilateral laminotomies and medial facetectomies
    • Does not require pedicle screw supplementation, but requires more neural retraction leading to higher potential for neurologic injury
    • Should be reserved for surgeons very familiar with this procedure.

Minimally Invasive Surgery (MIS)

• Paramedian muscle splitting approach is utilized to introduce dilators and a proprietary retractor system, available through most spine implant companies.
• MIS minimizes muscle dissection and devascularization (Figure 5, 6).

Figure 5.

Figure 6.

• This approach can result in shorter hospitalization, less blood loss, and less need for transfusion. However, there is a pronounced learning curve for MIS, with an increased complication rate during early experience.
• Clinical and radiographic outcomes are equivalent at 1 year; long-term data are not yet available.¹

Technique

The interbody fusion technique is the same for both the open and the MIS approach. Furthermore, the disc space preparation and arthrodesis principles are identical for both the TLIF and the PLIF procedures.

Transforaminal Lumbar Interbody Fusion (TLIF)

• Exposure and approach (open or MIS) as described above
• Facetectomy (Figure 7, 8)
  • Osteotomy of the inferior articular process without violating the pedicle above.
  • A transverse cut in line with the roof of the foramen and a vertical cut medial to the facet can be made with an osteotome. Alternatively, a burr or kerrison rongeurs can be utilized.
  • Ligamentum flavum is dissected away from the superior articular process of the caudal level and removed with kerrison rongeurs.
  • The superior articular process is removed down to the cephalad aspect of the pedicle, again without violating the pedicle.

Figure 7.

Figure 8.

• Identification and preparation of Kambin's triangular work zone (Figure 9)
  • Palpate and protect the exiting nerve root. Avoid excessive dissection or manipulation, as it can result in postoperative dysesthesias.
  • Visualize the traversing nerve root and the lateral border of the thecal sac.
  • Utilize bipolar cautery to coagulate the epidural venous plexus, which covers the disc space and surrounds the exiting and traversing nerve roots. Other hemostatic agents, including gelfoam with thrombin, cottonoids, floseal, or surgiflo, may be employed as needed.

Figure 9.

• Disc space distraction
  • Pedicle screw distraction (avoid excessive distraction, as it can compromise fixation) (Figure 10)
    • Can be performed using temporary rods or vendor-specific distraction tools
    • Can be performed on the contralateral side, the ipsilateral side, or bilaterally
  • Boney distraction
    • Utilizing a lamina spreader in the interspinous or interlaminar region
  • Interbody distraction (Figure 11)
    • Minimizes stress on posterior implants
    • Most powerful method of distraction
    • Can help restore vertebral alignment

Figure 10.

Figure 11.

• Pedicle screw insertion
  • Depending on the surgeon's preferred disc space distraction technique, screws can be placed at this point or after the interbody work has been completed.
  • Either the free hand or the fluoroscopic guided method is utilized for the standard open surgical technique (Figure 12).
  • Alternatively, percutaneous screws are placed using fluoroscopy or navigation for the MIS approach (Figures 13a-c)

Figure 12.

Figure 13a.

Figure 13b.

Figure 13c.

• Discectomy and endplate preparation (Figures 14a-b)
  • The traversing nerve root and the thecal sac are protected with a nerve root retractor.
  • A box annulotomy is made.
  • Often, endplate osteophytes can limit access to the disc space. A box chisel can be used to resect endplate osteophytes, allowing a larger entry portal.
  • Lateral fluoroscopy can be utilized to determine proper trajectory and depth of instruments, which can be marked (typically ~ 30mm).
  • Thorough discectomy is performed using pituitary rongeurs, curettes, and specialized disc shavers.
  • Careful dilation of the disc space is performed to facilitate complete discectomy and achieve optimum disc height restoration.
  • Do not violate the endplates, specifically in regions expected to load-share the interbody implants, as that will lead to subsidence.
  • Do not violate the anterior annulus or ligamentous restraints.

Figure 14a.

Figure 14b.

• Interbody implant sizing and selection (Figure 15)
  • The appropriate disc space height and depth are measured by serially dilating the interbody space with laser-etched blunt and bulleted paddle distracters.
  • Do not overdistract, which can result in excessive neural traction and could cause endplate damage.
  • Do not undersize, which may compromise alignment and stability.
  • Several types of implants are available for posterior interbody fusion, including:
    • Structural allografts
    • Titanium mesh cages
    • Threaded cages
    • Carbon fiber spacers
    • PEEK (polyetheretherketone) spacers (author's preference)
      • Curved
      • Bulleted
      • Parallel or lordotic

Figure 15.

• Bone graft selection and implant insertion (Figure 16)
  • Several forms of bone graft are available. The choice of graft should be based on scientific evidence combined with host factors, patient preference, surgeon experience, cost, and availability.
  • Graft choices include:
    • Autograft bone
      • Iliac crest
      • Local bone
    • Allograft bone
      • Cancellous
      • Demineralized bone matrix
    • Bone graft extenders
      • Ceramic
    • Osteoinductive promoters
      • rhBMP-2 (off-label use;  can be associated with ectopic bone formation, radiculitis, and neuropathy)
  • Biomechanically, the endplate is strongest posterolaterally. However, the best implant placement for creating optimum lordosis is anteriorly and centrally.
  • Once the implant is sized and the graft material selected, the implant can be tightly packed with morselized graft.
  • Autograft bone is tightly packed into the anterior 25% of the disc space, followed by careful insertion of the interbody implant.
  • The remainder of the graft material is packed and tamped around the interbody implant.
  • Final implant position should be confirmed with AP and lateral fluoroscopy.

Figure 16.

• Compression instrumentation and posterolateral arthrodesis (Figures 17, 18a-b)
  • Distraction is released if it was applied via pedicle screws.
  • Appropriate-sized lordotic rods are selected and torqued into a compressed position.
  • Morselized bone graft can be placed in the bilateral intertransverse regions and the contralateral interlaminar and facet regions.

Figure 17.

Figure 18a.

Figure 18b.

• Hemostasis and closure
  • Surgical hemostasis of the epidural space should be performed.
  • Neural foramina and spinal canal should be inspected and relieved of any bone graft material.
  • Valsalva maneuver can be performed to confirm the integrity of the thecal sac.
  • Finish with a standard layered closure over a drain.

Posterior Lumbar Interbody Fusion (PLIF)

The PLIF technique is very similar to the TLIF surgical procedure described above. The major difference is a more medial approach to the disc space with a potential of leaving both facet joints intact.

• Exposure and approach (open or MIS) as described in the approach section (Figure 3)

Figure 3.

• Facetectomy
  • Wide laminectomy PLIF
    • Bilateral osteotomy of the inferior articular process without violating the pedicle above.
    • A transverse cut in line with the roof of the foramen and a vertical cut medial to the facet can be made with an osteotome. Alternatively, a burr or kerrison rongeurs can be utilized.
    • The ligamentum flavum is dissected away from the superior articular process of the caudal level and removed with kerrison rongeurs.
    • The superior articular process is removed bilaterally down to the cephalad aspect of the pedicle, again without violating the pedicle.
  • Laminotomy and partial facetectomy PLIF
    • Standard laminotomies are performed bilaterally with kerrison rongeurs.
    • Preserve the lateral half of the facet joints and midline structures.
• Identification and preparation of Kambin's triangular work zone – bilaterally (Figure 9)
  • Similar principle as described above for TLIF. However, the safe work zone for the laminotomy with partial facetectomy technique is narrow, affording maximally about a 1.3-cm wide window.
  • Palpate and protect the exiting nerve root. Avoid excessive dissection or manipulation, which can result in postoperative dysesthesias.
  • Visualize the traversing nerve root and the lateral border of the thecal sac.
  • Utilize bipolar cautery to coagulate the epidural venous plexus, which covers the disc space and surrounds the exiting and traversing nerve roots. Other hemostatic agents, including gelfoam with thrombin, cottonoids, floseal, or surgiflo may be used as needed.

Figure 9.

• Disc space distraction – three options
  • Pedicle screw distraction – avoid excessive distraction, which can compromise fixation (Figure 10)
    • Only relevant for the wide laminectomy and facetectomy approach supplemented with posterior instrumentation
    • Can be performed using temporary rods or vendor-specific distraction tools
    • Can be performed on the contralateral side, the ipsilateral side, or bilaterally
  • Boney distraction
    • Utilizing a lamina spreader in the interspinous or interlaminar region
  • Interbody distraction (Figure 11)
    • Preferred distraction technique for the limited laminotomy and facetectomy PLIF technique
    • Minimizes stress on posterior implants
    • Most powerful method of distraction
    • Can help restore vertebral alignment

Figure 10.

Figure 11.

• Pedicle screw insertion
  • This is not necessary with limited laminotomy and facetectomy PLIF. However, most commercially available PLIF implants do not meet the biomechanical criteria for surface area coverage to result in successful arthrodesis without pedicle screw supplementation.
  • Depending on the surgeon's preferred disc space distraction technique, screws can be placed at this point or after the interbody work has been completed.
  • The free hand or fluoroscopic guided method is used for the standard open surgical technique (Figure 12).
  • Alternatively, percutaneous screws are placed using fluoroscopy or navigation for the MIS approach (Figures 13a-c).

Figure 12.

Figure 13a.

Figure 13b.

Figure 13c.

• Discectomy and endplate preparation – bilaterally (Figures 19a-c)
  • The traversing nerve root and the thecal sac are protected with a nerve root retractor.
  • A box annulotomy is made bilaterally
  • Often, endplate osteophytes can limit access to the disc space. A box chisel can be used to resect the endplate osteophytes, allowing a larger entry portal.
  • Lateral fluoroscopy can be utilized to determine proper trajectory and depth of instruments, which can be marked (typically ~ 30mm).
  • Thorough discectomy is performed using pituitary rongeurs, curettes, and specialized disc shavers.
  • Careful dilation of the disc space is performed to facilitate complete discectomy and achieve optimum disc height restoration.
  • Do not violate endplates, specifically in regions expected to load-share the interbody implants, as that will lead to subsidence.
  • Do not violate the anterior annulus or ligamentous restraints.

Figure 19a.

Figure 19b.

Figure 19c.

• Interbody implant sizing and selection – bilaterally (Figure 15)
  • The appropriate disc space height and depth are measured by serially, dilating the interbody space with laser-etched blunt and bulleted paddle distracters.
  • Do not overdistract, which can result in excessive neural traction and could cause endplate damage. This is especially important in the limited laminotomy and facetectomy approach, as the 1.3-cm wide working window cannot allow the placement of tall implants without excessive neural traction.
  • Do not undersize, which may compromise alignment and stability.
  • Several types of implants are available for posterior interbody fusion, including:
    • Structural allografts
    • Titanium mesh cages
    • Threaded cages
    • Carbon fiber spacers
    • PEEK (polyetheretherketone) spacers (author's preference)
      • Curved
      • Bulleted
      • Parallel or Lordotic

Figure 15.

• Bone graft selection and implant insertion (Figures 20a,b)
  • Several forms of bone graft options are available. The choice of graft should be based on scientific evidence combined with host factors, patient preference, surgeon experience, cost, and availability.
  • Graft choices include:
    • Autograft bone
      • Iliac crest
      • Local bone
    • Allograft bone
      • Cancellous
      • Demineralized bone matrix
    • Bone graft extenders
      • Ceramic
    • Osteoinductive promoters
      • rhBMP-2 (off-label use; can be associated with ectopic bone formation, radiculitis and neuropathy)
  • Biomechanically, the endplate is strongest posterolaterally. For non-instrumented PLIF procedures in patients with average bone density, the total graft contact area should exceed 6.2 cm², or an area of 2.5cm x 2.5 cm, to avoid subsidence and to promote healing with optimal alignment.
  • Once the implant is sized and the graft material selected, the implant can be tightly packed with morselized graft and inserted in the interbody space bilaterally.
  • The remainder of the graft material is packed and tamped around the interbody implant.
  • Final implant position should be confirmed with AP and lateral fluoroscopy.

Figure 20a.

Figure 20b.

• Compression instrumentation and posterolateral arthrodesis (Figures 18a-b)
  • This is required only for the wide laminectomy and facetectomy technique
  • Distraction is released if it was applied via pedicle screws.
  • Appropriate-sized lordotic rods are selected and torqued into a compressed position.
  • Morselized bone graft can be placed in the bilateral intertransverse regions.

Figure 18a.

Figure 18b.

• Hemostasis and closure
  • Surgical hemostasis of the epidural space should be performed bilaterally.
  • The neural foramina and spinal canal should be inspected and relieved of any bone graft material.
  • Valsalva maneuver can be performed to confirm the integrity of the thecal sac.
  • Finish with a standard layered closure over a drain.

Pearls and Pitfalls

• Proper patient selection is the most important factor to clinical success.
• Revision procedures with epidural scarring may require a more lateral approach to the disc space to minimize neurologic retraction and injury.
• Concave endplates may require the use of a box osteotome to facilitate disc space access and placement of an optimum-sized graft.
• Meticulous endplate preparation is critical to a successful fusion. Avoid endplate violation as that will cause subsidence, compromise alignment, and may lead to an inferior result.
• Medial retraction of the thecal sac and traversing nerve root should be minimized and limited to the midline.
• EMG monitoring and frequent release of neurologic retraction can help reduce neurologic injury.
• Place the interbody implant anteriorly to maximize lordosis or place lordotic implant(s) with maximal surface area contact unilaterally or bilaterally.

Postoperative Care

• Patients are mobilized out of bed the day following surgery.
• Postoperative bracing is not typically needed for TLIF or instrumented PLIF.
• TLSO may facilitate postoperative mobilization and fusion for non-instrumented PLIF.

Outcomes

• Fusion rates for PLIF and TLIF are similar, with a rate of solid arthrodesis between 89% and 100%. Recent studies routinely show fusion rates above 90%.^2-5
• Clinical success rates vary somewhat, but most series report similar outcomes as with ALIF and combined anterior-posterior fusions.^{6, 7}
• Most studies on PLIF and TLIF demonstrate an approximately 80% overall patient satisfaction rate based on Visual Analog Scale (VAS) and Oswestry Disability Index (ODI).^{4-6, 8}

Complications

• Neurologic injury is an uncommon complication with modern PLIF and TLIF techniques, with incidence between 0% and 4%. Most of these injuries are neuropraxias due to excessive neural retraction and resolve spontaneously.^{5, 9, 10}
• Dural tears were commonly reported in the historic PLIF and TLIF literature, with an up to 18% incidence. However, recent studies demonstrate a 1%-5% range of durotomies, with the TLIF procedure having a lower rate than PLIF, presumably due to less neural retraction.^{5, 11, 12}
• Implant migration or failure is rare in TLIF and instrumented PLIF procedures, but has been reported to occur in as high as 2.4% of non-instrumented PLIF surgeries.
• Other complications associated with posterior instrumented lumbar fusions (PLF) can also occur in TLIF and PLIF surgeries and include:
  • Pedicle screw malposition
  • Infection
  • Hematoma

Note: Figures 2, 3, 4, 7, 10, 12, 14a-b, 16, 17, 19a-c, and 20a-b provided courtesy of Stryker Spine. All rights reserved. Figures 5, 6, 8, 9, 11, 13a-c, and 15 provided courtesy of Medtronic Sofamor Danek USA, Inc., copyright 2009. All rights reserved. Figure 18a-b provided courtesy of Synthes Spine. All rights reserved.

References

1. Park P, Foley KT. Minimally invasive transforaminal lumbar interbody fusion with reduction of spondylolisthesis: Technique and outcomes after a minimum of 2 years' follow-up. Neurosurg Focus. 2008;25:E16.
2. Miura Y, Imagama S, Yoda M, et al. Is local bone viable as a source of bone graft in posterior lumbar interbody fusion? Spine (Phila Pa 1976). 2003;28:2386-2389.
3. McAfee PC, DeVine JG, Chaput CD, et al. The indications for interbody fusion cages in the treatment of spondylolisthesis: Analysis of 120 cases. Spine (Phila Pa 1976). 2005;30:S60-5.
4. Lauber S, Schulte TL, Liljenqvist U, et al. Clinical and radiologic 2-4-year results of transforaminal lumbar interbody fusion in degenerative and isthmic spondylolisthesis grades 1 and 2. Spine (Phila Pa 1976). 2006;31:1693-1698.
5. Potter BK, Freedman BA, Verwiebe EG, et al. Transforaminal lumbar interbody fusion: Clinical and radiographic results and complications in 100 consecutive patients. J Spinal Disord Tech. 2005;18:337-346.
6. Hackenberg L, Halm H, Bullmann V, et al. Transforaminal lumbar interbody fusion: A safe technique with satisfactory three to five year results. Eur Spine J. 2005;14:551-558.
7. Kim JS, Kang BU, Lee SH, et al. Mini-transforaminal lumbar interbody fusion versus anterior lumbar interbody fusion augmented by percutaneous pedicle screw fixation: A comparison of surgical outcomes in adult low-grade isthmic spondylolisthesis. J Spinal Disord Tech. 2009;22:114-121.
8. Lee CK, Vessa P, Lee JK. Chronic disabling low back pain syndrome caused by internal disc derangements. the results of disc excision and posterior lumbar interbody fusion. Spine (Phila Pa 1976). 1995;20:356-361.
9. Villavicencio AT, Burneikiene S, Bulsara KR, et al. Perioperative complications in transforaminal lumbar interbody fusion versus anterior-posterior reconstruction for lumbar disc degeneration and instability. J Spinal Disord Tech. 2006;19:92-97.
10. Okuda S, Miyauchi A, Oda T, et al. Surgical complications of posterior lumbar interbody fusion with total facetectomy in 251 patients. J Neurosurg Spine. 2006;4:304-309.
11. Hee HT, Castro FP,Jr, Majd ME, et al. Anterior/posterior lumbar fusion versus transforaminal lumbar interbody fusion: Analysis of complications and predictive factors. J Spinal Disord. 2001;14:533-540.
12. Humphreys SC, Hodges SD, Patwardhan AG, et al. Comparison of posterior and transforaminal approaches to lumbar interbody fusion. Spine (Phila Pa 1976). 2001;26:567-571.