Lumbar Fusion Surgery

What is Lumbar Fusion Surgery?

Lumbar spinal fusion is a surgical procedure that permanently joins two or more vertebrae of the lower spine to eliminate painful or unstable motion between them. By creating a solid bone bridge across the treated segment — fusing the vertebrae together — fusion stabilises the spine, relieves nerve compression, corrects deformity, and reduces pain from degenerative instability.

Fusion is always combined with nerve decompression when nerve root compression is present, and typically includes placement of an interbody cage (a titanium or PEEK spacer filled with bone graft to promote fusion across the disc space) and pedicle screws connected by rods to provide immediate mechanical stability while the fusion matures.

At One Brain and Spine, our Melbourne neurosurgeons perform the full spectrum of lumbar fusion techniques using minimally invasive approaches, advanced spinal navigation, and intraoperative neuromonitoring. The most appropriate technique is selected based on each patient's specific diagnosis, anatomy, and surgical goals.

When is Lumbar Fusion Surgery Recommended?

• Spondylolisthesis — vertebral slippage requiring stabilisation
• Spinal instability — abnormal motion on flexion-extension X-rays
• Degenerative disc disease with significant back pain and disc collapse not responding to conservative treatment
• Recurrent disc herniation — particularly multiple recurrences at the same level
• After wide laminectomy that destabilises the spine
• Adjacent segment disease — degeneration at levels adjacent to a previous fusion
• Spinal deformity — scoliosis or kyphosis requiring correction

Lumbar Fusion Techniques — Which Approach is Right for You?

Several lumbar fusion techniques are available, each with specific advantages for different clinical situations. One Brain and Spine's neurosurgeons discuss all options and recommend the most appropriate approach for each patient:

TLIF — Transforaminal Lumbar Interbody Fusion

Minimally invasive posterior approach through the foramen on one side.  Removes the facet joint on the symptomatic side, inserts one cage, and provides excellent decompression and fusion. The most commonly performed posterior interbody fusion technique however may have a slightly decreased fusion rate compared to other techniques which allow placement of larger cages. Preferred for spondylolisthesis, recurrent disc herniation, and instability requiring posterior decompression.  A TLIF may be performed endoscopically in certain situations.

ALIF — Anterior Lumbar Interbody Fusion

Anterior abdominal approach in collaboration with a vascular surgeon. Provides the largest cage size, best disc height restoration, and superior lordosis correction. Back muscles completely untouched unless posterior pedicle screws are needed in certain instances. Preferred for L4-5 and L5-S1 levels when maximal disc height and alignment correction is required, particularly for deformity and revision surgery.

PLIF — Posterior Lumbar Interbody Fusion

Posterior approach with bilateral nerve root retraction and two cages. Provides bilateral direct neural decompression. Remains useful in selected cases requiring bilateral central disc level access and may have a higher incidence of fusion compared to a TLIF.

Lateral / Direct Lateral Interbody Fusion (XLIF / PTP)

Access to the lumbar disc from the side through the psoas muscle under neurological monitoring. The prone transpsoas (PTP) approach allows simultaneous access to the posterior spine and the disc space.  Allows for large cage insertion, improved fusion rates and correction of spinal deformity. Particularly useful for multilevel deformity correction and spondylolisthesis. Typically combined with posterior pedicle screw fixation.

Posterior Cervical Fusion

Stabilisation of the cervical spine from the posterior (back of neck) approach using lateral mass or pedicle screws and rods. Used for cervical instability, deformity, and multilevel myelopathy.

General Principles of Lumbar Fusion Surgery

All lumbar fusion procedures share common elements: nerve decompression, disc removal, interbody cage placement with bone graft, and pedicle screw and rod fixation. The specific approach, incision location, and technique vary by procedure type.

One Brain and Spine's neurosurgeons routinely use: intraoperative CT navigation or robotic-assisted pedicle screw placement for accuracy; continuous intraoperative neurophysiological monitoring (SSEP and MEP) to protect nerve function; synthetic bone graft substitutes (avoiding iliac crest harvest and chronic hip pain); and minimally invasive tubular retractor systems or spinal endoscopy to minimise muscle disruption.

Anaesthesia and Hospital Stay

All lumbar fusion procedures are performed under general anaesthesia. Hospital stays range from 1 to 5 days for single-level fusion, and longer for multilevel or more complex procedures. Inpatient rehabilitation may be recommended.

Lumbar fusion achieves significant improvement in leg pain in the large majority of appropriately selected patients. Back pain improvement is less predictable than leg pain relief but occurs in most patients over 6 to 12 months. Fusion rates exceed 90% at 12 months with modern techniques and bone graft substitutes. Long-term outcomes are best when surgery is performed for clear structural indications with appropriate patient selection.

Risks and Complications

General Surgical Risks

• Wound infection — approximately 1–2%; higher for multilevel procedures
• Bleeding — intraoperatively or postoperatively; rarely requires return to theatre
• CSF leak — approximately 1–2%

Fusion-Specific Risks

• Non-union (pseudarthrosis) — failure of the bone to fuse in 5%; more common in smokers, multi-level surgery, and poor bone quality; may require revision surgery
• Adjacent segment disease — accelerated degeneration at levels above or below the fusion
• Nerve injury — persistent or worsening leg pain, numbness, or weakness
• Implant malposition or failure — minimised by intraoperative navigation
• Persistent back pain — fusion does not guarantee resolution of back pain
• Bowel or bladder dysfunction — rare