Adult Spinal Deformity Surgery

What is Adult Spinal Deformity Surgery?

Adult spinal deformity surgery encompasses a range of surgical procedures designed to correct abnormal curvatures or alignment of the spine in adults, including degenerative scoliosis (S-shaped curvature), flatback deformity, kyphosis (hunching), and sagittal plane imbalance. These conditions cause progressive pain, neurological symptoms, and a decreasing ability to walk and stand upright. 

Unlike adolescent idiopathic scoliosis, adult spinal deformity most commonly arises from age-related degeneration — the progressive collapse, asymmetric degeneration, and rotational shift of intervertebral discs and facet joints causing the spine to curve, tilt, or lose its normal front-back curvature (lordosis). Adult spinal deformity also occurs after previous spinal intervention particularly if prior treatment has affected the spinal balance (posture), and fused the spine in an abnormal position.

Neurological symptoms arise when the deformity leads to nerve root and spinal canal compression at multiple levels.

Adult spinal deformity surgery is among the most complex operations in spine surgery — requiring extensive planning, advanced implant technology, staged approaches, and experienced surgical technique. At One Brain and Spine, our Melbourne neurosurgeons have subspecialty expertise in complex adult deformity correction, utilising robotic-assisted navigation, intraoperative CT, neuromonitoring, and modern deformity correction techniques.

Types of Adult Spinal Deformity

Degenerative Scoliosis

The most common form of adult spinal deformity. Asymmetric degeneration of the discs and facet joints causes a lateral curvature (scoliosis) to develop in the lumbar spine, typically after age 50. Symptoms are characterised by back and leg pain, neurogenic claudication, and progressive difficulty walking. The deformity is usually not only in one plane with a degree of lateral listhesis (sideways slippage) and rotational deformity that needs to be considered in any treatment plan.

Sagittal Plane Imbalance and Flatback Deformity

Loss of the normal front-back curve of the lumbar spine (lumbar lordosis) causes the torso to shift forward — the patient leans forward and cannot stand straight without bending the hips and knees. Flatback deformity may be profoundly disabling, causing severe axial back pain, fatigue, and significantly reduced walking tolerance. It may arise from degenerative disc collapse, prior malaligned lumbar fusion, or post-laminectomy deformity.

Thoracic and Thoracolumbar Kyphosis

Excessive forward rounding of the thoracic spine from Scheuermann's disease (multiple adjacent wedged vertebra), osteoporotic vertebral fractures, or degenerative change. Significant kyphosis causes pain, progressive neurological deficit, and trunk imbalance.

Adjacent Segment Deformity

Deformity developing above or below a previous spinal fusion — the levels adjacent to a fused segment are subjected to increased mechanical stress and may degenerate, collapse, and shift, requiring extension of the fusion construct.

When is Surgery Recommended?

Adult spinal deformity surgery is major surgery with significant risks and an extended recovery. It is recommended when:

• Conservative management — physiotherapy, activity modification, injections, pain management — has been thoroughly exhausted
• Symptoms are severely impacting quality of life — particularly the inability to stand upright, walk meaningful distances, or perform daily activities
• Progressive neurological deficit is present — weakness, numbness, or loss of bladder/bowel function
• Radiological evidence of progressive deformity, spinal instability, or significant sagittal imbalance is documented
• The patient is medically fit to tolerate a major surgical procedure and has realistic expectations of outcomes

Not all patients with adult spinal deformity require surgery. Many patients with mild to moderate curves and manageable symptoms are best managed non-surgically with a structured pain management and rehabilitation programme. The use of walking aids and braces may also be considered.  The decision to proceed with deformity correction surgery requires careful, individualised discussion and thorough informed consent with a specialised spinal deformity neurosurgeon.

Preoperative Planning — The Foundation of Deformity Surgery

Adult spinal deformity surgery requires extensive preoperative planning.  Radiological assessments required include:

1. Standardised full-length standing radiographs (stitched or EOS images).  This is the primary planning tool, providing measurement of all deformity parameters including Cobb angle, sagittal vertical axis (SVA), pelvic incidence, lumbar lordosis, and pelvic tilt. These measurements define the surgical targets for correction and the extent of the instrumentation needed.
2. MRI of the relevant spinal levels.  This assesses the degree of neural compression which may require decompression.  
3. Bone mineral density (DEXA) scan.  This measures bone density on the spine.  Augmentation of the implants may be utilised for osteopaenic (mildly weak) bone.  If osteoporosis (very weak bone) is present surgery will need to be delayed for bone strengthening treatment.
4. CT scan of the relevant spinal levels.   This assesses the bony anatomy for screw planning, and assists in planning where and how much bone resection needs to be performed during surgery to safely restore the spinal alignment.

Prior to all adult spinal deformity surgery a comprehensive medical work-up with our dedicated peri-operative physician will be required.  This will include blood tests, ECGs and any other investigations need to assess and optimise the heart, lung and kidney function.  

At One Brain and Spine, our neurosurgeons use computer-assisted surgical planning software to simulate the correction and plan the exact number, size, and trajectory of implants needed to achieve the target alignment. This planning is essential for complex multilevel deformity correction.

Surgical Approaches — Tailored to the Deformity

Adult spinal deformity correction typically involves a combination of approaches and techniques, individually planned for each patient. One Brain and Spine's neurosurgeons offer the full range:

Posterior Spinal Fusion with Instrumentation

The posterior approach is used to place screws into the pedicles of the vertebra which are then connected to contoured rods that translate and hold the spine into the correct alignment and position.  The number of levels fused depends on the extent of the deformity, ranging from limited short-segment fusion to long constructs from the thoracic spine to the sacrum and pelvis.  The posterior approach allows the surgeon to perform osteotomies (targeted bone resection or breaks) to loosen the spine and aid realignment as well as providing a bony surface for placement of bone graft.

Interbody Fusion — Disc Removal and Cage Placement

The anterior column denotes the majority weight bearing area of the spine and includes the vertebra bodies and discs.   Modern deformity surgery techniques focus on placement of large interbody cages in the anterior column to restore disc height and correcting any angular deformity at individual levels.  The number and type of cage placed is dependent on the individualised optimal surgical plan for each patient.

Multiple approaches to the anterior column may be used (often in conjunction) including are used:

• TLIF (Transforaminal Lumbar Interbody Fusion) —  posterior access for placement of an oblique cage
• PLIF (Posterior Lumbar Interbody Fusion) – posterior access for placement of bilateral straight cages.
• ALIF (Anterior Lumbar Interbody Fusion) — directly anterior access allowing disc height restoration and lordosis correction at L4-5 and L5-S1 in particular.  This procedure is performed in collaboration with a vascular access surgeon.
• LLIF (Lateral Lumbar Interbody Fusion) — lateral (side) access for placement of the widest cage.  This approach is ideal for multi-level upper lumbar through small flank incisions and does not require the use of an access surgeon.

Further detailed information about each interbody fusion technique can be found on the One Brain and Spine website.

Combining the anterior or lateral interbody fusion with posterior pedicle screw fixation provides circumferential (360-degree) fusion is the gold standard for complex adult deformity, maximising fusion rates and deformity correction at each level.  These approaches were previous performed staged (often on separate days) with repositioning of the patient however modern techniques allow adult deformity surgery to be performed more efficiently in a single position (prone or lateral) under a single anaesthetic.

Osteotomies — Bone Cuts for Major Deformity Correction

When deformity is rigid or severe, bone cuts (osteotomies) are required to mobilise the spine and enable correction. Three types are used depending on the severity and rigidity of deformity. 

• Ponte osteotomy (Grade 2) — removal of the posterior ligament complex and facet joints bilaterally at multiple levels; provides 5–10 degrees of correction per level.  This is the most common osteotomies performed.
• Pedicle subtraction osteotomy (PSO, Grade 3) — a wedge of bone is removed from the posterior and middle columns of a single vertebra, allowing the spine to hinge closed and gain 25–40 degrees of sagittal correction. This is a major procedure with potential for significant blood loss and should only be performed in experienced hands.  
• Vertebral column resection (VCR, Grade 5–6) — complete removal of one or more vertebrae for the most severe, rigid deformities.  This is a rare highly specialised procedure reserved for select cases

Sacropelvic Fixation

Long fusion constructs extending to the sacrum require fixation into the pelvis — using iliac bolts or S2 alar-iliac (S2AI) screws — to prevent the construct pulling out of the sacrum under the lever arm forces of a long-rod construct. Sacropelvic fixation is an essential component of most long deformity corrections.

Staging

Complex multilevel deformity corrections may be staged — performed in two separate operations on consecutive days or with a short interval, typically beginning with the anterior/lateral interbody work followed by the posterior correction and fixation. Staging reduces the physiological burden on the patient, limits blood loss at any single sitting, and allows the surgical team to proceed in a controlled manner.  

It is however becoming more common to complete the surgery under a single anaesthetic with the patient positioned in a single position.  This is possible due to innovative surgical approaches and the use of robotics and navigation to reduce to the cognitive and physical burden on the surgical team.

Technology 

Adult deformity surgery at One Brain and Spine is performed utilising the most up-to-date intra-operative equipment including modern intra-operative imaging platforms, navigation and robotics.  Continuous intraoperative neuromonitoring (SSEP and MEP) allows immediate detection of any change in spinal cord or nerve function, enabling rapid intervention before permanent injury occurs.

Anaesthesia, Blood Loss and Cell Salvage

Adult deformity surgery is lengthy — typically 4 to 10 hours depending on the complexity and number of levels. Blood loss can be substantial, particularly during osteotomies. Intraoperative cell salvage (autologous blood recycling), antifibrinolytic medications (tranexamic acid), and meticulous haemostatic technique are used routinely to minimise transfusion requirements.

Adult spinal deformity surgery — when carefully planned, performed by experienced surgeons with appropriate technology, and in correctly selected patients — achieves significant and durable improvement in pain, function, walking ability, and quality of life. The most dramatic improvements are seen in patients with significant sagittal imbalance who regain the ability to stand upright; many describe this as life-changing.

Published data from major spinal deformity registries demonstrates that 70–80% of appropriately selected patients achieve meaningful improvement in pain and disability scores at 2-year follow-up. Patient satisfaction rates are high when expectations are realistic and patient selection is rigorous.

It is important to understand that adult deformity surgery does not eliminate all back pain, and recovery is prolonged. The aim is meaningful, sustained improvement in function and quality of life — not a pain-free spine.

Risks and Complications

Adult spinal deformity surgery carries higher risks than simpler spinal procedures, commensurate with its complexity and duration. Thorough risk counselling is a mandatory part of the preoperative process at One Brain and Spine.

Medical and Anaesthetic Risks

• Cardiac and pulmonary complications — particularly in older patients with comorbidities; assessed and optimised preoperatively
• Deep vein thrombosis and pulmonary embolism — reduced by early mobilisation, stockings, and anticoagulation
• Blood transfusion requirement — reduced by cell salvage and tranexamic acid
• Delirium — particularly in elderly patients; managed with perioperative protocols

Surgical Risks

• Wound infection — approximately 3–5% for long deformity corrections; deep infection around implants is a serious complication potentially requiring implant removal and/or life-long antibiotic treatment.
• CSF leak (dural tear) — approximately 5–8%; higher in revision and osteotomy cases; managed conservatively in most cases
• Neurological deficit — new or worsening nerve root or spinal cord injury; risk depends on the extent of correction and osteotomy type; neuromonitoring significantly reduces but does not eliminate this risk; estimated at 1–5% for major corrections
• Rod fracture or implant failure — occurs in approximately 5–15% of long constructs over 5 years, particularly at the lumbosacral junction; may require revision surgery
• Non-union (pseudarthrosis) — failure of bony fusion at one or more levels; more common in smokers, osteoporosis, and multilevel constructs; rates of 5–15% for long fusions; may cause pain and eventual implant failure requiring revision
• Adjacent segment disease — degeneration at the level above or below the fusion construct
• Coronal or sagittal decompensation — failure to achieve or maintain target spinal alignment; may require revision
• Revision surgery — overall revision rates of 15–30% over 5 years for complex adult deformity; most common reasons include rod fracture, pseudarthrosis, adjacent segment disease, and infection

Alternatives to Surgery

Non-surgical management remains the first-line approach for the majority of patients with adult spinal deformity. This includes: structured physiotherapy and core stabilisation; pain medicine review and optimisation of medications; spinal injections (epidural steroids, nerve root blocks, facet joint injections) for neurogenic symptoms; activity modification and walking aids; bracing for pain relief (not corrective in adults). Surgery is a last resort after conservative measures have been thoroughly exhausted.