Adult Degenerative Scoliosis and Sagittal Imbalance

What is Adult Spinal Deformity (ASD)?

We use the term adult spinal deformity when the spine loses its normal alignment in one or more planes, and this is associated with pain, difficulty with movement, visible deformity, or neurological symptoms.

The most common deformity patterns include:

• Adult scoliosis — lateral curvature of the spine (thoracolumbar, lumbar, etc.).
• Kyphotic deformity — excessive forward bend, often in the thoracic or lumbar region.
• Loss of lumbar lordosis / flatback — the low back “straightens,” and the trunk leans forward.
• Sagittal imbalance — the head and trunk shift forward or backward, altering weight distribution and upright posture.

Adult spinal deformity may involve only a segment of the spine (e.g., lumbar) or affect the entire axis from the neck to the pelvis.

What are the main causes and types of deformity?

Identifying the deformity type accurately is essential, because it guides the treatment strategy.

Major categories of adult spinal deformity include:

• Residual adolescent scoliosis (e.g., adolescent idiopathic scoliosis — AIS) that was not treated adequately in youth and later presents with pain, progression, or neurological symptoms.
• Adult degenerative (de novo) scoliosis — develops gradually due to degenerative changes in discs and facet joints, most commonly in the lumbar or thoracolumbar spine.
• Degenerative kyphosis / flatback — loss of normal lordosis, sometimes after prior surgery or due to multi-level degeneration.
• Iatrogenic deformity — following earlier operations that altered natural alignment (e.g., insufficient lordosis, outdated instrumentation strategies).
• Deformity related to neuromuscular, congenital, or other conditions — e.g., cerebral palsy, spina bifida, congenital anomalies, or deformity after trauma, infection, or tumors.

In middle-aged and older adults, the most common pattern is degenerative scoliosis with sagittal imbalance, often combined with spinal canal stenosis and nerve root compression.

How common is it, and at what ages does it occur?

Adult scoliosis and degenerative spinal deformity are far more common than many people realize—and are often a hidden driver behind the broad diagnosis of “chronic low back pain.”

In adults over 60, some degree of scoliosis or other alignment disturbance is seen in a substantial proportion of routine X-rays—frequently without a prior diagnosis. However:

• not all patients are symptomatic,
• some remain stable for years, while others develop progressive worsening with pain, visible deformity, and declining function.

Symptoms most commonly begin:

• in midlife, with chronic mechanical low back pain,
• later, when spinal stenosis, radiculopathy, gait limitation, and instability are added.

How does it present clinically—what symptoms should concern me?

Unlike adolescents (where appearance may be the main issue), adults typically experience deformity mainly as pain and functional limitation.

Common symptoms include:

• Chronic low back or mid-back pain, worse with standing and fatigue.
• Leg pain (sciatica) — unilateral or bilateral, often in a radicular pattern.
• Neurogenic claudication — pain and/or numbness in the legs after a short period of walking, improving when sitting or bending forward.
• A sense that the trunk “leans” to one side or forward, and difficulty standing or walking upright for long.
• Cosmetic changes — shoulder/pelvic asymmetry, “hump,” rib prominence.

In more advanced cases, neurological manifestations (weakness, numbness, gait instability) may appear and warrant prompt specialist assessment.

How is the clinical evaluation performed?

The evaluation is not limited to “measuring the curve.” We assess the entire spinal axis and the nervous system.

Clinical assessment typically includes:

• Posture observation — front and side views; head–shoulder–pelvis alignment and global balance.
• Range of motion, pain triggers, muscle spasm patterns.
• Full neurological examination:
  • strength testing,
  • sensation,
  • reflexes, tone, and signs of myelopathy (hyperreflexia, clonus, Babinski, Hoffmann),
  • gait, balance, and coordination.
• Review of bladder/bowel symptoms (incontinence, urinary retention, bowel dysfunction), which can indicate significant neural compression.

Your symptoms and examination—combined with imaging—determine urgency and help decide between conservative versus surgical care.

Which tests and X-rays are needed?

Proper assessment requires a global, standing view of the spine and, when indicated, detailed evaluation of neural structures.

Full-length standing radiographs

• Standing PA and lateral full-spine radiographs (36-inch long cassette) — performed without external support, with elbows flexed and hands on the clavicles, to capture:
  • coronal deformity (scoliosis),
  • sagittal alignment (kyphosis, lordosis, global sagittal axis),
  • pelvic and hip position.
• On PA views we measure:
  • Cobb angles — magnitude of the scoliotic curve,
  • Coronal balance — relationship of the C7 plumb line to the central sacral vertical line.
• On lateral views we measure:
  • Sagittal Vertical Axis (SVA) — forward/backward shift of the trunk relative to the sacrum,
  • Thoracic kyphosis, lumbar lordosis, thoracolumbar junction angle.

MRI and CT / CT myelography

• MRI — essential when there is concern for:
  • spinal canal stenosis,
  • nerve root or spinal cord compression,
  • disc herniation, cysts, or other soft-tissue pathology.
• CT / CT myelography — useful for:
  • detailed assessment of bony anatomy and facet joints,
  • cases where MRI is contraindicated or when additional canal detail is needed.

What are spinopelvic parameters (SVA, PI, PT, SS), and why do they matter for surgical planning?

Modern deformity evaluation and correction relies on measurable spinopelvic alignment targets.

Key terms:

• Sagittal Vertical Axis (SVA) — the horizontal distance between the C7 plumb line and the posterosuperior corner of S1. A large positive SVA indicates the trunk is “falling” forward.
• Pelvic Incidence (PI) — a fixed anatomical parameter describing pelvic morphology and its relationship to the sacrum. It does not change with posture.
• Pelvic Tilt (PT) — reflects pelvic “retroversion.” As patients compensate for sagittal imbalance by rotating the pelvis backward, PT increases.
• Sacral Slope (SS) — the sacral angle relative to the horizontal. It relates mathematically to PI and PT (PI = PT + SS).

The relationship PI–LL (Pelvic Incidence minus Lumbar Lordosis) helps determine whether lumbar lordosis is appropriate for a given pelvis. A large mismatch suggests “flatback” and clinically relevant sagittal malalignment.

These parameters help the surgeon determine:

• how much lordosis/kyphosis correction is needed,
• which levels should be included in stabilization/fusion,
• how to avoid under-correction or over-correction, both linked to worse outcomes.

What are the non-surgical (conservative) options?

If there is no progressive neurological deficit, first-line management is often conservative care.

Common conservative strategies include:

• Targeted physiotherapy and core strengthening — improves muscular support, posture, and balance.
• Pain control and anti-inflammatory treatment — individualized, especially in patients with comorbidities.
• Image-guided injections / nerve blocks — in selected cases with significant radicular symptoms.
• Bracing — may reduce pain in selected patients but does not “correct” the deformity on X-ray.
• Osteoporosis management — particularly important in older adults, reducing fracture risk and improving future surgical safety if needed.

The goal is to reduce pain, improve function, and delay or avoid surgery. If symptoms remain severe despite structured conservative care, surgical options may be discussed.

When do we consider surgery, and what are the goals?

Surgery is a major decision and is always personalized, balancing potential benefit against risk.

Typical indications for surgical treatment in adult spinal deformity include:

• Severe, persistent pain that does not respond to well-executed conservative management.
• Neurological deficits (weakness, severe radiculopathy, neurogenic claudication, myelopathy).
• Progressive deformity with worsening posture, balance, and walking capacity.
• Bladder dysfunction (incontinence or retention) due to significant neural compression.
• Major impact on quality of life (loss of independence, inability to work, reduced social/family participation).

Main surgical goals:

• Decompression of the spinal cord and nerve roots.
• Stabilization where there is structural instability.
• Correction and balance in both coronal and sagittal planes, when appropriate.

What are the risks and expected benefits of surgical correction?

ASD surgery can be large and complex, with a higher risk of complications—but it can also offer substantial improvement in pain and function when appropriately indicated.

Potential benefits:

• Reduced pain in the back and legs.
• Improved walking tolerance and endurance in upright posture.
• Better posture and overall balance.
• Improved daily function and quality of life.

Possible risks/complications (examples):

• Blood loss and possible transfusion.
• Superficial or deep wound infection.
• Thromboembolic events (DVT, pulmonary embolism).
• CSF leak (dural tear).
• Neurological worsening (rare, but serious).
• Hardware loosening/breakage and potential need for revision surgery.

Age, comorbidities, and bone quality strongly influence risk. Even so, evidence shows that carefully selected, well-prepared older adults can experience meaningful gains in pain and function.

What is recovery like, and what about life after treatment?

Recovery after adult deformity treatment is gradual and depends on close collaboration between patient and care team.

General principles after major deformity surgery:

• Hospital stay of several days (or longer), depending on surgical magnitude.
• Early mobilization with physiotherapists (sitting, standing, assisted walking).
• Gradual return to daily activities over weeks to months.
• A structured rehabilitation and strengthening program to support the new alignment and protect the fusion.
• Realistic expectations — the goal is meaningful functional improvement, not “radiographic perfection.”

With conservative management, “recovery” focuses on:

• pain control,
• improving physical conditioning,
• posture education and spine-protection strategies.