Adult spinal deformity

Introduction

Spinal deformity refers to any 3D alteration of normal spinal geometry/anatomy. There are usually 3 main types of adult spinal deformity:

1. De novo, primary degeneratie scoliosis
2. Untreated adolescent idiopathic scolioisis that that progressed into adulthood
3. Secondray scoliosis, related to altered vertebral anatomy due to previous surgery, trauma, or metabolic bone disease.

Changes that develop into adulthood usually progress with the normal degeneration of the spine that occurs due to aging. Disc degeneration leads to axial rotation of the spinal motion segments. Rotatory deformity leads to ligamentous laxity and eventually into lateral listhesis of the vertebral bodies. In turn, there is the destruction of the diskoligmanetous complex and degeneration of the facet joints leading to abnormal motion at each vertebral segment. These eventually lead to reactive changes such as osteophyte formations, facet joint hypertrophy, ligamentum flavum hypertrophy.

The concavity of the curve can cause foraminal narrowing which is often further exacerbated by the associated loss of degenerative changes such as the loss of disc height leading to foraminal stenosis.

Epidemiology

Adult idiopathic scoliosis affects men and women equally ( in contrast to adolescent idiopathic scoliosis that affects girls more commonly). Patients will typically present in their 60s with symptoms including radiculopathy, neurogenic claudications and back pain.

Adult curves tend to progress on average 3 degrees per year.

Factors that predict a high risk of progression include:

1. A Cobb angle >30
2. Lateral listhesis > 6 mm
3. large degree of apical rotation

Surgical correction is known to be associated with a very high rate of complications up to 86% in some series, these complications include:

1. wound infection (up to 7.8%)
2. Intraoperative blood loss
3. Pulmonary embolism

Presentation

Patients typically present with a combination of multiple complaints, that can include:

1. Upper or lower back pain
   • Back pain is the most common presenting symptom
   • Distinguish between axial and radicular symptoms
   • Paraspinal muscle fatigue vs. instability at the painful segment
2. Radiating lower extremity pain or weakness
3. Paresthesia/Numbness
4. Neurogenic Claudications
5. Difficutly with gait or upright posture, decreased walking distance
6. Changes in the use of assistive devices
7. Neurologic deficits

Clinical Exam

1. Trunk Shift evaluation
2. Head balance in the coronla and sagital plane
3. Assymetry of the shoulders and/or pelvic griddle
4. look for pelvi obliquity and leg length discrepency.
5. Compensatory mechanisms such as pelvic retroversion, hip/knee flexion: evaluate for contractures with patient in the supine position
6. Evaluate the ridgidity of the curve ( forward and lateral bending)
7. Gait assessment
8. Dont’ forget to evalute for possible myelopathy (rule out concomittent cervical issues)

Radiographic evaluation

1. Full length AP and lateral radiographs
2. Cobb angle measurment and determination of Pelvic parameters
3. MRI particulalry in the presence of radicular or neurogenic symptoms
4. CT myelopgram if unable to undergo MRI
5. CT
   • Evaluation spondyotic changes
   • Fixation points
   • Evaluate previous constructs/fusion etc…
   • Evaluate bone quality using HU

Provocative Testing

1. Selective nerve root blocks useful to illicit diagnostic information (lack of response to injection maybe due to injeciton technique? )
2. Immediate relief likely attributed to injection, delayed relief possibly due to systematic absorption of the corticosteroids

Non-operative management

1. A trial of non operative managemtn Indicated for almost all patients with adult spinal deformity, particulalry in those with minor symptoms
2. No role for bracing in adult scoliosis as opposed to adolescent scoliosis. That’s mainly because progression if dues to degenerative changes and mechanical instability rather than longitudinal growth of the axial skeleton
3. Benefit of temporary relief from bracing (and often from botox injections) outweighed by the potential deconditionning of the paraspinal muscles and even possibly by skin complications seen in elederly patients wearinig braces.
4. Physical therapy
5. Pain management: If feasible recommend discontinuation of all narcotics preop to ensure that pain is manageable post operatively

Surgical Indications

1. Failure of non-operative management with significantly diminished quality of life or functional capacity
2. Lumbar curves > 30 degrees or with more than 6 mm of listhesis is any plane are at high risk for progression and therefore should be considered for surgery
3. Annual defomrity progression > 10 degrees
4. Listhesis increasing by greater than 3 mm

Optimization for Surgery

Given the typical age at presentation of 60-70 for patients with spinal deformity, it is quite important to medically optimize these patients before any intervention

1. High-risk spine patients are those who:
   1. Anticipated length of surgery of more thn 6 hours
   2. More than 6 vertebral levels included
   3. Staged procedure
   4. Significant medical comorbidities
2. Nutrition status optimization (serum pre albumin, transferrin):
3. BP control
4. Weight management
5. Iron supplementation, EPO before surgery?
6. Smoking cessation for at least 8 weeks before surgery
7. Correting vitamin D deficiency
8. Osteoporosis management
9. Psychosocial optimization
10. Setting the right expectations
11. Immediate preoperative care includes
    1. Hygiene measures ( Chlorhexidine showers, mupirocin nasally)
    2. Holding Anticoagulants and antithromotic agents
    3. Holing immunomodulators and chemotherapy

References

AO spine masters series. Volume 4, Chapter 1.