Spinal Deformities

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Overview of Spinal Deformities - Spine's Shape Shifters

  • Spinal deformities: Abnormal curvatures/alignments of the vertebral column in coronal or sagittal planes.
  • Normal Sagittal Curvatures:
    • Cervical lordosis (inward)
    • Thoracic kyphosis (outward)
    • Lumbar lordosis (inward)
  • Key Deformity Types:
    • Scoliosis: Coronal plane; lateral curvature > 10° (Cobb angle), often with vertebral rotation.
    • Kyphosis: Sagittal plane; excessive posterior thoracic curvature ("roundback").
    • Lordosis: Sagittal plane; increased anterior lumbar curvature ("swayback"). Spinal Deformities: Healthy, Kyphosis, Lordosis, Flat Back

⭐ Adam's forward bend test is a key screening tool for scoliosis, a common spinal deformity.

Scoliosis - The Lateral Curve Ball

  • Definition: Lateral spinal curvature >10° (Cobb angle), often with vertebral rotation.

  • Key Signs: Uneven shoulders/waist; Adams Forward Bend Test: rib/loin hump.

  • Diagnosis:

    • Cobb Angle: $Cobb Angle = \alpha + \beta$ (angle between endplates of most tilted vertebrae).
    • X-ray (Full Spine AP/Lat): Curve magnitude, pattern, flexibility.
    • Risser Sign (0-5): Skeletal maturity (crucial for progression risk & treatment).
  • Classification Highlights:

    TypeKey Points
    Idiopathic (80%)Adolescent (AIS) most common; girls > boys.
    CongenitalVertebral anomalies; often progressive.
    NeuromuscularCP, MD; often severe, long C-curves.
    OtherSyndromic (Marfan's, NF1), Degenerative.
  • Adolescent Idiopathic Scoliosis (AIS) Management: Goals: Halt progression, maintain trunk balance.

    • 📌 20-40-50 Rule (approx. for AIS):
      • Observation: Curves <20-25°. Regular follow-up until skeletal maturity.
      • Brace (e.g., TLSO): Curves 25-45° in skeletally immature (Risser 0-2).
      • Surgery (Spinal Fusion): Curves >45-50° (immature) or >50° (mature/progressive), or failed bracing.

⭐ In adolescent idiopathic scoliosis, curves <25° are typically observed, 25-45° in skeletally immature patients may require bracing, and >45-50° often indicate surgical consideration.

Cobb angle measurement on AP spinal X-ray for scoliosis

Kyphosis & Lordosis - Arch Enemies

  • Kyphosis: Excessive posterior thoracic spine curvature. Normal: 20-45°.
  • Lordosis: Excessive anterior lumbar spine curvature. Often physiological or compensatory.
FeatureScheuermann's KyphosisPostural Kyphosis
DeformityRigid, structuralFlexible, non-structural
CorrectionNot corrected by hyperextensionCorrected by hyperextension
X-ray FindingsThoracic kyphosis >45° (Sorensen criteria), ant. wedging ≥5° in ≥3 vertebrae, Schmorl's nodes, endplate irregularitiesNormal vertebrae
PainCommon, activity-related, at apexMild or absent, postural
HamstringsOften tightNormal

⭐ Scheuermann's kyphosis is a rigid deformity characterized by vertebral wedging of ≥5° in at least three adjacent vertebrae and is often associated with Schmorl's nodes and tight hamstrings.

Spondylolisthesis - The Vertebral Slip-Up

Spondylolisthesis: Forward slip of one vertebra over an adjacent caudal vertebra. Most common at L5-S1 (isthmic) or L4-L5 (degenerative).

  • Wiltse Classification (📌 DID TPI):

    • Type I: Dysplastic (Congenital sacral/L5 arch anomaly)
    • Type II: Isthmic (Pars interarticularis lesion; common in young athletes)
    • Type III: Degenerative (Facet/disc degeneration; older adults)
    • Type IV: Traumatic (Posterior element fracture, non-pars)
    • Type V: Pathologic (Bone disease: tumor, infection)
    • Type VI: Iatrogenic (Post-surgical)
  • Meyerding Grading of Slip:

    GradeSlip Percentage
    I<25%
    II25-50%
    III50-75%
    IV75-100%
    V>100% (Spondyloptosis)

Lateral X-ray: Spondylolisthesis with Scottie dog sign

⭐ The 'Scottie dog' sign on oblique lumbar radiographs, where the 'collar' represents the pars interarticularis fracture, is characteristic of isthmic spondylolisthesis.

Symptoms: Low back pain (activity-related), radiculopathy, neurogenic claudication, tight hamstrings. Commonly affects L5-S1 or L4-L5 levels.

High‑Yield Points - ⚡ Biggest Takeaways

  • Scoliosis: Cobb angle >10°; screen with Adam's forward bend test.
  • Congenital scoliosis: linked to vertebral anomalies (e.g., hemivertebrae) and VACTERL.
  • Adolescent Idiopathic Scoliosis (AIS): most common; Risser sign assesses skeletal maturity.
  • Scheuermann's kyphosis: anterior wedging ≥5° (≥3 vertebrae), Schmorl's nodes.
  • Spondylolisthesis: Meyerding grading; "scotty dog" sign for pars defect.
  • Bracing for AIS: effective for curves 25-45° in skeletally immature.
  • Scoliosis surgery: indicated for curves >45-50° or rapid progression.
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Practice Questions: Spinal Deformities

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A radiograph is obtained from a child with scoliosis. What is the name of the angle used to measure spinal curvature?

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A minimum of _____ degrees of Cobb's angle is usually required to define scoliosis

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A minimum of _____ degrees of Cobb's angle is usually required to define scoliosis

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Spinal Deformities - Free Indian Medical PG Review