Spina Bifida

Spina Bifida is a neural tube defect where the spinal column fails to close during the first 28 days of embryonic development.

Types of Spina Bifida

• Myelomeningocele (95% of cases):

  • Most severe open form - exposed neural placode
  • Spinal cord and meninges herniate through defect
  • Associated with significant neurological deficit
  • Requires immediate surgical closure after birth
  • Nearly always associated with Chiari II malformation

• Meningocele (4%):

  • Meninges herniate through defect, spinal cord intact
  • Usually better neurological function
  • May present as lumbosacral mass at birth
  • Surgical closure required

• Spina Bifida Occulta (1%):

  • Minor posterior arch defect without herniation
  • Often asymptomatic, incidental finding
  • Skin markers: Hair tuft, dimple, lipoma, hemangioma
  • May be associated with tethered cord

Epidemiology

• Incidence: 0.5-1 per 1000 live births in folate-fortified populations; 2-4 per 1000 historically
• Geographic variation: Highest in Celtic/British Isles and parts of China and Latin America; lowest where flour is mandatorily fortified
• Sex ratio: Slight female predominance
• Risk factors: Maternal folate deficiency, anticonvulsants (valproate, carbamazepine), maternal diabetes, obesity, hyperthermia, prior affected pregnancy, MTHFR polymorphisms

Prevention - Folic Acid

• Periconceptional supplementation: 400-800 mcg folic acid daily for all women planning pregnancy, starting at least 1 month pre-conception through the first trimester
• High-risk women: 5 mg daily (previous NTD pregnancy, antiepileptic drugs, diabetes, obesity)
• Mandatory flour fortification: Adopted in the USA (1998), Canada, Australia/New Zealand (2009), and over 80 countries; not yet mandatory across most of Europe
• Evidence: The MRC Vitamin Study RCT showed a 72% reduction in NTD recurrence with periconceptional folic acid; fortification programs reduce population NTD prevalence by roughly 30-50%

Associated Conditions

• Chiari II Malformation: Nearly 100% with myelomeningocele
• Hydrocephalus: 80-90% require VP shunt
• Tethered Cord: May develop progressively
• Syringomyelia: Common finding on MRI
• Neurogenic Bladder: Universal below lesion level
• Neurogenic Bowel: Requires bowel management program
• Cognitive Impairment: Variable, often preserved intelligence

Neurological Level and Motor Function

• The level of the lesion determines muscle function below
• Motor function is predictable based on spinal level
• Sensation is typically absent below the lesion
• The motor level often differs from the sensory level

Pathogenesis of Orthopaedic Deformities

Muscle Imbalance Principle

• Active muscles without functioning antagonists cause progressive deformity
• Example: Active hip flexors (L1-L2) without extensors (L5-S1) = hip flexion contracture
• Example: Active quadriceps (L3) without hamstrings = knee hyperextension

Specific Deformity Patterns by Level

• Thoracic Level:

  • No lower limb motor function
  • Paralytic hip dislocation (both hips)
  • Spinal deformity common (100% have scoliosis)
  • Severe kyphosis may interfere with sitting

• High Lumbar (L1-L2):

  • Hip flexors active, extensors absent → flexion contracture
  • Hip adductors active without abductors → adduction contracture
  • Progressive hip subluxation/dislocation (muscle imbalance)
  • Knee flexion contractures common

• Mid Lumbar (L3-L4):

  • Quadriceps active → community ambulators
  • Hip instability less severe
  • Knee extension possible but may have hyperextension
  • Foot deformities common (clubfoot, calcaneus)

• Low Lumbar (L5-S1):

  • Near-normal motor function
  • Mild foot deformities (pes cavus, clawing)
  • Good ambulatory potential
  • Less severe spinal issues

Why Orthopaedic Issues Are Universal

• Muscle Imbalance: Drives most deformities
• Lack of Sensation:
  • No protective sensation → unrecognized trauma
  • Pressure sores under braces and casts
  • Pathological fractures present with swelling (no pain)
• Gravity and Positioning:
  • Unopposed forces create contractures
  • Hip flexion contracture from prolonged sitting
• Osteoporosis:
  • Insensate, non-weight-bearing limbs become osteoporotic
  • High fracture risk with minimal trauma

The differential is for the flaccid lower-limb paralysis, foot deformities and neurogenic bladder seen in a child, plus the imaging differential of a lumbosacral mass or midline skin lesion.

History

Essential Information

• Neurological level: Documented motor and sensory level
• Ambulatory status: Current and best function achieved
• Bladder/bowel function: Clean intermittent catheterization, bowel program
• Prior surgeries: Closure, shunt, orthopaedic procedures
• Shunt status: Type, last revision, symptoms of malfunction

Red Flags to Identify

• Shunt malfunction symptoms: Headache, vomiting, irritability, decreased consciousness
• Tethered cord symptoms: Deteriorating gait, new weakness, increasing scoliosis, change in bladder function
• Skin breakdown: Location, duration, prior wounds
• Recent fractures: Often missed due to lack of pain

Physical Examination

Neurological Assessment

• Motor level: Test each myotome systematically
• Sensory level: Light touch and pinprick
• Reflexes: May be variable depending on level
• Document baseline for comparison

Spine Examination

• Scoliosis assessment: Adam's forward bend test, trunk shift
• Kyphosis: Lumbar kyphosis common, rigid vs flexible
• Skin over spine: Scars, sinus tracts
• Sitting balance: Essential for wheelchair users

Hip Examination

• Range of motion: Document flexion contracture (Thomas test)
• Hip stability: Barlow/Ortolani in infants, assess with motion
• Gait: If ambulatory, observe pattern
• Sitting posture: Pelvic obliquity from hip problems

Knee Examination

• Flexion contractures: Common, limit ability to use orthoses
• Hyperextension: May occur with quadriceps function
• Extension lag: Quadriceps strength assessment

Foot Examination

• Deformity type: Clubfoot, vertical talus, calcaneus, cavus
• Rigidity: Assess correctability
• Skin: Pressure points, calluses, ulcers
• Braceable: Can foot fit in AFO without pressure issues?

Skin Examination

• Critical assessment - insensate skin very vulnerable
• Under braces and orthoses
• Bony prominences
• Prior wound sites
• Signs of infection

Ambulatory Classification

Imaging:

• Spine X-ray: Scoliosis, kyphosis, vertebral anomalies.
• Hip X-ray: DDH, subluxation.
• Foot X-ray: Clubfoot, talus position.
• MRI Spine: Tethered cord (before scoliosis surgery).

Other:

• EMG: If level unclear.
• Urodynamics: Bladder function.

Complications of Spina Bifida - Orthopaedic Focus

Pressure Sores - Critical Issue

High-Risk Areas

• Under braces and orthoses
• Ischial tuberosities (wheelchair users)
• Sacrum and coccyx
• Heels and malleoli
• Over prominent hardware

Prevention Strategies

• Regular skin checks (daily for at-risk areas)
• Properly fitted orthoses - check at every visit
• Pressure-relieving cushions for wheelchairs
• Weight shifts and position changes
• Patient/family education

Management When Present

• Remove all pressure from area
• Wound care (may need plastic surgery)
• Underlying osteomyelitis may require debridement
• Can take months to heal

Pathological Fractures

• Mechanism: insensate, osteoporotic bone (femur/tibia) fractures with minimal or unrecognised trauma
• Presentation: swelling and warmth without pain; mimics infection (may have low-grade fever from fracture haematoma)
• Management: gentle splinting only; avoid prolonged immobilization which worsens osteoporosis and causes pressure sores; healing occurs but may be slow

Perioperative Complications

Latex Allergy

• Present in 30-70% of spina bifida patients
• Due to repeated procedures and latex exposure
• Mandatory latex-free OR for all procedures
• Pre-operative antihistamines in known cases

Shunt Considerations

• Inform neurosurgery of planned surgery
• Position to avoid pressure on shunt
• Monitor for signs of malfunction post-op
• May need shunt adjustment for positioning

Wound Healing

• Poor skin quality common
• Increased infection risk
• Consider plastic surgery involvement for complex closures
• Extended antibiotics often required

Immediate Postoperative Period

Skin Monitoring

• Critical in first 48-72 hours
• Cast windows for skin inspection
• Bivalved casts when possible
• Daily skin checks by nursing staff
• Teach family to inspect on discharge

Positioning

• Avoid pressure on shunt
• Pressure-relieving mattress
• Regular turning (every 2 hours minimum)
• Heel protection mandatory

Pain Management

• May have diminished pain perception
• But still need adequate analgesia - central processing intact
• Watch for signs of discomfort (irritability, vital signs)
• Regional blocks can be effective

Cast Care in Spina Bifida

• Insensate limbs cannot report problems - window/bivalved cast, well-padded over bony prominences, not too tight, parents check edges daily
• Keep duration short (skin tolerance), transition to a carefully moulded orthosis when safe

Rehabilitation

Goals by Level

• Thoracic: Maximize upper body strength, wheelchair skills
• L1-L2: Standing program if appropriate, transfers
• L3-L4: Gait training with appropriate orthoses
• L5-Sacral: Optimize gait efficiency, minimize energy expenditure

Orthotic Management

• Fitted by experienced orthotist
• Check fit at every clinic visit
• Anticipate growth - regular adjustments
• Replace when worn or outgrown

Ambulatory Outcomes by Level

Factors Affecting Outcome

Positive Prognostic Factors

• Lower neurological level (L4-Sacral)
• Preserved cognition
• Strong family support
• Access to multidisciplinary care
• Early intervention for deformities

Negative Prognostic Factors

• Higher lesion level
• Significant cognitive impairment
• Multiple shunt revisions
• Severe scoliosis
• Recurrent pressure sores

Life Expectancy

• Significantly improved with modern care
• Most patients with myelomeningocele reach adulthood
• Main causes of death: Shunt-related, renal failure, respiratory
• Quality of life can be excellent with appropriate support

Transition to Adult Care

• Plan transition from age 14-16 years
• Identify adult orthopaedic surgeon experienced with spina bifida
• Ongoing surveillance for:
  • Skin breakdown
  • Progressive deformity
  • New weakness (tethered cord)
• Spina Bifida Foundation support services

Global Epidemiology

• Prevalence: 0.5-1 per 1000 live births in folate-fortified countries; 2-4 per 1000 historically and in unfortified regions
• Highest rates: British Isles/Celtic populations, northern China, parts of Latin America
• Lowest rates: USA, Canada, Australia/New Zealand and other countries with mandatory flour fortification
• Mandatory fortification (now in over 80 countries) reduces population NTD prevalence by roughly 30-50%

Folic Acid Guidelines - Side by Side

Orthopaedic & Surgical Practice Consensus

• AAOS / POSNA & EPOS (European Paediatric Orthopaedic Society): deformity management individualised to functional level; preserve a plantigrade, braceable foot; avoid routine hip reduction in high-level lesions
• AO/Scoliosis Research Society: pre-operative spinal MRI to exclude symptomatic tethered cord; long posterior fusion to the pelvis for neuromuscular curves affecting sitting balance
• Fetal therapy consensus (post-MOMS): in-utero repair offered in selected centres meeting MOMS eligibility criteria, balanced against preterm birth and uterine risk

Registries & Surveillance

• EUROCAT (European congenital anomaly surveillance) and the ICBDSR track NTD prevalence and the impact of fortification policy internationally
• National Spina Bifida Patient Registry (USA) captures longitudinal multidisciplinary outcomes
• No dedicated implant registry exists for spina bifida; arthroplasty/instrumentation outcomes are drawn from neuromuscular subgroups within general registries

High- vs Limited-Resource Practice Variation

• High-resource: multidisciplinary clinics (paediatric orthopaedics, neurosurgery, urology, rehabilitation, orthotics), urodynamics-guided bladder care, fetal surgery programmes, custom orthoses and seating
• Limited-resource: late presentation of unrepaired/neglected defects, higher infection and pressure-sore burden, reliance on serial casting and simpler bracing; fortification programmes are the highest-yield public-health intervention