Spina Bifida

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

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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

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

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.

The management and surgical sections name the McHale procedure (proximal femoral resection-interposition) as the salvage option for the dislocated hip but never describe it. This matters because in spina bifida the goal of hip surgery is rarely a "stable, reduced" joint — it is comfort, sitting and hygiene in a limb where reduction does not improve walking.

When salvage (not reconstruction) is the aim

• The problem hip in an older, non-ambulatory patient is typically chronically dislocated, stiff and painful, sometimes with a windswept pelvis, pelvic obliquity, perineal-care difficulty or skin breakdown over the prominent femoral head.
• Reconstruction (open reduction, femoral and pelvic osteotomy) is inappropriate for the stiff, degenerate, insensitive-yet-painful hip; a resection/salvage procedure is chosen instead.

What the McHale procedure is

• Described by McHale and colleagues, it combines resection of the femoral head and neck with a proximal (subtrochanteric) valgus osteotomy of the femur.
• The valgus osteotomy angles the remaining proximal femur away from the acetabulum and ischium, so the femoral shaft points laterally. This resists the proximal migration and painful bony impingement that limit a simple Girdlestone-type head-and-neck excision (Castle resection) done alone.
• Soft tissue is interposed over the cut bone ends to cushion the construct — hence the "resection-interposition" descriptor.

Goals and caveats

• Goals: pain relief, improved hip range for comfortable sitting and perineal/hygiene access, and easier positioning — not restoration of a weight-bearing, ambulatory hip.
• Recognised problems: heterotopic ossification, proximal migration with recurrent impingement, and persistent or recurrent pain; postoperative traction/positioning and, in some hands, short-term immobilisation are used to limit migration — always weighed against the pressure-sore and osteoporosis risks of immobilising an insensate limb.

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

The topic repeatedly flags latex allergy (present in roughly 30-70% of spina bifida patients) as a mandatory perioperative consideration, but the reason it clusters in this population — and the concrete protocol — deserve development.

Mechanism and why spina bifida is high-risk

• Latex allergy is a Type I, IgE-mediated immediate hypersensitivity to soluble proteins in natural rubber latex (from Hevea brasiliensis), not to the finished rubber itself.
• Spina bifida patients are sensitised by early, repeated and mucosal/parenteral exposure: multiple operations from birth (closure, shunt, orthopaedic), and lifelong clean intermittent catheterisation with latex catheters. Cumulative number of operations is the strongest risk factor; myelomeningocele (versus lower dysraphism) and atopy add further risk.
• Sensitisation can be silent — a positive specific-IgE without prior clinical reaction still mandates avoidance, because the first clinical event may be intra-operative anaphylaxis.

Latex-fruit syndrome (cross-reactivity)

• Latex proteins (notably hevein/prohevein and class-I chitinases) cross-react with plant foods. Ask specifically about reactions to banana, avocado, kiwi and chestnut (the classic quartet), and also passionfruit, fig and papaya.
• A history of oral itch/swelling with these foods is a clinical clue to occult latex sensitisation.

Perioperative protocol

• Primary prevention is the highest-yield step: raising every child with spina bifida in a latex-free environment from birth measurably lowers sensitisation rates, so avoidance is not only a theatre issue.
• For any procedure: designate a latex-free (latex-safe) theatre — synthetic (nitrile/neoprene) gloves, latex-free catheters, tourniquets, drains, syringe plungers, medication vial bungs and anaesthetic circuit; schedule the patient first on the list to minimise airborne latex particulate from prior cases.
• Treat unexplained intra-operative cardiovascular collapse, bronchospasm or urticaria — often appearing minutes after induction/skin or mucosal contact — as latex anaphylaxis until proven otherwise; management is standard anaphylaxis care (remove the trigger, adrenaline, fluids, airway support).
• Routine antihistamine/steroid "premedication" does not reliably prevent latex anaphylaxis and does not replace strict avoidance.

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