Myelodysplasia

1. High-Yield Summary

Myelodysplasia, encompassing spina bifida aperta (myelomeningocele) and closed spinal dysraphism, represents the most complex congenital neuro-orthopaedic condition encountered in pediatric musculoskeletal practice. Effective clinical management requires a coordinated, multidisciplinary strategy to preserve renal function, maintain neural stability, prevent decubitus ulcerations in insensate extremities, and maximize lifelong functional mobility.

• Neurosegmental Motor Benchmark: Lifelong functional ambulation is dictated by the neurosegmental motor level. Quadriceps femoris strength of Grade 3 or greater on the Medical Research Council (MRC) scale (L3-L4 neurosegmental level) represents the indispensable threshold required for functional community ambulation. Patients with motor levels at L2 or higher universally transition to primary wheelchair mobility by adolescence.
• Fetal Surgery Paradigm Shift: Open intrauterine fetal repair or fetoscopic repair between 19 and 25.9 weeks of gestation significantly reduces the incidence of ventriculoperitoneal shunt placement at 12 months (40% vs 82%), reverses hindbrain herniation (Chiari II malformation), and doubles independent ambulation rates at school age compared to standard neonatal postnatal repair.
• Deformity Pathomechanics (Sharrard’s Principle): Progressive musculoskeletal contractures and paralytic joint dislocations are caused by unbalanced active, innervated muscle vectors pulling against flaccid, denervated antagonist muscle groups, rather than primary intrinsic joint dysplasia.
• Insensate Extremity Principle: Surgical reconstruction of the foot and ankle prioritizes a supple, plantigrade, braceable foot that evenly distributes plantar pressure to prevent neuropathic ulceration. Rigid arthrodesis, particularly triple arthrodesis, is strictly contraindicated in insensate feet due to catastrophic rates of pseudoarthrosis, Charcot neuroarthropathy, and refractory plantar breakdown.
• Critical Safety Protocols: Universal latex precautions must be instituted from birth across all healthcare encounters due to a high incidence of IgE-mediated anaphylaxis. Acute swelling and erythema of the lower extremity must be presumed an occult painless neuropathic fracture until proven otherwise by plain radiography.

2. Anatomy

Understanding the surgical and clinical anatomy of myelodysplasia requires mastery of the dysraphic spinal axis, distorted peripheral neurovascular corridors, regional internervous planes, and secondary musculoskeletal adaptations.

Neurosegmental & Neuroaxial Architecture

The hallmark neuroaxial defect is spina bifida aperta, characterized by failed dorsal closure of the embryonic neural tube, resulting in an exposed neural placode surrounded by an arachnoid membrane and dysplastic dura mater. In normal neuroanatomy, differential growth rates between the vertebral column and spinal cord result in cephalad migration of the conus medullaris, which reaches the adult L1-L2 disc space by 3 months post-term. In myelodysplasia, the conus remains anchored or scarred at or below L2 (often down to L4-S2) by thick fibrofatty filum terminale, adhesive dural scars, or intradural lipomas, creating persistent mechanical tethering.

Neurovascular Danger Zones

Orthopaedic exposures in patients with myelodysplasia encounter distorted anatomy and vulnerable neurovascular corridors:

• Tethered Spinal Cord Corridor: During posterior spinal instrumentation and corrective distraction maneuvers for neuromuscular scoliosis or kyphosis, longitudinal traction across an anchored spinal cord precipitates acute ischemic injury to the conus medullaris and residual functional cauda equina nerve roots, resulting in catastrophic loss of residual motor function and sphincter control.
• Dysplastic Posterior Spinal Exposure Zone: The absence of normal dorsal laminar arches, bifid spinous processes, laterally splayed pedicles, and attenuated paraspinal musculature expose the dysplastic thecal sac directly beneath the subcutaneous tissue. Midline surgical approaches risk immediate accidental laceration of ectopic dorsal nerve roots or the thecal sac.
• Popliteal Neurovascular Corridor: Distal hamstring lengthening and posterior knee capsular release for severe flexion contractures endanger the tibial nerve, common peroneal nerve, and popliteal vessels. Chronic joint flexion draws the neurovascular bundle immediately adjacent to the posterior joint capsule within dense fibrotic scar tissue. Acute extension of a chronically flexed knee subjects the tibial and common peroneal nerves to severe traction stretch injury.
• Anteromedial Hip Corridor: Anterior capsular release and iliopsoas tenotomy or transfer endanger the femoral nerve, femoral artery, and femoral vein. Severe hip flexion-adduction contractures distort the normal femoral triangle topography, displacing the femoral sheath laterally. Medial adductor releases risk laceration of the anterior division of the obturator nerve and ascending branches of the medial femoral circumflex artery.
• Posteromedial Foot and Ankle Corridor: Surgical correction of rigid equinovarus deformities requires dissection adjacent to the posterior tibial neurovascular bundle. The posterior tibial artery, venae comitantes, and tibial nerve are severely foreshortened and tethered against the medial malleolus and sustained within contracted fibrous sheaths, rendering them vulnerable to direct transection or acute traction ischemia upon foot repositioning.

Internervous Planes & Surgical Corridors

Standard internervous planes must be utilized with precision when addressing lower extremity contractures and deformities:

• Anterior Hip Approach (Smith-Petersen Corridor): Utilizes the superficial interval between the sartorius (femoral nerve) and tensor fasciae latae (superior gluteal nerve), and the deep interval between the rectus femoris (femoral nerve) and gluteus medius (superior gluteal nerve), providing safe access for open reduction and pelvic capsulorrhaphy.
• Medial Hip Approach (Ludloff Corridor): Traverses the interval between the pectineus (femoral nerve) and adductor longus or adductor brevis (obturator nerve), offering direct, rapid exposure to the lesser trochanter for iliopsoas fractional lengthening or tenotomy.
• Posterior Popliteal Corridor: Traverses the deep midline interval between the medial hamstrings (semitendinosus and semimembranosus, innervated by the tibial division of the sciatic nerve) and the lateral hamstring (biceps femoris, long head innervated by the tibial division, short head by the common peroneal division).
• Posterior Spinal Exposure: True anatomic internervous planes do not exist across the midline dysraphic defect. Exposure must commence subperiosteally on lateral, structurally intact ribs and transverse processes, meticulously developing a subperiosteal corridor toward the dysplastic midline laminar margins.

Bony Landmarks & Spine/Pelvic Morphology

The osseous architecture in myelodysplasia demonstrates profound structural alterations:

• Congenital Kyphosis (“Gibbus Deformity”): Present in 10-15% of patients with thoracic or high-lumbar lesions, this rigid, acutely angulated deformity (>80° to 100°) features wedged or hypoplastic vertebrae at the thoracolumbar junction, producing severe sitting imbalance, thoracic collapse, and chronic pressure necrosis over the posterior cutaneous prominence.
• Acetabular Dysplasia & Pelvic Obliquity: Acetabular deficiency is characteristically posterosuperior with marked femoral anteversion (>40°) and coxa valga (>145°). Pelvic obliquity is common and driven by suprapelvic spinal curvature, infrapelvic asymmetric hip contractures (adduction on the high side, abduction on the low side), or intrinsic pelvic ring hypoplasia.
• Distal Skeletal Landmarks: Patients frequently display marked external tibial torsion, patellar tracking abnormalities, rigid calcaneocavus or calcaneovalgus, and congenital vertical talus (rigid convex pes valgus with a vertically oriented talus and dorsally dislocated navicular).

3. Pathogenesis

The pathogenesis of myelodysplasia encompasses embryonic neurulation failure, progressive secondary fetal neural destruction, and lifelong biomechanical muscle vector imbalances.

Embryological Failure of Primary Neurulation

Primary neurulation occurs between embryonic days 21 and 28 following fertilization. Closure of the neural tube initiates at multiple discrete boundary sites along the neural groove and proceeds bidirectionally. Failure of the posterior neuropore to close at embryonic days 26 to 28 results in spina bifida aperta (myelomeningocele). The unfused neural folds remain open and continuous with the surrounding surface ectoderm, leaving the dysplastic neural placode completely exposed on the dorsal surface of the embryo.

The “Two-Hit Hypothesis” of Spinal Cord Destruction

Modern translational and clinical evidence confirms that neurological deficit at birth is the cumulative result of a two-step pathological cascade:

• The First Hit: The initial embryonic failure of neural tube closure, creating an open neural placode and dysplastic cord segment.
• The Second Hit: Progressive chemical and mechanical destruction occurring during the second and third trimesters of gestation. Direct, chronic exposure of the unmyelinated neural placode to toxic amniotic fluid constituents (digestive enzymes, meconium, urea), combined with hydrodynamic trauma and friction against the uterine wall, induces progressive neurocellular apoptosis, axonal loss, and irreversible destruction of anterior horn motor neurons. This biological principle forms the foundation for prenatal intrauterine surgical repair, which halts the second hit by establishing a protective barrier.

Biomechanical Muscle Vector Imbalances (Sharrard’s Principle)

Progressive orthopaedic deformities in myelodysplasia are not primary congenital malformations of the joints, but secondary structural adaptations caused by unbalanced active, innervated muscle forces pulling against paralyzed, flaccid antagonist groups:

• Paralytic Hip Subluxation and Dislocation: In patients with mid-lumbar lesions (L3-L4), active hip flexors (iliopsoas, innervated by L1-L3) and active hip adductors (adductor longus and brevis, innervated by L2-L4) function unopposed by paralyzed hip extensors (gluteus maximus, S1) and hip abductors (gluteus medius, L5). This powerful flexion-adduction force vector drives the femoral head posterosuperiorly, eroding the cartilaginous acetabular rim and causing progressive paralytic subluxation and dislocation.
• Knee Deformity Mechanics: Active L3-L4 quadriceps function unopposed by paralyzed hamstrings leads to dynamic hyperextension and fixed genu recurvatum. Conversely, intact hamstrings without functional quadriceps stabilization cause severe, energy-costly crouch gait and fixed flexion contractures.
• Foot and Ankle – Calcaneocavus Deformity: Intact L4 tibialis anterior function unopposed by a paralyzed gastrocnemius-soleus complex (S1-S2) pulls the forefoot into dorsiflexion, causing the calcaneus to rotate vertically and driving all ground reaction force directly onto the insensate heel pad.
• Foot and Ankle – Rigid Equinovarus (Clubfoot): Active posterior and anterior tibial muscles unopposed by evertors and peroneals produce severe hindfoot varus and forefoot adduction, combined with contracted gastrocsoleus-driven equinus.
• Foot and Ankle – Equinovalgus Deformity: Strong peroneal musculature (L5-S1) unopposed by paralyzed tibialis anterior and posterior musculature produces severe midfoot collapse and lateral column shortening.

4. Natural History

The natural history of myelodysplasia is characterized by predictable neurosegmental functional trajectories, the profound preventive impact of periconceptional folic acid, and a tendency toward functional deterioration during adolescence.

Epidemiology & Primary Prevention

Historically, the birth prevalence of myelodysplasia ranged from 1.5 to 2.5 per 1,000 live births globally. In North America and Western Europe, mandatory dietary folic acid food fortification and widespread prenatal screening have reduced live birth prevalence to approximately 0.3 to 0.5 per 1,000 live births. Periconceptional supplementation with 400 mcg of folic acid daily in women of reproductive potential reduces the occurrence of neural tube defects by 50% to 70%. In women with a previous affected pregnancy, high-dose supplementation (4 mg daily starting 3 months prior to conception through the first trimester) reduces recurrence risk from approximately 3-5% down to less than 1%.

Neurosegmental Mobility Trajectories

Longitudinal cohort studies confirm that functional ambulation correlates directly with the lowest functional neurosegmental motor level:

• Thoracic & High Lumbar (T1-L2): These patients achieve therapeutic standing or household ambulation in early childhood utilizing parapodiums or reciprocating gait orthoses (RGOs). However, by early adolescence (ages 11-14), 90% to 95% permanently transition to wheelchair mobility. The metabolic energy cost of braced ambulation at this level is 200% to 300% higher than normal walking, making wheelchair mobility far more efficient for educational and vocational activities.
• Mid-Lumbar (L3-L4): Children with functional quadriceps (MRC Grade >= 3) achieve independent household and community ambulation during primary school years using knee-ankle-foot orthoses (KAFOs) or ground reaction ankle-foot orthoses (GRAFOs) with forearm crutches. During the adolescent growth spurt, approximately 40% to 50% shift toward wheelchair use for long-distance community navigation to preserve energy and prevent joint breakdown, while retaining functional household ambulation.
• Low Lumbar (L5): Patients possess active knee extension, ankle dorsiflexion, and hip abduction (gluteus medius). They walk independently in the community with ankle-foot orthoses (AFOs). Although they demonstrate a persistent Trendelenburg lurch and lack dynamic push-off, more than 80% retain community ambulation throughout adulthood.
• Sacral (S1-S2): Possessing active gastrocsoleus, hamstring, and gluteus maximus function, these individuals achieve independent community ambulation without orthoses or with simple supramalleolar orthoses (SMOs). Long-term ambulation retention approaches 100% across adulthood.

Adolescent Functional Deterioration & Tethered Cord Syndrome

A substantial proportion of patients experience functional mobility decline during the adolescent growth spurt. This deterioration results from the rapid increase in body weight and limb lever arms outstripping marginal muscle strength, alongside secondary spinal cord tethering. Tethered cord syndrome manifests as progressive lower extremity spasticity, loss of previously documented motor grades, new or worsening foot deformities (particularly cavovarus), rapidly progressive neuromuscular scoliosis, back pain, and decline in urological continence.

5. Clinical Presentation

The clinical assessment must systematically delineate the child’s neurosegmental motor level, sensory boundaries, joint contractures, spine alignment, and multiorgan status.

History

The clinical interview should focus on key milestones and red-flag symptoms:

• Antenatal & Perinatal History: Maternal folic acid intake; maternal serum alpha-fetoprotein (MSAFP) screening; fetal anatomical ultrasound markers (lemon sign indicating bifrontal cranial indentations; banana sign indicating cerebellar caudal displacement); gestational age at closure; prenatal fetal intervention versus postnatal repair.
• Neurosurgical History & Shunt Surveillance: Presence of ventriculoperitoneal (VP) shunt; history and number of shunt revisions; acute symptoms of shunt obstruction or hydrocephalus (morning headache, recurrent vomiting, lethargy, irritability, behavioral changes, new sixth nerve palsy or diplopia, sunsetting eyes).
• Tethered Cord Symptoms: Unexplained loss of previously mastered motor milestones; sudden onset of lower extremity spasticity or clonus; asymmetric limb weakness; rapidly progressing spinal deformity; back or radicular lower extremity pain.
• Urological & Gastrointestinal Function: Clean intermittent catheterization (CIC) frequency (typically every 3 to 4 hours) and caregiver technique; history of febrile urinary tract infections, pyelonephritis, or known hydronephrosis; bowel management regimen and continence status.
• Cutaneous Integrity & Pressure History: History of non-healing skin abrasions, decubitus ulcers over the sacrum, ischia, greater trochanters, or feet; localized redness after orthosis wear.
• Latex Allergy Screen: Precise history of contact dermatitis, facial swelling, urticaria, or intraoperative hypotension associated with rubber products.

Physical Exam

A rigorous physical examination requires detailed motor and sensory mapping combined with provocative joint maneuvers:

• Neurosegmental Motor Assessment (T1-T12): Intercostal and abdominal muscle tone; Beevor sign (upward deflection of the umbilicus during attempted sit-up in lower thoracic paralysis); quadratus lumborum pelvic elevation (T12).
• Neurosegmental Motor Assessment (L1-L2): Iliopsoas (hip flexion) and adductor longus/brevis (hip adduction).
• Neurosegmental Motor Assessment (L3): Quadriceps femoris (knee extension against gravity).
• Neurosegmental Motor Assessment (L4): Tibialis anterior (ankle dorsiflexion with supination/inversion) and medial hamstrings.
• Neurosegmental Motor Assessment (L5): Extensor hallucis longus, extensor digitorum longus, peroneus tertius, and gluteus medius (hip abduction).
• Neurosegmental Motor Assessment (S1): Gastrocnemius-soleus complex (ankle plantarflexion), flexor hallucis longus, and gluteus maximus (hip extension).
• Neurosegmental Motor Assessment (S2-S4): Perianal sensation, voluntary anal sphincter contraction, and bulbocavernosus reflex.
• Sensory & Autonomic Mapping: Meticulous pinprick and light touch testing to define the boundary between sensate and insensate dermatomes. Inspection for vasomotor instability, dependent cyanosis, anhidrosis, and trophic skin changes.
• Spine & Trunk Assessment: Examination of the surgical repair scar; identification of midline stigmata (hypertrichosis, dermal dimples, subcutaneous lipomas); sitting and standing coronal alignment (scoliosis), sagittal alignment (kyphotic gibbus, lordosis), pelvic obliquity, and flexibility of curves on traction.

Provocative examination maneuvers must be documented with precision:

• Thomas Test: [Patient positioned supine; contralateral hip and knee are maximally flexed against the chest to obliterate compensatory lumbar lordosis while ipsilateral extremity is extended toward the examination table] -> Inability of the ipsilateral posterior thigh to lie flat against the table confirms fixed hip flexion contracture [Sensitivity 89%, Specificity 92%].
• Staheli Prone Extension Test: [Patient placed prone with bilateral lower extremities hanging dependent over the edge of the examination table; the examiner stabilizes the sacrum and pelvis with one hand while gently elevating the ipsilateral thigh into extension] -> Inability to extend the thigh to neutral (0°) or above horizontal reveals true fixed hip flexion contracture unmasked by pelvic lordotic compensation [Sensitivity 94%, Specificity 95%].
• Popliteal Angle Test: [Patient supine with the ipsilateral hip flexed to 90°; the examiner passively extends the knee until firm muscular resistance is encountered] -> Popliteal angle exceeding 45° to 50° denotes clinically significant hamstring contracture and posterior capsular tightness [Sensitivity 91%, Specificity 88%].
• Barlow and Ortolani Maneuvers: [In supine infant, Barlow test applies gentle posterior-axial force with the hip in adduction to provoke subluxation; Ortolani test gently abducts the flexed hip while anteriorly elevating the greater trochanter] -> Palpable sensation or audible clunk of the femoral head slipping out of (Barlow) or reducing into (Ortolani) the acetabular socket [Sensitivity 87%, Specificity 96% in neonates].
• Silfverskiöld Test: [Passive ankle dorsiflexion is measured with the knee in full extension and repeated with the knee flexed to 90°, maintaining the subtalar joint in neutral inversion/eversion] -> Restriction of dorsiflexion with the knee extended that completely normalizes with knee flexion confirms isolated gastrocnemius tightness; persistent restriction in both positions confirms contracture of the gastrocnemius-soleus complex or posterior ankle capsule [Sensitivity 95%, Specificity 93%].
• Galeazzi (Allis) Test: [Patient placed supine with hips and knees flexed to 90° with feet flat on the examination surface, comparing the relative height of bilateral knee points] -> Discrepancy in knee height denotes apparent femoral shortening secondary to unilateral hip dislocation or intrinsic femoral length inequality [Sensitivity 92%, Specificity 90%].

6. Imaging and Diagnostic Studies

The diagnostic imaging pathway encompasses multiplanar musculoskeletal radiography, comprehensive neuroaxial magnetic resonance imaging (MRI), and formal urodynamic evaluation.

Spine & Pelvic Radiography

Plain radiography forms the structural foundation of orthopaedic surveillance:

• Full-Length Spine Radiographs (AP and Lateral): Acquired in the erect standing or supported sitting position. Quantifies coronal Cobb angles for neuromuscular scoliosis, sagittal kyphosis (congenital gibbus angle), and lumbar lordosis. Evaluates congenital segmentation anomalies (hemivertebrae, unsegmented bars). Quantifies pelvic obliquity (measured as the angle between the horizontal line and a line connecting the teardrops or bilateral iliac crests).
• Pelvis and Bilateral Hip Radiographs (AP and Frog-Leg Lateral): Evaluates acetabular index (normal <24° by age 2; dysplastic >30°), Reimer’s migration percentage (percentage of femoral head ossific nucleus extruding lateral to Perkin’s line; >33% defines subluxation, 100% defines complete dislocation), Shenton line continuity, and femoral neck-shaft angle (coxa valga >140°).

Lower Extremity Radiography

Weight-bearing or simulated weight-bearing radiographs of the foot and ankle define multiplanar alignment:

• Talocalcaneal Angle (Kite’s Angle): Measured on AP and lateral projections. Normal ranges between 25° and 40°. An angle <20° confirms hindfoot varus (equinovarus / clubfoot), whereas an angle >45° confirms hindfoot valgus.
• Meary’s Angle (Talo-First Metatarsal Angle): Measured on lateral weight-bearing radiograph. A straight line (0° ± 5°) is normal; apex dorsal angulation indicates pes cavus, while apex plantar angulation indicates pes planus or rocker-bottom deformity.
• Lateral Tibiocalcaneal Angle: Normal resting alignment is approximately 70° to 80°; an angle <60° confirms acute calcaneus deformity, whereas an angle >90° confirms equinus deformity.

Advanced Neuroimaging

Cross-sectional neuroimaging is essential for identifying treatable central nervous system pathologies:

• Cranial MRI / CT: Evaluates ventriculomegaly, Chiari II malformation (downward herniation of the cerebellar vermis and brainstem through the foramen magnum, tectal beaking, compressed fourth ventricle), and VP shunt catheter positioning.
• Whole-Spine MRI (T1, T2, and 3D FIESTA/CISS Sequences): Evaluates spinal cord tethering (low-lying conus medullaris terminating below L2, thickened filum terminale >2 mm), intradural lipomas, epidermoid inclusion cysts, diastematomyelia (split cord malformation with an osseous or cartilaginous septum), and syringomyelia / hydromyelia (present in up to 40% of patients with Chiari II malformation).

Renal & Urodynamic Studies

Renal and bladder assessments protect lifelong renal parenchymal integrity:

• Renal & Bladder Ultrasonography: Evaluates hydronephrosis, hydroureter, renal parenchymal thickness, renal scarring, nephrolithiasis, and bladder wall hypertrophy/trabeculation.
• Video Urodynamic Studies (VUDS): The gold standard for assessing neurogenic lower urinary tract dysfunction. Evaluates detrusor hyperreflexia, detrusor-sphincter dyssynergia (DSD), and detrusor leak point pressure (DLPP). A DLPP > 40 cm H2O indicates dangerously elevated storage pressure with high risk for secondary vesicoureteral reflux, hydronephrosis, and irreversible renal failure.

7. Classification

Validated classification systems in myelodysplasia guide functional prognosis and dictate surgical decision-making.

The Hoffer Functional Ambulation Classification remains the benchmark system for stratifying mobility outcomes:

8. Treatment

The management of myelodysplasia demands a coordinated interdisciplinary algorithm that integrates medical stabilization, specialized orthotics, and carefully indicated operative reconstructions.

Medical / Nonoperative Management

Nonoperative care forms the continuous foundation of health maintenance throughout the patient’s lifespan:

• Multidisciplinary Clinic Architecture: Patients must be managed within a dedicated spina bifida clinic uniting pediatric orthopaedic surgery, pediatric neurosurgery, pediatric urology, physiatry, physical therapy, certified orthotists, enterostomal nursing, and social work to streamline surgical scheduling and surveillance.
• Neurogenic Bladder Protocol: Clean intermittent catheterization (CIC) initiated in early infancy every 3 to 4 hours. Oral anticholinergics (oxybutynin, tolterodine) or beta-3 agonists (mirabegron) are prescribed to suppress uninhibited detrusor hyperreflexia and maintain low intravesical storage pressure (<40 cm H2O). Refractory high detrusor pressures warrant intradetrusor botulinum toxin A injections. Prophylactic antibiotics are utilized selectively for recurrent febrile urinary infections.
• Neurogenic Bowel Regimen: Daily timed bowel evacuation protocols starting around age 2-3 years to establish social continence and prevent impaction. Modalities include high-fiber diets, osmotic laxatives (polyethylene glycol), glycerin or bisacodyl suppositories, retrograde transanal irrigation systems, or surgical antegrade continence enemas (MACE procedure).
• Orthotic Management – Parapodium (T1-L2): Static standing frame initiated at 12 to 18 months of age for thoracic and high lumbar (T1-L2) patients to encourage upright posture, promote femoral and acetabular development, enhance bone mineral density, and facilitate visual-spatial interaction.
• Orthotic Management – Reciprocating Gait Orthosis (RGO) / HKAFO (L1-L2): Utilized in motivated L1-L2 patients for therapeutic reciprocal ambulation; mechanically couples hip flexion of one limb with contralateral hip extension.
• Orthotic Management – Knee-Ankle-Foot Orthosis (KAFO) (L3): Indicated for L3 patients with quadriceps strength of Grade 3 who lack sufficient knee extension control or demonstrate recurvatum.
• Orthotic Management – Ground Reaction Ankle-Foot Orthosis (GRAFO) (L4): Indicated for L4 patients with quadriceps strength of Grade 4 or greater who display a crouch gait. The rigid anterior tibial shell resists ankle dorsiflexion in stance phase, creating an external knee extension moment.
• Orthotic Management – Ankle-Foot Orthosis (AFO) (L5): Articulated or solid custom AFOs for L5 patients to prevent foot drop during swing phase and provide midfoot stability.
• Orthotic Management – Supramalleolar Orthosis (SMO) / Foot Orthosis (FO) (S1-S2): Indicated for S1-S2 patients to stabilize dynamic hindfoot valgus or support moderate cavus feet.
• Universal Latex-Free Precautions: Complete elimination of natural rubber latex products across all clinical encounters from birth. The repeated mucosal and surgical exposure creates sensitization in up to 70% of individuals, predisposing to fatal anaphylaxis.

Operative Interventions

Surgical reconstruction in myelodysplasia is governed by explicit functional goals: preserve neural function, maintain a stable sitting and standing platform, correct joint contractures, and achieve a plantigrade, braceable, ulcer-free foot.

• Fetal Intrauterine Repair (MOMS Protocol): Performed via open hysterotomy or fetoscopic approach between 19 and 25.9 weeks of gestation for eligible maternal-fetal dyads, significantly decreasing hydrocephalus shunt rates and improving motor outcomes (MOMS trial protocol).
• Neonatal Spinal Closure: Performed within 24 to 48 hours of birth for postnatal presentations to prevent central nervous system ventriculitis and sepsis.
• Hydrocephalus Management & Shunting: Ventriculoperitoneal (VP) shunt insertion with programmable valves, or endoscopic third ventriculostomy with choroid plexus cauterization (ETV/CPC).
• Surgical Cord Detethering: Indicated for progressive neurological deterioration, escalating spasticity, or rapid scoliosis; involves laminectomy, intradural microneurolysis, and transection of the thickened filum terminale.
• Unilateral Paralytic Hip Dislocation Reconstruction: Indicated in ambulatory patients with L3-L4 motor function to prevent severe pelvic obliquity, secondary scoliosis, and sitting asymmetry. Involves open reduction, capsulorrhaphy, femoral varus derotation osteotomy (VDRO), pelvic osteotomy (Pemberton, Dega, or Salter), and balancing muscle transfer (iliopsoas transfer to the greater trochanter).
• Bilateral Paralytic Hip Dislocations (Nonoperative Mandate): Surgical reduction is CONTRAINDICATED in thoracic and high lumbar levels, and generally NOT recommended in mid-lumbar levels. Bilaterally dislocated hips remain mobile, flexible, and painless, whereas open reduction carries a high rate of recurrent dislocation, joint stiffness, avascular necrosis, pathologic fractures, and decubitus ulcers without conferring any measurable gain in ambulatory capacity.
• Knee Flexion Contracture Release: Fixed flexion contractures increase the quadriceps workload exponentially during braced ambulation. Addressed by fractional distal hamstring lengthening (semitendinosus, semimembranosus, gracilis, and biceps femoris), combined with posterior knee capsulotomy if contracture exceeds 30°. For skeletally mature patients with severe fixed flexion (>25°), distal femoral extension osteotomy with rigid blade-plate or locking plate fixation is preferred.
• Knee Extension / Hyperextension Realignment: Fixed hyperextension impairs sitting and brace fitting. Managed with V-Y quadricepsplasty or distal rectus femoris/vastus intermedius lengthening for rigid contractures >30°.
• Foot & Ankle Realignment Principles: The singular goal of foot and ankle reconstruction is to achieve a plantigrade, flexible, braceable, ulcer-free foot. Cosmetic appearance is subordinate to skin integrity.
• Equinovarus (Clubfoot) Correction: Initial treatment is modified Ponseti serial casting with early percutaneous Achilles tenotomy; extensive posteromedial release is reserved for rigid syndromic recurrences.
• Talectomy (Menelaus Procedure) Salvage: Indicated as a reliable salvage procedure for severe, rigid, recurrent equinovarus in non-ambulatory or household ambulatory children. Excision of the talus allows the calcaneus to displace posteriorly and superiorly into the ankle mortise, providing a stable, plantigrade foot with low recurrence and minimal risk of skin necrosis.
• Calcaneocavus Peabody Tendon Transfer: Managed with anterior tibialis tendon transfer through the interosseous membrane to the posterior calcaneus (Peabody procedure) combined with plantar fascia release to eliminate the unopposed dorsiflexion deforming vector and restore heel padding.
• Strict Prohibition of Triple Arthrodesis: Triple arthrodesis is strictly contraindicated in insensate feet. The combination of dense sensory loss, poor vascularity, and osteopenia leads to catastrophic nonunion rates (>50%), Charcot neuroarthropathy, and rigid bony prominences that cause intractable plantar ulceration and eventual lower extremity amputation.
• Neuromuscular Scoliosis Stabilization: Progressive curves exceeding 50° in ambulatory or non-ambulatory children require posterior spinal fusion and segmental pedicle screw instrumentation extending from upper thoracic spine (T2-T3) down to the pelvis/sacrum (utilizing bilateral iliac or S2-alar-iliac [S2AI] screws) to level pelvic obliquity and provide a stable sitting base.
• Congenital Kyphosis (“Gibbus”) Kyphectomy: Severe progressive thoracolumbar kyphosis exceeding 80° with impending skin necrosis requires posterior vertebral column resection (PVCR) or kyphectomy with rigid segmental instrumentation, often combined with myocutaneous flap advancement (latissimus dorsi or gluteal advancement) for durable soft tissue coverage.

Indications & Contraindications

Definitive numerical and clinical thresholds govern operative decision-making:

• Neuromuscular Scoliosis Fusion: Indicated for progressive curves >50° in skeletally immature or mature patients, or pelvic obliquity >15° compromising sitting balance.
• Gibbus Kyphectomy: Indicated for fixed thoracolumbar kyphosis >80° or progressive skin impingement over the apical bony prominence.
• Unilateral Hip Reconstruction: Indicated in ambulatory patients with L3-L4 motor function, quadriceps strength >= Grade 3, and Reimer’s migration percentage >33%.
• Hip Surgery Contraindication: Operative reduction is strictly contraindicated for bilateral paralytic hip dislocations in any patient, and for unilateral dislocations in non-ambulatory thoracic or L1-L2 patients.
• Knee Flexion Release: Indicated for fixed flexion contractures >15° to 20° in ambulatory children, or >30° in non-ambulatory children impeding wheelchair positioning.
• Triple Arthrodesis Contraindication: Triple arthrodesis is absolutely contraindicated in insensate extremities regardless of deformity magnitude.

9. Outcome

Modern outcomes in myelodysplasia are evaluated through validated patient-reported outcome measures (PROMs), long-term mobility retention data, and adult survivorship indices.

Functional Ambulation Retention

Longitudinal registry studies demonstrate that functional ambulation retention into adulthood is strictly tied to baseline neurosegmental level and quadriceps strength. Among community ambulators classified by the Hoffer system at age 10, over 85% of sacral and low-lumbar (L5) patients maintain community ambulation past the third decade of life. In contrast, mid-lumbar (L3-L4) ambulators demonstrate approximately 50% retention of household or limited community ambulation, with many adopting manual or power wheelchairs for vocational and community travel to optimize efficiency and minimize repetitive strain injuries to the upper extremities.

Patient-Reported Outcome Measures (PROMs)

Standardized assessment instruments evaluate physical function, quality of life, and social integration:

• Pediatric Outcomes Data Collection Instrument (PODCI): Demonstrates significant improvements in transfers and basic mobility following spinal deformity correction and contracture releases, while sports/physical function domains remain limited by neurosegmental level.
• Pediatric Quality of Life Inventory (PedsQL): Confirms that psychosocial health domains and perceived quality of life in young adults with myelodysplasia correlate more strongly with social continence (effective bowel and bladder management) and independent living skills than with independent walking capacity.
• Functional Independence Measure for Children (WeeFIM): Documents that self-care and sphincter control scores correlate directly with early multidisciplinary interventions and caregiver education.

Survivorship & Adult Transition

Modern multidisciplinary care has increased survival into adulthood to over 80-85%. However, adult health maintenance presents major challenges: secondary obesity affects up to 60-70% of non-ambulatory individuals; neuropathic decubitus ulcers develop in 30-40% of adult patients; and secondary renal failure remains a leading cause of premature mortality in patients with non-adherent bladder regimens.

10. Complications

Complications in myelodysplasia range from catastrophic perioperative emergencies to debilitating chronic neuropathic tissue breakdowns.

11. Pearls and Pitfalls

Expert management requires vigilant attention to unique clinical subtleties and the avoidance of common surgical traps:

• The “Swollen Warm Leg Trap” (Painless Occult Fracture): Never diagnose cellulitis, thrombophlebitis, or osteomyelitis in a child with myelodysplasia presenting with an acutely swollen, warm, erythematous thigh or leg without first obtaining plain radiographs. Flaccid, osteopenic bones fracture with trivial transfers or following cast removal. Lack of deep sensation eliminates pain, while denervation-induced autonomic dysregulation produces exuberant local hyperemia, dramatic soft tissue swelling, and massive hyperplastic callus that can be easily mistaken for an aggressive bone tumor or acute osteomyelitis.
• The “Shunt Before Spine Rule”: Always interrogate shunt function and obtain cranial neuroimaging prior to scheduling major elective spinal or lower extremity reconstructive surgery. Latent ventriculoperitoneal shunt malfunction or progressive hydromyelia can present subtly as rapidly progressing scoliosis. Correcting the spinal deformity in the setting of untreated hydrocephalus can precipitate acute brainstem herniation or permanent postoperative neurological loss.
• The “Plantigrade Braceable Foot Pearl”: In myelodysplastic foot surgery, never prioritize radiographic perfection over soft tissue compliance and plantigrade braceability. The sole objective is a soft, supple, plantigrade platform that evenly dissipates ground reaction forces inside an orthosis. A stiff, anatomically “perfect” foot will invariably develop focal high-pressure zones over rigid bony prominences, leading to intractable neuropathic ulcers and eventual amputation.
• The “Bilateral Hip Trap”: Resist the urge to perform open reduction and femoral/pelvic osteotomies for bilateral paralytic hip dislocations in myelodysplasia. Bilaterally dislocated hips remain supple, mobile, painless, and well-balanced. Surgical reduction carries an unacceptably high rate of stiffness, redislocation, avascular necrosis, pathologic fractures, and decubitus ulcerations without improving ambulatory capacity or energy consumption.
• The “Universal Latex Mandate”: Treat every patient with myelodysplasia as having a confirmed, life-threatening latex allergy from the moment of birth. Never permit natural rubber latex gloves, Foley catheters, tourniquets, or vial stoppers into the operating room, clinic, or emergency suite.

12. Controversy

Several major areas of ongoing clinical debate continue to shape the surgical and medical management of myelodysplasia:

• Prenatal Open Hysterotomy vs. Minimally Invasive Fetoscopic Repair: The landmark MOMS trial established that open prenatal hysterotomy repair at 19 to 25.9 weeks significantly reduces ventriculoperitoneal shunting and improves motor outcomes compared to postnatal closure. However, open maternal hysterotomy carries substantial maternal risks, including uterine dehiscence, uterine rupture in future pregnancies, and mandatory delivery via Cesarean section. Over the past decade, minimally invasive percutaneous and laparotomy-assisted fetoscopic repair techniques have emerged, demonstrating comparable rates of hindbrain herniation reversal and ambulatory gains with significantly lower maternal morbidity and permitting vaginal delivery. Ongoing trials are defining whether fetoscopic repair provides equal long-term dural sealing and equivalent neurosegmental durability at school age.
• Management of Bilateral Paralytic Hip Dislocations: While there is strong surgical consensus that unilateral paralytic hip dislocations in ambulatory patients (L3-L4) require reconstruction to prevent pelvic obliquity and secondary scoliosis, the management of bilateral dislocations remains controversial in borderline ambulatory patients. Proponents of surgical reconstruction argue that maintaining concentric reductions optimizes biomechanical lever arms and improves standing stability. Conversely, the overwhelming majority of long-term natural history studies demonstrate that bilateral relocations universally result in stiff, painful hips with high complication rates, and that untreated bilateral dislocations do not impede functional walking or sitting. Modern consensus strongly favors nonoperative observation for bilateral paralytic dislocations.
• Prophylactic Cord Detethering vs. Observation for Progressive Scoliosis: In a child with myelodysplasia presenting with progressive spinal curvature without overt urological or lower extremity motor decline, the role and timing of surgical cord detethering prior to spinal deformity correction is debated. One school of thought advocates mandatory prophylactic neurosurgical detethering to halt curve progression and prevent intraoperative traction-induced neural injury during subsequent spinal fusion. The opposing viewpoint maintains that asymptomatic radiological tethering is near-universal in repaired myelomeningocele, that detethering carries a risk of secondary scarring and additional neurological deficit, and that spinal fusion can be safely performed without prior detethering provided distraction forces are avoided and multimodal intraoperative neuromonitoring is strictly maintained.

13. Evidence-Based Synthesis

Modern clinical decision-making is grounded in high-quality randomized controlled trials and prospective registry analyses, corroborated by seminal biomechanical and anatomical descriptions.

14. References

• Adzick NS, Thom EA, Spong CY et al. A Randomized Trial of Prenatal versus Postnatal Repair of Myelomeningocele. New England Journal of Medicine. 2011. doi:10.1056/NEJMoa1014379 [Level I: Multicenter Randomized Controlled Trial (MOMS)]
• Houtrow AJ, Thom EA, Fletcher JM et al. Prenatal Repair of Myelomeningocele and School-age Functional Outcomes. Pediatrics. 2020. doi:10.1542/peds.2019-1544 [Level I: Randomized Trial Long-Term Follow-up Cohort (MOMS2)]
• Hoffer MM, Feiwell E, Perry R et al. Functional Ambulation in Patients with Myelomeningocele. The Journal of Bone & Joint Surgery. 1973. doi:10.2106/00004623-197355010-00014 [Level IV: Seminal Prognostic Cohort Study]
• Sharrard WJW. The Orthopaedic Surgery of Spina Bifida. Clinical Orthopaedics and Related Research. 1973. doi:10.1097/00003086-197305000-00016 [Level V: Seminal Surgical Review & Biomechanical Analysis]
• Dias LS. Surgical Management of Knee Contractures in Myelomeningocele. Journal of Pediatric Orthopaedics. 1982. doi:10.1097/01241398-198202020-00002 [Level IV: Retrospective Therapeutic Case Series]
• Menelaus MB. TALECTOMY FOR EQUINOVARUS DEFORMITY IN ARTHROGRYPOSIS AND SPINA BIFIDA. The Journal of Bone and Joint Surgery. British volume. 1971. doi:10.1302/0301-620x.53b3.468 [Level IV: Therapeutic Case Series / Surgical Technique]

15. Master Class Pro-Tip

When approaching lower extremity deformities in myelodysplasia, always remember that an insensate foot obeys completely different biological rules than an idiopathic or cerebral palsy foot. Never perform a triple arthrodesis or aggressive multi-articular fusion on an insensate extremity; the nonunion rate exceeds 50%, and any residual rigid bony prominence will inevitably generate an intractable plantar neuropathic ulcer. Instead, focus entirely on creating a supple, plantigrade, brace-tolerant foot through judicious tendon transfers, soft tissue releases, and selective extra-articular or salvage resections such as a talectomy. When operating on the hip, never attempt to reduce bilateral paralytic dislocations; leaves the hips mobile, symmetric, and painless. In every case, maintain absolute universal latex precautions, and treat any acute warm, swollen lower extremity as an occult neuropathic fracture until proven otherwise by plain radiography.

Master Class Surgical Pearl: Strategic Orthopaedic Realignment and Neuropathic Tissue Preservation in Myelodysplasia