#separator:tab #html:true #tags column:3 #reference column:4 What is the 2007 consensus definition of Cerebral Palsy (Rosenbaum et al., DMCN)? A group of permanent disorders of the development of movement and posture, causing activity limitation, that are attributed to non-progressive disturbances that occurred in the developing fetal or infant brain.

Accompaniments: Disturbances of sensation, perception, cognition, communication, behavior, epilepsy, and secondary musculoskeletal problems. CP::Definition Rosenbaum2007 InternationalConsensus Lovell & Winter Ch. 14, p. 488 What is the population prevalence of Cerebral Palsy in developed nations? Approximately 2.0 to 2.5 per 1,000 live births.

Trend: The prevalence has remained remarkably stable over the past 50 years. Increased survival of extremely low birth weight (ELBW, <1000g) and extremely preterm (<28 weeks) infants counterbalances decreases in term hypoxic birth trauma. CP::Epidemiology Prevalence ELBW Lovell & Winter Ch. 14, p. 488 What percentage of cerebral palsy cases are caused by acute intrapartum hypoxia (birth asphyxia)? Only 10% to 20%.

The vast majority (80% to 90%) are due to antenatal developmental, genetic, vascular, or environmental factors occurring prior to labor. CP::Etiology Intrapartum Hypoxia Antenatal Lovell & Winter Ch. 14, p. 488 Who was Dr. William John Little, and what was his historical contribution to cerebral palsy? English orthopaedic surgeon who in 1861 first linked abnormal parturition with spastic diplegia (termed "Little's Disease").

Little popularized subcutaneous tenotomies for equinus and was the first to bridge the gap between neurology and orthopaedic surgery. CP::History WilliamLittle LittlesDisease Tenotomy Lovell & Winter Ch. 14, p. 488 What was Sigmund Freud's contribution to the understanding of cerebral palsy in 1893? Freud challenged Little's concept by proposing that difficult labor is frequently an effect/symptom of pre-existing abnormal fetal brain development rather than the primary cause of cerebral palsy. CP::History SigmundFreud AntenatalEtiology Lovell & Winter Ch. 14, p. 488 What was Sir William Osler's contribution to cerebral palsy in 1889? Published the seminal monograph The Cerebral Palsies of Children, establishing the first clinical classification into hemiplegia, bilateral spasticity, and paraplegia. CP::History WilliamOsler Classification Lovell & Winter Ch. 14, p. 488 What brain pathology characterizes a primary insult during the FIRST trimester of pregnancy (0–12 weeks)? Disorders of brain morphogenesis and organogenesis:
• Lissencephaly (smooth brain / agyria)
• Holoprosencephaly
• Microcephaly
• Neural tube defects

Etiologies: Chromosomal anomalies, genetic mutations, TORCH infections, maternal teratogens. CP::Neuroembryology FirstTrimester Morphogenesis Malformations Lovell & Winter Ch. 14, p. 489 What is Periventricular Leukomalacia (PVL), and what gestational age is at peak risk? Ischemic infarction and cystic necrosis of the deep periventricular white matter adjacent to the lateral ventricles.

• Peak Vulnerability: 24 to 34 weeks gestation (Second to early Third Trimester).
• Anatomic Basis: Premature arterial borderzones (watershed regions) have limited autoregulation and high vulnerability of immature pre-oligodendrocytes.
• Clinical Outcome: Spastic Diplegia (lower extremity corticospinal fibers run closest to the ventricular walls). CP::Neuroembryology PVL Preterm SpasticDiplegia Lovell & Winter Ch. 14, p. 489 What neuropathology occurs in full-term infants (>36 weeks) suffering severe acute hypoxic-ischemic encephalopathy (HIE)? Selective neuronal necrosis of the metabolically active deep gray matter:
• Basal Ganglia (putamen, globus pallidus)
• Thalamus
• Parasagittal sensorimotor cortex

Clinical Presentation: Dyskinetic (athetoid / dystonic) cerebral palsy or severe spastic quadriplegia. CP::Neuroembryology HIE TermAsphyxia BasalGanglia Dyskinetic Lovell & Winter Ch. 14, p. 489 Neonatal focal arterial ischemic stroke (most commonly Middle Cerebral Artery territory) leads to which clinical type of CP? Unilateral Spastic Cerebral Palsy (Spastic Hemiplegia).

Presents with asymmetric hand preference before 12 months of age, unilateral fisting, and asymmetric lower extremity kicks. CP::Neuroembryology MCAStroke Hemiplegia Lovell & Winter Ch. 14, p. 489 Why is the persistence of primitive infant reflexes (Moro, ATNR, STNR, palmar grasp) beyond 6 months clinically significant? Primitive reflexes are normally eliminated by 4 to 6 months due to descending corticospinal myelination.

Persistence indicates upper motor neuron damage, prevents the emergence of equilibrium and protective righting reactions, and leads to fixed contractual postures. CP::Development PrimitiveReflexes ATNR UMN Lovell & Winter Ch. 14, p. 489 List the 5 internationally validated five-level classification systems used in cerebral palsy: 1. GMFCS: Gross Motor Function Classification System
2. MACS: Manual Ability Classification System
3. CFCS: Communication Function Classification System
4. EDACS: Eating and Drinking Ability Classification System
5. VSS: Viking Speech Scale CP::Classification 5LevelSystems Multidisciplinary Lovell & Winter Ch. 14, p. 490 Describe GMFCS Level I: Walks without limitations.
• Walks indoors and outdoors; climbs stairs without holding a railing.
• Can run and jump, but speed, balance, and coordination are limited.
• Gross motor curves peak near 100% GMFM score by age 5–6. CP::Classification GMFCS LevelI Lovell & Winter Ch. 14, p. 490-492 Describe GMFCS Level II: Walks with limitations.
• Walks in most settings; climbs stairs holding a railing.
• Experiences difficulty walking long distances and balancing on uneven terrain, inclines, or crowded spaces.
• Minimal to no ability to run and jump. CP::Classification GMFCS LevelII Lovell & Winter Ch. 14, p. 490-492 Describe GMFCS Level III: Walks using a hand-held mobility device.
• Walks using canes, crutches, or a posterior rollator/walker indoors.
• Uses wheeled mobility when traveling long distances in the community.
• May climb stairs holding a railing with physical supervision. CP::Classification GMFCS LevelIII Lovell & Winter Ch. 14, p. 490-492 Describe GMFCS Level IV: Self-mobility with limitations; may use powered mobility.
• Uses wheeled mobility in most home, school, and community settings.
• May walk short distances at home with body-weight support walkers or physical assistance.
• Requires adaptive seating and assistance for transfers. CP::Classification GMFCS LevelIV Lovell & Winter Ch. 14, p. 490-492 Describe GMFCS Level V: Transported in a manual wheelchair in all settings.
• Severe limitations in head and trunk control.
• No independent antigravity postural control; requires custom-molded seating supports.
• 90% incidence of progressive hip displacement. CP::Classification GMFCS LevelV Lovell & Winter Ch. 14, p. 490-492 What is the MACS (Manual Ability Classification System), and how does it grade upper limb function? Classifies how children handle objects in daily tasks:
• Level I: Handles objects easily and successfully.
• Level II: Handles most objects with reduced quality/speed.
• Level III: Handles objects with difficulty; requires modifications.
• Level IV: Handles limited, easily managed objects with adaptation.
• Level V: Does not handle objects; severely limited even for simple actions. CP::Classification MACS UpperLimb Lovell & Winter Ch. 14, p. 491 What is the clinical significance of EDACS (Eating and Drinking Ability Classification System) in PMR? Categorizes eating and drinking safety and efficiency into 5 levels.

Clinical Value: Essential for identifying aspiration risk, chronic pulmonary micro-aspiration, and malnutrition. Levels IV and V indicate unsafe swallowing, necessitating enteral tube feeding (PEG/gastrostomy). CP::Classification EDACS Swallowing Aspiration Lovell & Winter Ch. 14, p. 491 At what age do GMFM-66 gross motor curves plateau in children with cerebral palsy? Between 3 and 6 years of age.

• GMFCS Level V curves plateau earliest (around 3 years of age at 15–20% GMFM score).
• GMFCS Level I curves plateau latest (5 to 6 years of age at >90% GMFM score). CP::NaturalHistory MotorPlateau GMFMCurves Lovell & Winter Ch. 14, p. 492 What is the "Natural History Fallacy" in pediatric cerebral palsy research? The mistaken attribution of gross motor improvements to an intervention (e.g., physical therapy, hyperbaric oxygen, Botox) during the first 4 years of life, when the gains actually reflect the child's natural developmental ascent curve.

Rule: Association is not causation; all intervention studies in young children require rigorous control groups. CP::NaturalHistory NaturalHistoryFallacy ResearchMethodology Lovell & Winter Ch. 14, p. 492 Why do adolescents in GMFCS Levels III and IV frequently experience functional loss of walking ability in the second decade? 1. Rapid growth and body mass gain exceed the torque capacity of hypoplastic, weakened muscles.
2. Progressive lever-arm dysfunction: Worsening crouch gait, external tibial torsion, and foot collapse increase the energetic cost of walking.
3. Joint pain and fatigue lead to transitioning to manual or power wheelchairs. CP::NaturalHistory FunctionalDecline Adolescence GMFCSIII Lovell & Winter Ch. 14, p. 492 What is the foundational cardinal axiom regarding cerebral palsy pathology? "The brain injury in cerebral palsy is static and non-progressive, but the secondary musculoskeletal pathology is relentlessly progressive." CP::Pathophysiology CardinalAxiom Neuromusculoskeletal Lovell & Winter Ch. 14, p. 493 Explain the "Sarcomere Length Paradox" in spastic muscle (Lieber, Fridén, Graham): Despite spastic muscles being short and contracted clinically, their in vivo resting sarcomeres are paradoxically hyper-lengthened (3.5 to 4.0+ µm vs normal 2.5 to 2.7 µm).

Mechanism: Spastic muscle suffers a failure of longitudinal sarcomerogenesis (fewer serial sarcomeres). Fewer sarcomeres are stretched over the bone's length, placing them on the descending limb of the active length-tension curve (early passive tension + profound active weakness). CP::Pathophysiology SarcomereParadox Lieber LengthTension Lovell & Winter Ch. 14, p. 493 What alterations occur in the Extracellular Matrix (ECM) and satellite stem cells of spastic muscle? • Extracellular Matrix: Marked proliferation of dense endomysial and perimysial collagen (fibrosis), leading to severe passive stiffness.
• Satellite Cells: Profound depletion and transcriptional dysfunction of muscle satellite stem cells, causing muscle belly volume reduction (30% to 50% hypoplasia). CP::Pathophysiology ECMFibrosis SatelliteCells MuscleVolume Lovell & Winter Ch. 14, p. 493 How does the Modified Tardieu Scale distinguish dynamic spasticity from fixed contracture? • R1 Angle (Angle of Catch): Angle at which resistance/catch is felt during high-velocity stretch (V3) → reflects dynamic neural spasticity.
• R2 Angle: Full passive range of motion measured at slow speed (V1) → reflects fixed structural contracture.
• Dynamic Range (R2 – R1):
  - Large (R2 – R1 > 20°): Tone reduction (BoNT-A, SDR) indicated.
  - Small (R2 – R1 < 5°): Fixed contracture; surgical lengthening required. CP::Examination TardieuScale R1R2 SpasticityVsContracture Lovell & Winter Ch. 14, p. 494 Define Spasticity vs Dystonia: • Spasticity: Velocity-dependent resistance to passive stretch with exaggerated tendon reflexes resulting from upper motor neuron / pyramidal pathway lesion.
• Dystonia: Involuntary sustained or intermittent muscle contractions causing twisting and repetitive movements or abnormal postures; triggered by voluntary action or stress (basal ganglia / extrapyramidal). CP::Tone Spasticity Dystonia UMN Lovell & Winter Ch. 14, p. 494 What are Gage's 4 mechanisms of Lever-Arm Dysfunction in cerebral palsy? 1. Lever-arm deficiency: Loss of fulcrum (e.g., patella alta weakening quadriceps mechanical advantage).
2. Lever-arm malfunction: Torsional bony deformities (e.g., femoral anteversion + external tibial torsion).
3. Abnormal force vector: Misdirected muscle line of action (e.g., adductor pull displacing the femoral head).
4. Underlying muscle weakness: Inability of hypoplastic muscle to generate required internal joint moments. CP::Biomechanics LeverArmDeficiency Gage CrouchGait Lovell & Winter Ch. 14, p. 495 What are the 4 essential components of modern 3D Instrumental Gait Analysis (IGA)? 1. 3D Kinematics: Joint angles across sagittal, coronal, and transverse planes (motion capture).
2. 3D Kinetics: Ground reaction force vectors, joint moments, and joint powers (force plates).
3. Dynamic EMG: Timing of muscle activation (surface/fine-wire).
4. Pedobarography: Plantar pressure distribution and dynamic center of pressure. CP::GaitAnalysis IGA Kinematics Kinetics EMG Lovell & Winter Ch. 14, p. 496 What is the Gillette Gait Index (GGI) / Normalcy Index? A single composite index calculated from 16 kinematic variables comparing a patient's gait to a healthy control database.

A lower score represents a more normal gait; a higher score represents greater pathology. Used as the primary outcome measure in Level I SEMLS trials. CP::GaitAnalysis GGI GilletteGaitIndex OutcomeMeasure Lovell & Winter Ch. 14, p. 496 What is the Gait Deviation Index (GDI)? A validated metric derived from 9 kinematic variables. A score of 100 indicates normal gait; every 10 points below 100 represents 1 standard deviation from typical gait. CP::GaitAnalysis GDI Kinematics Lovell & Winter Ch. 14, p. 496 Describe Pattern 1: True Equinus (Rodda & Graham Classification): • Ankle: Plantarflexion throughout stance (forefoot contact).
• Knee: Full extension or genu recurvatum in mid-to-terminal stance.
• Hip: Full extension; pelvis neutral.
• Etiology: Gastrocnemius or gastrosoleus contracture.
• Treatment: Strayer gastrocnemius recession or hinged AFO with plantarflexion stop. CP::GaitPatterns TrueEquinus Pattern1 Strayer Lovell & Winter Ch. 14, p. 497 Describe Pattern 2: Jump Gait (Rodda & Graham Classification): • Ankle: Equinus throughout stance.
• Knee: Excessive flexion at initial contact, followed by sudden "jump" extension in late stance.
• Hip: Flexion and adduction contracture.
• Etiology: Spastic gastrocnemius, hamstrings, and hip flexors.
• Treatment: Gastrocnemius recession + medial hamstring lengthening. CP::GaitPatterns JumpGait Pattern2 HamstringLengthening Lovell & Winter Ch. 14, p. 497 Describe Pattern 3: Apparent Equinus (Rodda & Graham Classification) and its CRITICAL PITFALL: • Ankle: Normal neutral dorsiflexion (0° to 10° DF).
• Knee: Excessive flexion throughout stance (>20°).
• Hip: Excessive flexion and anterior pelvic tilt.
• Clinical Pearl: The child appears to walk on toes because the limb is functional shortened by flexed hips and knees, NOT by calf contracture!
• FATAL PITFALL: DO NOT lengthen the Achilles tendon! Lengthening the heel cord causes catastrophic iatrogenic crouch gait. CP::GaitPatterns ApparentEquinus Pattern3 SurgicalPitfall Contraindication Lovell & Winter Ch. 14, p. 497 Describe Pattern 4: Crouch Gait (Rodda & Graham Classification): • Ankle: Excessive dorsiflexion / calcaneus (>15° DF) with midfoot collapse.
• Knee: Severe flexion (>30°) throughout stance phase.
• Hip: Excessive flexion and anterior pelvic tilt.
• Etiology: Soleus weakness, iatrogenic post-Achilles lengthening, tight hamstrings, patella alta.
• Management: Ground Reaction AFO (GRAFO), Distal Femoral Extension Osteotomy (DFEO) + Patellar Tendon Advancement (PTA). CP::GaitPatterns CrouchGait Pattern4 GRAFO DFEO Lovell & Winter Ch. 14, p. 497-498 What is the definition, clinical test, and management of "Stiff Knee Gait"? • Definition: Peak swing-phase knee flexion <50° or delayed timing, causing foot clearance failure and tripping.
• Clinical Test: Positive Duncan-Ely test (prone knee flexion induces sudden ipsilateral hip flexion).
• Dynamic EMG: Inappropriate, continuous rectus femoris firing in swing phase.
• Surgical Gold Standard: Rectus Femoris Transfer to Semitendinosus (Perry & Gage). CP::GaitPatterns StiffKneeGait DuncanEly RectusTransfer Lovell & Winter Ch. 14, p. 498, 519 What is the incidence of hip displacement according to GMFCS Level? • GMFCS Level I: 0% to 5%
• GMFCS Level II: 15%
• GMFCS Level III: 41%
• GMFCS Level IV: 69%
• GMFCS Level V: 90%

Clinical Principle: Hip displacement risk correlates strictly with GMFCS level, NOT with topographical subtype. CP::HipSurveillance Incidence GMFCSLevels Lovell & Winter Ch. 14, p. 499 State the formula and clinical cut-offs for Reimers Migration Percentage (MP): $$\text{MP} = \frac{\text{Width of Ossified Head Lateral to Perkins' Line}}{\text{Total Width of Femoral Head}} \times 100$$

• MP < 10%: Normal
• MP 10% to 33%: Borderline / At Risk
• MP > 33%: Subluxation (surgical threshold)
• MP 100%: Complete Dislocation CP::HipSurveillance ReimersMP PerkinsLine Formula Lovell & Winter Ch. 14, p. 499 What is the radiographic surveillance frequency for children at GMFCS Levels IV and V? AP Pelvis radiograph every 6 to 12 months starting at age 2 years, continuing annually until skeletal maturity.

Rationale: Hips displace "silently" without pain until severe secondary cartilage destruction, pelvic obliquity, and severe scoliosis develop. CP::HipSurveillance SurveillanceProtocol MelbourneGuidelines Lovell & Winter Ch. 14, p. 499-500 What are the 3 tiers of surgical intervention for hip displacement in cerebral palsy? 1. Preventive (Age 2–5, MP 30–40%): Soft tissue release (adductor longus + gracilis tenotomy + psoas lengthening over pelvic brim).
2. Reconstructive (MP > 33% with acetabular dysplasia): Femoral Varus Derotation Osteotomy (VDRO) + Pelvic Osteotomy (Dega/Pemberton/San Diego) ± open reduction.
3. Salvage (Chronic painful dislocation in GMFCS V): Castle proximal femoral resection arthroplasty or McHale valgus osteotomy. CP::HipSurgery SurgicalTiers VDRO Dega Castle Lovell & Winter Ch. 14, p. 500-502 What are the target angles during a Femoral Varus Derotation Osteotomy (VDRO)? • Neck-Shaft Angle (NSA): Correct to 120° to 125° (avoid <115° to prevent excessive Trendelenburg lurch).
• Anteversion: Correct excessive anteversion (50–60°) down to 10° to 15°.
• Fixation: 90° or 100° AO/ASIF fixed-angle blade plate. CP::HipSurgery VDRO TargetAngles BladePlate Lovell & Winter Ch. 14, p. 520 Define Single-Event Multilevel Surgery (SEMLS): The correction of all musculoskeletal deformities across both lower extremities simultaneously (4 to 10 surgical procedures at hip, knee, and foot levels) during a single operative session under one general anesthetic, followed by one structured rehabilitation period. CP::SEMLS Definition MultilevelCorrection BirthdaySyndrome Lovell & Winter Ch. 14, p. 503 What is the optimal age window to perform SEMLS in children with spastic diplegia? Between 8 and 12 years of age.

Reasons:
1. Gross motor function has plateaued on the GMFM curve.
2. Gait pattern is mature and stable.
3. Bones accept rigid internal fixation with AO plates/screws (allowing early weight-bearing without spica casts).
4. Sufficient cognitive maturity to cooperate with postoperative rehabilitation. CP::SEMLS Timing AgeWindow Lovell & Winter Ch. 14, p. 503 What was the key finding of the landmark Level I Randomized Controlled Trial of SEMLS (Thomason, Graham et al., JBJS 2011)? SEMLS combined with structured rehabilitation produced a 50% improvement in the Gillette Gait Index (GGI) compared to physical therapy alone, along with significant improvements in physical function and quality of life (PODCI).

Caveat: Children generally remain within their preoperative GMFCS functional level (Level II remains Level II, but with superior biomechanical efficiency). CP::SEMLS LevelIRCT Evidence ThomasonGraham Lovell & Winter Ch. 14, p. 503-504 What is the Silfverskiöld Test, and what does a positive test indicate? Evaluates ankle dorsiflexion with knee flexed to 90° vs fully extended:
• Positive Test: Ankle dorsiflexion is restricted (<0°) with knee in extension, but corrects to neutral/dorsiflexion (>10°) with knee flexed to 90°.
• Indication: Indicates isolated gastrocnemius tightness (since gastrocnemius crosses both knee and ankle, while soleus crosses only the ankle).
• Procedure: Strayer distal gastrocnemius recession. CP::SurgicalAtlas SilfverskioldTest Gastrocnemius Equinus Lovell & Winter Ch. 14, p. 504 Describe the surgical technique of the Strayer Distal Gastrocnemius Recession: 1. Position: Prone with thigh tourniquet.
2. Incision: 2–3 cm posteromedial longitudinal incision over distal calf at gastrocnemius musculotendinous junction.
3. Nerves: Sural nerve and lesser saphenous vein identified and protected.
4. Plane: Enter avascular interval between gastrocnemius aponeurosis and soleus.
5. Transection: Transversely divide the gastrocnemius aponeurosis at distal extent of medial muscle belly.
6. Correction: Ankle dorsiflexed to 0° with knee extended; allow 1.5–2.5 cm gap to open.
7. Soleus: If dorsiflexion <0°, perform transverse incision of anterior soleus fascia.
8. Fixation: Suture recessed aponeurosis to soleus with 3-0 absorbable sutures.
9. Post-op: Below-knee cast in neutral for 6 weeks; immediate full weight-bearing. CP::SurgicalAtlas StrayerTechnique GastrocnemiusRecession Lovell & Winter Ch. 14, p. 504-505 Why is formal Achilles tendon lengthening (TAL / Vulpius heel cord release) considered hazardous in spastic diplegia? Achilles lengthening lengthens both the gastrocnemius AND soleus. Weakening the soleus destroys the plantarflexor-knee extension couple during mid-to-terminal stance, resulting in uncontrollable excessive ankle dorsiflexion and iatrogenic crouch gait. CP::SurgicalAtlas AchillesPitfall TAL CrouchGait Lovell & Winter Ch. 14, p. 504 In Medial Hamstring Lengthening, why is the Semitendinosus muscle sutured to the Semimembranosus before transection? To prevent excessive proximal muscle retraction and preserve vital hip extensor function of the hamstring complex. CP::SurgicalAtlas HamstringLengthening Semitendinosus HipExtension Lovell & Winter Ch. 14, p. 519 What is the postoperative mobilization protocol following a Rectus Femoris Transfer to Semitendinosus? STRICTLY NO CAST!
Active and passive knee range of motion is commenced on Postoperative Day 1 (or continuous passive motion, CPM).
• Target: 30° flexion by Week 1, 60° by Week 2, 90° by Week 3.
• Full knee extension maintained during sleep using a removable knee immobilizer.

Reason: Cast immobilization leads to dense fibrous adhesions that completely destroy the tendon gliding transfer. CP::SurgicalAtlas RectusTransfer PostopProtocol NoCast CPM Lovell & Winter Ch. 14, p. 519-520 During adductor release for hip subluxation, why is complete transection of the Adductor Brevis avoided? 1. Complete division puts the posterior branch of the obturator nerve at high risk of transection.
2. Over-division of adductor brevis risks an uncorrectable, fixed abduction deformity.

Guideline: Manually stretch adductor brevis; divide only adductor longus and gracilis. CP::SurgicalAtlas AdductorRelease AdductorBrevis ObturatorNerve Lovell & Winter Ch. 14, p. 522 Why is Psoas lengthening "Over the Pelvic Brim" (POTB) preferred over tenotomy at the lesser trochanter in ambulant children? POTB divides only the deep tendon while preserving the surrounding iliacus muscle fibers, retaining active hip flexion power needed to advance the swing leg. Complete tenotomy at the lesser trochanter causes severe hip flexor paralysis and difficulty climbing stairs. CP::SurgicalAtlas Psoas POTB HipFlexion Lovell & Winter Ch. 14, p. 522-523 What are the surgical steps of the Extra-Articular Subtalar Arthrodesis (Shore / modified Fulford technique)? 1. Dual incisions: 1 cm dorsal talar stab + 3 cm sinus tarsi incision.
2. Elevate distally-based U-flap of extensor digitorum brevis (EDB).
3. Evacuate sinus tarsi contents down to bare cortical bone with Coughlin hemispherical reamers.
4. Manually reduce dorsolateral peritalar subluxation (invert heel, raise medial arch).
5. Advance guide wire from dorsal talus across sinus tarsi into anterior process of calcaneus.
6. Insert fully-threaded cannulated cancellous screw, countersinking head flush with talus.
7. Press-fit cylindrical cortico-cancellous allograft/autograft into sinus tarsi.
8. Suture EDB flap with non-absorbable nylon. Below-knee cast 6 weeks (full weight-bearing from Week 2). CP::SurgicalAtlas SubtalarArthrodesis ShoreTechnique SinusTarsi Lovell & Winter Ch. 14, p. 530-531 What are the key technical details of Galveston Pelvic Instrumentation for neuromuscular scoliosis? • Segmental fusion from T2/T3 down into the pelvis.
• Entry point on posterior superior iliac spine (PSIS).
• The contoured rod prong passes between the inner and outer cortical tables of the ilium into the thick column of bone immediately cephalad to the greater sciatic notch (depth of 6 to 9 cm).
• Corrects severe pelvic obliquity and provides rigid anchor to support sitting. CP::SurgicalAtlas GalvestonPelvicInstrumentation NeuromuscularScoliosis Lovell & Winter Ch. 14, p. 542-544 What is the mechanism of action of Botulinum Toxin Type A (BoNT-A)? Cleaves SNAP-25 (Synaptosomal-Associated Protein 25), a presynaptic SNARE protein, thereby inhibiting calcium-mediated vesicular exocytosis of acetylcholine at the neuromuscular junction, producing temporary (3–6 months) chemodenervation. CP::Pharmacology BoNTA Mechanism SNAP25 Acetylcholine Lovell & Winter Ch. 14, p. 505 What are the recommended maximum doses for OnabotulinumtoxinA (Botox) and AbobotulinumtoxinA (Dysport) in pediatric cerebral palsy? • Botox (OnabotulinumtoxinA): 10 to 15 Units/kg body weight (Absolute maximum: 400 to 600 Units per session).
• Dysport (AbobotulinumtoxinA): 20 to 30 Units/kg body weight (Absolute maximum: 1000 Units per session).

Safety Warning: Exceeding recommended dose/kg risks systemic toxin spread causing generalized muscle weakness, dysphagia, and fatal respiratory compromise, especially in GMFCS V. CP::Pharmacology BoNTA DosageLimits SafetyWarning Lovell & Winter Ch. 14, p. 505-506 What are the optimal patient selection criteria for Selective Dorsal Rhizotomy (SDR)? 1. CP Type: Pure spastic diplegia (pyramidal).
2. Age: 3 to 8 years old.
3. GMFCS Level: Level II or III.
4. Motor Control: Good selective voluntary motor control and preserved underlying antigravity trunk/lower limb strength.
5. Absence of: Dystonia, choreoathetosis, ataxia, or fixed joint contractures.
6. Motivation: Highly cooperative child and family committed to 1–2 years of intensive post-SDR physical therapy. CP::Neurosurgery SDR PatientSelection SelectiveDorsalRhizotomy Lovell & Winter Ch. 14, p. 507-508 What is the principal risk or downside of Selective Dorsal Rhizotomy (SDR)? Tone reduction is irreversible and frequently unmasks severe underlying primary muscle weakness that was masked by spasticity.

Orthopaedic sequelae: Progressive lumbar hyperlordosis, spondylolysis, spondylolisthesis, and hip subluxation if adductor spasticity remains unbalanced. CP::Neurosurgery SDR AdverseEffects MuscleWeakness Lovell & Winter Ch. 14, p. 508 What are the indications and life-threatening complication of Intrathecal Baclofen (ITB) Therapy? • Indications: Severe generalized spasticity and mixed dystonia in non-ambulant children (GMFCS IV and V) to alleviate pain, ease positioning, and facilitate nursing care.
• Life-Threatening Emergency: Acute Baclofen Withdrawal Syndrome (due to catheter kinking, disconnection, or pump failure) causing rebound spasticity, hyperthermia, seizures, rhabdomyolysis, disseminated intravascular coagulation (DIC), and death. Managed with high-dose IV benzodiazepines and emergency intrathecal baclofen re-infusion. CP::Pharmacology ITB BaclofenWithdrawal MedicalEmergency Lovell & Winter Ch. 14, p. 508-509 How does a Ground Reaction Ankle-Foot Orthosis (GRAFO / FRO) stabilize the knee in crouch gait? The GRAFO has a rigid anterior proximal shell over the tibia. By preventing excessive stance-phase ankle dorsiflexion, it directs the ground reaction force (GRF) vector anterior to the knee joint center, generating an external knee extension moment that resists crouch. CP::Orthotics GRAFO GroundReaction KneeExtensionMoment Lovell & Winter Ch. 14, p. 510 What is the primary indication for a Hinged AFO with Plantarflexion Stop vs a Solid AFO? • Hinged AFO with PF Stop: Permits active ankle dorsiflexion in swing and terminal stance while blocking plantarflexion beyond 90°. Indicated for GMFCS I & II ambulators with isolated true equinus and preserved quadriceps strength.
• Solid AFO: Rigidly locks the ankle at 0°. Indicated for severe spasticity, coronal instability (varus/valgus), postoperative protection after SEMLS, or non-ambulators. CP::Orthotics HingedAFO SolidAFO Biomechanics Lovell & Winter Ch. 14, p. 510 What foot deformity is the Supramalleolar Orthosis (SMO) indicated for? Mild to moderate pes planovalgus / hindfoot pronation in ambulant children with mild diplegia or hemiplegia.

Terminates above the malleoli; controls coronal hindfoot alignment while preserving full sagittal ankle plantarflexion and dorsiflexion. CP::Orthotics SMO Planovalgus HindfootPronation Lovell & Winter Ch. 14, p. 510 What are the typical components of the spastic hemiplegic upper extremity deformity? 1. Shoulder internal rotation and adduction (pectoralis major, subscapularis).
2. Elbow flexion (brachialis, biceps brachii).
3. Forearm pronation (pronator teres, pronator quadratus).
4. Wrist flexion and ulnar deviation (flexor carpi ulnaris).
5. Thumb-in-palm deformity (adductor pollicis, flexor pollicis brevis).
6. Swan neck or boutonniere finger deformities. CP::UpperLimb SpasticHemiplegia Posture Lovell & Winter Ch. 14, p. 515-517 What is "Green's Transfer" for spastic wrist flexion deformity? Transfer of the Flexor Carpi Ulnaris (FCU) tendon to the Extensor Carpi Radialis Brevis (ECRB) tendon.

Biomechanical effect: Removes a deforming wrist flexor/ulnar deviator and converts it into an active wrist extensor, dramatically improving hand opening and grasp efficiency. CP::UpperLimb GreensTransfer FCUtoECRB TendonTransfer Lovell & Winter Ch. 14, p. 516 What are the surgical components for correcting a severe "Thumb-in-Palm" deformity? 1. Myotomy / Release: Release of adductor pollicis and first dorsal interosseous from the third metacarpal.
2. Web Space Deepening: First web space four-flap or Z-plasty.
3. Tendon Augmentation: Rerouting or rerouting/advancement of extensor pollicis longus (EPL) or abductor pollicis longus (APL).
4. Joint Stabilization: Capsulodesis or arthrodesis of the thumb MCP joint if hyperextensible. CP::UpperLimb ThumbInPalm AdductorPollicis ZPlasty Lovell & Winter Ch. 14, p. 517