Courtesy: Sean Tabaie, MD, FAAOS, George Washington University, Washington DC, USA
Cerebral Palsy and Hip Involvement
Introduction
Cerebral palsy (CP) is one of the most common causes of childhood physical disability and frequently affects the musculoskeletal system.
Hip involvement is a major source of:
- Pain
- Functional limitation
- Difficulty with sitting and hygiene
- Reduced quality of life
Early recognition and surveillance are essential to prevent progressive hip displacement and long-term disability.
Cerebral Palsy: Overview
Definition
Cerebral palsy is a group of:
- Permanent
- Non-progressive disorders of the developing brain
that affect:
- Movement
- Posture
- Motor control
Important Principle
Although the neurological injury is static:
- Musculoskeletal deformities are progressive
This distinction is critical in management planning.
Epidemiology
Important epidemiological points include:
- Incidence approximately 2 per 1000 live births
- Most common physical disability in children
Improved survival of premature infants has contributed to increased prevalence.
Etiology
Multifactorial Causes
Cerebral palsy may result from:
- Prematurity
- Hypoxic injury
- Infections
- Genetic abnormalities
Hypoxia is not always present.
Pathophysiology
Sequence of Deformity
Brain injury leads to:
- Spasticity
- Muscle imbalance
- Contracture formation
- Progressive skeletal deformity
These musculoskeletal changes worsen over time if untreated.
Types of Cerebral Palsy
Spastic Type
- Most common form
- Characterized by increased muscle tone and spasticity
Dyskinetic Type
- Involuntary abnormal movements
- Variable muscle tone
Ataxic Type
- Poor coordination
- Balance abnormalities
GMFCS Classification
Gross Motor Function Classification System
The GMFCS classifies patients into:
- Levels 1–5
based on functional mobility.
Clinical Importance
Higher GMFCS levels correlate with:
- Greater disability
- Increased risk of hip displacement
Hip Involvement in Cerebral Palsy
Importance
The hip is the second most commonly affected joint in cerebral palsy.
Hip pathology significantly affects:
- Mobility
- Sitting balance
- Hygiene
- Caregiver burden
- Quality of life
Hip Displacement
Mechanism
Hip displacement occurs due to:
- Spasticity
- Muscle imbalance
- Progressive contractures
This gradually produces:
- Subluxation
- Dislocation
Migration Percentage
Definition
Migration percentage is the most important radiographic measurement for hip displacement.
It measures the proportion of the femoral head positioned outside the acetabulum.
Interpretation
Less Than 30%
- Usually stable
- Observation recommended
30–50%
- Increased risk
- Requires close monitoring
Greater Than 50%
- Surgical intervention should be considered
Greater Than 90%
- Indicates hip dislocation
Risk Factors for Hip Displacement
The most important predictor is:
- Higher GMFCS level
Patients with severe functional limitation have the highest risk.
Natural History
Early Stage
Initially, hip displacement may be:
- Painless
- Clinically silent
Progressive Disease
Over time, untreated displacement can lead to:
- Pain
- Fixed deformity
- Pelvic obliquity
- Sitting imbalance
- Difficulty with hygiene and care
Clinical Evaluation
Examination
Assessment should include:
- Hip abduction
- Contractures
- Limb length discrepancy
- Pelvic alignment
- Sitting posture
- Functional ability
Regular examination is essential.
Imaging
Standard Radiographs
The primary investigation is:
- AP pelvis radiograph
Important Measurements
Radiographs help assess:
- Migration percentage
- Acetabular index
- Hip congruity
Hip Surveillance
Importance
Hip surveillance programs are highly effective in preventing late dislocation.
Regular monitoring allows:
- Early detection
- Timely intervention
Proven Benefit
National surveillance programs in several countries have demonstrated:
- Reduced incidence of painful dislocation
- Improved outcomes
Management
Non-Operative Treatment
Conservative Measures
Options include:
- Physiotherapy
- Oral medications
- Botulinum toxin injections
Limitations
Non-operative treatment has:
- Limited ability to prevent progressive displacement
Soft Tissue Surgery
Adductor Release
Soft tissue procedures commonly include:
- Adductor tenotomy
- Soft tissue balancing
Purpose
These procedures may:
- Improve hip abduction
- Delay progression of displacement
particularly in early disease.
Bony Surgery
Varus Derotation Osteotomy (VDRO)
VDRO corrects:
- Femoral valgus
- Excessive anteversion
and improves hip containment.
Pelvic Osteotomy
Dega Osteotomy
Dega osteotomy improves:
- Acetabular coverage
- Hip stability
Often combined with femoral osteotomy.
Complications
Potential complications include:
- Recurrence of displacement
- Avascular necrosis
- Heterotopic ossification
- Persistent stiffness
Long-term follow-up is important.
Salvage Procedures
Indications
Salvage procedures are reserved for:
- Severe deformity
- Painful chronic dislocation
- Non-reconstructable hips
Goals
Primary aims include:
- Pain relief
- Improved sitting balance
- Easier nursing care
Key Clinical Pearls
- Cerebral palsy is neurologically non-progressive but orthopedically progressive.
- Hip displacement risk increases with higher GMFCS level.
- Migration percentage is the key radiographic measurement.
- Early hip surveillance prevents late dislocation.
- Soft tissue release may delay progression in early disease.
- VDRO and pelvic osteotomy improve containment and stability.
- Untreated hip displacement can severely impair quality of life.
Final Take-Home Message
Hip involvement is a major source of morbidity in children with cerebral palsy.
Progressive muscle imbalance and spasticity can lead to:
- Hip subluxation
- Dislocation
- Pain
- Functional disability
Early surveillance, timely intervention, and multidisciplinary management are essential to preserve hip function and improve long-term outcomes.
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