Down Syndrome Orthopaedic

Down Syndrome (Trisomy 21) is the most common chromosomal abnormality.

• Genetics: Extra chromosome 21 (Trisomy 21).
• Incidence: 1 in 700-1000 live births.
• Key Feature: Generalized ligamentous laxity affecting all joints.
• Associated Conditions: Cardiac defects, hypothyroidism, leukemia, cognitive impairment.

Ligamentous Laxity

• Collagen abnormalities lead to ligamentous laxity.
• All joints are hypermobile.
• Transverse ligament of C1 is lax → atlantoaxial instability.

Why Hip Instability Develops

• Unlike DDH which is present at birth, hip instability in DS may develop later.
• Lax capsule and ligaments allow progressive subluxation.
• May present at 2-10 years with painful limp.

Scoliosis is listed as a key concern in the summary and two scoliosis radiographs sit in the imaging atlas, but the body never develops it — yet it is genuinely examinable. Scoliosis is more common in Down syndrome than in the general population, driven by the same generalised ligamentous laxity and hypotonia as the other manifestations, so it behaves like a syndromic curve rather than an idiopathic one.

Patellar instability is named in the summary, the classification and the management algorithm ("realignment surgery, MPFL, tibial tubercle transfer"), but the entity itself is never developed. Recurrent — and sometimes habitual or fixed — patellar dislocation is common in Down syndrome because three factors stack up: ligamentous laxity, hypotonia (a weak extensor mechanism / vastus medialis), and valgus malalignment (genu valgum, planovalgus, external tibial torsion). It is frequently bilateral.

Cervical Spine Complications

Hip Surgery Complications

Anaesthetic and Perioperative Risks

Critical considerations for surgery in Down Syndrome:

• Difficult Airway: Macroglossia, small trachea, atlantoaxial instability
• Cardiac Disease: 40-50% have congenital heart defects - preoperative echo essential
• Respiratory Issues: Subglottic stenosis, sleep apnoea - postoperative monitoring crucial
• Immune Dysfunction: Higher infection risk - meticulous sterile technique
• Osteoporosis: Hardware complications more common - adequate fixation

Long-term Orthopaedic Issues

• Progressive Hypotonia: May affect rehabilitation outcomes
• Joint Laxity: Leads to instability, recurrent dislocations
• Accelerated Osteoarthritis: Hip and knee arthritis in young adults
• Cervical Degeneration: Early spondylosis due to laxity
• Pes Planus Progression: May require orthotic support lifelong

Cervical Fusion Rehabilitation

• Immobilisation: Halo or rigid collar for 3-6 months
• Activity Restriction: No contact sports, high-risk activities indefinitely
• Monitoring: Clinical and radiographic follow-up until fusion confirmed
• Long-term: Annual surveillance for adjacent segment disease

Hip Surgery Recovery

Special Considerations

• Communication: Adapt instructions for cognitive level
• Family Support: Essential for compliance with bracing
• School/Therapy: Coordinate with educational services
• Cardiac Monitoring: If heart disease present

Follow-up Protocol

• Early: 2, 6, 12 weeks for wound, neurological status
• Medium-term: 3, 6 months for radiographic healing
• Long-term: Annual for skeletal maturity, late complications
• Transition: Plan adult care by age 16-18

Cervical Spine Outcomes

Hip Outcomes

• Open Reduction (Under 2yrs): 60-70% satisfactory long-term
• Open Reduction (Over 2yrs): Higher AVN, redislocation rates
• Pelvic Osteotomy: Improves coverage when hip reducible
• Salvage Procedures: Palliative for failed reconstruction

Functional Outcomes

Key Prognostic Points

• AAI Fusion: Good outcomes if done for symptomatic patients before permanent deficit
• Hip Reconstruction: High failure rate (30-40%), AVN common, but function often maintained
• Early Intervention: Better outcomes for both spine and hip issues
• Overall: Most orthopaedic issues manageable with good quality of life achievable

Global epidemiology

• Down syndrome occurs in roughly 1 in 700-1000 live births worldwide; live-birth prevalence varies with maternal age distribution and the availability and uptake of prenatal screening.
• Symptomatic atlantoaxial instability is rare (around 1-2%) even though radiographic instability is reported in 10-20%; pes planovalgus is near-universal.

Side-by-side guidance

Registry and outcome notes

• No DS-specific arthroplasty registry exists, but national joint registries (NJR UK, AOANJRR Australia, AJRR US, SHAR Sweden) capture small numbers of DS arthroplasties; pooled data show higher revision and complication rates than matched controls.

High- vs limited-resource practice

• In well-resourced settings, MRI, CT-based screw planning and rigid instrumentation are standard, and multidisciplinary clinics coordinate cardiac, airway and orthopaedic care.
• In limited-resource settings, plain radiography and clinical surveillance predominate; the priority is recognising myelopathic symptoms early and avoiding avoidable cervical trauma (careful intubation, neutral positioning), since access to complex paediatric spine surgery may be limited.

1. Routine cervical screening radiographs

• The single largest controversy. The AAP (2011) and most paediatric bodies have abandoned routine asymptomatic screening films because the atlantodental interval is a poor predictor of who develops myelopathy and is stable over time in most children.
• The Special Olympics, however, still mandates a documented neurological clearance (historically a screening lateral radiograph) before athletes participate in high-risk events. This creates a real-world tension: clinicians may be asked to obtain films that their own national guideline no longer endorses.
• Pragmatic position: prioritise a careful neurological history and examination at every visit; image when symptomatic, before procedures requiring neck manipulation, or when a sporting body specifically requires documentation.

2. ADI thresholds vs neural canal width

• Numbers vary between sources (ADI greater than 4.5mm, greater than 5mm, or greater than 10mm). Increasingly the space available for the cord (SAC, posterior interval) and dynamic MRI cord signal are regarded as more meaningful than ADI alone.

3. Surgical timing in asymptomatic AAI

• Whether to fuse a markedly increased ADI in an asymptomatic child is unresolved. Prophylactic fusion carries a high complication and nonunion rate, so most surgeons reserve operation for symptomatic instability, progressive radiographic change, or cord signal change.

4. Hip reconstruction vs early arthroplasty

• Reconstruction has high redislocation and revision rates; some advocate accepting a stable subluxation and planning for later arthroplasty rather than repeated failed childhood reconstructions.