Developmental Foot Deformities in Patients with Connective Tissue Disorders

Introduction

• Foot deformities across syndromic conditions often share common underlying factors:

  • Generalized joint laxity

  • Bone deformities

  • Hypotonia and hypermobility

• These deformities account for a significant proportion of orthopaedic complaints in patients with genetic and connective tissue disorders.

• The most common contributors include:

  • Increased ligamentous laxity

  • Muscle hypotonia

  • Excessive joint mobility

Syndromes Covered in This Review

• Down syndrome (DS)

• Marfan syndrome (MFS)

• Ehlers–Danlos syndrome (EDS)

• Larsen syndrome (LS)

• Osteogenesis imperfecta (OI)

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Down Syndrome

General Features

• Caused by trisomy 21 due to chromosomal nondisjunction

• Associated musculoskeletal findings:

  • Cervical spine instability

  • Scoliosis

  • Hip and patellar instability

Foot and Ankle Manifestations

• Foot deformities seen in approximately 30% of patients

• Common deformities:

  • Pes planus

  • Hallux valgus (secondary to ligament laxity)

  • Syndactyly

  • Calcaneal valgus

  • Bony deformities

Management

Conservative

• Orthotic management to improve gait mechanics and kinematics:

  • UCBL (University of California–Berkeley Lab) orthoses

  • Supramalleolar orthoses

  • Ankle–foot orthoses (AFOs)

• Adjunctive physical therapy enhances outcomes

Surgical

• Reserved for severe deformities or functional limitation:

  • First-ray realignment for severe hallux valgus

  • Exostectomy for symptomatic medial eminence

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Marfan Syndrome

Genetic and Systemic Features

• Autosomal dominant connective tissue disorder

• Genetic mutations:

  • FBN1 gene (Type 1)

  • TGFBR1 and TGFBR2 genes (Type 2)

Multisystem Involvement

• Ocular: lens subluxation, myopia, retinal detachment

• Cardiovascular: aortic root dilation, aneurysm, rupture, mitral valve prolapse

• Skeletal:

  • Scoliosis

  • Thoracic lordosis

  • Pectus excavatum

  • Hip instability

  • Joint laxity

  • Acetabular protrusion

  • Reduced bone mineral density

Foot Deformities

• Predominantly:

  • Pes planus

  • Hallux valgus

Management

Conservative

• Custom foot orthoses with medial longitudinal arch support

Surgical

• Triple arthrodesis may be considered for:

  • Painful, rigid pes plano-valgus deformities

  • Improved stability and function

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Ehlers–Danlos Syndrome

Key Characteristics

• Heterogeneous connective tissue disorder

• Molecular defects involving collagen types I, III, and V

Classic Triad

• Skin hyperextensibility

• Joint hypermobility

• Tissue fragility

Foot and Ankle Manifestations

• Pes planus

• Hallux valgus with bunions

• Hammertoes and claw toes

• Clubfoot

• Achilles tendon contracture

• MTP joint subluxations

• Chronic ankle instability leading to recurrent falls

Management

Conservative

• Ankle bracing (e.g., ankle-stabilizing orthoses)

• Foot orthoses to reduce pain and fatigue

Surgical

• Often challenging due to:

  • Severe joint hypermobility

  • Poor tissue quality

• Surgery reserved for selected cases with significant disability

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Larsen Syndrome

Genetic Background

• Can be autosomal dominant or recessive

• Caused by mutations in the FLNB gene (chromosome 3p14)

Clinical Features

• Congenital dislocations of:

  • Hips

  • Knees

  • Elbows

• Spinal deformities:

  • Scoliosis

  • Cervical kyphosis

• Skeletal and other features:

  • Short, wide distal phalanges

  • Craniofacial anomalies

  • Hearing loss due to malformed ear ossicles

Foot Deformities

• Clubfoot deformities:

  • Equinovarus

  • Equinovalgus

Management

Conservative

• Ponseti method:

  • Serial casting

  • Percutaneous Achilles tenotomy

Surgical

• Reserved for resistant or recurrent cases:

  • Posteromedial soft-tissue release

• High risk of recurrence despite conservative treatment

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Osteogenesis Imperfecta

Pathophysiology

• Quantitative and qualitative defects in collagen synthesis

Systemic Features

• Short stature

• Hearing loss

• Blue sclera

• Cardiopulmonary anomalies

• Dentinogenesis imperfecta

Orthopaedic Manifestations

• Recurrent fractures

• Long-bone bowing

• Genu valgum

• Coxa vara

• Joint laxity

• Scoliosis

• Skeletal fragility

Foot Deformities

• Pes planovalgus (24–75%)

• Skew foot (midfoot ligament laxity)

• Clubfoot deformities

Management

Conservative

• AFOs to prevent equinus contractures

Surgical

• Reserved for severe deformities or failure of conservative care:

  • Osseous and soft-tissue procedures

  • Bilateral subtalar arthroereisis for pes planus

  • Subtalar and navicular–cuneiform arthrodesis for skew foot

  • Ponseti method for clubfoot, with surgery for resistant cases

Surgical Challenges

• Poor bone quality may lead to:

  • Nonunion at osteotomy sites

  • Unsatisfactory outcomes after subtalar extra-articular arthrodesis

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Key Takeaway

Foot deformities in syndromic conditions are multifactorial and progressive, requiring:

• Early recognition

• Individualized orthotic management

• Careful patient selection for surgery due to high complication and recurrence rates