Blount's Disease Flashcards

Blount's Disease Overview

• Blount's Disease, also known as tibia vara, is a non-inherited, idiopathic condition leading to progressive genu varum in children.
• The deformity features multiplanar components including proximal tibial varus, internal tibial torsion, procurvatum, and shortening.

Epidemiology

• Risk factors include being overweight, early walkers with physiological varus, family history, and being of Afro-Caribbean descent.

Background Information

• Angular deformities in lower limbs can be physiological or pathological and are primarily coronal plane deformities.
• First described in 1937, Blount's is the most common pathological cause of genu varum.
• Conditions can manifest as infantile (bilateral, severe) or adolescent (unilateral, mild) forms, diagnosed with metaphyseal-diaphyseal angle (MDA) or Drennan's angle greater than 16°.

Anatomical Considerations

• Normal limb alignment transitions from varus to valgus in early childhood.
• The Salenius Graph illustrates changes in tibiofemoral angle throughout childhood, stabilizing by age 7-8.

Aetiology and Pathogenesis

• The condition arises from excessive medial pressure on the physis, resulting in impaired blood supply and potential physis bar formation.
• The Heuter-Volkmann principle indicates that increased compression forces lead to reduced longitudinal growth.

Classification

• Infantile Blount's can be classified using the Langenskiold classification, consisting of 6 radiological stages defining the progression of the disease.

Clinical Presentation

• Patients typically present with painless genu varum which may be unilateral or bilateral and progressive, often seen in overweight children.

Diagnosis

• Diagnosis involves clinical evaluation and radiological investigations, with a primary differential diagnosis being rickets.
• Key hematological tests include Vitamin D, CMP, and ALP. Radiographic examinations assess tibiofemoral angle, MDA, and epiphyseal-diaphyseal angles.

Radiographic Features

• Key angles measured during weight-bearing X-rays include MDA (angle >16° is a key diagnostic criterion), tibiofemoral angle, and epiphyseal-diaphyseal angle (EPA).
• Classic radiological features include metaphyseal beaking and fragmentation of the medial metaphysis.

Differential Diagnosis

• Common differentials for genu varum include rickets, osteogenesis imperfecta, physeal injury, and skeletal dysplasia.

Management Overview

• Early intervention aims at restoring the mechanical axis before skeletal maturity to prevent degenerative arthritis.
• Non-operative treatments are controversial, with surgical options recommended based on age and severity.

Non-Operative Management

• Bracing may be indicated for early-stage disease but is often met with compliance challenges in young patients.
• Obesity can contraindicate bracing, requiring continued monitoring for 18-24 months for bony changes.

Surgical Management

• Surgery varies with age and severity; goals include overcorrection into 10-15° valgus.
• Options include hemiepiphyseodesis, corrective osteotomy, or bony bar resection.
• Hemiepiphyseodesis utilizes lateral tibial epiphyseodesis and is suited for mild deformities.

Osteotomy Techniques

• Osteotomies can be medial opening wedge or less commonly lateral closing wedge, addressing multi-planar deformities.
• Surgical technique includes careful dissection and correction below the tibial tubercle.

Bar Resection Principals

• Indicated for high-grade deformities and involves meticulous pre-operative imaging and surgical techniques to remove abnormal bony structures while preserving cartilage.

Explore the key concepts of Blount's Disease through informative flashcards. This quiz covers definitions, epidemiology, and the unique characteristics of this condition affecting pediatric populations. Perfect for students and health professionals looking to enhance their understanding of tibia vara.