Limb Deficiencies

Fibula Hemimelia

Aetiology

  • No inheritance pattern.
  • Most common of limb deficiencies.
  • Post-axial hypoplasia.
  • Variable length of fibula missing (partial to complete).
  • Often no syndromic disorder; children are intellectually normal.
  • Variable expression (mild to severe).
  • Strongly associated with multiple other limb deformities/deficiencies.

Classification

  • Achterman & Kalamachi
    • Traditional classification based on the amount of fibula present.
    • Type 2: More likely to have concurrent deficiencies.
  • Birch Classification
    • Based on foot and limb function.
    • Guides treatment.

Clinical Presentation

  • Birth presentation:
    • Valgus ankle.
    • Anteromedial bow of tibia with skin puckering.
    • Proportionate limb length discrepancy (LLD remains same ratio at maturity).

Features to Look for in Assessment:

Area Features
Hip & Femur CSF, PFFD, Shortening
Knee ACL (and PCL) deficiency, Valgus (hypoplastic LFC), Patella maltracking/hypoplasia
Leg Anteromedial bowing, Skin puckering, Shortening
Ankle Valgus (rarely varus), Ball-and-socket ankle
Foot Tarsal coalition, Absent lateral rays, Syndactyly of remaining toes

Management

  • Treatment dictated by other bones and soft tissues, not the fibula.
  • Preserve/correct knee for prosthetic fitting.

  • Salvage vs. Amputation:

    > 3 absent rays: Better outcome with amputation.
    • Flail foot: Perform amputation (Symes) before age 3 for less psychological impact.
  • Address individual problems as necessary.

Proximal Femoral Focal Deficiency (PFFD)

Definition

  • Spectrum of disease:
    • Congenital Shortening of the Femur (CSF): Mild, normal hip development.
    • Proximal Femoral Focal Deficiency (PFFD): Severe, no proximal femur (head may be present).
    • Limb is very short.

Aetiology

  • Non-hereditary, unknown cause.

Associated Problems

  • More likely syndromic.
  • High incidence of other deficiencies (50%):
    • Fibula hemimelia (50-70%).
    • Upper limb deficiencies.
    • Hip dysplasia.
    • Coxa vara.

Management

Principles

  • Decision based on:
    • Hip dysplasia/stability.
    • Function and muscle bulk of the lower leg.
    • Bone deficiencies.
    • Knee and ankle stability/contracture.
    • Presence of proximal femur or femoral head.
    • Importance of feet (for ADLs if upper limbs are deficient).

Options

  1. Lengthening
    • Predicted discrepancy <20 cm with functional lower leg.
    • Address acetabular dysplasia/coxa vara before lengthening.
    • Use distraction osteogenesis with external fixator.
  2. Knee Fusion and Foot Ablation
    • Non-functional ankle: Fusion for better prosthetic fit.
  3. Van Ness Rotationplasty
    • Rotate functional ankle to act as knee joint in a prosthesis.
  4. Femoro-pelvic Fusion (Brown’s Procedure)
    • For non-functional hip and proximal femur.
  5. Prosthetic Fitting
    • Required in all cases.

Tibial Hemimelia

Key Facts

  • Less common than fibula hemimelia: 1/million.
  • Clinical presentation:
    • 75% have other anomalies.
    • Equinovarus foot (rare in other conditions).
    • Variable tibial deficiency.
    • Grossly unstable ankle and knee.

Associations

  • Pre-axial polydactyly.
  • Lobster claw hand.
  • PFFD.

Management

  • Depends on knee extension:
    • If knee extends, consider reconstruction.
    • If not, use prosthesis after foot ablation.

Clinical Assessment of a Limb Deficiency

Examination

  1. Standing (Front, Side, Back)
    • Scars, shortening, angular deformity, muscle wasting, skin changes, spine assessment.
  2. Palpation
    • ASIS height, block test for pelvic leveling.
  3. Gait Analysis
    • Observe compensation for shortening (e.g., equinus, vaulting, circumduction).
  4. Lie Down
    • Square pelvis, check angular deformities and bony landmarks.
  5. Range of Motion
    • Joint ROM, stiffness, correctibility of deformities, joint instability (ACL, PCL, MCL).
  6. Neurological Status
    • Examine upper limbs, spine, abdomen.
    • Obtain full history and limb X-rays.

Congenital Pseudoarthrosis of the Tibia (CPT)

Aetiology

  • Congenital anterolateral bowing of tibia (distal 1/3).
  • Poor bone quality, propensity to fracture.
  • Healing is poor, leading to pseudoarthrosis.

Epidemiology

  • 1/200,000 live births.

Associations

  • Most commonly linked to Type 1 Neurofibromatosis (50%):
    • Only 10% of NF patients develop CPT.
  • Fibrous dysplasia.
  • Often idiopathic.

Types

  • Boyd Classification (1-6):
    • Based on severity.
    • Variations include sclerotic, cystic, or string-like tibia, associated fibula pseudoarthrosis, and ankle valgus.

Differential Diagnosis

  • Osteogenesis imperfecta.
  • Rickets.
  • Fibrous dysplasia.
  • (CPT is almost never bilateral.)

Management Goals

  • Early diagnosis and fracture prevention.
  • Achieving bony union.
  • Preventing re-fracture.
  • Correcting LLD.

Non-operative Management

  • If found before fracture:
    • Splinting (KAFO).
    • Total contact casting.
    • Fracture risk reduces after maturity.

Surgical Options

  1. IM Nail and Cortical Grafting
    • Nail through heel; retained until maturity.
    • Prevents re-fracture; controls ankle valgus.
    • Suitable for younger children.
  2. Ilizarov Technique
    • Resection and compression with bone transport.
    • Corrects LLD; used for failed nailing.
  3. Vascularised Free Fibula Transfer
    • Complex; requires expertise.
    • No better clinical outcomes.
  4. Amputation
    • After 3 failed union attempts.

Outcomes

  • 70% union rates for all methods.
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