TOACS FCPS Station · X‑ray Long Bones: Osteogenesis Imperfecta (OI)

📷 X‑ray Long Bones (AP view)

$X-ray long bones showing bowed femurs, fractures, and osteopenia in osteogenesis imperfecta$

Figure 1 · AP long bone radiograph · Osteogenesis Imperfecta – Bowed Femurs & Fractures

🔍 Key radiographic features:

✓ Multiple fractures – healing and healed fractures at various stages
✓ Bowed long bones – femoral and tibial bowing (especially in Type III)
✓ Osteopenia – decreased bone density with thin cortices
✓ Popcorn calcifications – metaphyseal areas (Type III)
✓ Wormian bones – intrasutural bones (skull X‑ray)

📋 Clinical scenario (examiner prompt)

A 1‑month‑old child presents with a history of multiple fractures from minimal trauma, bowed legs, and short stature. On examination, there are blue sclerae and dentinogenesis imperfecta. A long bone X‑ray (AP view) is shown.

Multiple fractures Bowed femurs Blue sclerae Dentinogenesis imperfecta

🧑‍⚕️ Examiner tasks · TOACS

1. Identify the diagnosis from the X‑ray and clinical context.

2. Describe the X‑ray findings (fractures, bowed bones, osteopenia).

3. Explain the pathophysiology (COL1A1/COL1A2 mutation → defective collagen).

4. Discuss classification and management (Sillence types, bisphosphonates, rodding).

⚠️ Key concept: Osteogenesis imperfecta (OI) is a genetic disorder of type I collagen (COL1A1/COL1A2) leading to brittle bones. Type III (progressive deforming) is characterized by multiple fractures at birth, bowed femurs, triangular facies, white sclerae, and dentinogenesis imperfecta. IV pamidronate (bisphosphonate) reduces fractures and improves mobility.

🎯 Expected answers (for examiners)

• Diagnosis: Osteogenesis imperfecta (likely Type III or IV)
• X‑ray findings: Multiple fractures (healing/healed), bowed long bones, osteopenia
• Pathophysiology: Defective type I collagen (COL1A1/COL1A2) → bone fragility
• Management: IV pamidronate (bisphosphonates), physical therapy, intramedullary rodding, genetic counseling

⚡ Quick FCPS‑style MCQ

A child with bowed femurs, multiple fractures, blue sclerae, and dentinogenesis imperfecta most likely has:

A. Osteogenesis imperfecta Type I B. Osteogenesis imperfecta Type III C. Rickets D. Hypophosphatasia

📌 Topic summary ·

Type I
Blue sclerae, mild fractures

Type II
Perinatal lethal, crumpled femurs

Type III
White sclerae, progressive deformity

Type IV
White sclerae, moderate severity

Treatment
IV pamidronate (bisphosphonate)

Rodding
Intramedullary telescoping rods

OI Type	Sclerae	Severity	Key Feature
Type I	Blue	Mild	Hearing loss, fractures decrease after puberty
Type II	Blue	Lethal	Crumpled femurs, beaded ribs
Type III	White	Severe	Bowed femurs, triangular facies, popcorn calcifications
Type IV	White	Moderate	Variable short stature

🩻 TOACS FCPS Station · X‑ray Long Bones: Osteogenesis Imperfecta (OI)

📷 X‑ray Long Bones (AP view)

🧑‍⚕️ Examiner tasks · TOACS

📌 Topic summary ·