Makindo Medical Notes

Related Subjects: |Osteoporosis |Osteogenesis Imperfecta

⚠️ Osteogenesis Imperfecta (OI) is a dominantly inherited connective tissue disorder caused by defective type I collagen. It is characterised by fragile, brittle bones and multiple systemic features. Adults with OI usually have milder phenotypes (commonly Type I).

📖 About

• 🦴 Brittle bones: Recurrent fractures with minimal trauma.
• 📉 Osteopenia/osteoporosis: Reduced bone mass predisposing to fragility.
• 🧬 Inheritance: Usually autosomal dominant (COL1A1, COL1A2 mutations).
• ⚙️ Pathophysiology: Collagen type I is reduced in quantity or abnormal in structure ➝ bone matrix weakened ➝ systemic connective tissue fragility.
• 📊 Prevalence: ~6–7 per 100,000 worldwide (rare disease).

🧬 Types of OI

• Type I (Mild): Most common. Childhood fractures, blue sclerae, hearing loss, normal stature.
• Type II (Perinatal lethal): Multiple in-utero fractures, underdeveloped lungs ➝ neonatal death.
• Type III (Severe, progressive): Deforming, short stature, scoliosis, barrel chest, respiratory compromise.
• Type IV (Moderate): Intermediate severity; fractures before puberty, mild–moderate deformity.
• Type V: Hypertrophic callus at fracture sites, interosseous membrane calcification.
• Type VI: Mineralisation defect seen on biopsy.
• Type VII: Rare, short femora/humeri, coxa vara; clustered in specific populations.

🩺 Clinical Features

• 💥 Recurrent fractures (may occur during birth/infancy).
• 👁️ Blue sclerae (Types I & III most characteristic).
• 🔺 Triangular facies, macrocephaly.
• 👂 Progressive hearing loss (ossicular involvement).
• 🦷 Dentinogenesis imperfecta (weak, brittle teeth).
• 🫁 Barrel chest, scoliosis, respiratory compromise.
• 🤸 Joint laxity and dislocations.
• 📏 Short stature in moderate–severe forms.

🧾 Differentials

• ❌ Non-accidental injury (NAI): Important to consider in children with multiple fractures ➝ careful history, genetic testing may be needed.
• 🦴 Juvenile osteoporosis / secondary osteoporosis: Consider in older children/adults with fragility fractures.

🔎 Investigations

• 📸 X-rays: Multiple fractures, bowing of long bones, osteopenia.
• 🧬 Genetic testing: COL1A1, COL1A2 mutations confirm diagnosis.
• 🧪 Bone density (DEXA): Baseline and monitoring tool.
• 🧠 Hearing tests & dental assessment for systemic features.

💊 Management

• 🦴 Bisphosphonates: Reduce fracture rates & bone pain (esp. in children).
• 🛠️ Orthopaedic support: Casting, splinting, intramedullary rodding for deformities, spinal fusion for scoliosis.
• 🏃 Physiotherapy & exercise: Improves muscle tone, mobility, independence.
• 🧑‍⚕️ Multidisciplinary care: Orthopaedics, endocrinology, dentistry (for dentinogenesis), ENT (hearing loss), physiotherapy, psychology.
• 🚭 Lifestyle: avoid smoking, alcohol, and unnecessary steroids.
• 👶 Family planning: genetic counselling important.

📝 OSCE / Exam Pearls

• Always differentiate OI from child abuse in paediatrics.
• Blue sclerae + multiple fractures = classic OI (esp. Type I).
• Bisphosphonates improve quality of life but are not curative.
• Multidisciplinary approach is key to management.
• Hearing loss and dentinogenesis imperfecta are high-yield extra-skeletal features to mention in exams.

📚 Reference

Osteogenesis Imperfecta Foundation – Medical Guide