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Osteogenesis imperfecta (brittle bone disease)
An inherited disorder of type 1 collagen, usually a dominant mutation in COL1A1 or COL1A2, causing fragile bones that break with minor trauma, sometimes with blue sclerae, dental involvement and hearing loss.
Why it matters in the exam
Questions present a child with repeated fractures from a minor mechanism and ask you to tell osteogenesis imperfecta from child abuse — a very important differential, including legally. Clues in favour of the disease: bluish sclerae, translucent fragile teeth (dentinogenesis imperfecta), lax joints, short stature, wormian bones in the skull, a family history and hearing loss from adolescence or adulthood. In contrast, posterior rib fractures, metaphyseal corner fractures and fractures at different stages of healing without bone disease suggest abuse. The Sillence classification divides the disease by severity: type I is mild, type II is perinatally lethal, type III is progressive and deforming and type IV is moderate. Treatment combines bisphosphonates to thicken bone and reduce fractures, physiotherapy to maintain strength and movement, and surgery to insert intramedullary rods that lengthen with growth (telescoping rods) to straighten deformities and prevent repeated fractures. In daily practice, remember that fracture care itself is different: immobilise for as short a time as possible to avoid worsening bone loss, and prefer intramedullary rod fixation over plates and screws, which create weak points at their ends. The exam also asks about genetic counselling for parents, the risk of passing the disease to offspring and lifelong dental and hearing follow-up. Adults with the mild type may first present with multiple fractures or early osteoporosis, so ask about childhood fractures and relatives with a similar problem.
Key points
- An inherited type 1 collagen disorder with fragile bones.
- Blue sclerae, dental involvement and hearing loss are key clues.
- Important differential: child abuse.
- Sillence: I mild, II lethal, III deforming, IV moderate.
- Treatment: bisphosphonates, physiotherapy and intramedullary rods.
Summary table
| Type (Sillence) | Severity | Key features |
|---|---|---|
| I | Mildest and most common | Blue sclerae, relatively few fractures, hearing loss in adulthood, near-normal height |
| II | Perinatally lethal | Many fractures in utero, deformed ribs, respiratory failure |
| III | Severe and deforming | Progressive deformity of long bones and spine, very short stature |
| IV | Moderate | Normal or greyish sclerae, moderate fractures and deformity |
| General treatment | All surviving types | Bisphosphonates, physiotherapy, intramedullary rods, hearing and dental follow-up |
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Sources
- Lovell and Winter's Pediatric Orthopaedics, 8th ed. (2020) — Skeletal Dysplasias and Osteogenesis Imperfecta
- Rockwood and Wilkins' Fractures in Children, 9th ed. (2019) — Child Abuse and Pathologic Fractures
Sources are given for further reading; the text is written afresh and not copied from them.
Reviewed by the Examqo AI Professor · 2026-11-06. The text may contain errors; when in doubt, check the source.