Osteogenesis imperfecta

Group of heritable connective tissue disorders causing fragile bones that fracture with minimal trauma due to defective type I collagen.

• Although rare, recognizing OI is crucial so that children with frequent fractures are not misjudged as abuse victims. It's also a classic exam topic linking blue sclerae, brittle teeth, and early hearing loss to a collagen defect.

• Multiple fractures with minimal trauma (severity ranges from a few childhood fractures to in utero fractures in lethal forms).
• Blue sclerae (bluish tint of the eye whites due to translucent sclera), dentinogenesis imperfecta (translucent, brittle teeth), and hearing loss in adulthood are telltale clues.
• Severe forms present with short stature, limb deformities (bowing), scoliosis or barrel chest, and joint laxity; in type II (most severe) infants can be born with rib fractures and underdeveloped lungs.

1. Fractures + blue sclerae or tooth abnormalities in a child → suspect OI rather than child abuse.
2. For moderate-to-severe OI, early bisphosphonate therapy (e.g., IV pamidronate) can improve bone density and reduce fractures.

1. Bisphosphonates (e.g., IV pamidronate or zoledronate) to increase bone mineral density and reduce fracture risk; ensure adequate calcium & vitamin D intake.
2. Orthopedic interventions: surgical intramedullary rodding of long bones to stabilize frequent fractures and correct deformities; prompt casting or fixation of acute fractures with careful handling.
3. Rehabilitative and supportive care: physical therapy and low-impact exercise to strengthen muscles, bracing and mobility aids (braces, wheelchairs) as needed, plus specialized dental care and hearing aids if hearing loss develops.

• Mnemonic: patients with OI "can't BITE" – *B*ones fracture easily, *I* (eye) blue sclerae, *T*eeth abnormalities, *E*ar hearing loss.

• Basilar invagination (C1 neck deformity) in OI can cause brainstem compression – watch for headaches, ataxia, or cranial nerve deficits and refer for urgent neurosurgical evaluation.
• Severe respiratory compromise (e.g., an infant with a small, fragile ribcage or a patient with advanced scoliosis) – monitor pulmonary function and support ventilation as needed, as respiratory failure can occur.

1. Child with multiple fractures → assess for OI features (blue sclerae, dentinogenesis imperfecta, family history) while also evaluating for abuse risk.
2. Obtain a skeletal survey (full-body X-rays) to document all fractures and look for OI signs (diffuse osteopenia, wormian bones in skull, old healed fractures).
3. Confirm diagnosis with genetic testing for COL1A1/COL1A2 mutations (preferred) or collagen biochemical analysis from a skin biopsy.
4. Determine OI type/severity (Types I–IV clinical classification) to guide prognosis and therapy.
5. Multidisciplinary management: involve orthopedics, endocrinology, and rehabilitation early – implement bisphosphonates, plan for rodding surgery if needed, and provide physical therapy and family education on fracture prevention.

• Newborn with multiple fractures at birth, limb bowing, and blue sclerae → Osteogenesis imperfecta, perinatal lethal type (Type II).
• Toddler with frequent fractures but also blue sclerae and opalescent teeth; no evidence of bruising or neglect → OI (Type I), not child abuse.
• 30-year-old with early-onset hearing loss and history of childhood fractures → Mild OI presenting with adult hearing loss (otosclerosis).