Osteogenesis Imperfecta



Abnormality of type 1 collagen

- amino acid substitution of glycine with another amino acid

- prevents triple helix formation


Many many deformities described

- some 286 mutations of Type 1 collagen described


Sillence Classification


There are actually now 7 


Type I

- mild

- AD

- blue sclera


Type II

- lethal in utero

- AR

- blue sclera


Type III

- severe

- AR

- white sclera

- multiple deformities without intervention

- wheelchair bound and non ambulatory


Type IV

- moderate to severe

- white sclera

- AD

- very rare









Skin biopsy

- assessment of type 1 collagen

- fibroblast cell culture


DNA study


Skeletal Manifestations


Frequent multilevel fractures with limb deformity

- tibia

- femur

- forearm


Osteogenesis Imperfecta ForearmOsteogenesis Imperfecta Wrist


Osteogenesis Tibial BowOsteogenesis Imperfecta Tibial Bow 2


OI ForearmOI Shoulder


Coxa vara

- femoral neck shaft < 110o

- correct with multiple osteotomies





- indicated for curve reaching 40o as will be progressive and non flexible

- > 60o impairs respiratory function



- bony fragility

- increased use of pedicle and TP hooks and sublaminar wires


Basilar impression / invagination


Very serious problem

- the foramen magnum invaginating into the posterior fossa

- leads to stenosis with resultant hydrocephalus 

- compression of the cerebellum, brain stem, and cervical cord


Lateral cervical spine radiograph

- upward migration of the cervical spine into the base of the skull

- deformity may be subtle and requires careful scrutiny of the radiographs


Various descriptions of the characteristic skull shape

- Darth Vader


Extraskeletal Manifestations


Blue sclera 

- due to translucent sclera can see underlying choroid and blood vessels

- due to defect type 1 collagen


Dentinogenesia imperfecta 

- teeth appear brownish or bluish

- are soft, translucent and prone to cavities

- defect type 1 collagen


Hearing problems

- defect hearing bones


Fragile skin and fragile capillaries


Valvular Disease


Mitral prolapse and Aortic Regurgitation




Nonoperative Management




Increase BMD and cortical thickness and cancellous trabeculation

- reduces bone pain

- decrease fracture rate

- maintains shape of long bones and vertebrae


Mechanism of action

- inhibits osteoclasts



- very poor bioavailability (.6 - 7)

- incorporated into skeleton

- long half life there (1.5 - 10 years)



- need period off medications

- doesn't decrease fracture healing but probably does decrease osteotomy healing (i.e. avoid around time of IM rodding)

- osteonecrosis of the jaw: a rare side effect in adults, not seen in children




Glorieux et al NEJM 1998

- increased BMD by 40%

- reduced fracture rate by 1.7 per year

- evidence new bone formation in vertebrae

- did not alter rate fracture healing


Bone marrow transplant


Increased mesenchymal stem cells


Operative Management




Prevent fractures

Treat or prevent deformity




Multilevel osteotomy with IMN

- must be expandable or get fracture and deformity below level


Expandable telescopic IM rods



- lengthen as the bone grows

- male and female portions

- lock in epiphysis top and bottom


Sheffield Rods

- T piece

- 20% revision at 5 years


Fassier-Duval Rods

- epiphyseal portion is threaded