OI

Question 1

What is OI?

Answer 1

AKA Brittle Bone Disease
Inherited disorder of connective tissue resulting in fragile bones and recurrent fractures, muscle weakness, and ligamentous laxity, diffuse osteoporosis—> results in increased frequency of fractures even from minimal trauma

Incidence = 1 in 200,000-300,000 live births; 1 in 10,000 individuals
Mild to severe forms classified differently

Severe forms – multiple fractures at birth and infants do not usually survive. In some cases infants are born with multiple fractures.

PT should be aware of social isolation due to being overprotected due to recurring fractures

Question 2

Clinical Features

Answer 2

fragile bones and recurrent fractures, muscle weakness, and ligamentous laxity
Blue sclera- occurs because in OI the sclera is thinner and the blue appearance is caused by the veins in the eye showing through.
Dentinogenesis imperfecta- defect in dentin, gray or blue or brown in appearance, increased cracking, wear, decay (baby teeth more affected than adult teeth)
Hernias- Umbilical or inguinal
Hearing loss
Easy bruising
Excessive sweating
Loose or dislocated joints
Intelligence levels- high

Question 3

Diagnosis

Answer 3

Clinical features
Biochemical Test (Collagen)
Molecular Test (DNA)
Clinical Features are variable between different types. Primary impairments: bone fragility, short stature, scoliosis, ligament laxity, weak muscles, bowing of long bones, failure of postnatal growth, multiple fractures sustained from minor or no trauma. 

Detects 90+% of collagen type I mutations

Moderate OI: often identified after several fractures have resulted from slight trauma

R/o other disorders

DEXA scan can be used to look at bone density

Question 4

Management of OI

Answer 4

No known cure
Medical management- bisphosphonates, bone marrow transplant
Surgical management- intermedullary rods in long bones
PT management
Family education, support, and counseling
ROM and strengthening program
Modifications to reduce injury
Splinting, casting, assistive devices
Aquatic Therapy
Be aware of signs/symptoms of fracture including: inflammation, bruising, irritability, deformity, self-limiting activities

Biphosphonates inhibit osteoclast activity, has been shown to decrease fracture rates in Types I, III, and IV.

Rehab goals should focus on: prevention of deformities of head, spine, and extremities, decrease cardiorespiratory compromise through positioning programs, maximize the child’s ability to move actively.

Question 5

Causes of OI

Answer 5

Inherited condition that results from an abnormality in the type 1 collagen, resulting in weak bones. Abnormality in processing procollagen to Type I collagen
Collagen fails to mature based reticular fiber stage
Failure to produce organized collagen

Question 6

Fracture MGMT

Answer 6

Once one fracture occurs = bone more susceptible to subsequent fx

Generally heal within normal healing time, resulting callus may be large but poor quality

Immobilization

Rods for long bones– often use telescoping rods to accomodate for growth