3: Osteogenesis Imperfecta

What is osteogenesis imperfecta (OI)?

Inherited connective tissue disorder due to type I collagen defect

collagen station that results in fragile bones

Common name for OI?

Brittle bone disease

Incidence of OI?

1 in 10,000–20,000 births

Defect in collagen synthesis

Collagen fibers fail to mature beyond the reticular fiber stage

Osteoblasts have normal or increased activity, but fail to produce and organize the collagen

types I-IV

Lamellar organization in an irregular mesh-like pattern

type V

Normally developed Type I collagen fiber, but can’t be translated into bone

type VI, VII, VIII

Pathophysiology of OI types I–IV?

Defect in collagen synthesis

Collagen fibers fail to mature beyond the reticular fiber stage

Osteoblasts have normal or increased activity, but fail to produce and organize the collagen

Pathophysiology of OI type V?

Lamellar organization in an irregular mesh-like pattern

Pathophysiology of OI type VI, VII, VIII?

Normally developed Type I collagen fiber, but can’t be translated into bone

What is the Sillence classification of OI? How many subtypes?

Uses a numeric system to delineate the different subtypes of OI

11 subtypes

Most common mild OI type?

type I

mild OI includes what types?

I, IV

characteristics of mild OI

• Normal/near-normal stature

• Bone fragility (fewer fractures over lifespan)

• Minimal to no bone deformity

• Blue or gray sclerae (classic for type I)

• Normal life expectancy

• May have dentinogenesis imperfecta

• Hearing loss common in adulthood

Functional ability in mild OI?

• Independent ambulation most cases

• temporary mobility aids after fractures

• Participates in age-appropriate activities with fracture precautions

• Normal lifespan

PT focus in mild OI

• Safe mobility

• Fitness

• Posture

• Education on activity modification

types included in moderate OI

V, VI, VII, XII

characteristics of moderate OI

• Moderate bone fragility with recurrent fractures

• Variable short stature (often below average but not extreme)

• Bone deformity, typically bowing of long bones

• May have scoliosis, vertebral compression fractures

• Ligamentous laxity and muscle weakness

• Hearing loss in adolescence/adulthood

• normal to slightly reduced lifespan

functional ability in moderate OI

• Many ambulate- may require bracing (KAFOs, HKAFOs) or occasional assistive devices (walker, crutches, or wheelchair for distance)

• Frequent fractures = limit endurance and participation

• Stature usually shorter than peers

• Functional independence possible (with adaptations)

PT focus for moderate OI

• Strengthening

• Joint protection

• Adaptive equipment

• Endurance training

types involved in severe OI

II, III, VIII, IX, X, XI,

characteristics of severe OI

• Severe bone fragility → multiple fractures at birth or in infancy

• Very short stature

• Significant bone deformities (long bone bowing, scoliosis, chest wall deformity)

• Dentinogenesis imperfecta common

• Respiratory complications often limit lifespan in severe forms

type __ OI = most severe survivable form, progressive deformities, wheelchair dependence

III

Type ___ OI = perinatal lethal

II

functional ability in severe OI

• Most require wheelchair for mobility

• Some = limited household ambulation with orthotics and assistive devices

• Progressive deformities and recurrent fractures limit standing/walking ability

• Independence in self-care achievable with adaptations

PT focus in severe OI

• Safe transfers

• Respiratory care

• Supported mobility (wheelchair skills, standing programs)

• Maximizing participation

common S/SX in OI

• Lax Joints

• Weak Muscles

• Osteoporosis

• Recurrent Fractures

• Bowing of Long Bones

• Scoliosis

• Blue Sclerae

• Dentinogenesis Imperfecta

• Deafness

• Hernias

• Easy Bruising

• Excessive Sweating

progression of OI depend on?

type and fracture management/healing

____ ____ play a role in subsequent impairments in OI

growth patterns → Many children use assistive devices for mobility

Main medication for OI?

Bisphosphonates

what do bisphosphonates do

inhibit osteoclast activity, decreasing normal bone turnover

Why give vitamin D in OI?

Assist calcium absorption

what type of surgery may improve collagen and mineral content?

bone marrow transplant

surgical interventions for OI

Intramedullary Rods: telescoping rods can be adjusted with growth

Spinal Fusion

what to avoid in PT evaluation for those with OI?

PROM

MMT → observational assessment instead

PT evaluation for OI

• History and Fracture History

• Gross motor development/timing of milestones → Standardized Assessment

• ROM/Strength

• Posture

• Endurance

• Gait/Mobility

• Coordination/Balance

• Pain

• Assistive Devices/Bracing

safe handling techniques in OI

• gently at broad surface areas

• support head/trunk/extremities simultaneously

• soft padding during positioning, transfers, therapy

• encourage independent mobility/movement

• keep trunk/limbs midline position

• carry close to the body

AVOID these techniques when handling OI

• Lifting by underarms, limbs or rib cage

• Sudden, jerky movements

• PROM or manual assistance

• Twisting or segmental separation of trunk

• Grasping or lifting through fingertips (utilize your whole hand)

PT goals for OI

• Family Education

• Safe Weight Bearing

• Aerobic Conditioning

• Strengthening in a safe environment

• Maximizing gait and functional independence

• Interdisciplinary Approach

PT management of OI

• Education on fracture care & safe handling

• Age-appropriate developmental skills

• Weight bearing activities to improve bone density

• Positioning → seating, standing frames

• Good skeletal alignment

• Mobility → alternative mobility early

• Strengthening

• Aerobic Activity

• Maximize independent mobility and function

what OI intervention has good results but is contraindicated in those with telescoping rods or joint subluxations?

whole body vibration (WBV)

what intervention is safe, gravity-eliminated environment

aquatics

Take-Home Points

• Positioning

• Prevention of fractures

• Increase bone density

• Safe mobility

• Developmental & Functional skills