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OSTEOGENESIS IMPERFECTA

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INTRODUCTION AKA Brittle Bone Disease Genetically determined ... and osteopenia Achondrogenesis Achondroplasia Pyknodysostosis Rickets Menkes syndrome ... – PowerPoint PPT presentation

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Title: OSTEOGENESIS IMPERFECTA


1
OSTEOGENESIS IMPERFECTA
  • Scott M. Heithoff

2
INTRODUCTION
  • AKA Brittle Bone Disease
  • Genetically determined disorder of connective
    tissue characterized by bone fragility
  • There is an abnormal quality and/or quantity in
    type I collagen
  • The clinical disease state is manifested in
    tissues in which the principle matrix protein is
    type I collagen (bone, dentin, sclerae, and
    ligaments
  • Incidence is about 120,000 in the population
  • Intelligence is not affected

3
INTRODUCTION - HISTORY
  • Malebranche (1674)
  • Provided first description
  • Ekman (1788)
  • Earliest scientific description - congenital
    osteomalacia
  • Vrolik (1849)
  • Named disorder osteogenesis imperfecta

4
PATHOPHYSIOLOGY
  • Inability to produce normal collagen and osteoid
    at normal rates
  • The disturbance is in both enchondral and
    intramembranous bone formation
  • Cartilaginous epiphyses are normal
  • Defect is thought to be at the cellular level
    with an inability to synthesize the normal amino
    acid makeup of collagen fibers
  • Caused by mutations in COL1A1, COL1A2 genes

5
CLINICAL MANIFESTATIONS
  • Depends on the type of OI
  • There is a wide spectrum of manifestations,
    ranging from perinatal lethal forms with crumpled
    bones and severe deformity to clinically silent
    forms with subtle osteopenia and no deformity
  • Classic triad described by Adair and Dighton in
    1912
  • fragile bones
  • blue sclera
  • early deafness

6
CLINICAL MANIFESTATIONS
  • Four major clinical features - depending on type
  • osteoporosis with abnormal bone fragility -
    Hallmark of OI
  • blue sclerae - Due to increased corneal
    translucency
  • defective dentition
  • presenile onset of hearing impairment
  • Can have a hypermetabolic state - have
    predisposition for malignant hyperthermia
  • Ligamentous laxity

7
CLINICAL MANIFESTATIONS
  • Can see multiple bony manifestations
  • General fragility of bone
  • Short stature
  • Scoliosis up to 40
  • Defective dentinogenesis - soft translucent,
    brown teeth
  • Trefoil shaped pelvis
  • Protrusio acetabuli

8
CLINICAL MANIFESTATIONS
  • Common Xray features
  • Generalized osteopenia
  • Slender long bones
  • Trumpet shaped metaphyses
  • Popcorn calcifications
  • Wormian skull bones

9
CLINICAL MANIFESTATIONS
  • Must differentiate from child abuse
  • Common child abuse fractures
  • Multiple fractures in different stages of healing
  • Posterior rib fractures
  • Metaphyseal corner fractures
  • Also look for bruises, burns, and retinal
    hemorrhages

10
DIAGNOSIS
  • Diagnosis of OI is still based primarily on
    clinical and radiographic criteria
  • There have been lab tests described
  • Culture of dermal fibroblasts for
    characterization of type I collagen - found in
    85
  • Matching of child's type I collagen with
    molecular abnormalities may establish the
    diagnosis, but not matching does not exclude the
    diagnosis
  • Serum calcium, phosphate, magnesium, Vit D, and
    PTH levels are all WNL

11
DIFFERENTIAL DIAGNOSIS
  • Infancy
  • Hypophosphatemia can present with multiple
    fractures, deformities, and osteopenia
  • Achondrogenesis
  • Achondroplasia
  • Pyknodysostosis
  • Rickets
  • Menkes syndrome
  • Homocystinuria

12
DIFFERENTIAL DIAGNOSIS
  • Childhood and adolescence
  • Idiopathic juvenile osteoporosis Generalized
    osteopenia and propensity to fracture
  • Leukemia
  • Fibrous dysplasia

13
CLASSIFICATION
  • There have been many different classifications
    throughout history
  • Looser (1906) congenita and tarda,
    differentiating when the fractures occurred
  • Seedorff (1949) congenita and tarda (gravis
    (lt1yr) Vs levis (gt1 yr.))
  • Sillence (1979) Types I - IV, most widely
    accepted
  • Shapiro (1985) congenita (A,B) and tarda (A,B)

14
CLASSIFICATION SILLENCE
  • Type I
  • Autosomal dominant
  • Common mild form
  • Incidence 3-5100,000
  • 50 reduction in the production of type I
    collagen
  • See fractures later in childhood, decrease
    towards adolescence

15
CLASSIFICATION SILLENCE
  • Type I
  • Blue sclerae
  • Xray - slender and gracile long bones, thin
    cortices, and deformities secondary to fractures
  • Subtypes A and B

16
CLASSIFICATION SILLENCE
  • Type II
  • Autosomal recessive
  • 1 40,000 - 60,000
  • Lethal in perinatal period
  • Mutations in glycine residues of type I collagen
  • Dark blue sclera
  • Xray - Femurs with crumpled concertina
    appearance, beaded ribs

17
CLASSIFICATION SILLENCE
  • Type III
  • Autosomal recessive
  • Severe form
  • Fractures at birth, progressive deformity
  • Normal sclera and hearing
  • Xray - Short bones, wormian skull bones,
    platyspondylia, scoliosis

18
CLASSIFICATION SILLENCE
  • Type IV
  • Autosomal dominant
  • Rare 5 of OI
  • Moderately severe
  • Glycine point mutations
  • Normal sclera and hearing
  • Subtypes A and B

19
CLASSIFICATION SHAPIRO
  • Congenita - Fractures at birth or in utero
  • A Crumpled femurs and ribs Sillence II
  • B Normal bone contours, but with fractures
    Sillence III
  • Tarda - Fractures after birth
  • A Fractures before walking Sillence III
  • B Fractures after walking Sillence I

20
CLASSIFICATION SHAPIRO
  • Shapiro attempted to correlate this
    classification with a musculoskelatal prognosis
  • Congenita A 94 mortality
  • Congentia B 8 mortality, 59 wheelchair,
    33 ambulate
  • Tarda A 33 wheelchair, 67 ambulatory
  • Tarda B 100 ambulatory

21
MANAGEMENT
  • Medical management is controversial and mostly
    ineffective.
  • Calcium and phosphorous intake has no beneficial
    effect
  • Growth hormone and calcitonin have been shown to
    increase bone density
  • Bisphosphonates have been suggested to have a
    protective effect, but research is still ongoing
  • Gene therapy is currently under investigation

22
MANAGEMENT
  • Goals of treatment of OI
  • Maximize function
  • Minimize disability
  • Achieve relative independence in activities of
    daily living
  • Attain the greatest possible degree of mobility
  • Allow social integration
  • Maintain overall health

23
MANAGEMENT
  • Can use the Sillence classification as a guide
  • Type I Limited to conventional fracture care
  • Type II Lethal
  • Type III and Type IV Challenging
  • Management challenges for the orthopedist
    include
  • Fracture prevention
  • Fracture management
  • Limitation of deformity
  • Optimization of function

24
MANAGEMENT
  • Closed management of fractures is the mainstay of
    treatment
  • Fractures heal readily with exuberant callus, but
    the callus is identical in structure to the rest
    of the skeleton - plastic and easily deformed
  • Fractures often lead to malunions and
    psudoarthrosis with resultant long bone deformity

25
MANAGEMENT
  • There is a place for the use of bracing and
    orthotics in the management of the children
  • Braces help support lax joints and maximize
    function
  • Lightweight bracing can be helpful for external
    support to promote stance and ambulation
  • Must be followed closely to assure proper fit and
    function

26
MANAGEMENT
  • Surgical intervention
  • Controversy over the timing and type of surgery
  • Has been advocated as early as 6 weeks
  • Some accept the deformity and treat closed, wait
    until 5 years of age, and then do corrective
    osteotomies
  • Indications for surgery
  • Recurrent fractures
  • Deformity that impairs function

27
MANAGEMENT
  • General principles of surgical management
  • Avoid surgery in patients under 2 years of age
  • Avoid plate and screw fixation in favor of
    intramedullary fixation
  • Use gentle technique for muscle preservation and
    minimize soft tissue bleeding
  • Avoid the use of bone-clamps

28
MANAGEMENT
  • Sofield osteotomy
  • Fragmentation, realignment, and IM rod fixation
    of the bone using multiple corrective osteotomies
  • Morel technique
  • Closed osteoclasis with traction followed by
    pneumatic splints
  • Bailey-Dubow
  • consists of a hollow tube or sleeve with a solid
    rod that telescopes inside

29
MANAGEMENT
  • Treatment of scoliosis is also a challenge
  • Bracing has been found ineffective secondary to
    the soft deformed rib cage and truncal shortening
  • Curves are difficult to control secondary to poor
    quality of bone
  • Newer methods of segmental spinal instrumentation
    are changing the approach to these problems
  • It has been recommended that curves be fused
    early ( at 40 deg) to halt progression

30
SUMMARY
  • Disorder of type I collagen
  • Sillence classification most widely used and
    accepted
  • Closed management is often difficult secondary to
    multiple fractures and deformities of the bone
  • Surgical management is also difficult secondary
    to the above and also the osteopenia of the bones
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