Osteogenesis ImperfactaHereditary condition resulting from a decreasein the amount of normal Type I collagenType I collagen ( important for )BoneLigamentsTeethWhite ScleraSkin
Type I collagen deficiency can result from decreased collagen secretion production of abnormal collagenManifest by increase bone fragility low bone mass ( Osteopenia )Both Autosomal dominant and Autosomal recessive formsCan be severe or mild (Tarda)Osteogenesis Imperfecta
Orthopaedic manifestations Bone fragility and fracturesfractures heal in normal fashion initiallybut the bone is does not remodelcan lead to progressive bowing ligamentous laxity Short stature Scoliosis Codfish vertebrae (compressionfx) Basilar invagination Olecranon apophyseal avulsion fx
SymptomsMild casesmultiple fractures during childhoodSevere casespresent with fractures at birth and can be fatalNumber of fractures typically decreases as patient ages andusually stops after pubertyBut deformity persist.Basilar invaginationBrain Stem dysfunctionapnea, altered consciousness, ataxia, or myelopathyusually in third or fourth decade of life, but can be as early as teenageyears
Physical examMultiple fractures leads toSaber shin appearance of tibiaBowing of long bonesScoliosis
Sillence Classification of Osteogenes Imperfecta(simplified)Type IMildest form. Presents at preschool age (Tarda).Autosomal dominantblue scleraHearing deficit in 50%.Divided into type A and B based on tooth involvementType IIAutosomal recessiveBlue scleraLethal in perinatal period
Type IIIAutosomal recessiveNormal sclereaFractures at birth.Progressively short stature.Most severe survivable formType IVAutosomal dominant normalModerate severity.Bowing bones and vertebral fractures are common.Hearing normal.Divided into type A and B based on tooth involvement
Type VHypertrophic callus after fracture.Ossification of IOM ( radius/ulna and tibia/fibula )Type VIModerate severity. Similar to type IVType VIIAssociated with rhizomelia and coxa varaType V, VI, VIIAdded to the original classification system .No Type I collagen mutationBut have abnormal bone on microscopy and a similar phenotype
Radiographs Thin cortices Generalized osteopenia Long bone thin and bowed Pelvis may show acetabular protrusion Fractures that are at different stages of healing The vertebra maybe biconcave.
DiagnosisDiagnosis is based on family history associatedwith typical radiographic and clinical featuresNo commercially available diagnostic test(varietyofgeneticmutations)laboratory values are typically within normal rangePossible methods include Fibroblast culturing to analyze type I collagen (positivein80%oftypeIV) can be used for confirmation of diagnosis in equivocalcases Collagen analysis of a punch biopsy Iliac crest biopsy which shows a decrease in cortical widths andcancellous bone volume, with increased bone remodeling.
Treatment of FracturesFracture preventionEarly bracingDecrease deformity.Stabilize lax joints.Decrease fractures incidence.BisphosphonatesGrowth hormoneClinical studies showed no increase in bone massBone marrow transplantation
BisphosphonatesPrevent bone mass loss and decrease bone resorption by suppressing the activity ofosteoclasts. IndicationsOsteoporosisMetastatic bone diseaseMultiple myelomaPagets diseasePolyostotic fibrous dysplasiaTotal joint arthroplasty to prevent osteolysisEarly stage avascular necrosisOsteogenesis imperfecta ContraindicationsSevere renal diseaseLumbar fusion decreased spinal fusion ratesHypersensitivity.Pregnancy. Side Effects & ComplicationsJaw osteonecrosisAtypical subtrochanteric and femoral stress fracturesRadiographic changes consistent with osteopetrosisBisphosphonates in O IIndicated in most cases of OI to reduces fracture rate andpainCombined with calcium and vitamin DIncrease cortical thickness by inhibiting osteoclastsDoes not affect development of scoliosisTreatment is less effective after completion of growth.
PamidronateInjectable bisphosphonate(Cyclic Intravenous )Increases cortical bone thicknessIncrease bone mass and density.Decreases the incidence of fractures.Relieves chronic bone pain.Increases activity levels.Decreases the reliance on mobility aids.Increases the height of the collapsedvertebral bodies.BUTNotdecreasetheincidenceofscoliosis.ZebralinesRadiographically Pamidronate therapy creates growth lines in the bone
Bone marrow transplantationUsed with some successIntroduces normal marrow stem cells that couldpotentially differentiate into normal osteoblasts,Problems of graft rejection and graft versus hostreactions limit this approach.
Fracture treatmentNonoperativechild is less than 2 yearstreataschildwithoutOIOperativeFixation with Telescoping rodespatients > 2 yearsallow continued growth
Treatment of Long Bone DeformitiesRealignment Osteotomy with rod fixation(Sofield-Miller procedure)Indicated in severe deformity toCorrect the deformityReduce fracture ratesTechniques includeNontelescopic devicesTelescopic devices
Treatment of ScoliosisObservationCurve less than 45 °Bracing is ineffectiveOperativeposterior spinal fusionIndicationsfor curves > 45 ° in mild forms and> 35 ° in severe formsTechniqueChallenging due to fragility of bonesUse allograft instead of iliac crest autograftLarge blood loss