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Paediatrics FCRS > Tibial bowing > Flashcards

Tibial bowing Flashcards

Neurofibromatosis Fibular hemimelia Posteriomedial bowing Tibial Deficiency/ Hemimelia

1
Q

Define neurofibromatosis?

A
  • An autosomal Dominant disorder of Neural crest origin
  • characterised by
    • Extremity deformities
      • congential anterolateral bowing & pseudoarthrosis of tibia/fibula/ forearm
      • hemihypertrophy
    • Spine invovlement
      • scolosis & kyphosis
      • Atantoaxial instability
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2
Q

What is the epidemiology of neurofibromatosis?

A
  • 1: 3,000 births for NF1
  • Genetics
    • Autosomal dominant
    • Mutation in NF1 gene on chromosome 17q21
    • Codes for neurofibromin protein
      • ​negatively regulates Ras signalling pathway
      • Neurofibromin def-> increaed Ras activity
      • affects RAS dependent MAPK activity which is essential for Osteoclast function and survival
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3
Q

Name associated conditions of neurofibromatosis ?

A
  • Scoliosis
  • anterolateral bowing of tibia
  • forearm bowing - less common than tibia
  • neoplasiaa
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4
Q

What is the prognosis of NF?

A
  • Normal life expectancy
  • high incidence of malignancy & hypertension
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5
Q

What is the diagnostic criteria of Neurofibromatosis?

A
  • 2 or more of the following
    • 6 or more cafe au lait macules >5mm diameter in pretubertal individuals and >15mm in postpubertal individuals
    • 2 or more Neurofibrommas of any type or one plexiform neurofibroma
    • freckling in axillary or inguinal region
    • optic glioma
    • 2 or more Lisch modules- iris haemartomas
    • a distincitve osseous lesion- eg sphenoid dysplasia/ thinning of cortex with or wout pseudarthrosis
    • a first degree relative w NF1
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6
Q

What is the classification of NF?

A
  • NF1
    • Von recklinghaussen disease
    • Most common
  • NF2
    • assoc with bilateral vestibular schwannomas
  • Segmental NF2
    • Features of NF1 but involving a single body segment
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7
Q

What is the presentaton of NF?

A
  • Anterolateral bowing of tibia
  • Radial bowing
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8
Q

What is seen on examination of a pt with NF?

A
  • Veroccous hyperplasia
  • hemihypertrophy- see pic
  • cafe au lait spots
  • axillary freckling
  • scoliosis
  • anterolateral bowing or pseudoarthrosis of tibia
  • dermal plxiform neurofibroma
  • Lish nodules - benign pigmented haemartomas of iris
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9
Q

Name the neoplasias of NF?

A
  • Neurofibromas plexiform- type
    • pathogonomic for NF1
    • Present in 4% of NF1
    • maybe dermal or deep tissue
    • often assoc with limb overgrowth
    • can undergo malignant change-> Neurofibrosarcoma
  • Wilms Tumour
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10
Q

Describe the scoliosis in NF?

A
  • Most common site for invovlement of NF1
  • Not seen in NF2
  • 2 forms
    • ​Idopathic
      • _​_long curves
      • tx resembles that for idiopathic scoliosis
    • Dystrophic
      • ​curve is typically thoracic kyphoscoliosis
      • short segmented and steep curve ( invovled 4-6 vertebra)
      • disorted ribs and vertebra
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11
Q

What is seen in maging the spine in NF scoliosis?

A
  • xrays
    • Vertebral scalloping
    • penciling of ribs- >3 assoc with rapid curve progression
    • enlarged foramina
  • MRI
    • always obtained preop to identify any dural ectasia /dumbell lesions- neurofibroma of the nerve root
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12
Q

Describe the tx of NF scoliosis?

A

Non operative

  • observation vs bracing
    • not efective in dystrophic scoliosis
    • NF idiopathic scoliosis tx like adolescent idopathic scoliosis
    • cobb angle <25o observe
    • Cobb angle 25-45o bracing
    • cobb angle >450 = operation

Operative

  • Decompression ASF, PSF + instrumentation
    • for dystrophic scoliosis in young children <7 yrs
    • complx
      • high rate of pseudoarthrosis w PSF alone 40%
      • pseudoarthrosis high w ASF& PSF 10%
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13
Q

Describe the epidemiology of anterolateral bowing in NF?

A
  • assoc with NF-1
  • 50% with anterolateral bowing have NF1
  • only 10% of NF1 have anterolateral bowing
  • thinning cortices-> pathological fx
  • Repeated fx ->may progress to pseudoarthrosis
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14
Q

What are the DDX of anteromedial bowing

A
  • Fibular hemimelia and congenital loss of lateral rays of foot
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15
Q

What are the ddx of this bowing?

A
  • Postermedial bowing
    • usually congential due to …
    • abnormal uterine position
    • dorsiflexed foot pressed against anterior tibia
    • wlll develop-> LLD
    • assoc with Calcaneovalgus foot deformity
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16
Q

What is the tx of anterolat bowing in NF?

A

Non operative

  • Bracing in total contactorthosis
    • bowing without pseudoarthrosis/ fx
    • goal is to prevent furthur bowing
    • spontaneous remodelling is not expected
    • osteotomy for bowing is CI

Operative

  • Bone grafting with surgical fixation
    • for bowing with pseudoarthrosis/ fx
  • Amputation with prothesis fitting
    • for 3 failed surgical attempts
    • Syme superior to BKA due to atrophic and scarred calf muscle
17
Q

What sugical techniques are available for correction of pseudoarthrosis/ tibia fx bowing?

A
  • Intramedullary nailing with bone graft
    • resecr pseudoarthrosis
    • insert charnley- williams rod antegrade thru resection site and retrograde thru heel
    • at <4yr fix to calcaneus
    • 5-10 fix to talus
    • at 2 yrs post 2 nd surgery to push rod proximally to free ankle joint
  • Free fibular graft
    • often need to take from contralateral side because ipisalteral fibular is not normal
    • ilizarov ex fix
18
Q

What is fibular hemimelia?

A
  • Fibular deficiency
  • most common congential long bone deficiency
  • consists of shortening or entire absence of fibula
19
Q

What is the genetics of fibular hemimelia?

A
  • No known inheritance pattern
  • linked to Sonic hedge-hog gene
20
Q

What are the associated conditions of fibular hemimelia?

A
  • Anteromedial tibial Bowing
    • ​most common cause is fibular hemimelia
  • Ankle instability
    • secondary to ball and socket joint
  • Tarsal Coalition- 50%
  • equinovalgus foot deformity
  • Absent lateral rays
  • femoral abnormalities- Proximal femoral focal deficiency, coxa vara
  • Cruciate ligament deficiency
  • Genu valgum
    • secondary to lateral femoral condyle hyperplasia
  • Significant leg length discrepancy
    • shortening of femur/tibia
21
Q

Name a classification system of fibular hemimelia?

A
  • Birch
  • based on limb length and foot function
  • directs tx
22
Q

What are the classical findings on examination of fibular hemimelia pt?

A
  • Short limb
  • skin dimpling over midanterior tibia
  • equinovalgus foot
  • often missing lateral toes
  • genu valgum
23
Q

What is seen on xrays of fibular hemimelia?

A
  • Fibula is either absent or shortened
  • tibial spines are underdeveloped
  • intercondylar notch is shallow
  • ball and socket ankle joint
    • ​secondary tarsal coalition
24
Q

What is the tx of fibular hemimelia?

A
  • Goal is by stability and level of foot and ankle function as well as degree of limb shortening

Non operative

  • Observation
    • shoe lift
    • bracing

OPerative

  • Contralateral Epiphysiodesis
    • mild LLD <5cm
    • stable , plantigrade foot
  • Limb Length procedure
    • Plantigrade, functional foot with stable ankle
    • LLD <30%
    • involves resection of fibular analge to avoid future foot problems
  • Syme or Boyd amputaton
    • non functional, unstable foot
    • LLD >30%
    • usually done at 1 yr of age
25
Q

What is this and the cause ?

A
  • posteromedial bowing of tibia-
    • ​physiological bowing result of..
  • intrauterine positioning
  • usually involves medial and distal third of tibia
  • no genetic involvement
26
Q

What are the associated conditions of posteromedial tibial bowing?

A
  • Calcaneovalgus foot
    • PM bowing is often confused with calcaneovalgus foot
    • may occur together or independent of each other
27
Q

What is the most common sequlae of posteromedial bowing?

A
  • Leg length discrepancy of 3-4cm
28
Q

What are the symptoms and signs of postmedial tibial bowing?

A
  • Present at birth :)

Signs

  • Posteromedial bowing
    • apex deformity is in the distal tibia- see pic
  • Calcaneovalgus foot deformity
    • apex of deformity is at the ankle
29
Q

What is seen on imaging a posteriomedial tibial bowing?

A
  • Ap and lateral radiographs
    • Posteriomedial bowing
      *
30
Q

What is the tx of posteriomedial tibial bowing?

A
  • Non operative
    • observation
      • for bowing deformity that usually corrects over 5-7 years
      • tx with parental strectchiing if assoc with calcaneovalgus foot
  • Operative
    • Age- appropriate epiphysiodesis of long limb
    • for projected leg length discrepancy
31
Q

What are the complciations of posteromedial tibial bowing?

A
  • Leg length discrepancy
    • pt may have residual 2-5cm length leg discepancy at maturity
    • may require age-appropriate epiphysiodesis of long limb
32
Q

What is tibia deficiency?

A
  • A longitudinal deficiency of the tibia with varying degrees of tibial absence
    • previously known as tibia hemimelia
  • Genetics
    • Autosomal Dominance inheritance pattern
      • genetic counselling
33
Q

What are the associated conditions of tibia deficiency?

A
  • Musculoskeletal conditions present in 75% of pts
    • Lobster claw hand
    • preaxial polydactyly
    • ulnar aplasia
34
Q

What is the classification of tibia deficiency?

A
  • Jones
    • Complete absence of tibia
    • **Partial absence of tibia into **
      • proximal
      • distal
      • ankle diastasis
35
Q

What is seen on physical exam of a child with tibial deficiency?

A
  • Shortening of affected extremity
  • anteriorlateral bowing of tibia
  • prominent fibular head

ROM and stability

  • Knee usually flexed w assoc flexion contracture
  • important to evaluate for active knee extension- intact quads and any FFD of knee
  • tx based on stability of knee

Foot deformity

  • Often rigid equinovarus & supination deformity
  • Sole of foot faces perineum
36
Q

What is seen with imaging in a case of tibial deficiency?

A
  • AP and lateral tibia/fibula
    • shows deficiency of tibia
    • early radiographs show small & minimally ossified distal femoral epiphysis
37
Q

What is the tx of tibial deficiency?

A
  • Operation
    • Knee disarticulation + prothesis fitting
      • for complete absence of tibia
      • no active knee extension- most cases
    • Tibiofibular synostosis with modified Syme ampitation
      • prox tibia present with intact extensor mechanism & minimal flexion contraction
    • Syme/Boyd amputation
      • for ankle diastasis
    • Brown Procedure
      • centralisation of fibula under femur
      • high failure rate no longer recommended

Paediatrics FCRS (27 decks)

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