Leg conditions

Question 1

What is proximal femoral focal deficiency?

Answer 1

• A Congential defect of the proximal femur
• it is a spectrum of disease including
  
  • Absent hip
  • Cervical pseudoarthrosis- see pic
  • Absent Femur
  • Shortened Femur

Question 2

What is the epidemiology of proximal femoral focal deficiency?

Answer 2

• Bilateral in 50% cases
• Rare autosomal Dominant form exists
• Associated with SONIC HEGDE- HOG GENE ( limb bud gene)

Question 3

What is the pathophysiology of proximal femoral focal deficiency?

Answer 3

• Defect in the primary ossification centre ( cartilage anlage)

Question 4

Name associated conditions of proximal femoral focal deficiency?

Answer 4

• Fibular Hemimelia- 50%
• ACL Deficiency
• Coxa Vara
• Knee contractures

Non orthopaedic manifestations

• Dysmorphic facies found in rare autosomal dominant type

Question 5

What is the Classification system of proximal femoral focal deficiency?

Answer 5

• AITKEN
• Class A= Femoral head present, Acetabulum Normal
• Class B= Femoral head present, Acetabulum mildy dysplastic
• Class C= femoral head absent, Severly dysplastic acetabulum
• Class D= Absent Femoral head and acetabulum

Question 6

What is seen at physical exam of a pt with proximal femoral focal deficiency?

Answer 6

• Severely shortened one or both legs
  
  • Percentage of shortening remains constant with growth
• Short bulky thigh is flexed, abducted and externally rotated
• Normal feet - most common

Question 7

What are the goals of tx in proximal femoral focal deficiency?

Answer 7

• Tx must be individualised to the pt based on
  
  • Leg discrepancy
  • Present of foot deformities
  • Adequacy of Musculature
  • proximal joint stability

Question 8

What are the options for tx for proximal femoral focal deficiency?

Answer 8

• Non operative
  
  • Observe
    
    • with bilateral deficency
  • Extension Prothesis
    
    • Less attractive option due to large proximal segement of prothesis
    • assists patient when attempting to pull self up to stand
• Operative
  
  • Limb lengthening with/without contralateral epiphysiodesis
    
    • If predicted LLD of <20cm at maturity
    • Stable hip and functional foot
    • femoral length >50% of opposite side
    • Femoral head present- Aitken A/B
    • CI= unaddressed varus, proximal pseudoarthorosis, or acetbular dysplasia
  • Syme amputation and Knee fusion​
    
    • Hip stable ( aitkena/b) foot of affected side is proximal to knee joint- syme 10-14 mo, knee fusion 3-4 yrs= wear AK prothesis
    • need for improved prosthetic fit, function and appearance
    • prosthetic kness will not be below the level of contralteral knee at maturity
    • ispislateral foot is at level of contralateral knee or more proximal
  • Femoral- pelvic fusion
    
    • Unstable hip =aitken C/D- absent femoral head
  • VAN - NESS ROTATIONPLASTY
    
    • ipsilateral foot at level of contralateral knee
    • Ankle with >60% of motion
    • Absent femoral head- aitken c/d
    • 180 degree rotational turn thru femur
    • ankle dorsiflexion becomes knee flexion
    • allow use of BK prosthesis to improve gait and efficiency- seep pic
  • Amputation
    
    • for femoral length <50% opposite side
    • perserve as much length as possible
    • amputate thru JOINT if possible in order to avoid overgrowth which can lead to diffcult prosthesis fitting
    • Fit for prothesis UL 6 mon, LL 1 yr

Question 9

What is Hemihypertrophy?

Answer 9

• A condition of asymetric limb size

Question 10

What are the most common causes of hemihypertrophy?

Answer 10

• Neurofibromatosis
• Idiopathic
• Beckwith- wiedemann syndrome
• associated with Wilm’s tumour- renal abnormaliites, do USS until 5 years

Question 11

What is the tx of hemihypertrophy?

Answer 11

• Based on principles of leg length discrepancies

Question 13

What are the common causes of limb length discrepancy?

Answer 13

• Congential
  
  • Hemihypertrophy
  • Dysplasias
  • Proximal femoral focal deficiency
  • DDH
• Paralytic conditions
  
  • Spascitiy - cerebral palsy
  • polio
• Physis disruption
  
  • Infection
  • trauma
  • Tumour

Question 14

What is the epidemiology of LLD?

Answer 14

• 2cm LLD occurs in up to 2/3rd population

Question 15

What are the associated conditions of LLD?

Answer 15

• Back pain
  
  • increased prevalence of back pain
• Osteoarthritis
  
  • Decreased coverage of femoral head on long leg side leads to OA 84% of time
• Structural scoliosis
  
  • LLC increasea the incidence of structural scoliosis
• Inefficiency Gait
• Equinus Contracture

Question 16

What is the classification of LLD?

Answer 16

• STATIC
  
  • Malunion of femur/tibia
• PROGRESSIVE
  
  • Physeal growth arrest
  • congential
    
    • absolute discrepancy increases
    • proportion stats the same

Question 17

What are the symptoms and signs of LLD?

Answer 17

• Usually asymptomatic

Signs

• Block testing
  
  • W pt standing add blocks under short leg until pelvis is level, then measure blocks to determine discrepancy
  • Block testing is considered best initial screening method
• Tape measurement
  
  • Measure from ASIS to medial malleolus w tape
  • evaluate for hip, knee, and ankle contractures
    
    • effects apparent limb length
    • hip adduction contracture= apparant shortening of adducted side
      *

Question 18

What imaging is useful in LLD?

Answer 18

• Scanography/HKA- see pic
  
  • measure discrepancy with scanogram
• Bone hand films
  
  • determine bone age
• CT Scanography
  
  • Is most accurate diagnostic test with contractures of hip, knee or ankle

Question 19

What are the LLD predictions?

Answer 19

• General assumptions
  
  • growth continues until 14 yrs girls, 16 yrs boys
• Methods to predict LLD at maturitry
  
  • Mosley charts- growth remaining
  • estimation techique- arithmetic method
    
    • assumes certain contribution from physis to longitudinal growth
    • leg growth 23mm/year w most of that coming from knee (15mm/yr)
    • proximal femur 3mm/year
    • distal femur 9mm/yr
    • proximal tibia 6mm/yr
    • distal tibia 5mm/yr
• Can be tracked with
  
  • Green- anderson tables
  • mosley straight line graph
    
    • improves on green-anderson method by formatting data in graph form
    • accounts for differences between skeletal and chronologic age
• Multipler method

Question 20

What is the tx of LLD?

Answer 20

Non operative

• Shoe lift/observation
  
  • if <2cm projected LLD at maturity

Operative

• Shortening of long side via Epiphysiodesis of femur/tibia or both
  
  • ​2-5cm projected LLD
• ​Limb lengthening of short side
  
  • ​if projected >5cm LLD
  • lengthening often combined with shortening proceedure epiphyiosdesis/osteotomy long side
• Physeal bar exicision
  
  • if bony bridge involves <50% physis
  • at least 2 years of growth
    *

Question 21

What is the surgical technique of limb lengthening?

Answer 21

• Distraction osteogenesis- Ilizarov prinicples
  
  • initation
    
    • perform osteotomy and plate fixator
    • metaphyseal corticotomy to preserve medullary canal and blood supply
  • distraction
    
    • wait 5-7 days then begin distraction
    • distract 1mm per day
    • follow distraction keep fixator on for as many days as you lengthened
  • concurrent proceedure
    
    • Some ream over a nail so ex-fix can be removed sooner
    • lengthening often combined with a shortening proceedure- epiphysiodesis/ostectomy on long side

Question 22

What are the compilications of LLD?

Answer 22

• Incomplete arrest/angular deformity
  
  • open technique
  • percutaneous technique
• Pin site infections
• Fractures
• Delayed union
• Premature ossification of lengthening
• Joint subluxation/dislocation