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- Physiological - normal on Salenius curve
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- Idiopathic = Blount’s (diagnosis of exclusion) [usually bilateral]
- Secondary to:
- Dysplasias - achondroplasia, SED and MED (though more valgus)
- Metabolic - Ricket’s
- Syndromic - Down’s syndrome
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- Trauma - malunion, physeal bars
- Infection
- Tumor - osteochondromas, enchondroma (though more valgus)
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- Describe picture
- My concern is if this is pathological or physiological. Assess with Hx, PE and Invx
- Hx = unilateral, duration, family history (MED, SED, achondroplasia, age of walking, TIT
- PE = Unilateral, Weight, Female Cover test to confirm not tibia torsion. If BILATERAL - look for features of Rickets
- Invx - XR with Salenius Curve
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- Cover test = cover tibia and look at knee. if knee is straight or varus = genu varus. If after covering, knee is valgus then its ok.
- It is to differentiate internal tibia torsion from blounts.
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- 0/2/4/6 yo = 15/0/10/5
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- metaphyseal-diaphyseal angle (MDA) is formed between a line connecting the most distal points of the medial and lateral proximal tibial metaphyseal beak and a line perpendicular to a line parallel to the lateral tibial cortex
- > 16 = blounts
- > 11 in < 2 year = likely progress
- < 9= likely physiological
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- Angle between epiphysis and line from tip of meaphyseal beak to midpoint of tibia plateau
- [normal < 20 °]
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- Look at where mechanical axis passes through the knee
- Divid the Tibia plateau into 4 quarters. Zones 1/2/3 (3 is out of knee)
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- mLDFA (mechanical lateral distal femoral angle) = angle between line from center of femoral head to center of knee // distal femur joint line
- MPTA (Mechanical proximal tibia angle) = angle between tibia axis and tibia plateau
- Both angles normal is 87 °. Measuring the angles can tell us if the valgus is originating from tibia or femur
- In this case, mLDFA is 77 while MPTA is 87, so deformity is in femur ➔will benefit from DFO
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- "varus Lateral THRUST"
BLOUNTS
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- Definition = Growth disorder of posteromedial aspect of proximal tibia physis resulting in varus, internal rotation and procurvartum (VIP) of tibia
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- 50% in infantile
- Adolescent usually unilateral
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- Infantile blounts - 0-3 yo
- Juvenile 3-10 yo
- Adolescent > 10 yo - less common, severe
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- Langenskoid
- Stage 1 = Early beaking of metaphysis
- 2 = worse beaking of metaphysis
- 3 = downsloping of epiphysis [Depression]
- 4 = downsloping epiphysis crossing physis [Step off]
- 5 = epimetaphyseal bridge
- 6 = physeal bar
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- Early stages 1-2 = Valgus producing brace to correct based on "Heuter Volkman's law" ➔ follow up w 6 monthly XR ➔ if progress may need op
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- Growth plate modulation
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- Aim to do before 4 yo to reduce recurrence
- Multiple types described
- Familiar with the Rab osteotomy which is a oblique, biplanar osteotomy allowing correction of internal rotation and varus deformityhttps://www.ncbi.nlm.nih.gov/pmc/articles/PMC2832880/
- Goal = correct to slight valgus as physeal abnormality still present (over correction); or you can do an epiphysiodesis on the lateral side also ➔ can LEAD to LLD
- Medial tibia plateau elevation
- External Ilizarov frame
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- Bracing not effective
- Depends on bone age
- Growth modulation in form of hemiepiphysiodesis
- Osteotomy
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- need to follow up for limb length discrepancy
- Can lengthen tibia proximally OR epiphysiodesis of the contralaterai side.
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- Familiar with the Rab osteotomy which is a oblique, biplanar osteotomy allowing correction of internal rotation and varus deformity
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- Poor prognosis = obesity, severe langenskoild, age > 4.5 years