Blount Disease Flashcards
Infantile definition?
pathologic genu varum from 2-5 years of age
- bilateral
- males
- more common than adolescent
Adolescent dfeinition?
Pathologic genu varum in >10 years of age
Mechanical cause?
medial overload in genetically susceptible individuals
- producing an osteochondrosis of the proximal medial tibial physis and epiphysis, which can progress to a physeal bar
Other causes of pathologic genu varum:
- persistent physiologic varus
- rickets
- OI
- MED, SED
- focal fibrocargilatinous defect
- TAR syndrome
- proximal physeal injury
Normal progression of limb axis:
genu varum until 2 years
- neutral alignment at 14 months
- peak genu valgum at 3 years
- physiologic valgus ~ 7 years of age
Langenskold Classification
grade I-IV with increasing medial metaphyseal beaking and sloping
- types V and VI have epiphyseal-metaphyseal bony bridge
What is the Blount’s deformity?
tibia vara, flexion, and intenral rotation
- compensatory distal femoral valgus
MDA Angle
Drennan’s angle
>16 degres is abnormal and has 95% risk of progression
<10 deg has 95% of natural resolution of bowing
Indication for KAFO?
Stage I and II in children < 3 years of age
- needs 2 years of bracing
- poor outcomes if obese and bilateral
Indications for Surgery?
Stage I and II in children >3 years, as well as stages III-VI in all ages
- failed brace treatment with deformity progression
- MDA >20 degrees
By what age should you try and perform surgery for Blount’s if necesary?
by age 4!
What should your osteotomy correction goal be?
10-15 deg of valgus overcorrection because medial physeal growth abnormalities persist (this in young children with lots of remaining growth)
Treatment for Adolescent Blount?
always surgical unless very mild cases
- lateral tibia/fibula epiphysiodesis in mild deformity with remaining skeletal growth
- proximal tibia osteotomy in cases with severe deformity and skeletal maturity
