Updated: 6/14/2021

Infantile Blount's Disease (tibia vara)

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  • summary
    • Infantile Blount's disease is progressive pathologic genu varum centered at the tibia in children 2 to 5 years of age.
    • Diagnosis is suspected clinically with presence of a genu varum/flexion/internal rotation deformity and confirmed radiographically with an increased metaphyseal-diaphyseal angle.
    • Treatment ranges from bracing to surgery depending on patient age, severity of deformity, and presence of a physeal bar. 
  • Epidemiology 
    • Risk factors
      • overweight children
      • early walkers (< 1 year)
      • Hispanic and African American
  • Etiology
    • Best divided into two distinct disease entities
      • Infantile Blount's(this topic)
        • pathologic genu varum in children 2 to 5 years of age
        • male > female
        • more common
        • bilateral in 50%
      • Adolescent Blount's
        • pathologic genu varum in children > 10 years of age
        • less common
        • less severe
        • more likely to be unilateral
    • Pathophysiology
      • likely multifactorial but related to mechanical overload in genetically susceptible individuals including
        • excessive medial pressure produces an osteochondrosis of the medial proximal tibial physis and epiphysis
          • osteochondrosis can progress to a physeal bar
  • Anatomy
    • Genu varum is a normal physiologic process in children
      • physiologic genu varum
        • genu varum (bowed legs) is normal in children less than 2 years
        • genu varum migrates to a neutral at ~ 14 months
        • continues on to a peak genu valgum (knocked knees) at ~ 3 years of age
        • genu valgum then migrates back to normal physiologic valgus at ~ 7 years of age
  • Classification
    • Langenskiold Classification
      • type I thru IV consist of increasing medial metaphyseal beaking and sloping
      • type V and VI have an epiphyseal-metaphyseal bony bridge (congenital bar across physis)
      • provides prognostic guidelines
    • Infantile versus Adolescent Blount's
      Infantile Blounts
      Adolescent Blounts
      Age
      2-5yrs
      >10yrs
      Bilaterally
      50% bilateral
      Usually unilateral
      Risks
      Early walking, large stature, obesity
      Obesity
      Classification
      Langenskiold
      No radiographic classification
      Severity
      More severe physeal/ epiphyseal disturbance
      Less severe physeal/ epiphyseal disturbance
      Bone Involvement
      Proximal medial tibia physis, producing genu varus, flexion, internal rotation, AND may have compensatory distal femoral VALGUS
      Proximal tibia physis, AND may have distal femoral VARUS and distal tibia valgus
      Natural History
      Self-limited - stage II and IV can exhibit spontaneous resolution
      Progressive, never resolves spontaneously (thus bracing unlikely to work)
      Treatment options
      Bracing and surgery
      Surgery only
  • Presentation
    • Physical exam
      • genu varum/flexion/internal rotation deformity
        • usually bilateral in infants
        • may exhibit positive 'cover-up test'
      • often associated with internal tibial torsion
      • leg length discrepancy
      • usually NO tenderness, restriction of motion, effusion
      • lateral thrust on walking
  • Imaging
    • Radiographs
      • views
        • ensure that patella are facing forwards for evaluation (commonly associated with internal tibial torsion)
      • findings suggestive of Blounts disease
        • varus focused at proximal tibia
        • severe deformity
        • asymmetric bowing
        • medial and posterior sloping of proximal tibial epiphysis
        • progressing deformity
        • sharp angular deformity
        • lateral thrust during gait
        • metaphyseal beaking
          • different than physiologic bowing which shows a symmetric flaring of the tibia and femur
      • measurements
        • metaphyseal-diaphyseal angle (Drennan)
          • angle between line connecting metaphyseal beaks and a line perpendicular to the longitudinal axis of the tibia
          • >16 ° is considered abnormal and has a 95% chance of progression
          • Drennan angles between 11-16° necessitate close observation for the progression of tibia vara
          • <10 ° has a 95% chance of natural resolution of the bowing
        • tibiofemoral angle
          • angle between the longitudinal axis of the femur and tibia
  • Differential 
    • The following conditions can also lead to pathologic genu varum
      • persistent physiological varus
      • osteogenesis imperfecta
      • MED
      • SED
      • metaphyseal dysostosis (Schmidt, Jansen)
      • focal fibrocartilaginous defect
      • thrombocytopenia absent radius
      • proximal tibia physeal injury (radiation, infection, trauma)
  • Treatment
    • Nonoperative
      • brace treatment with KAFO
        • indications
          • Stage I and II in children < 3 years
        • technique
          • bracing must continue for approximately 2 years for resolution of bony changes
        • outcomes
          • improved outcomes if unilateral
          • poor results associated with obesity and bilaterality
          • if successful, improvement should occur within 1 year
    • Operative
      • proximal tibia/fibula valgus osteotomy
        • overcome the varus/flexion/internal rotation deformity
        • indications
          • Stage I and II in children > 3 years
          • Stage III, IV, V, VI
          • age ≥ 4y (all stages)
          • failure of brace treatment
            • progressive deformity
          • metaphyseal-diaphyseal angles > 20 degrees
        • technique
          • perform osteotomy below tibial tubercle
          • staged procedures may be required for Stage IV, V, VI
          • epiphysiolysis required in stage V and VI
        • outcomes
          • risk of recurrence is significantly lessened if performed before 4 years of age
      • growth modulation
        • technique
          • tension band plate and screws
      • physeal bar resection
        • indication
          • at least 4y of growth remaining
        • technique
          • perform together with osteotomy
          • interpositional material is usually fat or PMMA
      • hemiplateau elevation
        • technique
          • may be performed together with osteotomy
  • Techniques
    • Proximal tibia/fibula valgus osteotomy
      • goals of correction
        • overcorrect into 10-15° of valgus because medial physeal growth abnormalities persist
        • distal segment is fixed in valgus, external rotation and lateral translation
      • technique
        • staples and plates function by increasing compression forces across the physis which slows longitudinal growth (Heuter-Volkmann principle)
        • temporary lateral physeal growth arrest with staples or plates can be used
          • increasing use for correction in younger patients
        • include a bar resection (epiphysiolysis) when a physeal bar is present (Langenskiold V and VI)
          • consider hemiepiphysiodesis if bar > 50%
        • medial tibial plateau elevation is required at time of osteotomy if significant depression is present
        • consider prophylactic anterior compartment fasciotomy
  • Complications
    • Compartment syndrome (with high tibial/fibular osteotomy)
      • prophylactic release of anterior compartment
    • Recurrence of tibial vara
      • severe cases of Infantile Blount's disease may develop a physeal bar
        • can result in progressive varus after a well executed proximal tibial valgus osteotomy
        • may require a lateral tibial hemiepiphysiodesis or bar resection
  • Prognosis
    • Best outcomes with early diagnosis and unloading of the medial joint with either bracing or an osteotomy
    • Young children with stage II and stage IV can have spontaneous correction

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(OBQ13.171) A 17-month-old boy is referred to your office for abnormal gait. He began walking at 15 months of age. His mother reports that he has always had bowed legs, but the deformity has steadily worsened. A video of the child's gait is shown in Video V. What is the most appropriate next step in management?

QID: 4806
FIGURES:
1

Observation

10%

(361/3534)

2

Bracing

8%

(285/3534)

3

Standing, full-length bilateral lower extremity radiographs

78%

(2774/3534)

4

Bilateral knee MRIs

0%

(8/3534)

5

Bilateral proximal tibial osteotomies

2%

(84/3534)

L 2 C

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(OBQ08.124) A 32-month-old male with severe infantile Blounts disease has been treated with full time bracing for the past year. At most recent follow-up, the varus deformity of his bilateral legs has worsened despite compliance with bracing. What treatment is now recommended?

QID: 510
1

Observation, discontinuation of bracing

4%

(116/2619)

2

Observation, continuation of full-time bracing

14%

(379/2619)

3

Bilateral proximal tibial osteotomies

67%

(1751/2619)

4

Bilateral distal femur osteotomies

3%

(83/2619)

5

Bilateral proximal tibial medial hemiepiphysiodesis

11%

(280/2619)

L 3 C

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(OBQ08.183) Lateral tibial physeal stapling is a treatment option for adolescent Blount’s disease. How is the staple an example of the Hueter-Volkmann principle?

QID: 569
1

Increased compression along the growth plate slows longitudinal growth

85%

(1767/2084)

2

Decreased compression along the growth plate slows longitudinal growth

2%

(46/2084)

3

Increased tension along the growth plate slows longitudinal growth

8%

(168/2084)

4

Decreased tension along the growth plate slows longitudinal growth

3%

(65/2084)

5

Increased compression along the plate increases longitudinal growth

1%

(27/2084)

L 2 C

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(SAE07PE.69) Figure 29 shows the AP radiograph of a 14-year-old boy. The radiographic findings are most consistent with what pathologic process?

QID: 6129
FIGURES:
1

Septic arthritis

2%

(5/240)

2

Hemophilia

2%

(5/240)

3

Juvenile rheumatoid arthritis (JRA)

3%

(8/240)

4

Adolescent Blount’s disease

49%

(117/240)

5

Infantile Blount’s disease

43%

(103/240)

L 3 E

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(SAE07PE.20) Examination of an obese 3-year-old girl reveals 30 degrees of unilateral genu varum. A radiograph of the involved leg with the patella forward is shown in Figure 10. Management should consist of

QID: 6080
FIGURES:
1

continued observation until skeletal maturity.

5%

(10/202)

2

fitting for a valgus-producing hinged knee-ankle-foot orthosis.

27%

(54/202)

3

lateral proximal tibial hemiepiphysiodesis.

23%

(46/202)

4

proximal tibiofibular osteotomy and acute correction.

41%

(82/202)

5

proximal tibiofibular epiphysiodesis and osteotomy with lengthening.

3%

(6/202)

N/A E

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(OBQ05.23) A 30-month-old boy has worsening bilateral bowleg deformities, and radiographs depicting Langenskiold stage II are shown in Figure A. The most appropriate initial management should consist of which of the following?

QID: 60
FIGURES:
1

Observation

21%

(425/1982)

2

Bracing with knee-ankle-foot orthoses

63%

(1255/1982)

3

Bracing with ankle-foot orthoses

2%

(35/1982)

4

Proximal tibia/fibula valgus osteotomy with bar resection

5%

(107/1982)

5

Proximal tibia/fibula valgus osteotomy with hemiepiphysiodesis

7%

(147/1982)

L 3 C

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(SBQ04PE.3) A valgus producing proximal tibial osteotomy with 10 degrees of overcorrection is the most appropriate treatment for which of the following patients with tibia vara?

QID: 2188
1

A 4-year-old obese child with Blount's disease, Langenskiöld stage IV

70%

(596/851)

2

An 18-month-old child with a proximal tibia metaphyseal-diaphyseal angle of 11 degrees

1%

(11/851)

3

A 2-year-old obese child with Blount's disease, Langenskiöld stage II disease

5%

(42/851)

4

A 5-year-old child with untreated renal osteodystrophy and a proximal tibia metaphyseal-diaphyseal angle of 16 degrees

10%

(83/851)

5

A 8-year-old child with distal femoral varus and a lateral distal femoral angle of 95 degrees

12%

(106/851)

L 2 C

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