Blount's Disease: Difference between revisions

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== Clinical Presentation  ==
== Clinical Presentation  ==
* Unilateral or bilateral (mostly with early onset) presentation
* Unilateral or bilateral (mostly with early onset) presentation
* Multiplanar deformities of the lower leg includes:<ref name=":0" />
* Multiplanar progressive deformities of the lower leg includes:<ref name=":0" />
** [[Tibia|Tibial]] varus
** [[Tibia|Tibial]] varus
** Procurvatum
** Procurvatum
** Internal torsion
** Internal torsion
** [[Leg Length Discrepancy|Limb shortening]]
** [[Leg Length Discrepancy|Limb shortening]] (due to altered growth)
** Distal [[Femur|femoral]] varus (in late-onset)
** Distal [[Femur|femoral]] varus (in late-onset)


* Early onset [[Knee Osteoarthritis|knee osteoarthritis]] as result of deformities<br>
* Gait abnormalities:
This entity can lead to a progressive deformity with gait deviations, limb-length discrepancy, and premature arthritis of the knee6-8. Compared with children of normal weight, overweight children showed a substantially higher peak internal knee abduction moment during early stance, with increased loading of the medial compartment of the knee joint.
** Increased [[knee]] abduction
 
** Increased medial load to the [[knee]]
The clinical manifestations of both forms of Blount disease may represent an alteration in the normal growth and development of the lower limb in genetically predisposed children through distinct but related pathways.Unlike the case in children with early-onset Blount disease, approximately one-third of the varus deformity in adolescents with late-onset disease may be attributable to the distal part of the femur4,34.
* Early onset [[Knee Osteoarthritis|knee osteoarthritis]] as result of deformities
 
== Diagnostic Procedures  ==
== Diagnostic Procedures  ==
[[X-Rays|X-rays]] (AP and lateral views) are done as the main tool for diagnosis.However, none of these radiographic markers can be considered in isolation, and repeated clinical and radiographic examination is essential to establish the diagnosis31A full-length radiograph allows detailed assessment of the mechanical axis procurvatum deformity of the proximal part of the tibia is typically noted on the full-length lateral radiograph of the tibiaA scanogram and an assessment of bone age are useful for a complete assessment of current and future limb-length discrepancy.An intraoperative arthrogram is helpful for delineating the articular surface3A magnetic resonance imaging scan can also define intra-articular changes such as posteromedial depression of the tibial plateau and hypertrophy of the medial meniscus in children with early-onset disease38,Fat-suppressed and proton-weighted magnetic resonance images are particularly helpful in detecting growth plate irregularities and early physeal bar formation44. Although advanced imaging is not routinely indicated for patients with late-onset Blount disease, changes in the adjacent distal femoral epiphysis and physis have been observed on magnetic resonance imaging scans of adolescents45. Computed tomography scanning, particularly with three-dimensional reconstructions, can also be useful for preoperative planning in children with early-onset Blount disease who present with recurrent deformities46 (Figs. 5-A through 5-E). While advanced imaging techniques provide more detailed information than do plain radiographs, the additional cost, radiation exposure, and potential need for sedation and general anesthesia associated with some of these modalities should be considered.
Diagnosis are normally made by a clinical assessment and the use of [[X-Rays|X-rays]] (full length, AP and lateral). [[X-Rays|X-rays]] are use to determine and measure the extent of the deformities. In late-onset Blount's disease, advanced imaging are not routinely done. Other additional investigations include:<ref name=":0" />
 
* Scanogram:  To determine leg length discrepancy
metaphyseal-diaphyseal angle24-27, epiphyseal-metaphyseal angle28, and relative contributions to the varus deformity by the femur and tibia29,30 that can help to differentiate physiologic bowing from early-onset Blount disease in children who are less than two years old
* Arthrogram (intra-operative):  Assessment of articular surface postion
* [[CT Scans|CT scan]]:  3D surgical planning (early-onset disease with recurrent deformities)
* [[MRI Scans|MRI]]:  Determine
** Determine intra-articular changes to tibial plateau (e.g. posteromedial depression)
** Look for medial meniscus hypertrophy in early-onset disease
** Assess physeal bar formation and changes to growth plates


=== Langenskiöld classification ===
=== Langenskiöld classification ===
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** Ossification of medial physis with cessation of growth
** Ossification of medial physis with cessation of growth
** Normal lateral tibial growth
** Normal lateral tibial growth
* <br>


== Outcome Measures  ==
== Outcome Measures  ==

Revision as of 16:39, 25 May 2020

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Description[edit | edit source]

Blount's disease, also known as tibia vara, is a developmental growth disorder of the tibia that causes the lower leg to angle outwards, causing bowing of the leg. It is characterised by progressive multiplanar deformities of the leg caused by disordered endochondral ossification of the proximal medial tibial physis.

The cause of Blount's disease is assumed to be multifactoral, mostly mechanically due to childhood obesity.[1] This can be described by the effects of increased weight on the growth plates. The medial proximal tibia fails to develop normally, resulting in genu varum.[2]  Unlike bowlegs, which tend to straighten as the child develops, Blount's disease is progressively worsening. It can cause severe bowing and can affect one or both legs.

Pathogenesis[edit | edit source]

Looking at the Heuter-Volkmann principle, the pathogenesis of Blount's disease can be described as growth inhibition caused by excessive compressive forces. This pressure on the medial proximal tibia causes structure and function alterations on the cartilage of the epiphysis, further causing chondrocytes and delaying in epiphysis ossification. The increase in medial load with obesity usually lead to genu varum.

Etiology / Epidemiology[edit | edit source]

The following are known predisposing factors of Blount's disease:[1]

  • This condition is more common among children of African and Scandanavian ancestry.
  • It is associated with obesity, short stature, and early walking.
  • There does not appear to be an obvious genetic factor.

genetic, humoral, biomechanical, and environmental factors control physeal growth and influence the development of normal lower-limb alignment. control physeal growth and influence the development of normal lower-limb alignment. T

Classification[edit | edit source]

Blount's disease is mostly catagorised into early-onset if it develops in children under 4 years old, and late-onset, when it develops after the age of 4.[1] The late-onset type can further be classified into juvenile (age 4 - 10) and adolescent (after the age of 10) Blount's disease.[3]

t. Also, there are comparable histologic findings at the proximal tibial growth plate9-11

Clinical Presentation[edit | edit source]

  • Unilateral or bilateral (mostly with early onset) presentation
  • Multiplanar progressive deformities of the lower leg includes:[1]
  • Gait abnormalities:
    • Increased knee abduction
    • Increased medial load to the knee
  • Early onset knee osteoarthritis as result of deformities

Diagnostic Procedures[edit | edit source]

Diagnosis are normally made by a clinical assessment and the use of X-rays (full length, AP and lateral). X-rays are use to determine and measure the extent of the deformities. In late-onset Blount's disease, advanced imaging are not routinely done. Other additional investigations include:[1]

  • Scanogram: To determine leg length discrepancy
  • Arthrogram (intra-operative): Assessment of articular surface postion
  • CT scan: 3D surgical planning (early-onset disease with recurrent deformities)
  • MRI: Determine
    • Determine intra-articular changes to tibial plateau (e.g. posteromedial depression)
    • Look for medial meniscus hypertrophy in early-onset disease
    • Assess physeal bar formation and changes to growth plates

Langenskiöld classification[edit | edit source]

This classification system are used to describe the radiographic changes and are divided into 6 progressive type in early onset Blount's disease, describing changes with aging.[1][4]

  • Stage 1: Age 2-3
    • Metaphyseal irregularities in ossification zone
    • Slow development of epiphysis in medial aspect of tibia
    • Medial and/or distal beaking of medial epiphysis
  • Stage 2: Age 2.5-4
    • Medial physeal line depresses sharply
    • Beaking medially
    • Wegde-shaping and underdevelopment of medial epiphysis
  • Stage 3: Age 4-6
    • Metaphyseal beak depression deepens
    • Metaphysis "step"
    • Medial part of epiphysis more wedge-shaped and underdeveloped
  • Stage 4: Age 5-10
    • Narrowing of physis
    • Enlargement of epiphysis
    • Metaphysis "step" deepens
    • Depression in medial metaphysis ocupied by epiphysis
  • Stage 5: Age 9-11
    • Clearly separated epiphysis in two parts
    • Epiphysial plate partially double
    • Articular surface medially sloping
  • Stage 6: Age 10-13
    • Ossification of medial physis with cessation of growth
    • Normal lateral tibial growth

Outcome Measures[edit | edit source]

add links to outcome measures here (see Outcome Measures Database)

Medical management[edit | edit source]

Conservative management[edit | edit source]

Children who develop severe bowing before the age of 3 may be treated with bracing. However, bracing may fail, or bowing may not be detected until the child is older.

Surgical management[edit | edit source]

  • Realignment tibial osteotomy: To be done before the age of 4 to decrease the risk of recurrent lower extremity deformity and to restore leg length where needed.[1]
  • Distraction osteogenesis: For late-onset disease:[1]
    • Aim to achieve multiplanar correction
  • The growth of just the outer half of the tibia can be surgically restricted to allow the child’s natural growth to reverse the bowing process. This much smaller surgery is most effective in children with less severe bowing and significant growth remaining.[1]


Differential Diagnosis[edit | edit source]

add text here relating to the differential diagnosis of this condition


Resources[edit | edit source]

add appropriate resources here

Case Studies[edit | edit source]

add links to case studies here (case studies should be added on new pages using the case study template)

References[edit | edit source]

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  1. ↑ 1.0 1.1 1.2 1.3 1.4 1.5 1.6 1.7 1.8 Sabharwal S. Blount disease. Journal of Bone and Joint Surgery 2009;91(7):1758-76.
  2. ↑ Erkus S, Turgut A, Kalenderer O. Langenskiöld classification for blount disease: Is it reliable? Indian journal of orthopaedics 2019;53(5):662.
  3. ↑ Thompson GH, Carter JR. Late-onset tibia vara (Blount's disease). Current concepts. Clinical orthopaedics and related research 1990(255):24-35.
  4. ↑ Radiopedia. Langenskiold classification of Blount disease. Available from: https://radiopaedia.org/articles/langenskiold-classification-of-blount-disease (accessed 06/05/2020).
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