orthopedics journal ckub current review

2. Introduction :-
• Blount disease is a developmental condition characterized by disordered
endochondral ossification of the medial part of the proximal tibial physis resulting in
multiplanar deformities of the lower limb.
• Progressive pathologic genu varum centered at the tibia commonly seen 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.
• Risk factors overweight children, early walkers (< 1 year) & Hispanic and African
Americans.
• Obesity can substantially increase the compressive forces generated on the medial
compartment of the knee joint in a child leading to genu varum,(As per Heuter’s
Volkmann law.)

3. • Secondary to the asymmetrical growth
with relative inhibition of the
posteromedial portion of the proximal
tibial growth plate, a three-dimensional
deformity of the tibia occurs, viz –
-Procurvatum (apex anterior),
-Internal rotation,
-Possible limb shortening in
unilateral cases.
• This entity can lead to a progressive
deformity with gait deviations, limb-
length discrepancy, and premature
arthritis of the knee.

4. Classification
Based on age of onset:-
• Early-onset(Also called infantile type, onset at before 4 years)
• Juvenile type (onset at the age of 4 - 10 years) and
• Adolescent type (onset after the age of 10 years).
Etiology and Pathogenesis
• A linear relationship between the magnitude of obesity and biplanar radiographic
deformities in children with the early-onset form of Blount disease and in patients with
a body-mass index of >40 kg/m2 irrespective of the age at the onset of the Blount
disease.
• Despite having a lower body-mass index, children with early-onset Blount disease had
more severe varus and procurvatum deformities of the proximal part of the tibia.
• Increased pliability of the unossified epiphyses of younger patients causing more
growth inhibition than occurs in adolescents

5. • An obese child with large thighs has difficulty adducting the hips adequately and
this may result in ‘‘fat-thigh gait’’ by producing a varus moment on the knees.
• Childhood obesity reduces bone mineral content to levels below what would be
predicted on the basis of body weight.
• Despite being referred to as tibia vara, Blount disease may involve other sources of
medial axis deviation arising from the distal part of the femur and an intra-articular
deformity creating dynamic varus malalignment. This is more commonly seen
adolescents with late-onset disease.
• Other factors linked with obesity like sleep apnea syndrome,have also been
implicated.

6. • A full-length radiograph allows detailed assessment of the mechanical axis deviation
and joint orientation angles, which are crucial for determining the site(s) of deformity
correction.
•Medial epiphysis is short, thin & wedged.
• Medial metaphyseal projection
(beaking),often palpable.
•Physeal contour is irregular, slopes
medially.
•Asymmetric bowing in bilateral cases

7. Stage 1 - Medial metaphyseal beaking.
Stage II - Saucer-shaped defect of medial metaphysis
Stage III -Saucer deepens into step
Stage IV- Sloping of epiphysis over medial beak
Stage V - Double epiphysis
Stage VI - Medial physeal bony bar
Progressive radiographic changes seen in early-onset Blount disease
Langeskiold
radiological staging

8. Radiographs and Imaging

9. Radiographic Indices seen for knee joiont
The mechanical tibiofemoral angle -
Angle between [A line drawn from the
center of the hip to the center of the
knee] and [A line drawn from the center
of the knee to the center of the ankle.]
The metaphyseal-diaphyseal angle of Drennan - Angle
between [A line drawn through the most distal aspects of
the medial and lateral beaks of the proximal tibial
metaphysis] & [A line perpendicular to a line drawn along
the lateral aspect of the tibial diaphysis.]
<10 = Will mostly undergo natural resolution
11- 16 = Needs a observation
>16 = Most cases will land up in blounts diease

10. Lateral Distal Femoral Angle (LDFA) is
defined by the angle between the femoral
mechanical axis and the articular surface of
the distal femur
Medial Proximal Tibia Angle (MPTA) is
defined by the angle between the tibial
mechanical axis and the articular surface
of the proximal tibia.

11. The percentage deformity of the tibia, % DT is
calculated as the degree of tibial varus divided by the
total amount of limb varus (femoral varus [FV] + tibial
varus [TV])
(Tibial varus is the medial angle between the
mechanical axis of the tibia and a line drawn parallel to
the distal femoral condyles)
(Femoral varus is represented by the medial angle
between the mechanical axis of the femur and a line
parallel to the distal femoral condyles.)

12. Management options
• Treatment is customized for each patient on the basis of a variety of factors,
including the child’s age, the magnitude of the deformity, the limb-length
discrepancy, psychosocial factors, and the surgeon’s training and experience.
• For infantile type we can go for both bracing (as in many cases of infantile type can
undergo a spontaneous resolution)and surgery, while only surgical options are
considered for adolescent Blounts.
• Management options include –
 Observation with repeat clinical and radiographic examinations
 Use of long leg orthoses
 Realignment osteotomy
 Lateral hemiepiphyseodesis,
 Gradual asymmetrical proximal tibial physeal distraction
 Resection of a physeal bar, and elevation of the medial tibial plateau.

13. Orthroses
• Because of high rate of spontaneous correction, in Langeskiold I or II stage or infantile
patients with age of <3 years, brace treatment can be tried.
• Brace which is advised is the KAFO brace which allows to control instabilities in the lower
limb by maintaining alignment and controlling motion.

14. External Fixation with Gradual Correction
• Gradual correction with distraction osteogenesis appears
to be a safe and reliable means of treating multiplanar
deformities, including limb-length discrepancy.
• The reported prevalences of neurovascular injury,
compartment syndrome, and loss of correction , have been
substantially lower than following acute deformity
correction in Blount disease.
• With the introduction of the Taylor Spatial Frame and
the ability to perform six axis deformity correction on the
basis of a computer-generated schedule,correction is
possible for multiplanar deformities with greater accuracy.

15. The patient underwent
gradual correction with
distraction osteogenesis
at the proximal part of
the tibia

16. Proximal Tibial Metaphyseal Osteotomy
• A variety of techniques have been advocated,
including closing wedge, opening wedge, dome,
serrated, and oblique osteotomies,chevron
osteotomy.
• Furthermore, different fixation methods have been
reported, including cast immobilization, smooth pins
and wires, inter-fragmentary screws, plates and
screws and external fixators.

17. Hemiepiphyseodesis(growth modulation)
• The authors recommended hemiepiphyseal stapling in children younger than ten years
old in whom the preoperative mechanical axis of the lower extremity is within the medial
half of the medial compartment.
•Done to allow growth in media physis to ‘catch up’ & thereby correcting the deformity.May
be of 2 types :-
A) Temporary – using bone staples.
- May recure after removal,
- High rate of failure in obese.
B) Permanent

18. Elevation of the Medial Plateau
• In the advanced stages of early-onset Blount disease, the tibia can translate laterally
with the medial femoral condyle falling into the posteromedial depression.
• Elevation with internal fixation can be done by use of a structural allograft.
• It is recommended for the few children older than six years of age who have severe
early-onset Blount disease (Langenskiold stage V or VI).

19. Physeal Bar Resection
• Resection of a physeal bar at the medial aspect of the proximal part of the tibia with
interposition of fat or silicone and a simultaneous valgus osteotomy is done.
• Used for treatment of moderate-to-advanced early-onset Blount disease (a
Langenskiold stage of > III)
Complications
• Compartment syndrome
• Recurrence
• Chronic joint pain
• Vascular occlusion
• Peroneal palsy
• Refracture