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Tibia Vara (Blount's Disease)

Definition

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Pathogenesis

• Exact aetiology is unknown; suggested factors include infection, trauma, osteonecrosis, and latent rickets - none proven
• Hereditary + developmental factors are the most likely cause
• Weight bearing is necessary for development: does not occur in non-ambulatory patients
• Early walking and obesity are clearly documented risk factors
• The growing "obesity epidemic" and vitamin D deficiency in children may be increasing prevalence
• Histologic changes are similar to slipped capital femoral epiphysis (SCFE), suggesting a common cause: excessive mechanical stress
• Focal fibrocartilaginous dysplasia is a differential cause - usually self-limiting and resolves spontaneously

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Classification: Two Types by Age at Onset

Infantile Type

• Begins before age 8 years (peak: 1-3 years)
• Bilateral and symmetric in 60% (vs. physiologic bowing which is 100% bilateral)
• Difficult to differentiate from physiologic bowing, especially before age 2
• Deformity is progressive (vs. physiologic bowing which resolves)
• More common in Afro-Caribbean children

Adolescent Type

• Begins after 8 years, before skeletal maturity
• No inciting event
• Deformity worsens with time
• More often unilateral
• Higher post-surgical recurrence than infantile form
• Affects all ethnic groups
• May present with significant intoeing in addition to varus

Special Variant: Proximal Tibial Epiphysis Slip

• Atraumatic "slip" in severely obese children
• Radiographic features: dome-shaped metaphysis, open physis, disruption of lateral epiphysis-metaphysis continuity, inferomedial translation of the epiphysis
• Treatment differs from conventional Blount disease

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Imaging

Radiographic Features

• Medial half of the proximal tibial epiphysis: short, thin, wedged
• Physis: irregular, slopes medially
• Medial metaphyseal projection (palpable but not diagnostic)
• Medial metaphyseal fragmentation = pathognomonic for progressive tibia vara

MRI Findings (additional soft-tissue abnormalities)

• Increased thickness of the chondroepiphysis at the proximal medial tibia
• Increased height and width of the medial meniscus
• Abnormal medial femoral epiphysis

Early Indicators of Blount Disease

1. Metaphyseal-diaphyseal (Drennan) angle >11 degrees - the most useful early indicator
2. Late resolution of tibial bowing on MRI
3. Length of fibula compared with tibia
4. Severity of proximal tibial angulation vs. distal femoral angulation

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Langenskiöld Classification (6 Stages)

• Stage I-III: Progressive medial epiphyseal irregularity and metaphyseal beaking
• Stage IV: Depression of the medial tibial plateau
• Stage V: Separation of the medial portion of the epiphysis
• Stage VI: The medial portion of the epiphysis fuses at a 90-degree downward angle (premature physeal closure)
• Campbell's Operative Orthopaedics, p.1502

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Differential Diagnosis of Tibia Vara (Tibial Bowing Causes)

• Grainger & Allison's Diagnostic Radiology, p.1901

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Treatment

1. Observation / Bracing

• Children aged 2-3 years: observation or knee-ankle-foot orthosis (KAFO) bracing
• Limited role for grades I-II at very young ages
• No bracing role once child is older than ~3 years with progressive deformity

2. Guided Growth (Lateral Temporary Hemiepiphysiodesis)

• Tension band plate ("eight-plate" technique) on the lateral proximal tibial physis
• Minimally invasive; growing support as first surgical option
• Common complication: implant failure in ~12% (especially in obese patients - use 4 screws or 2 eight-plates)
• Recurrence after plate removal due to slower medial physis growth rate

3. Tibial Osteotomy

• Indicated for progressive deformity in children older than 3 years
• Recurrence rates: <20% if done before age 4 vs. 80-90% if done after age 4
• Standard recommendation: valgus osteotomy of proximal tibia and fibula with mild overcorrection in young children (<4 years)

• Single-plane oblique osteotomy (Rab) - corrects varus + internal rotation simultaneously; allows postoperative cast wedging
• Crescent-shaped chevron osteotomy (Greene) - maintains limb length
• Hemicondylar tibial osteotomy (Zayer) - corrects posteromedial tibial epiphyseal slope

4. External Fixation

• Uniplanar fixator for isolated frontal-plane deformities
• Ilizarov technique: deformity correction + lengthening for adolescent patients
• Hexapod-based systems (e.g., Taylor Spatial Frame): preferred for obese adolescents with complex multiplanar deformities; allows computer-navigated post-operative correction

5. Medial Epiphysiolysis (Stage IV Infantile Tibia Vara)

• Elevation of medial tibial plateau to restore joint congruity
• Cortical bone grafts placed in opened wedge
• Often combined with proximal tibial opening wedge osteotomy + proximal fibular osteotomy

6. Management of Physeal Bar (Recurrence Prevention)

• CT or MRI preoperatively if: child >5 years, weight >95th percentile, medial physeal slope 50-70°, or Langenskiöld grade IV
• Bony bridge resection if growth potential remains
• Lateral tibial epiphysiodesis (age 9+ to skeletal maturity) to prevent recurrence
• In unilateral disease, contralateral epiphysiodesis to correct leg-length discrepancy

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Key Clinical Points (Summary Box)

• Blount's disease = clinically a sharp proximal tibial angulation (not a smooth bow)
• Infantile form more common in Afro-Caribbean children; adolescent form affects all groups
• Post-surgical recurrence is higher in adolescent form than infantile
• In unilateral cases: limb will be short after correction - consider concomitant tibial lengthening
• Initial metaphyseal beaking progresses to irregularity, fragmentation, and premature medial physeal fusion if untreated
• Femoral varus is significant in late-onset disease - Kline et al. showed ~10 degrees femoral varus more than ideal, accounting for 34-76% of genu varum
• Bailey and Love's Short Practice of Surgery, p.1456; Campbell's Operative Orthopaedics, pp.1499-1510

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TIBIA VARA (BLOUNT'S DISEASE)

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DEFINITION

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AETIOLOGY / PATHOGENESIS

• Exact cause unknown
• Abnormal enchondral ossification at medial proximal tibial physis
• Risk factors:
  • Early walking
  • Obesity (well-documented association)
  • Vitamin D deficiency
• Excessive mechanical stress on medial physis → growth suppression
• Does NOT occur in non-ambulatory children
• More common in Afro-Caribbean children (infantile form)

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CLASSIFICATION

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PATHOLOGY

• Medial tibial physis: irregular, slopes medially
• Medial metaphysis: beaking → fragmentation → premature fusion
• Result: varus + internal torsion of tibia + genu procurvatum

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LANGENSKIÖLD CLASSIFICATION (6 Stages)

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CLINICAL FEATURES

• Progressive bow legs (genu varum)
• Sharp angular deformity at proximal tibia (NOT smooth bow - distinguishes from physiologic)
• Significant intoeing (internal tibial torsion)
• Medial metaphyseal projection - palpable but NOT diagnostic
• Obese child, early walker

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DIAGNOSIS

X-Ray (AP standing full-leg)

• Medial epiphysis: short, thin, wedged
• Physis: irregular, slopes medially
• Medial metaphyseal fragmentation = PATHOGNOMONIC
• Tibiofemoral angle measured on full-leg standing X-ray

Key Radiological Measurements

1. Metaphyseal-Diaphyseal (Drennan) Angle >11° = early indicator (most important)
2. Mechanical axis deviation
3. Tibial metaphyseal-epiphyseal angle

MRI (additional findings)

• Increased thickness of medial chondroepiphysis
• Increased height/width of medial meniscus
• Abnormal medial femoral epiphysis

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DIFFERENTIAL DIAGNOSIS

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TREATMENT

A. Non-Surgical

• Ages 2-3 years: Observation or KAFO (Knee-Ankle-Foot Orthosis) bracing
• Only for early stages with mild deformity

B. Guided Growth (Lateral Hemiepiphysiodesis)

• Tension band plate / Eight-plate on lateral proximal tibial physis
• Minimally invasive
• Complication: implant failure ~12% (use 4 screws in obese patients)
• Recurrence possible after plate removal

C. Tibial Osteotomy (mainstay of treatment)

• Indicated: progressive deformity in children >3 years
• Valgus osteotomy of proximal tibia + fibula with mild overcorrection
• Recurrence:
  • <20% if done before age 4
  • 80-90% if done after age 4

• Rab oblique osteotomy - corrects varus + internal rotation simultaneously
• Greene crescent osteotomy - maintains limb length
• Zayer hemicondylar osteotomy - corrects medial plateau slope

D. External Fixation

• Ilizarov fixator: deformity correction + limb lengthening (adolescents)
• Hexapod / Taylor Spatial Frame: obese adolescents, complex multiplanar deformity, computer-navigated correction

E. Medial Epiphysiolysis (Stage IV)

• Elevation of depressed medial tibial plateau
• Cortical bone graft to maintain correction
• Combined with proximal tibial osteotomy + fibular osteotomy

F. Management of Physeal Bar (to prevent recurrence)

• CT/MRI preoperatively if: age >5 yrs, weight >95th percentile, medial physeal slope 50-70°, Langenskiöld grade IV
• Bony bridge resection + lateral epiphysiodesis
• Contralateral epiphysiodesis if leg length discrepancy in unilateral cases

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COMPLICATIONS

• Recurrence of deformity (most common)
• Leg length discrepancy
• Premature physeal closure → progressive varus
• Peroneal nerve injury (post-osteotomy)
• Compartment syndrome (post-osteotomy)
• Osteoarthritis of knee (long-term)

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EXAM HIGH-YIELD POINTS ⭐

1. Pathognomonic sign = medial metaphyseal fragmentation on X-ray
2. Drennan angle >11° = early radiological indicator
3. Langenskiöld Stage VI = premature fusion at 90°
4. Age <4 years osteotomy = recurrence <20%; >4 years = 80-90%
5. Sharp proximal tibial angulation clinically (NOT smooth bow)
6. Does NOT occur in non-ambulatory children
7. Bilateral 60% in infantile type (physiologic = 100% bilateral)
8. Adolescent form = higher recurrence after surgery than infantile

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• Next topic — give me another Ortho topic to cover?
• "Are ye" (Hindi) — like "okay got it, next question"?
• A specific topic like "Artery" (vascular anatomy)?
• Something else?

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✅ COMPLETE ANSWER GIVEN - TIBIA VARA

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📌 What You Should Do Now

• Langenskiöld diagram image
• X-ray image of bilateral Blount's
• Treatment age cutoffs (critical for exams)
• All osteotomy types by name
• Drennan angle value
• Recurrence rates

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TIBIA VARA (BLOUNT'S DISEASE)

Complete Theory Answer - Orthopaedics

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1. DEFINITION

• Varus of the tibia
• Internal torsion of the tibia
• Genu procurvatum (forward bowing at knee)

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2. INCIDENCE / EPIDEMIOLOGY

• Infantile form: more common in Afro-Caribbean children
• Adolescent form: affects all ethnic groups
• Related to "obesity epidemic" - cases may be rising
• Does NOT occur in non-ambulatory patients

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3. AETIOLOGY / PATHOGENESIS

• Exact cause unknown - enchondral ossification is altered
• Suggested causes (none proven): infection, trauma, osteonecrosis, latent rickets
• Most likely: combination of hereditary + developmental factors
• Proven risk factors:
  • Early walking
  • Obesity
  • Vitamin D deficiency
• Similarity with SCFE histology → common cause = excessive mechanical stress on medial physis
• Focal fibrocartilaginous dysplasia can mimic tibia vara but is usually self-limiting

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4. CLASSIFICATION

By Age (Box 34.2 - Campbell's)

Special Variant: Proximal Tibial Epiphysis Slip

• Atraumatic slip in severely obese children
• Radiograph: dome-shaped metaphysis, open physis, inferomedial translation of epiphysis, disruption of lateral epiphysis-metaphysis continuity
• Treatment differs from conventional Blount disease

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5. PATHOLOGY

• Medial tibial physis: irregular, slopes medially
• Proximal metaphysis: medial beak (palpable but NOT diagnostic)
• Medial metaphyseal fragmentation = PATHOGNOMONIC
• End result: premature fusion of medial physis → progressive varus

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6. LANGENSKIÖLD STAGING (6 Stages)

At Stage VI: medial physis fuses completely → no further growth correction possible

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7. CLINICAL FEATURES

• Progressive genu varum (bow legs)
• Sharp angular deformity at proximal tibia - NOT smooth bow (key distinction from physiologic)
• Significant intoeing (internal tibial torsion)
• Medial metaphyseal projection - palpable at proximal tibia
• Obese child, early ambulator
• Bilateral 60% in infantile type

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8. INVESTIGATIONS

A. X-Ray (Standing AP full-leg radiograph)

• Medial epiphysis: short, thin, wedged
• Physis: irregular, slopes medially
• Medial metaphyseal fragmentation = PATHOGNOMONIC
• Tibial vara X-ray showing bilateral proximal tibial varus:

B. Key Radiological Measurements

Drennan angle = angle between line through metaphyseal beaks (transverse tibial metaphysis axis) and perpendicular to longitudinal tibial axis

C. MRI Findings

• Increased thickness of medial chondroepiphysis
• Increased height and width of medial meniscus
• Abnormal medial femoral epiphysis
• Late resolution of tibial bowing (early indicator)

D. CT

• Identifies physeal bar preoperatively
• Indicated if: age >5 yrs, weight >95th percentile, medial physeal slope 50-70°, Langenskiöld grade IV

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9. DIFFERENTIAL DIAGNOSIS

Posteromedial bowing = usually physiologic, resolves spontaneously Anterolateral bowing = associated with NF1 and fibrous dysplasia

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10. TREATMENT

A. Observation + Bracing

• Age 2-3 years, early stages only
• KAFO (Knee-Ankle-Foot Orthosis)
• Limited role; osteotomy preferred once deformity is progressive

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B. Guided Growth (Lateral Temporary Hemiepiphysiodesis)

• Tension band plate ("eight-plate" technique) on lateral proximal tibial physis
• Allows medial physis to "catch up" by slowing lateral growth
• Minimally invasive
• Complications:
  • Implant failure ~12% (especially obese patients)
  • Use 4 screws or 2 eight-plates in obese patients
• Recurrence after plate removal due to slower medial physis growth rate

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C. Tibial Osteotomy (Mainstay of surgical treatment)

• Osteotomy before age 4 → recurrence <20%
• Osteotomy after age 4 → recurrence 80-90%

1. Transverse incision at lower pole of tibial tubercle
2. Steinmann pin placed at 45° - 1 cm distal to tibial tubercle
3. Osteotomy immediately distal to pin
4. Fibular osteotomy through separate incision (1-2 cm segment excised)
5. Leg rotated to valgus + external rotation
6. Long-leg cast, knee flexed 45°

• No weight bearing for 4 weeks
• Cast change at 4 weeks
• Pins removed if healing satisfactory
• Total immobilization: 8-10 weeks

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D. External Fixation

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E. Medial Epiphysiolysis (for Stage IV Infantile Tibia Vara)

• Elevation of depressed medial tibial plateau
• Osteotomy parallels articular surface medially → reaches subchondral bone
• Cortical bone grafts inserted to maintain articular congruity
• Combined with proximal tibial opening wedge osteotomy + fibular osteotomy

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F. Management of Physeal Bar (to prevent / treat recurrence)

• Child >5 years
• Weight >95th percentile
• Medial physeal slope 50-70°
• Langenskiöld grade IV

• Bony bridge resection if growth potential remains (can combine with osteotomy)
• Lateral tibial epiphysiodesis - age 9 years to skeletal maturity
• Contralateral epiphysiodesis - for leg length discrepancy in unilateral cases
• Intraepiphyseal osteotomy - for older patients with failed previous treatment

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11. COMPLICATIONS

Complications of Disease (Untreated)

• Progressive varus deformity
• Premature medial physeal closure (Stage VI)
• Leg length discrepancy
• Osteoarthritis of knee (long-term)
• Medial compartment overload

Complications of Surgery (Osteotomy)

• Recurrence (most common - especially in older children)
• Peroneal nerve palsy (traction injury during valgus correction)
  • → Signs: sensory loss dorsum of foot + loss of active dorsiflexion WITHOUT pain
  • → Treatment: remove cast, return to preoperative position, remove all pressure on nerve
• Anterior compartment syndrome
  • → Signs: severe pain on plantarflexion of toes, reduced dorsiflexion
  • → Treatment: immediate fasciotomy
• Anterior tibial artery occlusion
  • → Treatment: return to preoperative position; if no improvement → immediate vascular surgery
• Pin track infection
• Undercorrection / overcorrection

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12. SUMMARY: EXAM HIGH-YIELD POINTS ⭐⭐⭐

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