Peds 2: Coronal Deformities - Tibia Varum/Genu Valgum

Key Concepts:

Terms in this set (24)

Tibia varum definition and types
defined as a varus deformity of the tibia with the apex of the deformity at the UPPER!! tibial metaphysis
• 3 forms - physiological, teratological (due to a fibrous tether most recently called fibrocarilagenous dysplasia) and non-physiological (Blount's disease)
Genu varum
means that the knee joint axis is rotated into varus (toward midline)
• Upper tibial metaphysis is normal
Tibia valgum
defined as a valgus deformity of the upper tibia (NOT PHYSIOLOGIC -
pathological), knees okay
• Almost always secondary to greenstick fracture of the upper medial tibial diaphysis (2 to trauma of the medial cortex of the proximal tibia)
• Usually remodel and will get better
Genu valgum
defined as lateral deviation of the distal femur on the coronal plane
• Symmetry is normal to a certain degree- age 2 to 6 normal
o Estimate axis of femur to tibia or radiological
• Unilateral - worrisome
• Malleoli widely separated when medial knees touch
• Knee deviated laterally
• Can't really do much- bracing works best for upper tibia (uaully varus)
natural history of varoid stage
From birth to age 2 years, most infants show tibia varum

• Even though this is a physiological event has an effect by causing STJ pronation to allow the medial column of the foot to reach the ground (can pronate or walk on the lateral side of the foot to get the medial side of the foot down)
natural hx of valgoid stage
age 2-6 years, some degree of genu valgum is present
types of tibial varum
• Upper metaphyseal - most common location
o Thigh-knee-ankle-ft orthosis

• Diaphyseal
o Often variation of rickets

• Lower metaphyseal
Blount's Disease
most common clinical syndrome
• Infantile Tibial Varum (Blount's Disease)
o Pathological tibia varum cannot be separated physiological tibia varum on physical examination alone

infantile
juevenile
adolescent
infantile blounts
2-5
Problem with posteromedial upper tibial physis- upper tibia goes into varus and flex anterior and starts to rotate internally
Characteristic lateral thrust in gait
juevenile blounts
4-10
Least common
Severe, BLE
Physis irregular and indistinct
May be slipped proximal tibial epiphysis
Advanced skeletal age for chronological age
• Adolescent Blounts
o Children over 9 years
o Idiopathic early closure on the medial side of the upper tibial physis
o Unfortunately, these children are too old to respond to bracing
o The only treatment is tibial valgus osteotomy
o Stereotypical Blount's Disease patient
Short stature (<50th percentile)
Obese (>99th percentile)
Early walking (<10 months)
Genetic background (typically African Americans)
Female
50% are unilateral
• Differential diagnosis of blounts
o Persistant physio TV

o Rickets
Renal
Vit d
Vit d resistant

o Fibrocartilaginous dysplasia

o Skeletal dysplasias
Metaphyseal dysostosis
Mucopolysaccharoidosis
long term effect of blounts
o Progressive Varus Deformity
o Epiphyseal Distortion
o Limb Length Inequality In Unilateral Cases
o Meniscal Tears
o Degenerative Arthritis
Pathophysiology of blounts
- purely mechanical
• Progressive upper tibial physeal dysfunction
• The thought is that early walking in a susceptible individual who is in the varoid stage of development results in excessive loading of the upper medial tibial metaphysis
• Results in decreased lineal growth on the medial side while the lateral side continues to grow
• This not only causes varus bowing, but becomes self- perpetuating by increasing the medial load
• Theoretically, reversing these forces should reverse the deformity
• This concept is the basis for non-operative treatment for Blout's disease
radio of blounts
AP and lateral x-rays of the knees are very helpful in making the differential diagnosis between physiological tibia varum and Blount's disease

Beak on the medial side (lateral side grows faster)4

Tibiometaphyseal (Levine-Drennen's) Angle

The shape of the upper tibial epiphysis is also useful
• In Blount's disease, the medial half flattens and becomes too small to support the medial femoral condyle
Tibiometaphyseal (Levine-Drennen's) Angle
• A line is drawn from the most medial margin of the upper tibial metaphysis to the lateral margin
• A second line is drawn either along the lateral tibial diaphyseal cortex or down the center of the diaphysis
• The deviation between the 2 is measured in degrees
• <12 (normal - physiological), >12-15 (Blount's disease -
pathological)
<9 physiologic, >16 indicates blounts: newer data
o Langenskiold Classification
6 stage classification based on the appearance of the medial metaphysis and the amount of beaking and irregularity
Almost impossible to distinguish between Langenskiold Stage I and physiological tibia varum
Yet, it is so important to do so because *early
Blount's disease responds to bracing*
Surgical results in managing Blount's disease
are less than desirable
I-VI
I = 2-3 years, VI - 10-13 years
II - complete restoration common
Restoration possible
• Non-operative treatment of blounts
o Infantile
Braces designed to distract the medial side of the knee while compressing the lateral side
blounts brace

single medial upright KAFO

no Tx for adolescent
operative Tx of Blounts for infants
Tibial corrective osteotomy

Excision of diseased medial portion of the tibial physis

Guided growth
Tibial corrective osteotomy
• Requires a proximal tibial osteotomy
• Often it is necessary to construct the osteotomy to allow correction both in the coronal and transverse planes
• This puts the proximal neurovascular structures at risk, and there is also an increased incidence of catastrophic compartment syndrome
• Usually not good, need several operations
Excision of diseased medial portion of the tibial physis
• The void is filled with fat or some other inert material (methymethacrylate) to prevent bony re-bridging
• Fat grafts do survive to prevent plate closure
operative Tx of Blounts for adolescents
Tibial corrective osteotomy
• Tibial valgus osteotomy
• Very dangerous - at trifurcation
• Incidence of compartment syndrome = high
Stapling the physis - slow lateral side
• Replaced now with cloverleaf plate
• Comorbidty Between Infantile Tibia Varum and Tibial Torsion
o Both tibia varum and internal tibial torsion may occur physiologically
o Their times for "normal" appearance also overlap
o Therefore, their appearance together may be circumstantial
o However, Blount's disease at any age is almost always associated with internal tibial torsion
o The reverse is not true
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