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Duke Orthopaedics
presents
Wheeless' Textbook of Orthopaedics

Pediatric Genu Varum


- Discussion:
    - most commonly presents at 14 to 36-months;
    - bowleg deformity in children w/ short stature & may indicate skeletal dysplasia;
    - developmental knee alignment:
           - normal knee alignment progresses from 10-15 deg of varus at birth to maximal valgus angulation of 10-15 deg at age of 3-3.5 yrs;
           - neutral alignment:
                   - neutral femoral-tibial alignment occurs at 12-14 months old;
                   - Greene: neutral femoral-tibial alignment at 14 months old;
- Exam:
    - degree of varus& tibial torsion are specifically measured & recorded;
          - a practical method of following the varus deformity is to trace the outline of the child's legs on the paper cover the examination table;
                   - parents can hold on to this until the next visit;
          - alternatively, hold the child's ankle together and measure the distance between the knees;
    - knee motion and ligamentous instability are also assessed;
    - in older child w/ untreated infantile tibia vara, mild laxity of LCL is common, but 14-36 mo. old child w/ this condition usually has ligamentous stability that
          is within normal limits;

- Radiographs:
    - physiologic bowing typically show flaring and bowing of tibia and femur in a symmetric fashion and is normal in children < 2 years of
              age (maximal at about 18 mo);
    - physiologic genu valgum, or knock knees, develops next, w/ maximal deformity occurring at 3 years of age;
    - gradual correction to ultimate alignment of slight genu valgum occurs by 9 years of age in the great majority of patients;
    - references:
          - Physiological bowing and tibia vara. The metaphyseal-diaphyseal angle in the measurement of bowleg deformities.

- Differential Dx:
    - Physiologic Bowing:
          - most common cause of genu varum;
          - becomes most apparent during the second year but almost always disappears by age 3;
          - involves both the femur and the tibia;
          - can be assocated with internal tibial torsion;
          - some orthopaedists will attempt to diminish this type of varus w/ casting;
          - references:
                - Normal limits of knee angle in white children--genu varum and genu valgum
                - Distal tibial deformity in bowlegs.  
    - Blounts Disease:
    - Trauma:
    - Osteogenesis Imperfecta
    - Osteochondroma
    - Hypophosphatemic rickets:
          - its sex-linked dominant inheritance may lead to early diagnosis;
          - short stature & genu varum are apparent;
          - ht at initial dx is usually <10 % & always< 25th
          - abnormal genu varum is seen in 95 % of these pts;
          - characterized by widening or rachitic-like changes at physis;
          - low serum phosphorus levels distinguish hypophosphatemic rickets from metaphyseal chondrodysplasia;
    - Metaphyseal chondrodysplasia:
          - an inherited disorder of bone growth that also causes bowing of lower extremities;
          - characterized by widening or rachitic-like changes at physis;
          - in Schmidt subtype (most common), height and limb alignment are w/in norml limits at birth, but genu varum persists & retarded growth is seen in preschool yrs;
          - low serum phosphorus levels distinguish hypophosphatemic rickets from metaphyseal chondrodysplasia



Normal limits of knee angle in white children--genu varum and genu valgum.

Use of the Metaphyseal-Diaphyseal Angle in the Evaluation of Bowed Legs.

Tibia vara caused by focal fibrocartilaginous dysplasia. Three case reports

Varus deformity of the distal end of the femur secondary to a focal fibrous lesion.

The development of the tibiofemoral angle in children.  

Genu varus and valgus in children.  

Variability of the Metaphyseal-Diaphyseal Angle in Tibia Vara: A Comparison of Two Methods.



Original Text by Clifford R. Wheeless, III, MD.

Last updated by Data Trace Staff on Thursday, May 10, 2012 4:53 pm