Coxa Vara and Acquired Coxa Vara

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- Discussion:
    - decreased neck shaft angle from defect in ossification of femoral neck;
    - it is bilateral in 1/3 to 1/2 of cases;
    - it can be congenital (noted at birth & differenitated from CDH by MRI),
          developmental (AD-progressive), or acquired (trauma, LCP, SCFE)

- Differential Dx:
    - Congenital:
          - Cleidocranial Dysplasia
          - Chondrodysplasia Punctata
          - Metaphyseal Chondrodysplasia
          - Gaucher's Disease
          - Multiple Epiphyseal Dysplasia
          - Proximal Focal Femoral Deficiency
          - Spondyloepiphyseal Dysplasia Congenita:
    - Aquired:
          - AVN: (DDH or Perthes)
          - Fibrous Dysplasia
          - SCFE
          - Rickets
          - Osteomyelitis of Hip and Septic Arthritis
          - Traumatic:
          - Paget's Disease:

- Clinical Manifestation:
    - most pts affected present between ages 2-6 years;
    - may present w/ waddling gait (bilateral) or painless limp (unilateral)
    - in congenital coxa vara, look for leg length descrepancy and fibular hemimelia;
    - range of motion of hip is usually restricted in all planes, w/ most significant limitations
            occuring in abduction and internal rotation;

- Radiographs:
    - typically the deformity will lie in the subtrochanteric region of the femur;
    - in developmental coxa vara, there will often be a triangular ossification in the   inferomedial femoral neck (calcar);
    - evaluation of Hilgenreiner's epiphyseal < (angle between Hilgenreiner's line & line thru proximal femoral physis) is key to treatment;
          - normally this angle is 25 deg or less;
          - angle < 45 deg will spontaneously correct, where as angle of > 60 deg (& neck shaft angle of < 110 deg) will usually require surgery;

- Indications for Treatment:
    - proximal femoral epiphyseal angle > 45 to 60 deg;
    - proximal femoral (valgus) +/- deroational osteotomy (Pauwel) is indicated for neck shaft angle less than 90 - 100 deg;
    - vertically oriented physeal plate
    - progressive deformities, or with significant gait abnormalities;

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Long-term results of valgus osteotomy for congenital coxa vara.

Developmental (infantile) Coxa Vara: a distinct entity.
      Amstutz H.C.   CORR 72:242,1970

Congenital coxa vara: A retrospective review.
      JN Weinstein et al.   J. Pediatric Orthopaedics.   Vol 4. 1984. p 70-77.

The Fate of the Capital Femoral Physis and Acetabular Development in Developmental Coxa Vara.
      Schmidt T.L., Kalamchi A.   J. Pediatr. Orthop. 2:534,1982

Coxa vara: A retrospective review.
      ME McCall.   Orthop Trans. Vol 19. 1995. p 854.