Coxa Vara - Etiology

• rare- 1/ 25000 live births, M=F, R=L, Bilat in 30%
• an autosomal dominant inheritance pattern has been described
• may be more common in negroes

• Histological abnormalities have been found in Bx of the femoral necks- Increase in width of the growth plate
  

• absenceof normal orderly progression of cartilage columns (similar to appearance of Blounts Dx)
  

• current theory - deformity due to a primary ossification defect in the inferior femoral neck. Physiologic shearing stresses in weight bearing fatigue the abnormal bone Resulting in progressive deformity

• Most present with a progressive gait deformity bw walking age and ~ 6 yo pain is rare
• unilateral dx- present with gait 2o to abductor weakness and a LLD
• bilateral dx - present with waddling gait similar to that of DDH

• Examination
• prominent and elevated greater trochanter
• +ve TrendelenbergLLD - usually mild, av 2.5 cm
• FFD with ­ ROM - esp abduction and IR

• XRay ­ neck- shaft angle

• more vertical position of the physeal plate- defined by the angle bw Hilgenreiners line and the line through the epiphyseal plate- normally 25o or less
• Fairbanks triangle - a triangular metaphyseal fragment in the inferior femoral neck surrounded by an inverted radiolucent Y ( represents a zone of abnormal osification with an interposed triangular segment of dystrophic bone)
• ­ in normal anteversion of the prox femur ( may become retroverted) coxa breva
  
• rarely mild acetebular dysplasia

Category: Orthopedics Notes