|Classification and external resources|
Different femoral abnormalities.
Coxa vara is a deformity of the hip, whereby the angle between the head and the shaft of the femur is reduced to less than 120 degrees. This results in the leg being shortened, and therefore a limp occurs. It is commonly caused by injury, such as a fracture. It can also occur when the bone tissue in the neck of the femur is softer than normal, meaning it bends under the weight of the body. This may either be congenital or the result of a bone disorder. The most common cause of coxa vara is either congenital or developmental. Other common causes include metabolic bone diseases (e.g. Paget's disease of bone), post Perthes deformity, osteomyelitis, and post traumatic (due to improper healing of a fracture between the greater and lesser trochanter). Shepherds Crook deformity is a severe form of coxa vara where the proximal femur is severely deformed with a reduction in the neck shaft angle beyond 90 degrees. It is most commonly a sequela of osteogenesis imperfecta, Pagets disease, osteomyelitis, tumour and tumour-like conditions (e.g. fibrous dysplasia).
Anatomy: in early skelatal devolopment a common physis serves the greater trochanter and the capital femoral epiphysis.This physis divides as growth continues in a balance that favours the capital epiphysis and creates a normal neck shaft angle (angle between the femoral shaft and the neck).The corresponding angle at maturity is 135 degres +/- 7. Another angle used for the measurement of coxavara is the cervicofemoral angle which is approximately 35 degrees at infancy and increases to 45 degrees after maturity. coxavara refers to an increase in the cervicofemoral angle or the decrese in neck shaft angle.
Devolopmental coxavara: More common Aeitiology: primary defect in enchondral ossification of the medial part of the femoral neck. Excessive interutrine pressure on the devoloping fetal hip. vascular insult. Faulty maturation of the cartilage and metaphyseal bone of the femoral neck. clinical feature:Presents after the child has started walking but before six years of age. Usually associated with a painless hip due to mild abductor weakness and mild limb length discripency . If there is a bilateral involvement the child might have a waddling gait or trendelenburg gait with an increased lumbar lardosis. The greater trochanter is usually prominent on palpation and is more proximal. Restricted Abduction and internal rotation .
X-ray: decreased neck shaft angle,increased cervicofemoral angle,vertical physis,shortened femoral neck decrease in femoral anteversion.H.E angle (hilgenriener epiphyseal angle- angle subtended btween a horozontal line connecting the triradiate cartilage and the epiphysisn normal angle is <30 degrees. Treatment: HE angle of 45 - 60 degrees observation and periodic follow up Indication for surgery :HE angle more that 60 Degrees, progressive deformity, neckshaft angle <90 degrees, devolopment of trendelenburg gait Surgery: subtrochantric valgus osteotomy with adequate internal rotaion of distal fragment to correct anteversion commone complication is recurrence. If HE angle is reduced to 38 degrees less evidence of recurrence post operative spica cast is used for a period of 6 - 8 weeks
Congenital coxavara: Presents at birth Is extreamly rare and associated with other congenital anomalies such as proximal femoral focal deficency,fibular hemimelia or anomalies in other part of the body such as cleidocranial dyastosis.usually unilateral.The femoral deformity is present in the subtrochantric area where the bone is bent . The cortices are thickened may be associated with overlying skin dimples.External rotation of the femur with valgus deformity of knee may be noted. this condition does not resolve and requires surgical management. surgery: valgus osteotomy to improve hip bio mechanics and length ,ARotational osteotomy to correct retroversion and lengthening
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