Radiology Cases Slipped Epiphysis

Description: Slip of Femoral capital epiphysis.
The length and angle of the neck of the Femur is useful for an erect hominid, especially when carrying things. Standing, the curves of both femora, pelvic rings and sacrum conduct the lines of force up into the spine. Moving requires the support to come from one side. The pelvis is tilted by the actions of the glutei (particularly Medius). It then becomes possible for the lines of force to be outside the centres of femoral neck and hip-joint. Shear forces may operate across the junction of femoral capital epiphysis and femoral neck. Activity and obesity may both increase these forces, explaining why boys were more likely to get this condition, especially when obese. Peak incidence is in early adolescence. The epiphysis is displaced backwards and medially, relative to the metaphysis (regarded as the fixed point, when standing). Since the pelvis and lower limbs are supposed to be symmetrical, the presence of one abnormality should alert the reader to subtle abnormality on the other side. The total incidence is of 20 to 40% of cases having bilateral slip, sooner or later.
Signs of slip include:
* Loss of height of epiphysis in projected image.
* Loss of width of epiphyseal plate in projected image.
* There is a reduction of that medial part of the metaphysis, normally within the acetabulum in the neutral view.
* The projected lateral margin of the metaphysis no longer intersects the epiphysis.
* Rotation of the pelvis towards the abnormal, stiffer, joint in a supine view (diverging rays).