"An AP pelvic x-ray is sufficient to establish the diagnosis and identify major fractures. The femoral head is typically projected superolateral to the acetabulum, the hip is flexed, internally rotated and adducted. Geometric magnification means that the normal contralateral femoral head appears larger."
"An anteriorly dislocated femoral head usually lies inferomedial to the acetabulum, with the femur in marked external rotation causing the lesser trochanter to be seen enface, and the femoral head is relatively magnified on an AP radiograph. A rare anterio-superior hip dislocation is harder to distinguish but still features an en face lesser trochanter and magnification 4."
"non-concentric reduction indicates the the presence of intra-articular bone or cartilage fragments and is an indication for open surgery or arthroscopy"
"Posterior dislocation in the absence of femoral neck fracture is best reduced under sedation immediately following X-ray diagnosis. This reduces the incidence of avascular necrosis of the femoral head and improves recovery of an associated sciatic nerve injury 4. Partial sciatic nerve recovery occurs in 60-70% 4."
"Pipkin femoral head fracture classification"
Expected headings
"Mechanism"
"Associations"
"Pearls and pitfalls"
"The affected lower limb is shortened, adducted and internally rotated. Associated sciatic nerve stretch/compression injury is a recognised complication, - the peroneal branch is more vulnerable, being relatively fixed 4."
"Internal rotation causes superimposition of the medial femoral cortex and the lesser trochanter, obscuring the latter. This is an important distinguishing feature; in anterior dislocation the lesser trochanter is seen en face due to external rotation 4."
"There is no proven benefit for detecting early avascular necrosis of the femoral head 4."
"Instability can be assessed by fluoroscopy under general anaesthesia. There is a variable relationship of instability to fracture extent, however fracture of the superior portion of the posterior acetabular wall and posterior acetabular rim avulsion are significant risk factors and may require internal fixation 4."