Traumatic hip dislocations in children are classified as anterior or posterior depending on where the femoral head lies after dislocation
3. In the literature, there is no reported superolateral traumatic hip dislocation. Our case had superolateral hip dislocation and we had a theory for mechanism; she sustained an unrecognized posterior hip dislocation with posterior rim fracture of acetabulum due to a seemingly low-energy trauma and dislocation reducted spontaneously. During this trauma, anterolateral part of the labrum teared and after that fused to the superior articular cartilage of the acetabulum. Posterior rim fracture of the acetabulum stimulated the growth plate of the ischial part of the acetabulum and overgrowth of the ischial part of the acetabulum developed, leading to acetabular dysplasia, femoral head gradually subluxated laterally and at the end of this process, superolateral hip dislocation developed.
Not all traumatic hip dislocations in children cause severe or incapacitating symptoms and ambulation may even be possible. As a result, treatment may be delayed or the diagnosis missed, and shortening of the limb and contracture are well-established, making reduction difficult 8. Preoperative traction, extensive soft tissue release, or primary femoral shortening should be considered if open reduction is required 8. Our case had no pain and according to us gradually developed superolateral dislocation was the main factor for this. We performed primary femoral shortening for obtaining reduction. Open reduction is a satisfactory treatment for late unreduced traumatic dislocation in children, but avascular necrosis rate is high 9. We had excellent outcome without avascular necrosis.
In our case, we observed intraoperative nonconcentric reduction due to labral entrapment and overgrowth of the ischial part of the acetabulum. Overgrowth of the ischial part of the acetabulum has not been previously described as an impediment to concentric reduction following dislocation of the pediatric hip.
For obtaining the concentric reduction, we excised tearing and fused part of the labrum and thinned the thickness of the ischial part of the acetabulum. We may be damaged the epiphysis of ischial part of the acetabulum but Shea et al. pointed that the absence of the acetabular epiphysis does not seem to effect adversely further growth and development of the acetabulum 7.
Persistent widening of the medial joint space and the lateralization of the femoral head after reduction should alert the surgeon of the need for further studies, and CT scans and MRI investigation play an important role in further diagnostics of these patients 2-4,7,10. In our case, increased of ischial thickness was visible on CT scan, but not on plain radiograph. Our preoperative plan was lack, so that our case needed second operation.
For concentric reduction of pediatric hip dislocation, removal of any interposed tissue is necessary even it is articular cartilage of the hip joint.