The radiological evaluation of multiple pin fixation of the femoral head.

Following pin fixation of the femoral neck, extrusion of a pin tip into the joint space cannot be excluded with conventional bi-plane radiography. A per-cervical pin was allowed to extrude from the head of a dried femur. Anteroposterior and lateral photographs and roentgenograms of this preparation, simulating corresponding intra-operative radiology, demonstrated misleadingly that the pin tip was wholly within the head. Careful intra-operative and post-operative screening is considered important to detect unwanted joint penetration and so avoid avascular necrosis and late degenerative change.