Locking compression plate fixation of Vancouver type-B1 periprosthetic femoral fractures.

BACKGROUND: Fractures occurring at or near the distal tip of a hip prosthesis with a stable femoral stem (Vancouver type-B fractures) are associated with many complications because of the inherently unstable fracture pattern. Locking compression plates use screws that lock into the plate allowing multiple points of unicortical fixation. Such unicortical fixation may lower the risk of damage to the cement mantle or a stable femoral stem during the treatment of a periprosthetic femoral fracture. The purpose of this study was to analyze clinically and radiographically a group of patients with a Vancouver type-B1 periprosthetic femoral fracture treated with open reduction and internal fixation with use of a locking compression plate.

METHODS: Fourteen consecutive patients (fourteen hips) with a Vancouver type-B1 periprosthetic femoral fracture were treated with a locking compression plate. There were five men and nine women with an average age of sixty-eight years at the time of fracture. All of the fractures occurred after a total hip arthroplasty performed with cement, and eleven of the arthroplasties were revisions. In addition to the plate, cortical strut allografts were used to stabilize five fractures. The patients were assessed clinically and radiographically.

RESULTS: The average duration of follow-up was twenty months. Eight fractures healed uneventfully at an average of 5.4 months. Three treatment constructs failed with fracture of the plate within twelve months after surgery. An additional three constructs also failed because of plate pullout. All failures except one occurred in constructs in which a cortical strut allograft had not been utilized.

CONCLUSIONS: On the basis of the high failure rate in this series of patients, locking compression plates do not appear to offer advantages over other types of plates in the treatment of type-B1 periprosthetic femoral fractures. Despite the potential to preserve the cement mantle, the locked screws did not appear to offer good pullout resistance in this fracture type. We believe that supplementation with strut allografts should be used routinely if this type of locking compression plate is selected to treat these fractures.