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Treating Bone Deficiencies During Hip Replacement Revision

Sometimes total hip replacements (THRs) fail and must be taken out. Pockets of bone loss can occur during this process. Impaction grafting reviewed in this article is a way to treat this problem.

Shaved bits of donor bone called an allograft are used to fill these bone defects. These tiny pieces of bone work well because they are easy to shape to fit the hole. When packed in tightly, the graft supports the implant until native (new) bone can form to stabilize the hip.

The process of filling the defect layer-by-layer and tamping down the bone is called impaction grafting. Metal mesh may be needed to shape a structure or scaffold. The graft fills in and around the mesh.

A trial implant is used to check the position and measure leg length. When everything is ready, cement is injected to seal everything together.

Long term results and problems after impaction grafting are also presented. Implant survival after 12 to 15 years is 85 per cent. Loosening of the implant in the remaining 15 per cent requires another revision surgery.

Infection is the most likely problem after bone grafting. Femoral (thighbone) fractures can occur during the operation from the force of the hammer used to tamp down the bone. Fractures can occur afterwards if the quality of bone graft is poor.

Impaction grafting can be used successfully when a THR must be revised and there's been a loss of bone stock during removal. Young patients are especially good candidates for this procedure. Impaction grafting has also been used with bone fractures to fill in the fracture line and speed up healing.

References: D. A. Oakes, MD, and Miguel E. Cabanela, MD: Impaction Bone Grafting for Revision Hip Arthroplasty: Biology and Clinical Applications. In Journal of the American Academy of Orthopaedic Surgeons. October 2006. Vol. 14. No. 11. Pp. 620-628.

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