Impaction Grafting with Allogran-N

Variables Affecting Initial Stability of Impaction Grafting for Hip Revision.

Clinical Orthopaedics & Related Research. (432):174-180, March 2005.
Gokhale, Satish FRCS ORTH ; Soliman, Ayman MSCORTH ; Dantas, João Pedro MD ; Richardson, James Bruce MD ; Cook, Frank BSC ; Kuiper, Jan-Herman PhD ; Jones, Peter PhD

Impaction grafting in revision arthroplasty was originally described for use in the acetabulum1, and later adapted for use in the femur2. The process involves cementing a femoral component into compressed bone graft.

An advantage of impaction grafting in orthopaedic revision surgery is the restoration of bone stock. However, the bone graft matrix requires more than the ability to support the in-growth of host bone tissue. A high level of physical robustness and structural integrity is required to withstand the dynamics of compaction involved in impaction grafting.

Allograft is commonly used for impaction grafting for hip revision. However, this is sometimes in short supply, and of variable quality. In many cases, osteoarthritic femoral heads are used by morselising the head to bone chips, the result of which is combined with fresh blood from the patient.

In 17 hip revision cases from the study of 56 patients, there was a shortage of available bone. The bone available was therefore combined equally with Allogran-N, a granular Hydroxyapatite bone graft substitute. This 50:50 mixture was then combined with fresh blood from the patient.

Allogran-N has been designed for use as a bone graft extender to be used in conjunction with allograft material, in order to reduce the surgeon’s reliance on allograft tissue, and the risks that have been associated with it’s use3.

The study explores the variables affecting initial stability of impaction grafting for hip revision. As Allogran-N was used in the study, this was one of the factors considered when analysing clinical results by multiple regression statistical analysis.

From the conclusions, it was evident that the use of Allogran-N as a synthetic bone graft extender was successful. Allogran-N’s hydroxyapatite granules did not adversely affect cup migration or stem subsidence.

These results indicate that the use of Allogran-N to augment allograft bone stock is an effective method of reducing dependence on allograft, without compromising performance requirements relating to graft stability.

References
1. Sloof T J, Huiskes R, van Horn J, Lemmens A J : Bone grafting in total hip replacment for acetabular protrusion. Acta Orthop Scand 55:593-596, 1984
2. Fowler J L, Gie G A, Lee A J, Ling R S: Experience with the Exeter total hip replacement since 1970. Orthp Clin North Am 19: 477-489, 1988
3. AAOS Bulletin, October 2004, Vol 52, No.5. “FDA’s tissue action plan: Safeguarding the public”

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