We would like to thank Mr Board for his interest in our paper and for the opportunity to provide information about our treatment of bone allografts. We agree that this is a clinically relevant and important topic.

We started bone impaction grafting on the acetabular side in 1979, and from the beginning we never washed the grafts. Hence, all our long- term reports on the acetabular side are based on non-washed fresh frozen morsellized bone allografts. (1)

When we began the current study on femoral bone impaction grafting in 1991, we continued that practice and so the bone grafts used in this femoral study were not washed.

We agree with Mr Board that washing of morsellized bone improves the resistance to subsidence in femoral bone impaction grafting.(2) Others showed increased mechanical properties and better interparticle stability after washing in laboratory models. (3,4,5) Also, in clinical models, washing seems to improve initial cup stability. (6,7)

Other potential advantages of washing bone chips are the reduction of the bacterial contamination grade and the improvement of the incorporation of these allografts. (8,9)

A theoretic negative aspect of washing could be the loss of biologically active factors which are released from the bone during the morzellization process. However,we have not found this adverse effect in several experiments.

We would stress that more important than washing or not washing the bone chips is the necessity to carefully remove all soft tissue and cartilage before milling the femoral head. The presence of cartilage remnants will adversely affect the mechanical properties of the construct. (4) In a human biopsy study it was shown that these cartilage remnants will not be incorporated into new bone and can be found intact many years after the original surgical procedure. (10)

We used the Novio Magus bone mill (Spiering Medische Techniek, Nijmegen, the Netherlands). The dimensions of bone chips used on the femoral side are for technical reasons small and we prefer chips between 2 to 5 mm. In the more proximal areas, such as the calcar region, larger chips can be used, which may be beneficial for stem stability.

In the light of our very satisfactory long-term results both on the acetabular and femoral sides using non-washed grafts, we currently continue that practice. We acknowledge, however, that there certainly is evidence that washing will be beneficial for immediate stability, longer-term incorporation as well as the reduced chance of having an infection.

References:

1. Schreurs BW, Bolder SBT, Gardeniers JWM, Verdonschot N, Slooff TJJH, Veth RPH. Acetabular revision with impacted morsellised cancellous bone grafting and a cemented cup. J Bone Joint Surg Br 2004;86-B:492-97.

2. Hostner J, Hultmark P, Karrholm J, Malchau H, Tveit M. Impaction technique and graft treatment in revisions of the femoral component. J Arthroplasty 2001;16:76-82.

3. Voor MJ, Nawab A, Malkani AL, Ullrich CR. Mechanical properties of compacted morselized cancellous bone graft using one-dimensional consolidation testing. J Biomechanics 2000;33:1683-88.

4. Bavadekar A, Cornu O, Godts B, Delloye C, Van Tomme J, Banse X. Stiffness and compactness of morselized grafos during impaction. Acta Orthop Scand 2001;72:470-76.

5. Dunlop DG, Brewster NT, Madabhushi SPG, Usmani AS, Pankaj P, Howie CR. Techniques to improve the shear strength of impacted bone graft. J Bone Joint Surg Am 2003;85-A:639-646.

6. Ullmark G. Bigger chip size and defatting of bone chips will increase cup stability. Arch Orthop Trauma urg 2000;120:445-7.

7. Arts JJC, N Verdonschot, Buma P and Schreurs BW. Larger bone graft size and washing of bone grafts prior to impaction enhances initial cemented cup stability after bone impaction grafting. Acta Orthopaedica, in press 2006.

8. Hirn MYJ, Salmela PM, Vuento RE. High-pressure saline washing of allografts reduces bacterial contamination. Acta Orthop Scand;72:83-85.

9. van der Donk S, Weernink, T, Buma P, Aspenberg P, Slooff TJJH, Schreurs BW. Rinsing morselized allografts improves bone and tissue ingrowth. Clin Orthop 2003;408:302-310.

10. van der Donk S, Buma P, Slooff TJJH, Gardeniers JWM, Schreurs BW. Incorporation of morselized bone grafts: a study of 24 human acetabular biopsy. Clin Orthop 2002;396:31-41.

To The Editor:

I was very interested to read the article by Schreurs, et al (1) reporting the results of femoral component revision with impaction bone- grafting. They report a 100% survival at a mean 10.4 years follow up which is impressive despite there being only 33 hips in the study.

My enquiry is regarding the preparation of the bone graft. The authors comment that a Novio Magus bone mill (Spierings Medische Techniek, Nijmegen, The Netherlands) was used to produce particles with a diameter of 2 to 5 mm, but they do not report any other treatment of the graft. In particular, was the morsellized bone washed or de-fatted?

There is evidence that washing of morsellized bone improves the resistance to subsidence in femoral impaction grafting (2) and in acetabular impaction grafting. (3) Graft incorporation may also be facilitated by rinsing of the graft. Bone chamber models in animals have shown increased bone ingrowth in both impacted and un-impacted bone when rinsed grafts were compared to unrinsed grafts. (4-6) Indeed some of this work has come from the authors’ institution.

If, as one might suspect, the earlier cases reported by the authors used graft that was not rinsed, do their exemplary results suggest that there is no need to rinse the graft? Is it now the authors’ practice to rinse the graft?

References:

1. Schreurs BW, Arts JJC, Verdonschot N, Buma P, Slooff TJJH, Gardeniers JWM. Femoral component revision with use of impaction bone- grafting and a cemented polished stem. J Bone Joint Surg [Am] 2005;87- A:2499-507.

2. Hostner J, Hultmark P, Karrholm J, Malchau H, Tveit M. Impaction technique and graft treatment in revisions of the femoral component. J Arthroplasty 2001;16:76-82.

3. Ullmark G. Bigger size and defatting of bone chips will increase cup stability. Arch Orthop Trauma Surg. 2000;120:445-7.

4. van der Donk S, Weernik T, Buma P, Aspenberg P, Slooff TJJH, Schreurs W. Rinsing morselized allografts improves bone and tissue ingrowth. Clin Orthop Rel Res 2003;408:302-10.

5. Thoren K, Aspenberg P, Thorngren K-G. Lipid extraction decreases the specific immunologic response to bone allografts in rabbits. Acta Orthop Scand 1993;64(1):44-6.

6. Thoren K, Aspenberg P, Thorngren K-G. Lipid extracted bank bone; bone conductive and mechanical properties. Clin Orthop Rel Res 1995;311:232-46.