Commentary & Perspective

Commentary & Perspective on
"Acetabular Reconstruction with Impaction Bone-Grafting and a Cemented Cup in Patients Younger Than Fifty Years Old"
by B. Willem Schreurs, MD, PhD, et al.

Commentary & Perspective by
Allan E. Gross, MD, FRCSC*,
Division of Orthopaedic Surgery, Mount Sinai Hospital, Toronto, Ontario, Canada

I would like to congratulate the authors of this article for developing a most useful technique for the repair of acetabular bone defects encountered often during revision arthroplasty of the hip and to a lesser degree during primary arthroplasty of the hip. The technique, which involves cementing a cup directly onto impacted morsellized allograft bone, is most effective when used for the treatment of contained defects, although the authors have also devised a wire-mesh method to convert an uncontained defect into a contained defect that can then be addressed by the impaction grafting technique. The authors have also published several articles related to relevant basic research, and they have been conscientious in studying retrieval specimens from patients who have undergone subsequent revisions after initially undergoing the impaction grafting technique. Their comprehensive program therefore encompasses excellent clinical and radiographic follow-up of patients, analysis of retrieval specimens from those patients for whom treatment has failed, and ongoing basic research, all of which have enabled the authors to study the biomechanical and biological aspects of their technique^1,2,3. This research has led to the development of technical refinements that have made the technique more effective over time. There is no question that this technique of impaction grafting on the acetabular side is an effective method for the indications cited above.

This study provided a minimum fifteen-year follow-up of patients who underwent impaction grafting on the acetabular side. This series is unique in that all patients were younger than fifty years of age, with an average age of 37.2 years. All patients were assessed clinically and radiographically. Twenty-three patients underwent this technique for primary replacement, and nineteen, for revision. Only one patient was lost to follow-up. The results were excellent considering that all of these patients had bone defects that required grafting with use of either autologous or allograft bone. The main indications for use of this method during primary arthroplasty were protrusio and congenital dislocation of the hip for which restoration of bone stock was necessary. The rate of survivorship was 92% at ten years, 83% at fifteen years, and 80% at twenty years. With revision of the cup for aseptic loosening as the end point, the rate of survivorship increased to 97% at ten years, 94% at fifteen years, and 91% at twenty years. To my knowledge, these results are comparable to or better than the results reported in any series of cemented cups; indeed, considering that these patients were all under the age of fifty years and had bone defects, the results are the best that I have read.

The authors do not compare their results to those attained with use of cementless cups in primary hip replacement. I assume that this is because they were unable to find a comparable series of primary hip replacement in patients under the age of fifty years who had bone defects. The authors have compared their results to the use of cementless cups in revision arthroplasty and have conceded that the survivorship of cementless cups is superior; however, the use of cementless cups has been associated with a high prevalence of osteolysis, which was not noted with the authors' technique.

There are some deficiencies in this paper, and these should be discussed. I would assume that this series of patients, for whom the minimum follow-up period was fifteen years, had undergone surgery while the technique was still evolving, yet the authors devoted only a small amount of space to the description of the actual technique of impaction grafting and to the manner in which they converted uncontained defects into contained defects. I realize that the technology has changed over the years, particularly with regard to the use of wire mesh, but I think it would have been helpful to add at least a few sentences about the technique used at that time, particularly with regard to the conversion of uncontained defects to contained defects.

It also would have been helpful if the authors had more extensively described the revisions of the primary replacement and the rerevisions of the revision arthroplasties. They state that in all eight of these revisions, acetabular reconstruction with bone graft was possible in combination with a standard acetabular implant. They do not state whether the same type of acetabular implant was cemented once again or whether they used a cementless implant for the revision. They state that acetabular reconstruction with bone graft was possible, but if, in fact, the authors are restoring bone stock with the original operation, why is bone grafting once again necessary? It is possible that the second operation was much less of a bone grafting procedure than the first one. Also, was revision of these hips technically difficult, or was it easier because of the impaction grafting technique? The authors also could have included more information regarding the retrieval specimens from the eight patients.

The authors have shown over the years that this technique is extremely effective. It is popular in parts of Europe, particularly in Holland, but it has not gained widespread acceptance throughout the world, particularly in North America. Most contained and combined defects can be addressed with cementless cups. Cementless cups can be used quite readily with morsellized or structural bone graft as long as the graft does not support more than 50% of the cup⁴. The technique is technically much easier to perform than the technique described in this paper, and the use of cementless components has some definite advantages. A cementless cup is much more forgiving than a cemented one should the surgeon, for whatever reason, decide to change the position of the cup. Cementless cups also provide a very wide range of options to increase stability. The use of trabecular metal will increase this range substantially. The authors have a major concern with osteolysis and cementless cups, and this is justified; however, the use of new bearing surfaces and better locking mechanisms will decrease the incidence of osteolysis in the future. I think that these are some of the reasons why impaction grafting, which embraces a cement philosophy, is not as accepted as the use of cementless cups throughout the world.

The developers of impaction grafting have reported excellent long-term results, and they have established a technique that has evolved as a result of careful clinical and radiographic scrutiny and ongoing basic research.

*The author did not receive grants or outside funding in support of his research or preparation of this manuscript. He did not receive payments or other benefits or a commitment or agreement to provide such benefits from a commercial entity. No commercial entity paid or directed, or agreed to pay or direct, any benefits to any research fund, foundation, educational institution, or other charitable or nonprofit organization with which the author is affiliated or associated.

References

1. Schreurs BW, van Tienen TG, Buma P, Verdonschot N, Gardeniers JW, Slooff TJ. Favorable results of acetabular reconstruction with impacted morsellized bone grafts in patients younger than 50 years: a 10- to 18-year follow-up study of 34 cemented total hip arthroplasties. Acta Orthop Scand. 2001;72:120-6.
2. Schreurs BW, Slooff TJ, Gardeniers JW, Buma P. Acetabular reconstruction with bone impaction grafting and a cemented cup: 20 years' experience. Clin Orthop. 2001;393:202-15.
3. Bolder SB, Schreurs BW, Verdonschot N, van Unen JM, Gardeniers JW, Slooff TJ. Particle size of bone graft and method of impaction affect initial stability of cemented cups: human cadaveric and synthetic pelvic specimen studies. Acta Orthop Scand. 2003;74:652-7.
4. Garcia-Cimbrelo E. Porous-coated cementless acetabular cups in revision surgery: a 6- to 11-year follow-up study. J Arthroplasty. 1999;14:397-406.

Copyright © 2004 by the The Journal of Bone and Joint Surgery, Inc.