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CLINICAL RESEARCH

CORR Insights®: What Are the Long-term Results of Cemented Revision THA with Use of Both Acetabular and Femoral Impaction Bone Grafting in Patients Younger Than 55 Years?

Kelley, Scott S. MD

Author Information
Clinical Orthopaedics and Related Research: January 2021 - Volume 479 - Issue 1 - p 92-94
doi: 10.1097/CORR.0000000000001528

Where Are We Now?

Verspeek et al. [6] reported the long-term follow-up of a previous study [5] on cemented revision THA with the use of acetabular and femoral impaction bone grafting in patients younger than 55 years of age. They acknowledged that this technique is technically demanding and that newer techniques and implant designs “may prove to be sufficient in most cases” [6]. However, they make a case that impaction grafting may still play a role in patients in whom it is imperative to regain bone stock, rather than bypass deficiencies.

The impaction technique was valuable in the 1990s, particularly because of the massive osteolysis that occurred in the precrosslinked polyethylene era. As the authors [6] noted, impaction grafting is a difficult procedure. A surgeon must be proficient at not only impaction grafting itself, but also cemented fixation. Many surgeons (especially in the United States) are no longer facile with cemented fixation; almost none are sufficiently skillful at impaction grafting to perform it well.

Apart from the technical difficulty, there are several reasons that impaction grafting is seldom used outside of a few centers that have a passion for it. First, crosslinked polyethylene has reduced the frequency of severe osteolysis, which once made impaction grafting appealing for bone-stock restoration. Additionally, when lysis is present, improved implants with more-reliable ingrowth surfaces allow surgeons to bypass areas of bone loss with greater confidence and reliability.

Revision arthroplasty techniques have often attempted to solve femoral and acetabular problems differently, for good reasons. Anatomically, the femur is a hollow column that can be reconstructed, replaced, or bypassed. The acetabulum is more like the hub of a wheel, for which it is not enough to restore a few spokes; instead, fixation needs to be circumferential, to connect the ilium, ischium, and pubic ramus. These techniques differ in other ways as well. The acetabulum and pelvis have better vascularity and better bone healing. In the nonarthroplasty setting, pelvic fractures are less prone to nonunions than proximal femoral fractures are. Cement is more difficult to use when the bone is bleeding and has performed better in the femur than in the acetabulum, hence the concept of hybrid hip replacement.

Because of these differences, currently, bone grafting is more commonly used with acetabular revisions than with femoral revisions. But I hasten to add that most acetabular revisions can be done well without a bone graft of any sort; for example, jumbo cups with complex ingrowth surfaces and cup cage techniques can regain bone stock, with results comparable to those of impaction grafting [2].

One concern with cemented impaction grafting is the degradation of grafts over time. In the study in this month’s Clinical Orthopaedics and Related Research®, the 10-year survivorship of 87% declined to 73% at 15 years [6]. This study demonstrates that osseointegration can be achieved with cemented impaction grafting in the long-term in 90% of patients. However, the total revision rate for all causes was 27% at 15 years. The loss of fixation over time, which is seen with many different bone grafting techniques, has contributed to the development of implants that achieve fixation and attachment to healthy host bone.

Broadly speaking, surgeons have two revision philosophies to choose from: cementless implants that achieve fixation in healthy host bone and bypass the bone deficiency or reconstituting bone using impaction allografting. Those who favor the former are counting on the idea that fixation to healthy bone will not loosen later. Those who favor the latter generally do so because they place a greater priority on regaining bone stock. Because the latter approach may be especially appealing in younger patients, the current study [6] is important because it demonstrates this approach to be generally durable.

Where Do We Need To Go?

We need to answer three questions raised by this paper [6]. Does the long-term fixation achieved with modern revision implant systems outperform those in this report on cemented impaction grafting? We need to critically compare newer techniques with one another using long-term follow-up periods in younger patients, with the success reported in this study.

Verspeek et al. [6] concluded that the “…impaction bone grafting technique…can facilitate an eventual future revision.” Only with comparable datasets will we be able to answer the following question: should we plan for failures using revision techniques that increase bone stock, or should we design implants that are resistant to loosening, such that increasing bone stock is not as necessary?

Lastly, is it possible to achieve both goals of continuing to improve fixation to host bone while restoring bone deficiency, which is achieved by impaction grafting? This has been the holy grail in hip revision surgery for many years. Successful restoration depends on revascularization of dead bone (or a bone substitute) without substantial resorption, while simultaneously achieving durable implant fixation. Impaction grafting techniques depend on cement interdigitating with a bone graft in such a way that it creates a 2-mm to 4-mm icing of bone around the cement mantle, resulting in an implant-cement-bone graft construct. Bone can remodel around and incorporate into this construct, unlike a bone graft with an ingrowth implant.

How Do We Get There?

The only way to know whether long-term fixation with modular revision implant systems outperforms impaction grafting would be to obtain comparable follow-up data on revision arthroplasties in younger patients. If newer generations of implants can be proven to perform better than any previous techniques in the long-term, then further modifications to what is working have increased potential. Because most institutions use a variety of techniques with different indications, making it difficult to obtain comparable groups, we may need to look elsewhere. Large national registries should be able to help us weigh in on this, although it may be challenging to ensure that the complexity of the revisions is comparable in different groups.

The question of whether to try to restore bone stock or focus on achieving durable fixation in the remaining bone is unanswered, and registries may also help us here. But the reality is that most current innovations are moving toward techniques that rely more on implant design to substitute for bone loss. These design elements include modular femoral stems, trabecular metal augments, jumbo cups with complex ingrowth (scratch-fit) surfaces, and custom-designed triflange cups. I hasten to add that our innovations may not prove equally successful on the acetabular and femoral sides, and so all major changes in implant-design philosophies must be introduced carefully [2, 4]. Custom-designed triflange cups may take cup revisions in a new direction with the use of a custom implant substitute for bone loss [1, 3]. Earlier triflange implants were not designed as precisely as the new ones; although the short-term data seem favorable in terms of the latest generation of these devices, it is too early to be confident about these devices.

Although ideally an implant would both restore missing bone and achieve biologic fixation, it is impossible to get dead bone to grow into porous surfaces. Impaction grafting proves that a surface can be created that allows an allograft to remodel and integrate into an implant construct. This suggests the possibility of ingrowth implant surfaces that are as bioactive as the bone film created by impaction grafting. But long-term follow-up has helped us to see that many well-intentioned approaches fall far short. As we gain longer experience with innovative cementless revision devices (such as triflange cups) we’ll need to compare them with impaction grafting. If these also fall short, then regaining bone stock should become our priority. Of course, the question of whether the bone stock restored by impaction allografting is sufficiently supportive to be useful in repeat revisions remains largely unanswered, and I hope that research groups interested in these techniques will focus on this question next.

References

1. Berasi CC 4th, Berend KR, Adams JB, Ruh EL, Lombardi AV Jr. Are custom triflange acetabular components effective for reconstruction of catastrophic bone loss? Clin Orthop Relat Res. 2015;473:528-535.
2. Konan S, Garbuz DS, Masri BA, Duncan CP. Modular tapered titanium stems in revision arthroplasty of the hip: the risk and causes of stem fracture. Bone Joint J. 2016;98:50-53.
3. Löchel J, Janz V, Hipfl C, Perka C, Wassilew GI. Reconstruction of acetabular defects with porous tantalum shells and augments in revision total hip arthroplasty at ten-year follow-up. Bone Joint J. 2019;101:311-316.
4. Ortega PC, Medeiros WB, More DO, Vasconcelos RF, da Rosa E, Roesler CRM. Failure analysis of a modular revision total HIP arthroplasty femoral stem fractured in vivo. Author links open overlay panel. Engineering Failure Analysis. 2020;114:104591.
5. te Stroet MAJ, Rijnen WHC, Gardeniers JWM, van Kampen A, Schreurs BW. Satisfying outcomes scores and survivorship achieved with impaction grafting for revision THA in young patients. Clin Orthop Relat Res. 2015;473:3867–3875.
6. Verspeek J, Nijenhuis TA, Kuijpers MFL, Rijnen WHC, Schreurs BW. What are the long-term results of cemented revision THA with use of both acetabular and femoral impaction bone grafting in patients younger than 55 years? Clin Orthop Relat Res. 2021;479:84-91.
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