European nations, especially Scandinavian countries, have used cemented fixation since the introduction of total hip arthroplasty. In Sweden, with arguably the best national-level data on prostheses survivorship, >90% of all stems are fixated with cement. In sharp contrast, it is estimated that in the United States, >88% of all femoral stems use cementless technology. This represents a diametrically opposed difference in philosophical approach: the so-called North Atlantic Divide. The departure in North America from cemented femoral stems can be traced to the coinage of the phrase cement disease, which implicated cement as a leading cause of osteolysis. This led to prolific innovation of uncemented technologies in North America, while European countries favored standardization enabled by the national arthroplasty registries. The term cement disease has been proven to be a misnomer, as supported by excellent outcomes from the Scandinavian registries, as well as excellent long-term outcomes for cemented stems in United States series, even in patients younger than 50 years. Like uncemented stems, there is variability in survivorship between femoral stems, and this appears to be related to specific design features. Despite the excellent long-term results, the use of cemented femoral components in Europe and Canada is decreasing in favor of uncemented stems. The reasons for this are not immediately obvious.
The method of femoral component fixation in total hip arthroplasty (THA) differs significantly between North America and Europe. National-level data from the United States, Canada, Denmark, the United Kingdom, Norway, and Sweden from 2006 demonstrates a low rate of cemented femoral fixation of approximately 10% in the United States and a high rate of approximately 90% in Sweden.1-6 Canadas cemented rate is closer to that of the United States, while the other European countries are closer to Swedens (Figure 1).1-6 The minority of stems are cemented in North America, while the majority are cemented in Europe. As such, a conceptual division can be drawn between North America and Europe regarding cemented femoral fixation: the so-called North Atlantic Divide. The reasons for the divide between North America and Europe are not immediately obvious but are worthy of further reflection.
Figure 1: Area graph representing the percentage of cemented femoral fixation by country in 2006 (red area=cementless fixation, blue=cemented fixation). The vertical line represents the geographical division between North America and Europe. In North America, <50% of femoral stems were fixated with cement in 2006, while in Europe >50% of femoral stems were fixated with cement, as represented by the horizontal line.
Total hip arthroplasty was initially indicated for use with bone cement on the femoral side. As such, both North America and European surgeons started down the same path of cemented femoral fixation. Excellent long-term results using cemented stems have been reported in the United States. Callaghan et al7 reported 90% survivorship at 25 years using the cemented Charnley stem (DePuy, Warsaw, Indiana), while Sanchez-Sotelo et al8 reported 96% survivorship at 15 years using the cemented Harris Design-2 stem (Stryker, Mahwah, New Jersey). Despite these excellent results, it appears there was a divergence in opinion between North America and Europe in 1987 with a landmark paper by Jones and Hungerford9 that coined the phrase cement disease. The authors state,
because of the inherent biologic and biomechanical properties of methylmethacrylate, it is unlikely that it can be rendered satisfactory in the long run for the young, the active, or the overweight patient, for whom alternatives are currently being sought.9 The authors also state that
the elimination of cement disease can only occur with the elimination of cement.9 North American surgeons appear to have generally moved away from cemented stems and begun a continuing innovation process of the femoral component, including morphology and surface coatings.
In contrast, European surgeons continued on a pathway of standardization. This was particularly true in Sweden, where peer feedback via the Swedish Hip Arthroplasty Registry illustrated patterns of successful outcomes associated with the usage of given components and fixation methods. As such, the majority of all femoral stems implanted in Sweden in 2006 were limited to 2 varieties: Lubinus SP2 (Waldemar Link GmbH, Hamburg, Germany) and Exeter (Stryker).4 The revision burden for THA in Sweden is arguably the lowest in the world at approximately 8%, and cumulative revision rates in Sweden have been decreasing every successive 5 years (Figure 2).4 The contrast between the numbers of types of femoral stems used in Sweden vs the United States is striking. It is difficult to ascertain exact data on the revision burden in the United States because of the lack of a national arthroplasty registry; however, it is generally agreed that it is higher than that of Sweden.
Figure 2: Decreasing cumulative revision rates over time in Sweden. Reprinted with permission from Kärrholm J, Garellick G, Herberts P. Swedish Hip Arthroplasty Register Annual Report 2006. Gothenburg, Sweden: Sahlgrenska University Hospital; 2007. Copyright © 2006, Swedish Hip Arthroplasty Register.
National registry data from Sweden, Norway, Denmark, and the United Kingdom demonstrate a clinically and statistically significant improvement in survivorship with cemented femoral components over uncemented in all patients.2-4,6 One common argument for continued innovation and use of uncemented stems is that cemented stems do not perform well in the young or active patient, as suggested by Jones and Hungerford9 in 1987. It is difficult to find evidence to support this notion, and substantial evidence exists to refute it. For example, results from Exeter stems show outstanding survivorship at 10- to 17-year follow-up of 99% in patients younger than 50 years.10 Furthermore, the national registry data from Sweden, Norway, Denmark, and the United Kingdom demonstrate improved survivorship for cemented stems over uncemented stems in young patients when the data is stratified by age.2-4,6 This is a consistent and statistically significant finding in all of these registries. The data are complete and comprehensive enough with the Swedish Hip Registry that risk ratios have been produced for surgical variables when performing THA in patients younger than 50 years.4 Implanting uncemented components in Sweden in a patient younger than 50 years increases the risk of revision with a risk ratio of 1.24, while using all cemented components reduced the risk of revision with a risk ratio of 0.68.4
The concept of cement disease appears to be entwined in the concept of the North Atlantic Divide. As the notion of cement disease has basically been refuted, the pathway of innovation in North America should be reconsidered. For example, now that cement has largely been removed from the equation in North America and aseptic loosening associated with osteolysis persists as the major mode of failure in THA, a new round of innovation is well underway in North America regarding the bearing surface. Is this justifiable given the past precedence of innovation based partly on a misnomer? Recall that the Swedish Hip Registry has arguably the best outcomes in terms of survivorship for THA yet has essentially no data on alternative bearings. The data reported in the registry is limited to metalonultrahigh molecular weight polyethylene. This is reflective of the intentional standardization of techniques and implants in the Swedish system, as opposed to innovation. This concept can be appreciated by comments in the Swedish Hip Arthroplasty Register Annual Report 2006: We should await long-term results concerning
highly cross linked polyethylene, before drawing firm conclusions from the promising short-term results.4
Figure 3: Increasing incidence of the use of uncemented femoral components in Canada, Denmark, Norway, the United Kingdom, and Sweden between 2003 and 2006.
The North Atlantic Divide seems to at least be partly associated with a philosophical difference in the approach to introducing new surgical technology and can be thought of as innovation vs standardization. Interestingly, despite the supportive evidence of the superior performance of cemented femoral stems even in young patients, the use of cemented femoral stems is decreasing in Europe and Canada (Figure 3).1-4,6 The reasons for this are not clear. One possible reason is that there is little research to be funded or papers to be written on well-accepted, highly studied cemented stems such as the Exeter. As physicians, we should reflect on these patterns and ensure ourselves that the innovation pathways on which we embarking are rational and evidence based, as opposed to innovation for the sake of innovation.
- Canadian Institute for Health Information. Canadian Joint Replacement Registry (CJRR) 2007 Annual ReportHip and Knee Replacements in Canada. Ottawa, Canada: Canadian Institute for Health Information; 2008.
- National Joint Registry Centre. National Joint Registry for England and Wales 4th Annual Report. Hemel Hempstead, United Kingdom: NJR Centre; 2007.
- Furnes O, Havelin L, Espehaug B, Steindal K, Sørås T. The Norwegian Arthroplasty Register Report 2007. Bergen, Norway: Haukeland University Hospital; 2007.
- Kärrholm J, Garellick G, Herberts P. Swedish Hip Arthroplasty Register Annual Report 2006. Gothenburg, Sweden: Sahlgrenska University Hospital; 2007.
- Ong KL, Kurtz SM, Lau E, Bozic KJ, Berry DJ, Parvizi J. Prosthetic joint infection risk after total hip arthroplasty in the Medicare population. J Arthroplasty. In press.
- Overgaard S, Pedersen A. Danish Hip Arthroplasty Register Annual Report 2007. Aarhus, Denmark: Aarhus University Hospital; 2007.
- Callaghan JJ, Albright JC, Goetz DD, Olejniczak JP, Johnston RC. Charnley total hip arthroplasty with cement. Minimum twenty-five-year follow-up. J Bone Joint Surg Am. 2000; 82(4):487-497.
- Sanchez-Sotelo J, Berry DJ, Harmsen S. Long-term results of use of a collared matte-finished femoral component fixed with second-generation cementing techniques. A fifteen-year-median follow-up study. J Bone Joint Surg Am. 2002; 84(9):1636-1641.
- Jones LC, Hungerford DS. Cement disease. Clin Orthop Relat Res. 1987; (225):192-206.
- Lewthwaite SC, Squires B, Gie GA, Timperley AJ, Ling RS. The Exeter Universal hip in patients 50 years or younger at 10-17 years followup. Clin Orthop Relat Res. 2008; 466(2):324-331.
Dr Dunbar is from Dalhousie University, Halifax, Nova Scotia, Canada.
Dr Dunbar is a consultant for Stryker Orthopaedics and has received institution research support from DePuy, Wright Medical Technology, Smith & Nephew, and Zimmer.
Presented at Current Concepts in Joint Replacement 2008 Winter Meeting; December 10-13, 2008; Orlando, Florida.
Correspondence should be addressed to: Michael J. Dunbar MD, FRCSC, PhD, Dalhousie University, 1796 Summer St, Ste 4822, Halifax, Nova Scotia, B3H 3A7 Canada.