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Metal-on-Metal Resurfacing Arthroplasty
The Journal of Arthroplasty Vol. 20 No. 4 Suppl. 2 2005
Metal-on-Metal Resurfacing Arthroplasty No Way Under the Sun!—In the Affirmative David S. Hungerford, MD
Abstract: I have been charged in this debate format to refute the idea suggested in the title. To do this, I will address 2 questions: (1) What problem does it solve? and (2) What risk does it pose? The answers to these questions will support my conclusion that metal-on-metal resurfacing arthroplasty is the wrong operation to be making a reappearance at this time. Key words: arthroplasty, aseptic loosening, metal-on-metal resurfacing. n 2005 Elsevier Inc. All rights reserved.
linked polyethylene. All modern bearing surfaces have strong laboratory support for long-term survival, but none of them have sufficient clinical history to warrant a declaration of success. Although MoM resurfacing may indeed solve this problem, its use can only be justified if other solutions prove to fail or if it proves to be safer and/or less expensive than the alternatives.
What Problem Does it Solve? When resurfacing arthroplasty made its first appearance in the 1970s, aseptic loosening was an unsolved problem, particularly in patients younger than 40 years. Aseptic loosening frequently resulted in disastrous loss of bone stock. This is no longer a problem. Recurrent dislocation has been a significant problem in the past, but, with better techniques and more careful exposure, this too is not a problem looking for a solution. For particularly high-risk patients, larger femoral heads used with highly cross-linked polyethylene seem to be a reasonable solution. The remaining problem for which a solution is still being sought is long-term wear. For patients 20 to 30 years old, a 50-year prosthesis is necessary. It is possible that metal-on-metal (MoM) resurfacing could be the answer. However, it is no more likely to be an answer than conventional total hip arthroplasty with an MoM bearing surface—nor for that matter ceramic-on-ceramic or metal-on–highly cross-
What Risks Does it Pose? Herein lie the greatest reasons for concern about the place of MoM resurfacing in the surgical armamentarium for hip disease in the young. Certainly, given the additional cost, it could never be justified in typical arthroplasty patients presenting in their mid 60s for treatment. The surgical exposure is more difficult than for conventional arthroplasty. Reports of sciatic nerve palsy are higher in resurfacing arthroplasty than in conventional arthroplasty, almost certainly because of retention of the head and neck and the difficulties of exposure. In addition, there is another potential source of failure in fracture of the femoral neck. With current metallurgy, this never happens anymore with conventional arthroplasty. The greatest concern however is the increased body burden of metal ions with all MoM bearing surfaces and particularly MoM resurfacing. This is well documented in the literature, and concern
From the Orthopedic Surgery, Johns Hopkins University, Baltimore, Maryland. No benefits or funds were received in support of the study. Reprint requests: David S. Hungerford, MD, 5601 Loch Raven Blvd, POB G-1, Baltimore, MD 21239. n 2005 Elsevier Inc. All rights reserved. 0883-5403/05/2004-2019$30.00/0 doi:10.1016/j.arth.2005.03.023
68
Metal-on-Metal Resurfacing Arthroplasty ! David S. Hungerford
has been raised by multiple authors. Clarke et al [1] reported a 4-fold increase in chrome and cobalt in the serum with 28-mm MoM conventional arthroplasty and nearly a 10-fold increase in MoM resurfacing arthroplasty when they compared patients with control subjects. Brodner et al [2], in a 5-year follow-up of the Metasul prosthesis, documented that these abnormalities persisted for the entire length of follow-up. This finding was confirmed for MoM resurfacing for up to 52 months of follow-up by Savarino et al [3]. The main issue for these findings is whether or not they matter. There are legitimate concerns about the long-term biologic consequences of these abnormalities. Baldwin et al [4] and Faccioni et al [5] have demonstrated DNA cleavage, in vitro and in vivo, proportional to metal ion levels. MacDonald [6] summarized the concerns about MoM resurfacing in a major critique in the December 2004 issue of the Clinical Orthopedics and Related Research, citing cost, biologic, carcinogenic, and hypersensitivity concerns that should dampen enthusiasm for this procedure. Proponents argue that the volume of wear debris from an MoM prosthesis is only a minute fraction of the volume of wear from a conventional metal on high-density polyethylene arthroplasty. However, Doorn et al [7] point out that because the particle size for MoM articulations is only a fraction of the size of the highdensity polyethylene particle, the actual number of metal particles is much greater. For all these reasons, I do not believe that MoM resurfacing arthroplasty will survive as a viable concept in the armamentarium of surgery for the
69
hip. Having said this, it is not the concept itself that is at the center of the concern, but the bearing materials that are currently in use. It is possible that a new bearing material that will eliminate all these concerns will appear and that the concept will regain a new life.
References 1. Clarke MT, Lee PT, Arora A, et al. Levels of metal ions after small- and large-diameter metal-on-metal hip arthroplasty. J Bone Joint Surg Br 2003;85:913. 2. Brodner W, Bitzan P, Meisinger V, et al. Serum cobalt levels after metal-on-metal total hip arthroplasty. J Bone Joint Surg Am 2003;85-A:2168. 3. Savarino L, Granchi D, Ciapetti G, et al. Ion release in stable hip arthroplasties using metal-on-metal articulating surfaces: a comparison between short- and medium-term results. J Biomed Mater Res A 2003; 66:450. 4. Baldwin EL, Byl JA, Osheroff N. Cobalt enhances DNA cleavage mediated by human topoisomerase II alpha in vitro and in cultured cells. Biochemistry 2004; 43:728. 5. Faccioni F, Franceschetti P, Cerpelloni M, et al. In vivo study on metal release from fixed orthodontic appliances and DNA damage in oral mucosa cells. Am J Orthod Dentofacial Orthop 2003;124:687. 6. MacDonald SJ. Metal-on-metal total hip arthroplasty: the concerns. Clin Orthop 2004;86. 7. Doorn PF, Campbell PA, Worrall J, et al. Metal wear particle characterization from metal on metal total hip replacements: transmission electron microscopy study of periprosthetic tissues and isolated particles. J Biomed Mater Res 1998;42:103.
Metal-on-Metal Resurfacing Arthroplasty No Way Under the Sun!—In the Affirmative David S. Hungerford, MD
Abstract: I have been charged in this debate format to refute the idea suggested in the title. To do this, I will address 2 questions: (1) What problem does it solve? and (2) What risk does it pose? The answers to these questions will support my conclusion that metal-on-metal resurfacing arthroplasty is the wrong operation to be making a reappearance at this time. Key words: arthroplasty, aseptic loosening, metal-on-metal resurfacing. n 2005 Elsevier Inc. All rights reserved.
linked polyethylene. All modern bearing surfaces have strong laboratory support for long-term survival, but none of them have sufficient clinical history to warrant a declaration of success. Although MoM resurfacing may indeed solve this problem, its use can only be justified if other solutions prove to fail or if it proves to be safer and/or less expensive than the alternatives.
What Problem Does it Solve? When resurfacing arthroplasty made its first appearance in the 1970s, aseptic loosening was an unsolved problem, particularly in patients younger than 40 years. Aseptic loosening frequently resulted in disastrous loss of bone stock. This is no longer a problem. Recurrent dislocation has been a significant problem in the past, but, with better techniques and more careful exposure, this too is not a problem looking for a solution. For particularly high-risk patients, larger femoral heads used with highly cross-linked polyethylene seem to be a reasonable solution. The remaining problem for which a solution is still being sought is long-term wear. For patients 20 to 30 years old, a 50-year prosthesis is necessary. It is possible that metal-on-metal (MoM) resurfacing could be the answer. However, it is no more likely to be an answer than conventional total hip arthroplasty with an MoM bearing surface—nor for that matter ceramic-on-ceramic or metal-on–highly cross-
What Risks Does it Pose? Herein lie the greatest reasons for concern about the place of MoM resurfacing in the surgical armamentarium for hip disease in the young. Certainly, given the additional cost, it could never be justified in typical arthroplasty patients presenting in their mid 60s for treatment. The surgical exposure is more difficult than for conventional arthroplasty. Reports of sciatic nerve palsy are higher in resurfacing arthroplasty than in conventional arthroplasty, almost certainly because of retention of the head and neck and the difficulties of exposure. In addition, there is another potential source of failure in fracture of the femoral neck. With current metallurgy, this never happens anymore with conventional arthroplasty. The greatest concern however is the increased body burden of metal ions with all MoM bearing surfaces and particularly MoM resurfacing. This is well documented in the literature, and concern
From the Orthopedic Surgery, Johns Hopkins University, Baltimore, Maryland. No benefits or funds were received in support of the study. Reprint requests: David S. Hungerford, MD, 5601 Loch Raven Blvd, POB G-1, Baltimore, MD 21239. n 2005 Elsevier Inc. All rights reserved. 0883-5403/05/2004-2019$30.00/0 doi:10.1016/j.arth.2005.03.023
68
Metal-on-Metal Resurfacing Arthroplasty ! David S. Hungerford
has been raised by multiple authors. Clarke et al [1] reported a 4-fold increase in chrome and cobalt in the serum with 28-mm MoM conventional arthroplasty and nearly a 10-fold increase in MoM resurfacing arthroplasty when they compared patients with control subjects. Brodner et al [2], in a 5-year follow-up of the Metasul prosthesis, documented that these abnormalities persisted for the entire length of follow-up. This finding was confirmed for MoM resurfacing for up to 52 months of follow-up by Savarino et al [3]. The main issue for these findings is whether or not they matter. There are legitimate concerns about the long-term biologic consequences of these abnormalities. Baldwin et al [4] and Faccioni et al [5] have demonstrated DNA cleavage, in vitro and in vivo, proportional to metal ion levels. MacDonald [6] summarized the concerns about MoM resurfacing in a major critique in the December 2004 issue of the Clinical Orthopedics and Related Research, citing cost, biologic, carcinogenic, and hypersensitivity concerns that should dampen enthusiasm for this procedure. Proponents argue that the volume of wear debris from an MoM prosthesis is only a minute fraction of the volume of wear from a conventional metal on high-density polyethylene arthroplasty. However, Doorn et al [7] point out that because the particle size for MoM articulations is only a fraction of the size of the highdensity polyethylene particle, the actual number of metal particles is much greater. For all these reasons, I do not believe that MoM resurfacing arthroplasty will survive as a viable concept in the armamentarium of surgery for the
69
hip. Having said this, it is not the concept itself that is at the center of the concern, but the bearing materials that are currently in use. It is possible that a new bearing material that will eliminate all these concerns will appear and that the concept will regain a new life.
References 1. Clarke MT, Lee PT, Arora A, et al. Levels of metal ions after small- and large-diameter metal-on-metal hip arthroplasty. J Bone Joint Surg Br 2003;85:913. 2. Brodner W, Bitzan P, Meisinger V, et al. Serum cobalt levels after metal-on-metal total hip arthroplasty. J Bone Joint Surg Am 2003;85-A:2168. 3. Savarino L, Granchi D, Ciapetti G, et al. Ion release in stable hip arthroplasties using metal-on-metal articulating surfaces: a comparison between short- and medium-term results. J Biomed Mater Res A 2003; 66:450. 4. Baldwin EL, Byl JA, Osheroff N. Cobalt enhances DNA cleavage mediated by human topoisomerase II alpha in vitro and in cultured cells. Biochemistry 2004; 43:728. 5. Faccioni F, Franceschetti P, Cerpelloni M, et al. In vivo study on metal release from fixed orthodontic appliances and DNA damage in oral mucosa cells. Am J Orthod Dentofacial Orthop 2003;124:687. 6. MacDonald SJ. Metal-on-metal total hip arthroplasty: the concerns. Clin Orthop 2004;86. 7. Doorn PF, Campbell PA, Worrall J, et al. Metal wear particle characterization from metal on metal total hip replacements: transmission electron microscopy study of periprosthetic tissues and isolated particles. J Biomed Mater Res 1998;42:103.