Hip resurfacing: The metal-on-metal bearing material is not the problem by Dr. AmstutzThe success of total hip replacement (THR) in the 20th century has been tremendous with improvements in the durability of new designs, bearing materials and fixation techniques. However, the young and active patients have historically had high revision rates compared with older, more sedentary patients, notably when the etiology of the disease is osteonecrosis. Despite great improvements in cementless stem fixation, hip resurfacing arthroplasty (HRA) has the advantages of replicating leg length and offset, and maintaining proximal bone unlike THR. Moreover, dislocation in THR remains a problem when small femoral heads are used. Resurfacing patients also do not report thigh pain as it sometimes happens after THR.When it comes time for revision surgery, as should be expected for most young and active patients, whether treated with a resurfacing or a primary THR, the preserved bone stock with hip resurfacing provides more favorable conditions for a successful surgery and the technical difficulty of the conversion is comparable to that of a primary THR. This enables patients seeking to restore their previous lifestyle to be more active than with a THR, and numerous authors have reported high levels of physical activity in patients after hip resurfacing.Preserving bone and replacing only the affected articular surfaces has always been and remains a worthy treatment goal, but the first generation of hip resurfacing suffered from the use of ultra-high molecular weight polyethylene sterilized in air, a material unsuitable for a large bearing size in young and active patients. Unfortunately, and because of the poor results of the materials used during that era, many become detractors of the concept of resurfacing.The current generation of resurfacing devices uses a metal-on-metal (MoM) bearing because the volumetric wear is low, even with large diameter components, and the material permits manufacturing of thin one-piece acetabular components with porous ingrowth for cementless fixation.Recent long-term data show that certain currently available hip resurfacing devices can reach up to 99.7% survivorship at 10 years in patients with good bone quality and implanted with large component sizes. The importance of patient selection for hip resurfacing and the key role of component size have been highlighted by the reports of several large centers and the findings of hip registries. However, improvements in surgical technique have considerably reduced the rate of aseptic femoral failures (femoral neck fractures and femoral component loosening) associated with the learning curve of the surgeons who pioneered the procedure, even with patients who have risk factors.In the past 3 years, the report of numerous adverse local tissue reactions (ALTR) has raised doubts in the orthopedic community over the benefits of MoM implants used for HRA and even more so for THR, probably because of the corrosion products generated at the ball-stem tapered interface. Often misunderstood, the hypersensitivity or allergic reactions to metal are a very rare occurrence. In nearly every case, ALTR are associated with increased wear from poorly positioned or poorly designed components or both. The recall of a particular MoM resurfacing device resulted in intense medico-legal solicitations accompanied by grossly unbalanced reporting in a media blitz and has brought intense scrutiny to all MoM devices. Anxiety has grown among patients and surgeons despite the fact that the vast most of MoM devices are functioning well with up to 20 years of follow-up. This was only aggravated by two reports of extremely rare cases of cobaltism in association with very high wear of a metal-on-metal bearing. Naysayers abound, but few have researched the literature where the answers to the problem can be found (i.e., proper acetabular component design and orientation).The acetabular components with the largest femoral head coverage have been associated with low production of metal ions and a virtual absence of ALTR. The hypothesis tested in several centers is that a reduced coverage of the head coming from a combination of increased abduction and/or anteversion leads to more instances of edge loading, and in the case of the recalled device, a possible double edge loading, increasing the volumetric wear of the device.The current focus of most debates about MoM bearings has so far been the wear properties of the material. I believe that the problems ALTR associated with MoM devices, unlike the first generation of resurfacing with polyethylene bearings, are not a bearing material issue per se, but one of device design and technique and can be prevented by proper component socket design and optimized socket orientation in both the coronal and sagittal planes.Because the need for proper socket orientation is so crucial, emphasis must be placed on using systems in which the instrumentation provides the surgeon with the tools to precisely implant the socket. Since all currently available designs have a reduced coverage in the smaller sizes, safe zones for socket orientation should be determined for all systems using an accurate measurement method for both cup abduction and anteversion (e.g. Einzel-Bild-Rontgen-Analyse; Innsbruck, Austria) in a large series with long-term results. After analysis of our 1350 Conserve Plus Hips (Wright Medical Technology), a safe zone was produced for all sizes suggesting 42° ± 10° of abduction angle and a 15· ± 10· of anteversion angle, which I believe represents a target well within reach for an experienced surgeon.Although the study of navigation systems applied to hip resurfacing has so far essentially focused on the placement of the femoral component, a case could certainly be made for the use of navigation systems, which have shown efficacy in positioning accurately the acetabular component in THA, especially for inexperienced surgeons. Just as in THR, exposure of the acetabular cavity is essential for an accurate placement of the cup and, despite short-term reports of hip resurfacing performed with small incisions, the minimally invasive surgery technique can hardly be recommended for this procedure.Unfortunately, the critical importance of these factors has not been well-understood until recently, the common belief being that a large diameter head solves the problem of dislocation in THR just as it does with HRA, while component orientation was less important because of the increased jump distance.Every bearing material used in joint replacement has had its specific downsides, and this remains true today despite all the technological advances. For example, the necessity of proper acetabular component orientation for ceramic-on-ceramic bearings to prevent dislocation, chipping, runaway wear and squeaking was identified after clinical experience and resolved after in vitro testing. Similar to the ceramic-on-ceramic bearing wear, the MoM wear issues of design and component orientation became apparent after clinical experience, and there is tangible evidence that the problem is solvable. Clearly, this is highly desirable since MoM is the only proven and highly successful material for resurfacing at the present time permitting high levels of activity. The well-oriented and fixed components continue to perform at up to 15 years, with no increase in blood-ion concentration.The porous fixation of the one-piece acetabular components used in the current designs of hip resurfacing is usually a cobalt chromium aggregate of beads with or without hydroxy apatite coating although several hip resurfacing systems now have titanium plasma spray porous sockets. This type of fixation, although reliable, may not match the performance of recently developed porous tantalum or titanium material mimicking trabecular bone. This new technology has already been adapted to hip resurfacing, although its availability is currently limited.While most surgeons understand the increased difficulty of performing resurfacing compared with THR, there has been insufficient education for surgeons to gain supervised experience. Fellowships and resident training programs to learn the hip resurfacing techniques hopefully can produce more experienced surgeons ready to use with competence the full spectrum of reconstructive devices available today and in the future.Improving the socket designs of existing devices to provide larger femoral head coverage by the socket will give the surgeon more flexibility of implantation and lessen the likelihood of abnormal wear. Modifications to socket designs are already in progress to address the weaknesses identified with certain devices. The manufacturing quality of MoM bearings is excellent nowadays in most designs, particularly the control of clearance and roundness of the components, and is certainly sufficient to produce safe and successful hip arthroplasty devices as long as conservative guidelines for cup implantation are followed. However, there will undoubtedly be further improvements and reduction in the wear properties of MoM bearings in the near future.MoM hip resurfacing is not a new technology any more, and the devices that have been approved by the FDA after sufficient clinical trials have been available for more than a decade. It is important to avoid making statements about a procedure based on the poor results of subsequent designs which were still in their experimental (non-FDA approved) phase.Many have written off MoM HRA, and this is unfortunate because superb results have been achieved with several devices in several centers for the young and active patient. The MoM bearing, unlike polyethylene of first generation devices, is not the problem. It is a treatment option for arthritis that is worth pursuing and improving. It just makes sense to save the head and neck, and adhere to a fundamental tenet of orthopedics espoused by our forebears — save bone.It is my fervent desire to improve surgeon and patient education and emphasize that there are techniques to solve the problems associated with MoM hip resurfacing. Charles Kettering said, “The world hates change, yet it is the only thing that has brought progress.”
— Harlan C. Amstutz MD Los Angeles Disclosure: Amstutz has received research support from St. Vincent’s Medical Center, and research and royalities from Wright Medical Technology.
Amstutz HC, Dorey F, O’Carroll PF. THARIES resurfacing arthroplasty. Evolution and long-term results. Clin Orthop. 1986;213:92-114.
Amstutz H, Le Duff M, Campbell P, et al. Clinical and radiographic results of metal-on-metal hip resurfacing with a minimum ten-year follow-up. J Bone and Joint Surg Am. 2010;92(16):2663-2671.
Amstutz H, Le Duff M, Campbell P, Dorey F. The effects of technique changes on aseptic loosening of the femoral component in hip resurfacing. Results of 600 Conserve Plus with a 3-9 year follow-up. J Arthroplasty. 2007;22(4):481-489.
Amstutz HC, Takamura K, Le Duff M. The effect of patient selection and surgical technique on the results of Conserve Plus hip resurfacing-3.5- to 14-year follow-up. Orthop Clin North Am. 2011; 42(2): 133-142.
Amstutz H, Wisk L, Le Duff M. Sex as a patient selection criterion for metal-on-metal hip resurfacing arthroplasty. J Arthrop. 2011;26(2):198-208.
Anissian HL, Stark A, Gustafson A, et al. Metal-on-metal bearing in hip prosthesis generates 100-fold less wear debris than metal-on-polyethylene. Acta Orthop Scand. 1999;70(6):578-582.
Archibeck M, Berger R, Jacobs J, et al. Second-generation cementless total hip arthroplasty. Eight to eleven-year results. J Bone Joint Surg Am. 2001;83(11):1666-1673.
Bader R, Steinhauser E, Zimmermann S, et al. Differences between the wear couples metal-on-polyethylene and ceramic-on-ceramic in the stability against dislocation of total hip replacement. J Mater Sci Mater Med. 2004;15(6):711-718.
Baad-Hansen T, Kold S, Nielsen P, et al. Comparison of trabecular metal cups and titanium fiber-mesh cups in primary hip arthroplasty: a randomized RSA and bone mineral densitometry study of 50 hips. Acta Orthop. 2011;82(2):155-160.
Bailey C, Gul R, Falworth M, et al. Component alignment in hip resurfacing using computer navigation. Clin Orthop Relat Res. 2009;467(4):917-922.
Ball S, Le Duff M, Amstutz H. Early results of conversion of a failed femoral component in hip resurfacing arthroplasty. J Bone Joint Surg Am. 2007;89:735-741.
Banerjee M, Bouillon B, Banerjee C, et al. Sports activity after total hip resurfacing. Am J Sports Med. 2010;38(6):1229-1236.
Barrett A, Davies B, Gomes M, et al. Computer-assisted hip resurfacing surgery using the acrobot navigation system. Proc Inst Mech Eng H. 2007;221(7):773-785.
Beaulé P, Dorey F. Survivorship analysis of cementless total hip arthroplasty in younger patients. J Bone Joint Surg Am. 2001;83(10):1590-1591.
Berry D, von Knoch M, Schleck C, Harmsen W. Effect of femoral head diameter and operative approach on risk of dislocation after primary total hip arthroplasty. J Bone Joint Surg Am. 2005;87(11):2456-2463.
Bowsher J, Nevelos J, Williams P, Shelton J. ‘Severe’ wear challenge to ‘as-cast’ and ‘double heat-treated’ large-diameter metal-on-metal hip bearings. Proc Inst Mech Eng H. 2006;220(2):135-143.
Callaghan JJ, Forest EE, Sporer SM, et al. Total hip arthroplasty in the young adult. Clin Orthop. 1997;344:257-262.
Callaghan JJ, Heithoff BE, Goetz DD, et al. Prevention of dislocation after hip arthroplasty: lessons from long-term followup. Clin Orthop. 2001;393:157-162.
Capello W, D’Antonio J, Feinberg J, Manley M. Ten-year results with hydroxyapatite-coated total hip femoral components in patients less than fifty years old. A concise follow-up of a previous report. J Bone Joint Surg Am. 2003;85(5):885-889.
Chandler HP, Reineck FT, Wixson RL, McCarthy JC. Total hip replacement in patients younger than thirty years old. J Bone Joint SurgAm. 1981;63(9):1426-1434.
Chevillotte C, Trousdale R, Chen Q, et al. The 2009 Frank Stinchfield Award: “Hip squeaking”: a biomechanical study of ceramic-on-ceramic bearing surfaces. Clin Orthop Rel Res. 2010;468(2):345-350.
Cordingley R, Kohan L, Ben-Nissan B. What happens to femoral neck bone mineral density after hip resurfacing surgery? J Bone Joint Surg Br. 2010;92(12):1648-1653.
D’Antonio JA, Capello WN, Manley MT, Feinberg J. Hydroxyapatite coated implants. Total hip arthroplasty in the young patient and patients with avascular necrosis. Clin Orthop. 1997;344:124-138.
De Haan R, Campbell P, Su E, De Smet K. Revision of metal-on-metal resurfacing arthroplasty of the hip: the influence of malpositioning of the components. J Bone Joint Surg Br. 2008;90(9):1158-1163.
De Haan R, Pattyn C, Gill H, et al. Correlation between inclination of the acetabular component and metal ion levels in metal-on-metal hip resurfacing replacement. J Bone Joint Surg Br. 2008;90(10):1291-1297.
De Smet K, Van Der Straeten C, Van Orsouw M, et al. Revisions of metal-on-metal hip resurfacing: lessons learned and improved outcome. Orthop Clin North Am. 2011;42(2):259-269.
Dorr DL, Kane III JT, Conaty P. Long-term results of cemented total hip arthroplasty in patients 45 years old or younger. J Arthroplasty. 1994;9(5):453-456.
Dorr LD, Wan Z, Longjohn DB, et al. Total hip arthroplasty with use of the Metasul metal-on-metal articulation. Four to seven-year results. J Bone Joint Surg Am. 2000;82(6):789-798.
Dowdy PA, Rorabeck CH, Bourne RB. Uncemented total hip arthroplasty in patients 50 years of age or younger. J Arthroplasty. 1997;12(8):853-862.
Duffy GP, Berry DJ, Rowland C, Cabanela ME. Primary uncemented total hip arthroplasty in patients <40 years old: 10- to 14-year results using first-generation proximally porous-coated implants. J Arthroplasty. 2001;16(8) Suppl 1:140-144.
Engh CJ, Culpepper Wn, Engh C. Long-term results of use of the anatomic medullary locking prosthesis in total hip arthroplasty. J Bone Joint Surg Am. 1997;79(2):177-1784.
Engh CA, Hooten JP Jr., Zettl-Schaffer KF, et al. Porous-coated total hip replacement. Clin Orthop. 1994;298:89-96.
Eswaramoorthy V, Biant L, Field R. Clinical and radiological outcome of stemmed hip replacement after revision from metal-on-metal resurfacing. J Bone Joint Surg Br. 2009;91(11):1454-1458.
Eswaramoorthy V, Moonot P, Kalairajah Y, et al. The Metasul metal-on-metal articulation in primary total hip replacement: clinical and radiological results at ten years. J Bone and Joint Surg Br. 2008;90(10):1278-1283.
Fisher N, Killampalli V, Kundra R, e al. Sporting and physical activity following hip resurfacing. Int Orthop. 2010;May 30. [Epub ahead of print].
Ganapathi M, Vendittoli P, Lavigne M, Günther K. Femoral component positioning in hip resurfacing with and without navigation. Clin Orthop Relat Res. 2008; Epub ahead of print.
Garbuz D, Williams D, Greidanus N, et al. Serum metal ion and ultrasound assessment of asymptomatic metal-on-metal hip replacement. Annual Meetingof the American Academy of Orthopaedic Surgeons. San Diego, CA, 2011.
Garrett S, Bolland B, Yates P, et al. femoral revision in hip resurfacing compared with large-bearing metal-on-metal hip arthroplasty. J Arthroplasty. 2011;2011 Mar 15. [Epub ahead of print].
Georgiades G, Babis G, Hartofilakidis G. Charnley low-friction arthroplasty in young patients with osteoarthritis: outcomes at a minimum of twenty-two years. J Bone Joint Surg Am. 2010;91(12):2846-2851.
Graves S. Annual Report. Australian Orthopaedic Association – National joint replacement registry. Adelaide, 2009.
Hannouche D, Zaoui A, Zadegan F, et al. Thirty years of experience with alumina-on-alumina bearings in total hip arthroplasty. Int Orthop. 2011;35(2):207-213.
Heithoff BE, Callaghan JJ, Goetz DD, et al. Dislocation after total hip arthroplasty: a single surgeon’s experience. Orthop Clin North Am. 2001;32(4):587-591, viii.
Herman K, Highcock A, Moorehead, J, Scott S. A comparison of Leg Length and Femoral Offset discrepancies in Hip Resurfacing, Large Head Metal-on-Metal and Conventional Total Hip Replacement: a case series. J Orthop Surg Res. 2011; 6(1): 65.
Hohmann E, Bryant A, Tetsworth K. A comparison between imageless navigated and manual freehand technique acetabular cup placement in total hip arthroplasty. J Arthroplasty. 2011; Jan 20. [Epub ahead of print].
Howie DW, Campbell D, McGee M, Cornish BL. Wagner resurfacing hip arthroplasty. The results of one hundred consecutive arthroplasties after eight to ten years. J Bone Joint Surg Am. 1990;72(5):708-714.
Jameson S, Langton D, Nargol A. Articular surface replacement of the hip: a prospective single-surgeon series. J Bone Joint Surg Br. 2010;92(1):28-37.
Joshi AB, Porter ML, Trail IA, Hunt LP, et al. Long-term results of Charnley low-friction arthroplasty in young patients. J Bone Joint Surg Br. 1993;75(4):616-623.
Kim S, Kyung H, Ihn J, et al. Cementless metasul metal-on-metal total hip arthroplasty in patients less than fifty years old. J Bone Joint Surg Am. 2004;86:2475-2481.
Kishida Y, Sugano N, NishiiT, et al. Preservation of the bone mineral density of the femur after surface replacement of the hip. J Bone Joint Surg Br. 2004;86(3):185-189.
Kumar M, Shetty M, Kiran K, Kini A. Validation of navigation assisted cup placement in total hip arthroplasty. Int Orthop. 2011;May 3. [Epub ahead of print].
Langton D, Jameson S, Joyce T, et al. A review of 585 serum metal ion results post hip resurfacing: cup design and position is critical. American Academy of Orthopaedic Surgeons. New Orleans, LA, 2010.
Langton D, Jameson S, Joyce T, et al. Early failure of metal-on-metal bearings in hip resurfacing and large-diameter total hip replacement: a consequence of excess wear. J Bone Joint Surg Br. 2010;92(1):38-46.
Langton D, Jameson S, Joyce T, et al. The effect of component size and orientation on the concentrations of metal ions after resurfacing arthroplasty of the hip. J Bone Joint Surg Br. 2008;90(9):1143-1151.
Langton D, Sprowson A, Joyce T, et al A. Blood metal ion concentrations after hip resurfacing arthroplasty: a comparative study of articular surface replacement and Birmingham Hip Resurfacing arthroplasties. J Bone Joint Surg Br. 2009;91(10):1287-1295.
Langton D, Sprowson A, Mahadeva D, et al. Cup anteversion in hip resurfacing: validation of EBRA and the presentation of a simple clinical grading system. J Arthroplasty. 2009;25(4):607-613.
Le Duff M, Amstutz HC. Sporting activity after hip resurfacing: Changes over time. Orthop Clin North Am. 2011;42(2):161-167.
Liang T, You M, Xing P, et al. Uncemented total hip arthroplasty in patients younger than 50 years: A 6- to 10-year follow-up study. Orthopedics. 2010;Apr 16 [Epub ahead of print].
Matthies A, Underwood R, Cann P, et al. Retrieval analysis of 240 metal-on-metal hip components, comparing modular total hip replacement with hip resurfacing. J Bone Joint Surg Br. 2011;93(3):307-314.
Mao X, Wong A, Crawford R. Cobalt toxicity – an emerging clinical problem in patients with metal-on-metal hip prostheses? Med J Aust. 2011;194(12):649-651.
McBryde C, Theivendran K, Thomas A, et al. The influence of head size and sex on the outcome of birmingham hip resurfacing. J Bone Joint Surg Am. 2010;92(1):107-112.
McGrath M, Marker D, Seyler T, et al. Revision of surface replacement is comparable to primary total hip arthroplasty. Clin Orthop Relat Res. 2008;467:94-100.
McKellop H, Park S-H, Chiesa R, Doorn P, et al. In vivo wear of three types of metal on metal hip prostheses during two decades of use. Clin Orthop Relat Res. 1996;329:S128-S140.
McMinn D, Daniel J, Pynsent P, Pradhan C. Mini-incision resurfacing arthroplasty of hip through the posterior approach. Clin Orthop. 2005;441:91-98.
Min B, Song K, Bae K, et al. Second-generation cementless total hip arthroplasty in patients with osteonecrosis of the femoral head. J Arthroplasty. 2008;23(6):902-910.
Mont M, Ragland P, Marker D. Resurfacing hip arthroplasty: comparison of a minimally invasive versus standard approach. Clin Orthop. 2005;441:125-131.
Mont M, Seyler T, Ulrich S, et al. Effect of changing indications and techniques on total hip resurfacing. Clin Orthop Relat Res. 2007;465:63-70.
Naal F, Maffiuletti N, Munzinger U, Hersche O. Sports after hip resurfacing arthroplasty. Am J Sports Med. 2007;[Epub ahead of print].
Narvani A, Tsiridis E, Nwaboku H, Bajekal R. Sporting activity following Birmingham hip resurfacing. Int J Sports Med. 2006;27(6):505-507.
Nevelos JE, Ingham E, Doyle C, et al. Analysis of retrieved alumina ceramic components from Mittelmeier total hip prostheses [In Process Citation]. Biomaterials. 1999;20(19):1833-1840.
Nunley R, Zhu J, Brooks P, et al. The learning curve for adopting hip resurfacing among hip specialists. Clin Orthop Relat Res. 2010;468(2):382-391.
Olsen M, Chiu M, Gamble P, et al. A comparison of conventional guidewire alignment jigs with imageless computer navigation in hip resurfacing arthroplasty. J Bone Joint Surg Am. 2010;92(9):1834-1841.
Ortiguera C, Pulliam I, Cabanela M. Total hip arthroplasty for osteonecrosis. Matched -pair analysis of 188 hips with long-term follow-up. J Arthroplasty. 1999;14(1):21-28.
Rubash HE, Sinha RK, Shanbhag AS, Kim SY. Pathogenesis of bone loss after total hip arthroplasty. Orthop Clin North Am. 1998;29(2):173-186.
Saito S, Ryu J, Ishii T, Saigo K. Midterm results of Metasul metal-on-metal total hip arthroplasty. J Arthropl. 2006;21(8):1105-1110.
Schmalzried T. Metal-metal bearing surfaces in hip arthroplasty. Orthopedics. 2009;32-9:E-publication.
Schmalzried TP, Peters PC, Maurer BT, et al. Long-duration metal-on-metal total hip arthroplasties with low wear of the articulating surfaces. J Arthroplasty. 1996;11(3):322-331.
Sinha R, Dungy D, Yeon H. Primary total hip arthroplasty with a proximally porous-coated femoral stem. J Bone Joint Surg Am. 2004;86(6):1254-1261.
Smolders J, Hol A, Rijnders T, van Susante J. Changes in bone mineral density in the proximal femur after hip resurfacing and uncemented total hip replacement: A prospective randomised controlled study. J Bone Joint Surg Br. 2010;92(11):1509-1514.
Su E, Sheehan M, Su S. Comparison of bone removed during total hip arthroplasty with a resurfacing or conventional femoral component a cadaveric study. J Arthroplasty. 2010;25(2):325-329.
Treacy R, McBryde C, Shears E, Pynsent P. Birmingham hip resurfacing: a minimum follow-up of ten years. J Bone Joint Surg Br. 2011;93(1):27-33.
Tower S. Arthroprosthetic cobaltism: neurological and cardiac manifestations in two patients with metal-on-metal arthroplasty: a case report. J Bone Joint Surg Am. 2010;October 29 E-pub.
Witjes S, Smolders J, Beaulé P, etal. Learning from the learning curve in total hip resurfacing: a radiographic analysis. Arch Orthop Trauma Surg. 2009;129(10):1293-1299.
Yoo J, Takamura K, Le Duff M, et al. Contact patch to rim distance predicts metal ion levels in hip resurfacing. Clin Ortho Rel Res. 2012; submitted.