Margin-of-safety Algorithm Used with EOS Imaging to Interpret MHRA Warning for 46-48mm MOM Arthroplasty
Keywords:BHR Resurfacing Arthroplasty, cup inclination, edge wear, MHRA alert, EOS, MOM
The Medical Healthcare Products Regulatory Agency (MHRA June-2015) warned of higher risks with 46-48mm sizes of BHR hip resurfacing arthroplasty (HRA). The most common condemnation of adverse results in MOM bearings has been termed edge loading. We originally developed a margin-of-safety (MOS) algorithm to define edge loading of cups in simulator studies. This method integrated simulator wear-patterns with respect to cup diameters and cup designs. The algorithm’s simplicity lay in the fact that with wear-patterns and rim-profile angles predetermined, the only input required was the cup inclination-angle. The algorithm demonstrated that the margin-of-safety decreased in smaller cups due to the tribo-mechanics of spherical CoCr bearings, a previously unrecognized feature. For the 46mm and 48mm cups highlighted in the MHRA alert, the critical cup inclinations where edge-wear became a risk occurred at 65-66°, revealing an insignificant difference with respect to diameters. The MOS-algorithm also indicated that lower lateral-inclination angles were particularly beneficial, i.e. a 46mm cup positioned at 50° inclination would exhibit a higher margin of safety than either 48mm or 50mm sizes positioned at 55° inclination. This evidence supported clinical studies that recommended BHR cup inclinations up to 50-55° and lower as optimal for reducing metal-ion concentrations. In a patient with normal spine mobility, our EOS imaging demonstrated that the inclination in the 46mm cup steepened by 9° from standing to the seated position while margin-of-safety was reduced by 50%. Our 2nd patient with a stiff spine sat with the same component orientations as in his standing posture. Thus MOM impingement and subluxation in different functional postures may also provoke rim-damage mechanisms. Here the combination of EOS imaging and the MOS-algorithm may aid understanding of such risks. Thus the margin-of-safety algorithm confirmed and helped explained the relative risks in the 46mm and 48mm cups highlighted by the MHRA. The algorithm’s stratification by cup rim-profile, inclination angle and cup diameter may assist the surgeon determine which patients may be more at risk for edge wear with the smaller BHR cups.
Langton DJ, Sprowson AP, Joyce TJ, Reed M, Carluke I, Partington P, Nargol AV. 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;91-10:1287-95.
Hart AJ, Sabah S, Henckel J, Lewis A, Cobb J, Sampson B, Mitchell A, Skinner JA. The painful metal-on-metal hip resurfacing. J Bone Joint Surg Br 2009;91-6:738-44.
Mabilleau G, Kwon YM, Pandit H, Murray DW, Sabokbar A. Metal-on-metal hip resurfacing arthroplasty: a review of periprosthetic biological reactions. Acta Orthop 2008;79-6:734-47.
Vendittoli PA, Mottard S, Roy AG, Dupont C, Lavigne M. Chromium and cobalt ion release following the Durom high carbon content, forged metal-on-metal surface replacement of the hip. J Bone Joint Surg Br 2007;89-4:441-8.
Kwon YM, Mellon SJ, Monk P, Murray DW, Gill HS. In vivo evaluation of edge-loading in metal-on-metal hip resurfacing patients with pseudotumours. Bone Joint Res. 2012;1-4:42 -9.
Underwood RJ, Zografos A, Sayles RS, Hart A, Cann P. Edge loading in metal-on-metal hips: low clearance is a new risk factor. J Eng in Med 2012;226-3:217 - 6.
McHugh D, Currier J, Kennedy F, Collier J, Van Critters D. Plastic Deformation from Edge Loading is common on Retrieved Metal-on-Metal Hips and Can Be Predicted With Finite Element Analysis. In: Kurtz SM, Greenwald SA, Mihalko WM, Lemons JA, eds. Metal-On-Metal Total Hip Replacement Devices, 2013:235-50.
Morlock MM, Bishop NE, Zustin J, Hahn M, Ruther W, Amling M. Modes of Implant Failure After Hip Resurfacing: Morphological and Wear Analysis of 267 Retrieval Specimens. J Bone Joint Surg Am 2008;90:89 -95.
De Haan R, Pattyn C, Gill HS, Murray DW, Campbell PA, De Smet K. Correlation between inclination of the acetabular component and metal ion levels in metal-on-metal hip resurfacing replacement. J Bone Joint Surg Br 2008;90-10:1291-7.
Jeffers JR, A, Taylor A, Tuke M. The problem with large diameter metal-on-metal acetabular cup inclination. Bulletin of the NYU Hospital for Joint Diseases 2009;67 -2:189 - 92.
Shimmin AJ, Walter WL, Esposito C. The influence of the size of the component on the outcome of resurfacing arthroplasty of the hip. Journal of Bone and Joint Surgery BR 2010;92 -B:469 - 76.
Griffin WL, Nanson CJ, Springer BD, Davies MA, Fehring TK. Reduced articular surface of one-piece cups. A cause of runaway wear and early failure. Clin Orthop Relat Res 2010;468:2328 - 32.
Matharu GS, McBryde CW, Pynsent WB, Pynsent PB, Treacy RBC. The outcome of the Birmingham Hip Resurfacing in patients aged < 50 years up to 14 years post-operatively. Bone Joint J 2013;95-B:1172-7.
De Smet K. Revisions of hip resurfacings from an independent specialist center. ISTA 28th Annual Congress. Vienna, Austria, 2015.
Daniel J. Mortality and implant revision rates following hip resurfacings and hip replacements. ISTA 28th Annual Congress. Vienna, Austria, 2015.
Leslie I, Williams S, Brown C, Isaac G, Jin Z, Ingham E, Fisher J. Effect of bearing size on the long-term wear, wear debris, and ion levels of large diameter metal-on-metal hip replacements-An in vitro study. J Biomed Mater Res B Appl Biomater 2008;87-1:163-72.
Bowsher JG, Clarke IC, Williams PA, Donaldson TK. What is a “normal” wear pattern for metal-on-metal hip bearings? J Biomed Mater Res B Appl Biomater 2009;91-1:297-308.
Brodner W, Grubl A, Jankovsky R, Meisinger V, Lehr S, Gottsauner-Wolf F. Cup inclination and serum concentration of cobalt and chromium after metal-on-metal total hip arthroplasty. J Arthroplasty 2004;19-8 Suppl 3:66-70.
Wang L, Williams S, Udofia I, Isaac G, Fisher J, Zhongmin J. The effect of cup orientation and coverage on contact mechanics and range of motion of metal-on-metal hip resurfacing arthroplasty. J Eng in Med 2012;226-11:887-6.
Clarke IC, Burgett-Morena MD, Donaldson TK, Smith EJ, Savissar C, Bowsher JG. Validation of clinical edge-wear in ‘Steep-cups’ using 40 - 70 degrees dynamic inclinations in novel MOM simulator study. ISTA 28th Annual Congress. Vienna, Austria, 2015.
Amstutz HC, Le Duff M, Johnson AJ. Socket position determines hip resurfacing 10-year survivorship. Clinical Orthopaedics and Related Research 2012;470:3127 - 33.
Yoon JP, Le Duff MJ, Johnson A, Takamura KM, Ebramzadeh E, Amstutz CA. Contact patch to rim distance predicts metal ion levels in hip resurfacing. Clin Orthop Relat Res 2013;471:1615-21.
Matthies AK, Henckel J, Cro S, Suarez A, Noble PC, Skinner J, Hart AJ. Predicting Wear and Blood Metal Ion Levels in Metal-on-Metal HIp Resurfacing. J Orthop Res 2014;32-1:167-74.
Lazennec JY, Rousseau MA, Rangel A, Gorin M, Belicourt C, Brusson A, Catonne Y. Pelvis and total hip arthroplasty acetabular component orientations in sitting and standing positions: measurements reproductibility with EOS imaging system versus conventional radiographies. Orthop Traumatol Surg Res 2011;97-4:373 - 80.
Lazennec JY, Rousseau MA, Brusson A, Folinais D, Amel M, Clarke IC, Pour AE. Total Hip Prostheses in Standing, Sitting and Squatting Positions: An Overview of Our 8 Years Practice Using the EOS Imaging Technology. Open Orthop. J. 2015;9:26-44.
Lee R, Essner A, Wang A. Tribological considerations in primary and revision metal-on-metal arthroplasty. J Bone Joint Surg Am 2008;90 Suppl 3:118-24.
Clarke IC, Donaldson TK, Savisaar C, Bowsher JG. New algorithm permits accurate depiction of cup-wear patterns in clinical and simulator studies. ISTA 28th Annual Congress. Vienna, Austria, 2015.
Bengs BC, Sangiorgio SN, Ebramzadeh E. Less range of motion with resurfacing arthroplasty than with total hip arthroplasty. Acta Orthop 2008;79-6:755-62.
Clarke IC, Donaldson TK, Burgett MD, Smith EJ, Bowsher J, Savisaar C, John A, Lazennec JY, McPherson E, Peters CL. Normal and Adverse Wear Patterns Created In-vivo on MOM Surfaces - a retrieval study representing four vendors. In: Kurtz SM, Greenwald SA, Mihalko WM, Lemons JA, eds. Metal-on-Metal Total Hip Replacement Devices. Vol. STP1560. West Conshohocken, PA: ASTM International, 2013 157-92.
Langton, DJ, Jameson, SS, Joyce, TJ, Gandhi, JN, Sidaginamale, R, Mereddy, P, Lord, J, Nargol, AV. Accelerating failure rate of the ASR total hip replacement J. Bone Joint Surg. Br 2011; 93-8: 1011 – 1016.
Bergmann G, Deuretzbacher G, Heller M, Graichen F, Rohlmann A, Strauss J, Duda GN. Hip contact forces and gait patterns from routine activities. J Biomech 2001;34-7:859-71.
Esposito CI, Walter WL, Roques A, Tuke MA, Zicat BA, Walsh WR, Walter WK. Wear in alumina-on-alumina ceramic bearings. A retrieval analysis of edge loading. J Bone Joint Surg Am 2012;7:901-7.
Halim T, Burgett M, Donaldson TK, Savisaar C, Bowsher JG, Clarke IC. Profiling the third-body wear damage produced in CoCr surfaces by bone cement, CoCr, and Ti6A14V debris: A 10-cycle metal-on-metal simulator test. J Eng in Med 2014;Proc. IMechE -H:1-11.
Halim T, Clarke IC, Burgett-Moreno M, Donaldson TK, Savisaar C, Bowsher JG. A Simulator Study of Adverse Wear with Metal and Cement Debris Contamination in metal-on-metal (MOM) Hip Bearings. J Bone Joint Research (UK) 2015;4:29-3
How to Cite
Copyright (c) 2015 Ian Clarke, Jean-Yves Lazennec
This work is licensed under a Creative Commons Attribution-NonCommercial 4.0 International License.
Copyright and License Agreement:
Authors who publish with the Reconstructive Review agree to the following terms:
- Authors retain copyright and grant the journal right of first publication with the work. Reconstructive Review follows the Creative Commons Attribution-NonCommercial CC BY-NC. This license allows anyone to download works, build upon the material, and share them with others for non-commercial purposes as long as they credit the senior author, Reconstructive Review, and the Joint Implant Surgery & Research Foundation (JISRF). An example credit would be: "Courtesy of (senior author's name), Reconstructive Review, JISRF, Chagrin Falls, Ohio". While works can be downloaded and shared they cannot be used commercially.
- Authors are able to enter into separate, additional contractual arrangements for the non-exclusive distribution of the journal's published version of the work (e.g., post it to an institutional repository or publish it in a book), with an acknowledgement of its initial publication in this journal.
- Authors are permitted and encouraged to post their work online (e.g., in institutional repositories or on their website) prior to and during the submission process, as it can lead to productive exchanges, as well as earlier and greater citation of published work.