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How to Interpret Metal Ions in THA
Journal Pre-proof How to interpret metal ions in THA Michael J. Taunton, MD PII:
S0883-5403(20)30028-0
DOI:
https://doi.org/10.1016/j.arth.2020.01.010
Reference:
YARTH 57718
To appear in:
The Journal of Arthroplasty
Received Date: 1 January 2020 Accepted Date: 3 January 2020
Please cite this article as: Taunton MJ, How to interpret metal ions in THA, The Journal of Arthroplasty (2020), doi: https://doi.org/10.1016/j.arth.2020.01.010. This is a PDF file of an article that has undergone enhancements after acceptance, such as the addition of a cover page and metadata, and formatting for readability, but it is not yet the definitive version of record. This version will undergo additional copyediting, typesetting and review before it is published in its final form, but we are providing this version to give early visibility of the article. Please note that, during the production process, errors may be discovered which could affect the content, and all legal disclaimers that apply to the journal pertain. © 2020 Elsevier Inc. All rights reserved.
1
2019 AAHKS Symposium Submission
2
Adverse Local Tissue Reactions in THA: Who, When and How to Revise.
3 4
Title: How to interpret metal ions in THA
5 6
Running Title: How to interpret metal ions in THA
7
1
Introduction Modern total hip arthroplasty has seen an unfortunate increase in proportional implant failures secondary to Adverse Local Tissue Reactions (ALTR) secondary to wear of Metal on Metal (MoM) bearings and Mechanically Assisted Crevice Corrosion (MACC) related to Corrosion at implant junctions and tapers. These failures are born out of a desire to improve the outcomes of primary THA. MoM bearings for hip resurfacing arthroplasty (HRA) and total hip arthroplasty (THA) were designed and popularized for an ability to use a large femoral head, with a reduced risk of instability, and a lower rate of volumetric wear than was seen in metal on polyethylene constructs.1-4 More recently, dual modular neck femoral implants were popularized in THA to add intraoperative flexibility to change neck length, angle, and version after the stem was already placed. 5 However, the inflammatory reaction and soft tissue damage related to ALTR secondary to metal wear debris and corrosion byproducts can be devastating. An appropriate and time sensitive evaluation, diagnosis, and treatment of ALTR are key components for the best possible outcome for these patients. Mechanisms of Metal Ion Release In addition to a thorough clinical work-up with three-dimensional imaging, whole blood, serum, and now synovial fluid levels of Chromium and Cobalt have been used to screen, diagnose, and monitor patients with ALTR. In order to interpret metal ion levels in the presence of hip arthroplasty, one must first understand the mechanisms of release. There are two major mechanisms for metal release in hip arthroplasty implants. First, metal release from bearing wear. The metal release from normal bearing wear is Chromium predominant. The particles are small and uniform. There is a low level of Cobalt relative to the Chromium. Such is the case in a typical MoM HRA. However, in the case of edge loading, material release is accelerated. This can occur in the case of a malpositioned acetabular implant.6 In this second scenario, there is a high Cobalt material wear with larger particles. In the third metal release mechanism, MACC, metal is released at junctions through corrosion. Both Cobalt and Chromium are released, but there is a Cobalt predominant picture. Work up of painful THA with Cobalt Chromium bearings and/or Junctions.
When presented with an arthroplasty of concern, the surgeon must determine what metal ions levels to obtain, and then incorporate those levels into a treatment algorithm. In my practice, any patient with a painful hip arthroplasty with Chromium and Cobalt in the system has whole blood metal levels checked. At my institution, our lab prefers whole blood collected in an EDTA tube, as there is a lower risk of contamination. Metal levels extracellular and intracellularly are measured. In an ISO level 7 class clean room, 100 mcL whole blood is mixed and then pipetted. The blood is then diluted with 2.4 mL 10 mcM EDTA + 0.002% NaOH + 10 ng/mL Li. Chromium and Cobalt are analyzed on an Inductively-coupled Plasma Mass Spectrometer (ICPMS). The analytical measuring range (AMR) is from 1 to 200 ng/mL for Chromium and Cobalt in whole blood. When screening tests for infection or metal reaction are positive, or if I am planning revision THA, I aspirate the affected hip and send the synovial fluid for Cell count, cultures, as well as Cobalt, Chromium, and Titanium levels. We began obtaining synovial metal levels to help get a handle on the clearance from blood and determine the bad actor in the case of bilateral hip arthroplasties with Cobalt present. Additionally, studies have shown an association between the synovial fluid levels with those from whole blood and serum. Once the surgeon has obtained whole blood and/or synovial fluid for metal level analysis, interpretation and integration into the clinical scenario begins. The AAHKS consensus statement regarding risk stratification of metal on metal hip arthroplasty separates hips in to three risk groups based on blood or serum Cobalt levels, with 3 ng/ml being low risk.7 To pause, we must remember metal level cutoffs are a component of an algorithm, and are not in a vacuum. Interpretation of Metal Ion Levels in metal bearings and metal junction hip arthroplasty To better understand the clinical utility of metal levels in hip arthroplasty including metal bearings and/or metal junctions, we performed a prospective study of aseptic hip arthroplasty revisions with ALTR matched with revisions without ALTR. We obtained metal levels in whole blood and synovial fluid of 29 hip arthroplasties with ALTR and 29 without ALTR prior to aseptic revision THA. Whole blood Cobalt The consensus statement from AAHKS outlined low risk hip arthroplasties as having blood or serum Cobalt ion less than 3 ng/ml. In our study, whole blood Cobalt
levels in the ALTR hips were almost 50 times higher in the ALTR group, Chromium 10 times. (Figure 1) However, when we examined the Receiver Operating Curve of whole blood Cobalt in metal on metal hip arthroplasty for ALTR detection, the threshold for ALTR was 36.5 ng/ml, with an AUC of 0.96, a sensitivity of 80%, and a specificity of 77%. (FIGURE 2) Additionally, when we separated out the different hip arthroplasty constructs in hips with ALTR, we found large variations in whole blood metal ion levels. Cobalt 2.5 ng/ml for HRA, 29 ng/ml for Metal on metal THA, and 11.7 ng/ml for Dual modular femoral necks in THA. The HRA’s would be considered “low risk” in the consensus statement. With the variability demonstrated in the constructs, the study outlines the limitations of decision making on Whole blood metal ion levels alone. Synovial Cobalt These limitations of whole blood Cobalt levels outline where synovial fluid metal ion levels can be helpful. The study found that Cobalt levels were over 150 times higher in the synovial fluid of ALTR hips. The Chromium levels were over 300 times higher. (Figure 3) The synovial fluid Cobalt had the highest correlation with ALTR compared to the other tests, with a threshold of 19.75 ng/ml – a lower value than in Whole blood. Additionally, the area under the curve is 0.97 with a superior sensitivity of 92% and a specificity of 89%. (figure 4). Additionally, when we separated out the different hip arthroplasty constructs in hips with ALTR, we found large variations in synovial fluid metal ion levels and Cobalt-to-Chromium Ratios. (Figure 5.) Cobalt /Chromium Ratios in ALTR based on implant type. The whole blood Cobalt-to-Chromium Ratio was 2.5 in ALTR vs. 1.0 in Non-ALTR. However, the Cobalt-to-Chromium ratios in synovial fluid are also highly variable based on implant type. The study found low Cobalt-to-Chromium in the resurfacing and metal on metal, but much higher absolute Cobalt and Chromium ion levels in the metal on metal in both whole blood and synovial fluid. This indicated more than one source for the metal products – wear and corrosion. The absolute Cobalt and Chromium levels found in dual modular femoral neck THA with ALTR are much lower in the synovial fluid than other implant types, but a much higher Cobalt-to-Chromium ratio at 2.59 ng/ml, indicative of a more corrosion based metal release from the arthroplasty. (Figure 5) Comparison of Whole Blood and Synovial fluid Cobalt-to-Chromium Ratios in ALTR
When the Cobalt-to-Chromium ratios in both whole blood and synovial fluid are compared for each implant type, the etiology of metal release is more easily understood. There is a continuum of the particle ratios released by the different mechanisms. (Figure 6) In HRA, particles are released by wear, with low Cobalt-toChromium ratios. In dual modular neck implants, particles are released by corrosion, with high Cobalt-to-Chromium ratios. The Metal on metal bearings are particularly interesting. The soluble Cobalt from the corrosion is released into the blood, but the wear Chromium predominant wear particles are demonstrated in the synovial fluid. Clinical Decision Making in the symptomatic Metal on Polyethylene THA What about metal on Polyethylene ALTR? In 43 patients with metal on polyethylene bearings and ALTR, Dr. Min Kwon and colleagues found a mean serum Cobalt level of 8.9 ng/ml with a Cobalt-to-Chromium ratio of 5.9 ng/ml. 8 Consistent with other studies, patients without ALTR had Blood Cobalt levels less than 1 ng/ml. With a cutoff of 1 ng/ml and an Area Under the Curve (AUC) of 96%, Serum Cobalt had a 95% sensitivity for identifying ALTR due to trunnionosis in metal on poly bearings. With a cutoff of 2 ng/ml and an AUC of 80% Serum Cobalt / Chromium ratio had 83% sensitivity for identifying ALTR due to trunnionosis in Metal on Poly bearings. Dr. Jacobs group, in a similar study of 44 patients with ALTR, found a cutoff of 1.43 ng/ml for Serum Cobalt Chromium ratio in ALTR.9
Conclusion/Recommendations In my practice I continue to rely on Whole blood metal levels initially. If Cobalt in Whole blood is greater than 1 ng/ml in any situation, I become concerned and will proceed with further testing for ALTR in the symptomatic hip. We can continue to use the consensus statement7 for metal on metal hips, with high risk being blood or serum Cobalt greater than 10 ng/ml, but our studies additionally reveal high risk if the Synovial fluid Cobalt is greater than 19 ng/ml in a metal on metal hip, or in THA with metal junctions. If the Cobalt-to-Chromium ratio is greater than 1.4 ng/ml in a metal on polyethylene hip, there is also a high sensitivity of ALTR. In Conclusion, The Interpretation of Whole Blood Metal ions is a Key component of the Algorithm in Treating the Symptomatic Hip arthroplasty but is not to be used in a Vacuum. Synovial fluid metal levels are a useful adjunct in certain situations.
References 1. Anissian HL, Stark A, Good V, Dahlstrand H, Clarke IC. The wear pattern in metal-on-metal hip prostheses. J Biomed Mater Res. 2001;58(6):673-8. Epub 2001/12/18. 2. Bozic KJ, Kurtz S, Lau E, Ong K, Chiu V, Vail TP, et al. The epidemiology of bearing surface usage in total hip arthroplasty in the United States. J Bone Joint Surg Am. 2009 Jul;91(7):1614-20. Epub 2009/07/03. 3. Duwelius PJ, Hartzband MA, Burkhart R, Carnahan C, Blair S, Wu Y, et al. Clinical results of a modular neck hip system: hitting the "bull's-eye" more accurately. Am J Orthop (Belle Mead NJ). 2010 Oct;39(10 Suppl):2-6. Epub 2011/02/10. 4. Jacobs JJ, Urban RM, Hallab NJ, Skipor AK, Fischer A, Wimmer MA. Metal-on-metal bearing surfaces. J Am Acad Orthop Surg. 2009 Feb;17(2):69-76. Epub 2009/02/10. 5. Molloy DO, Munir S, Jack CM, Cross MB, Walter WL, Walter WK, Sr. Fretting and corrosion in modular-neck total hip arthroplasty femoral stems. J Bone Joint Surg Am. 2014 Mar 19;96(6):488-93. Epub 2014/03/22. 6. Davda K, Lali FV, Sampson B, Skinner JA, Hart AJ. An analysis of metal ion levels in the joint fluid of symptomatic patients with metal-on-metal hip replacements. J Bone Joint Surg Br. 2011 Jun;93(6):738-45. Epub 2011/05/19. 7. Kwon YM, Lombardi AV, Jacobs JJ, Fehring TK, Lewis CG, Cabanela ME. Risk stratification algorithm for management of patients with metal-on-metal hip arthroplasty: consensus statement of the American Association of Hip and Knee Surgeons, the American Academy of Orthopaedic Surgeons, and the Hip Society. J Bone Joint Surg Am. 2014 Jan 1;96(1):e4. Epub 2014/01/03. 8. Kwon YM, MacAuliffe J, Arauz PG, Peng Y. Sensitivity and Specificity of Metal Ion Level in Predicting Adverse Local Tissue Reactions Due to Head-Neck Taper Corrosion in Primary Metal-onPolyethylene Total Hip Arthroplasty. J Arthroplasty. 2018 Sep;33(9):3025-9. Epub 2018/05/12. 9. Fillingham YA, Della Valle CJ, Bohl DD, Kelly MP, Hall DJ, Pourzal R, et al. Serum Metal Levels for Diagnosis of Adverse Local Tissue Reactions Secondary to Corrosion in Metal-on-Polyethylene Total Hip Arthroplasty. J Arthroplasty. 2017 Sep;32(9S):S272-S7. Epub 2017/05/18.
Figure 1.
Hip Resurfacing Cobalt Chromium Cobalt-to-Chromium Ratio
2.5 + 1.3 5.3 + 2.3 0.47
Metal on Metal THA 29.3 + 10.7 11.5 + 4.4 2.55
Dual Modular Neck THA 11.7 + 6.2 0.7 + 0.2 16.71
Figure 2.
Figure 3.
Cobalt Chromium Cobalt-to-Chromium Ratio
ALTR 1,833 + 663 3,128 + 1276 1.7
Non-ALTR 12.3 + 7.1 10.3 + 3.6 1.1
P value 0.008 0.01
Figure 4.
Cobalt Chromium Cobalt/Chrome Ratio
Resurfacing 484 + 216 932 + 555 0.52
MoM THA 2,529 + 924 4,299 + 1,796 0.59
Dual Mod Neck 38.1 + 23.8 14.7 + 3.72 2.59
S0883-5403(20)30028-0
DOI:
https://doi.org/10.1016/j.arth.2020.01.010
Reference:
YARTH 57718
To appear in:
The Journal of Arthroplasty
Received Date: 1 January 2020 Accepted Date: 3 January 2020
Please cite this article as: Taunton MJ, How to interpret metal ions in THA, The Journal of Arthroplasty (2020), doi: https://doi.org/10.1016/j.arth.2020.01.010. This is a PDF file of an article that has undergone enhancements after acceptance, such as the addition of a cover page and metadata, and formatting for readability, but it is not yet the definitive version of record. This version will undergo additional copyediting, typesetting and review before it is published in its final form, but we are providing this version to give early visibility of the article. Please note that, during the production process, errors may be discovered which could affect the content, and all legal disclaimers that apply to the journal pertain. © 2020 Elsevier Inc. All rights reserved.
1
2019 AAHKS Symposium Submission
2
Adverse Local Tissue Reactions in THA: Who, When and How to Revise.
3 4
Title: How to interpret metal ions in THA
5 6
Running Title: How to interpret metal ions in THA
7
1
Introduction Modern total hip arthroplasty has seen an unfortunate increase in proportional implant failures secondary to Adverse Local Tissue Reactions (ALTR) secondary to wear of Metal on Metal (MoM) bearings and Mechanically Assisted Crevice Corrosion (MACC) related to Corrosion at implant junctions and tapers. These failures are born out of a desire to improve the outcomes of primary THA. MoM bearings for hip resurfacing arthroplasty (HRA) and total hip arthroplasty (THA) were designed and popularized for an ability to use a large femoral head, with a reduced risk of instability, and a lower rate of volumetric wear than was seen in metal on polyethylene constructs.1-4 More recently, dual modular neck femoral implants were popularized in THA to add intraoperative flexibility to change neck length, angle, and version after the stem was already placed. 5 However, the inflammatory reaction and soft tissue damage related to ALTR secondary to metal wear debris and corrosion byproducts can be devastating. An appropriate and time sensitive evaluation, diagnosis, and treatment of ALTR are key components for the best possible outcome for these patients. Mechanisms of Metal Ion Release In addition to a thorough clinical work-up with three-dimensional imaging, whole blood, serum, and now synovial fluid levels of Chromium and Cobalt have been used to screen, diagnose, and monitor patients with ALTR. In order to interpret metal ion levels in the presence of hip arthroplasty, one must first understand the mechanisms of release. There are two major mechanisms for metal release in hip arthroplasty implants. First, metal release from bearing wear. The metal release from normal bearing wear is Chromium predominant. The particles are small and uniform. There is a low level of Cobalt relative to the Chromium. Such is the case in a typical MoM HRA. However, in the case of edge loading, material release is accelerated. This can occur in the case of a malpositioned acetabular implant.6 In this second scenario, there is a high Cobalt material wear with larger particles. In the third metal release mechanism, MACC, metal is released at junctions through corrosion. Both Cobalt and Chromium are released, but there is a Cobalt predominant picture. Work up of painful THA with Cobalt Chromium bearings and/or Junctions.
When presented with an arthroplasty of concern, the surgeon must determine what metal ions levels to obtain, and then incorporate those levels into a treatment algorithm. In my practice, any patient with a painful hip arthroplasty with Chromium and Cobalt in the system has whole blood metal levels checked. At my institution, our lab prefers whole blood collected in an EDTA tube, as there is a lower risk of contamination. Metal levels extracellular and intracellularly are measured. In an ISO level 7 class clean room, 100 mcL whole blood is mixed and then pipetted. The blood is then diluted with 2.4 mL 10 mcM EDTA + 0.002% NaOH + 10 ng/mL Li. Chromium and Cobalt are analyzed on an Inductively-coupled Plasma Mass Spectrometer (ICPMS). The analytical measuring range (AMR) is from 1 to 200 ng/mL for Chromium and Cobalt in whole blood. When screening tests for infection or metal reaction are positive, or if I am planning revision THA, I aspirate the affected hip and send the synovial fluid for Cell count, cultures, as well as Cobalt, Chromium, and Titanium levels. We began obtaining synovial metal levels to help get a handle on the clearance from blood and determine the bad actor in the case of bilateral hip arthroplasties with Cobalt present. Additionally, studies have shown an association between the synovial fluid levels with those from whole blood and serum. Once the surgeon has obtained whole blood and/or synovial fluid for metal level analysis, interpretation and integration into the clinical scenario begins. The AAHKS consensus statement regarding risk stratification of metal on metal hip arthroplasty separates hips in to three risk groups based on blood or serum Cobalt levels, with 3 ng/ml being low risk.7 To pause, we must remember metal level cutoffs are a component of an algorithm, and are not in a vacuum. Interpretation of Metal Ion Levels in metal bearings and metal junction hip arthroplasty To better understand the clinical utility of metal levels in hip arthroplasty including metal bearings and/or metal junctions, we performed a prospective study of aseptic hip arthroplasty revisions with ALTR matched with revisions without ALTR. We obtained metal levels in whole blood and synovial fluid of 29 hip arthroplasties with ALTR and 29 without ALTR prior to aseptic revision THA. Whole blood Cobalt The consensus statement from AAHKS outlined low risk hip arthroplasties as having blood or serum Cobalt ion less than 3 ng/ml. In our study, whole blood Cobalt
levels in the ALTR hips were almost 50 times higher in the ALTR group, Chromium 10 times. (Figure 1) However, when we examined the Receiver Operating Curve of whole blood Cobalt in metal on metal hip arthroplasty for ALTR detection, the threshold for ALTR was 36.5 ng/ml, with an AUC of 0.96, a sensitivity of 80%, and a specificity of 77%. (FIGURE 2) Additionally, when we separated out the different hip arthroplasty constructs in hips with ALTR, we found large variations in whole blood metal ion levels. Cobalt 2.5 ng/ml for HRA, 29 ng/ml for Metal on metal THA, and 11.7 ng/ml for Dual modular femoral necks in THA. The HRA’s would be considered “low risk” in the consensus statement. With the variability demonstrated in the constructs, the study outlines the limitations of decision making on Whole blood metal ion levels alone. Synovial Cobalt These limitations of whole blood Cobalt levels outline where synovial fluid metal ion levels can be helpful. The study found that Cobalt levels were over 150 times higher in the synovial fluid of ALTR hips. The Chromium levels were over 300 times higher. (Figure 3) The synovial fluid Cobalt had the highest correlation with ALTR compared to the other tests, with a threshold of 19.75 ng/ml – a lower value than in Whole blood. Additionally, the area under the curve is 0.97 with a superior sensitivity of 92% and a specificity of 89%. (figure 4). Additionally, when we separated out the different hip arthroplasty constructs in hips with ALTR, we found large variations in synovial fluid metal ion levels and Cobalt-to-Chromium Ratios. (Figure 5.) Cobalt /Chromium Ratios in ALTR based on implant type. The whole blood Cobalt-to-Chromium Ratio was 2.5 in ALTR vs. 1.0 in Non-ALTR. However, the Cobalt-to-Chromium ratios in synovial fluid are also highly variable based on implant type. The study found low Cobalt-to-Chromium in the resurfacing and metal on metal, but much higher absolute Cobalt and Chromium ion levels in the metal on metal in both whole blood and synovial fluid. This indicated more than one source for the metal products – wear and corrosion. The absolute Cobalt and Chromium levels found in dual modular femoral neck THA with ALTR are much lower in the synovial fluid than other implant types, but a much higher Cobalt-to-Chromium ratio at 2.59 ng/ml, indicative of a more corrosion based metal release from the arthroplasty. (Figure 5) Comparison of Whole Blood and Synovial fluid Cobalt-to-Chromium Ratios in ALTR
When the Cobalt-to-Chromium ratios in both whole blood and synovial fluid are compared for each implant type, the etiology of metal release is more easily understood. There is a continuum of the particle ratios released by the different mechanisms. (Figure 6) In HRA, particles are released by wear, with low Cobalt-toChromium ratios. In dual modular neck implants, particles are released by corrosion, with high Cobalt-to-Chromium ratios. The Metal on metal bearings are particularly interesting. The soluble Cobalt from the corrosion is released into the blood, but the wear Chromium predominant wear particles are demonstrated in the synovial fluid. Clinical Decision Making in the symptomatic Metal on Polyethylene THA What about metal on Polyethylene ALTR? In 43 patients with metal on polyethylene bearings and ALTR, Dr. Min Kwon and colleagues found a mean serum Cobalt level of 8.9 ng/ml with a Cobalt-to-Chromium ratio of 5.9 ng/ml. 8 Consistent with other studies, patients without ALTR had Blood Cobalt levels less than 1 ng/ml. With a cutoff of 1 ng/ml and an Area Under the Curve (AUC) of 96%, Serum Cobalt had a 95% sensitivity for identifying ALTR due to trunnionosis in metal on poly bearings. With a cutoff of 2 ng/ml and an AUC of 80% Serum Cobalt / Chromium ratio had 83% sensitivity for identifying ALTR due to trunnionosis in Metal on Poly bearings. Dr. Jacobs group, in a similar study of 44 patients with ALTR, found a cutoff of 1.43 ng/ml for Serum Cobalt Chromium ratio in ALTR.9
Conclusion/Recommendations In my practice I continue to rely on Whole blood metal levels initially. If Cobalt in Whole blood is greater than 1 ng/ml in any situation, I become concerned and will proceed with further testing for ALTR in the symptomatic hip. We can continue to use the consensus statement7 for metal on metal hips, with high risk being blood or serum Cobalt greater than 10 ng/ml, but our studies additionally reveal high risk if the Synovial fluid Cobalt is greater than 19 ng/ml in a metal on metal hip, or in THA with metal junctions. If the Cobalt-to-Chromium ratio is greater than 1.4 ng/ml in a metal on polyethylene hip, there is also a high sensitivity of ALTR. In Conclusion, The Interpretation of Whole Blood Metal ions is a Key component of the Algorithm in Treating the Symptomatic Hip arthroplasty but is not to be used in a Vacuum. Synovial fluid metal levels are a useful adjunct in certain situations.
References 1. Anissian HL, Stark A, Good V, Dahlstrand H, Clarke IC. The wear pattern in metal-on-metal hip prostheses. J Biomed Mater Res. 2001;58(6):673-8. Epub 2001/12/18. 2. Bozic KJ, Kurtz S, Lau E, Ong K, Chiu V, Vail TP, et al. The epidemiology of bearing surface usage in total hip arthroplasty in the United States. J Bone Joint Surg Am. 2009 Jul;91(7):1614-20. Epub 2009/07/03. 3. Duwelius PJ, Hartzband MA, Burkhart R, Carnahan C, Blair S, Wu Y, et al. Clinical results of a modular neck hip system: hitting the "bull's-eye" more accurately. Am J Orthop (Belle Mead NJ). 2010 Oct;39(10 Suppl):2-6. Epub 2011/02/10. 4. Jacobs JJ, Urban RM, Hallab NJ, Skipor AK, Fischer A, Wimmer MA. Metal-on-metal bearing surfaces. J Am Acad Orthop Surg. 2009 Feb;17(2):69-76. Epub 2009/02/10. 5. Molloy DO, Munir S, Jack CM, Cross MB, Walter WL, Walter WK, Sr. Fretting and corrosion in modular-neck total hip arthroplasty femoral stems. J Bone Joint Surg Am. 2014 Mar 19;96(6):488-93. Epub 2014/03/22. 6. Davda K, Lali FV, Sampson B, Skinner JA, Hart AJ. An analysis of metal ion levels in the joint fluid of symptomatic patients with metal-on-metal hip replacements. J Bone Joint Surg Br. 2011 Jun;93(6):738-45. Epub 2011/05/19. 7. Kwon YM, Lombardi AV, Jacobs JJ, Fehring TK, Lewis CG, Cabanela ME. Risk stratification algorithm for management of patients with metal-on-metal hip arthroplasty: consensus statement of the American Association of Hip and Knee Surgeons, the American Academy of Orthopaedic Surgeons, and the Hip Society. J Bone Joint Surg Am. 2014 Jan 1;96(1):e4. Epub 2014/01/03. 8. Kwon YM, MacAuliffe J, Arauz PG, Peng Y. Sensitivity and Specificity of Metal Ion Level in Predicting Adverse Local Tissue Reactions Due to Head-Neck Taper Corrosion in Primary Metal-onPolyethylene Total Hip Arthroplasty. J Arthroplasty. 2018 Sep;33(9):3025-9. Epub 2018/05/12. 9. Fillingham YA, Della Valle CJ, Bohl DD, Kelly MP, Hall DJ, Pourzal R, et al. Serum Metal Levels for Diagnosis of Adverse Local Tissue Reactions Secondary to Corrosion in Metal-on-Polyethylene Total Hip Arthroplasty. J Arthroplasty. 2017 Sep;32(9S):S272-S7. Epub 2017/05/18.
Figure 1.
Hip Resurfacing Cobalt Chromium Cobalt-to-Chromium Ratio
2.5 + 1.3 5.3 + 2.3 0.47
Metal on Metal THA 29.3 + 10.7 11.5 + 4.4 2.55
Dual Modular Neck THA 11.7 + 6.2 0.7 + 0.2 16.71
Figure 2.
Figure 3.
Cobalt Chromium Cobalt-to-Chromium Ratio
ALTR 1,833 + 663 3,128 + 1276 1.7
Non-ALTR 12.3 + 7.1 10.3 + 3.6 1.1
P value 0.008 0.01
Figure 4.
Cobalt Chromium Cobalt/Chrome Ratio
Resurfacing 484 + 216 932 + 555 0.52
MoM THA 2,529 + 924 4,299 + 1,796 0.59
Dual Mod Neck 38.1 + 23.8 14.7 + 3.72 2.59