The Journal of Arthroplasty 30 (2015) 416–418
Contents lists available at ScienceDirect
The Journal of Arthroplasty journal homepage: www.arthroplastyjournal.org
Failure of a Novel Ceramic-on-Ceramic Hip Resurfacing Prosthesis Gulraj S. Matharu, MBChB, MRCS a, Joseph Daniel, FRCS, MS (Orth) b, Hena Ziaee, BSc b, Derek J.W. McMinn, MD, FRCS b a b
The Royal Orthopaedic Hospital, Northfield, Birmingham, B31 2AP, United Kingdom The McMinn Centre, 25 Highfield Road, Edgbaston, Birmingham, B15 3DP, United Kingdom
a r t i c l e
i n f o
Article history: Received 15 July 2014 Accepted 11 October 2014 Keywords: ceramic-on-ceramic fracture hip resurfacing metal ions revision arthroplasty
a b s t r a c t We report the early failure of five ceramic-on-ceramic hip resurfacings (CoCHRs). The ceramic used for the acetabular liner was a novel ceramic-composite (two thirds polyurethane and one third alumina ceramic). All cases were revised for increasing metal ion levels (blood cobalt 3.93–208.0 μg/l and chromium 1.57–17.5 μg/l) due to ceramic liner fracture and/or accelerated wear of the ceramic femoral head coating. Patients underwent bearing exchange and revision using primary hip arthroplasty implants at a mean of 3.0 years following CoCHR. Intraoperatively all patients had metallosis. At 1 to 2 years of follow-up blood metal ions normalized with no complications. We do not recommend this particular type of ceramic-on-ceramic bearing for hip resurfacing. © 2014 Elsevier Inc. All rights reserved.
Well-designed and well-implanted metal-on-metal hip resurfacing (MoMHR) provides good clinical outcomes in selected young individuals with hip arthritis [1]. Despite this a small proportion of patients will develop problems related to high bearing wear and/or metal hypersensitivity requiring revision arthroplasty [1,2]. MoMHR is therefore contraindicated in a patient with metal allergy. If a ceramic-onceramic bearing could be used for hip resurfacing it would offer the benefit of reduced metal release [3,4] and circumvent adverse reactions to metal debris (ARMD), a phenomenon which has adversely affected the number of bone conservative arthroplasties performed in recent years [5]. However, historic ceramic-on-ceramic hip resurfacing (CoCHR) designs experienced high rates of aseptic loosening [6]. A new design CoCHR was offered to five patients with metal allergies, all of whom were young and otherwise suitable for hip resurfacing (HR) [1]. All five patients had excellent early results including low systemic metal ion concentrations, but subsequently developed symptoms and progressively increasing metal ion concentrations in the short-term requiring revision arthroplasty. This paper describes our experience with a novel CoCHR implant.
after detailed discussion with the patient and informed consent. All patients were suitable for HR but had a history of intolerance to metals and tested positive for nickel hypersensitivity on lymphocyte transformation testing. Each patient had normal renal function, with no other metal implants or hardware in the body. The CoCHR device consisted of a cemented femoral head with a metallic base made of cobaltchrome alloy and a solid ceramic coating. This articulated with an ESKA-Ceram (ceramic-composite comprising two thirds polyurethane and one third alumina ceramic) liner (Fig. 1) fitted into a poroussurface Titanium–Niobium acetabular shell through a secure taper locking mechanism. The acetabular component had an articular arc angle of 164 °. Measurements of the retrieved components showed the liner thickness to be 4.4 mm at the pole and 1.4 mm at the periphery. The thickness of the assembled shell-liner construct was 8.2 mm at the pole. The ceramic coating thickness of the femoral component was 0.74 mm. All surgeries were performed by the senior surgeon (DJWM) experienced in MoMHR using a mini-posterior approach. Patients underwent regular clinical, radiological, and metal ion follow-up as per the institution protocol (2 months, 6 months, 1 year, then annually) which included whole blood and urine cobalt and chromium assessments.
Patients and Methods Results Between 2008 and 2009 a CoCHR device (ESKA, Lübeck, Germany) was implanted in five patients (five hips) for primary osteoarthritis No grants or funding have directly been received by any of the authors for the work presented. The Conflict of Interest statement associated with this article can be found at http://dx. doi.org/10.1016/j.arth.2014.10.019. Reprint requests: Mr Joseph Daniel, FRCS, MS (Orth), The McMinn Centre, 25 Highfield Road, Edgbaston, Birmingham, B15 3DP, United Kingdom. http://dx.doi.org/10.1016/j.arth.2014.10.019 0883-5403/© 2014 Elsevier Inc. All rights reserved.
All five patients had an uneventful recovery and excellent early results. The mean acetabular component inclination and anteversion was 39.8 ° (range 34 °–47 °) and 14.2 ° (range 10 °–18 °) respectively. After up to 3 years of symptom-free hip function all patients developed symptoms (including clicking, discomfort, and pain) and progressively increasing systemic metal ion concentrations requiring revision surgery at a mean of 3.0 years (Table 1). All patients had highly elevated metal
G.S. Matharu et al. / The Journal of Arthroplasty 30 (2015) 416–418
Fig. 1. ESKA Ceram hip resurfacing components.
ion levels in whole blood (Fig. 2) and urine (median urine cobalt 971 μg/24 h and chromium 59.2 μg/24 h) prior to revision. Blood inflammatory markers were normal in all cases. Four patients were revised at this centre by the same surgeon using the same surgical approach. One patient (patient 5 in Table 1) had her revision surgery at another institution. All four patients revised at this centre had evidence of metallosis and effusions intraoperatively with black-stained periprosthetic tissues and jet black fluid (Fig. 3). In three of the four cases the ceramic liner was fractured. The ceramic femoral head coating was worn through to the metal base in all. None of the implants removed were loose, with no evidence of deep infection or softtissue destruction in any case. Revision was achieved with primary total hip implants with ceramic-on-polyethylene bearings used in all four cases. Histology demonstrated reactive changes with extensive metallosis, metal-laden macrophages and fibrosis, but no evidence of ALVAL. Microbiological samples sent from revision were all negative for infection. At a mean follow-up of 18 months following revision all patients were asymptomatic with no complications or need for surgical re-intervention. Systemic metal ion concentrations normalized in all cases after revision (Fig. 2). Discussion This represents the first case series in the literature of the outcomes of a modern CoCHR device. CoCHR was used in patients who were suitable for HR but had hypersensitivity to nickel, in order to avoid the risk
417
of ARMD. After an initial symptom-free and low metal ion release period, all patients developed symptoms and significantly raised blood and urine metal ion concentrations requiring revision. This was due to the development of an unintended metal-on-ceramic or metal-on-metal articulation by one of two mechanisms: (1) early ceramic liner fracture resulting in third body particle release, or (2) accelerated wear of the ceramic femoral head coating. Both these processes led to exposure of the underlying metal in the femoral component and subsequent catastrophic metal wear. We have subsequently discontinued the use of this CoCHR device. We are only aware of one case report describing a patient with metal allergy undergoing CoCHR subsequently developing metallosis requiring early revision [7]. The clinical presentation and intraoperative findings were similar to those described here with accelerated wear of the ceramic femoral head coating [7]. We are unaware of any published reports of the former mechanism of CoCHR failure caused by a fractured ceramic liner. Such liner fractures have been observed in early reports of ceramic-on-ceramic total hip arthroplasties (CoC THAs) [8] but are now less common with newer materials. In recent years CoC THAs have shown promising ten-year results in young patients with hip arthritis [9]. In contrast, HR with the bearing couple used in this series demonstrated poor short-term results, even when implanted by an experienced surgeon with excellent results in MoMHR [1]. It is important to note the ceramic used for the liners in this series was a novel polyurethane and alumina composite material. This is different to the ceramic used in current CoC hip bearings which are Alumina, Zirconia, or Alumina/Zirconia sintered ceramics. The spread of cup inclination and anteversion (Table 1) demonstrates that these were within the optimal range, therefore it is suspected that device positioning was not a problem. The failure mechanism is likely to be multi-factorial and related to the materials used and/or design features. It is possible the clearance between the liner and the shell was not adequate to allow it to fully lock. Furthermore the flexible liner material could have provided insufficient rigidity for secure fixation in the taper lock, leading to possible sliding and uncoupling of the liner within the shell. In addition, there are uncertainties about the fracture-resistance and wear-resistance of the materials under in-vivo loading conditions. Therefore these results cannot be generalized to all types of CoC hip implants [4,8]. As further research into alternative HR bearings continues we should be wary of unexpected failure modes.
Table 1 Details of Five Patients With Failed Ceramic-on-Ceramic Hip Resurfacings.
Age (years) at resurfacing/gender Body mass index (kg/m2) Acetabular/femoral component size (mm) Initial cup inclination (°) Initial cup anteversion (°) Presentation and symptoms Time to revision (years) Pre-revision ion concentrations Blood cobalt (μg/l) Blood chromium (μg/l) Urine cobalt (μg/24 h) Urine chromium (μg/24 h) Intraoperative findings
Revision performed Follow-up period after revision (years) Complications after revision Ion concentrations at latest follow-up after revision Blood cobalt (μg/l) Blood chromium (μg/l) Urine cobalt (μg/24 h) Urine chromium (μg/24 h)
Patient 1
Patient 2
Patient 3
Patient 4
Patient 5
39/F 31.6 50/42 47 18 Hip pain, Limp, clicking 1.9
50/F 21.5 52/44 42 13 Hip pain, clicking 2.4
42/F 28.3 56/48 34 10 Clicking, hip giving way 3.2
56/F 27.3 52/44 35 18 Occasional clicking 3.6
38/F 26.2 52/44 41 12 Clicking, hip discomfort 3.9
120 8.86 3.89 1.07 Liner spin out and edge fractured, head worn through, metallosis CoP THA 1 None
155 10.4 971 59.2 Liner edge fractured, head worn through, severe metallosis CoP THA 2 None
208 17.5 2783 125 Liner edge fractured, head worn through, severe metallosis, osteolysis CoP THA 2 None
53.1 13.1 1661 135 Ceramic head worn through, severe metallosis CoP THA 1 None
3.93 1.57 77.3 13.6 Ceramic head worn through, severe metallosis CoC THA NA NA
0.42 0.83 1.45 0.42
0.33 0.40 1.60 1.60
1.22 2.85 7.60 17.1
0.71 2.36 7.12 12.8
NA NA NA NA
CoP THA = ceramic-on-polyethylene total hip arthroplasty; CoC THA = ceramic-on-ceramic total hip arthroplasty; F = female; NA = data not available.
418
G.S. Matharu et al. / The Journal of Arthroplasty 30 (2015) 416–418
Fig. 2. Whole blood metal ion concentrations before and after the ceramic-on-ceramic hip resurfacing and revision procedures. Plots illustrate the mean and standard deviation.
Fig. 3. Intraoperative photograph showing effusion of black metal-stained fluid and the components retrieved at operation (fractured ceramic liner and femoral component with ceramic femoral head coating worn through).
In conclusion, we observed high early failure rates when using a novel CoC bearing for HR. We therefore recommend this particular type of CoC bearing is not used for HR. Acknowledgments All the work presented here was carried out by the four listed authors, and therefore there are no additional acknowledgments to be declared. References 1. McMinn DJ, Daniel J, Ziaee H, et al. Indications and results of hip resurfacing. Int Orthop 2011;35:231.
2. Holland JP, Langton DJ, Hashmi M. Ten-year clinical, radiological and metal ion analysis of the Birmingham Hip Resurfacing: from a single, non-designer surgeon. J Bone Joint Surg (Br) 2012;94-B:471. 3. Scholz J, Grundei H, Klingbeil K. ESKA-Ceram — a new material in hip endoprosthetics. Biomed Tech (Berl) 2000;45:377. 4. Dickinson AS, Browne M, Wilson KC, et al. Pre-clinical evaluation of ceramic femoral head resurfacing prostheses using computational models and mechanical testing. Proc Inst Mech Eng H 2011;225:866. 5. National Joint Registry for England and Wales: tenth annual report 2013. http://www. njrcentre.org.uk. [Accessed 4 October 2014]. 6. Knahr K, Salzer M, Plenk Jr H, et al. Experience with bioceramic implants in orthopaedic surgery. Biomaterials 1981;2:98. 7. Atrey A, Waite J, Hart A, et al. Failure of a ceramic-on-ceramic hip resurfacing due to metallosis. A case report. JBJS Case Connect 2014;4:e28. 8. Jeffers JR, Walter WL. Ceramic-on-ceramic bearings in hip arthroplasty: state of the art and the future. J Bone Joint Surg (Br) 2012;94-B:735. 9. Milošev I, Kovač S, Trebše R, et al. Comparison of ten-year survivorship of hip prostheses with use of conventional polyethylene, metal-on-metal, or ceramic-on-ceramic bearings. J Bone Joint Surg (Am) 2012;94-A:1756.
Contents lists available at ScienceDirect
The Journal of Arthroplasty journal homepage: www.arthroplastyjournal.org
Failure of a Novel Ceramic-on-Ceramic Hip Resurfacing Prosthesis Gulraj S. Matharu, MBChB, MRCS a, Joseph Daniel, FRCS, MS (Orth) b, Hena Ziaee, BSc b, Derek J.W. McMinn, MD, FRCS b a b
The Royal Orthopaedic Hospital, Northfield, Birmingham, B31 2AP, United Kingdom The McMinn Centre, 25 Highfield Road, Edgbaston, Birmingham, B15 3DP, United Kingdom
a r t i c l e
i n f o
Article history: Received 15 July 2014 Accepted 11 October 2014 Keywords: ceramic-on-ceramic fracture hip resurfacing metal ions revision arthroplasty
a b s t r a c t We report the early failure of five ceramic-on-ceramic hip resurfacings (CoCHRs). The ceramic used for the acetabular liner was a novel ceramic-composite (two thirds polyurethane and one third alumina ceramic). All cases were revised for increasing metal ion levels (blood cobalt 3.93–208.0 μg/l and chromium 1.57–17.5 μg/l) due to ceramic liner fracture and/or accelerated wear of the ceramic femoral head coating. Patients underwent bearing exchange and revision using primary hip arthroplasty implants at a mean of 3.0 years following CoCHR. Intraoperatively all patients had metallosis. At 1 to 2 years of follow-up blood metal ions normalized with no complications. We do not recommend this particular type of ceramic-on-ceramic bearing for hip resurfacing. © 2014 Elsevier Inc. All rights reserved.
Well-designed and well-implanted metal-on-metal hip resurfacing (MoMHR) provides good clinical outcomes in selected young individuals with hip arthritis [1]. Despite this a small proportion of patients will develop problems related to high bearing wear and/or metal hypersensitivity requiring revision arthroplasty [1,2]. MoMHR is therefore contraindicated in a patient with metal allergy. If a ceramic-onceramic bearing could be used for hip resurfacing it would offer the benefit of reduced metal release [3,4] and circumvent adverse reactions to metal debris (ARMD), a phenomenon which has adversely affected the number of bone conservative arthroplasties performed in recent years [5]. However, historic ceramic-on-ceramic hip resurfacing (CoCHR) designs experienced high rates of aseptic loosening [6]. A new design CoCHR was offered to five patients with metal allergies, all of whom were young and otherwise suitable for hip resurfacing (HR) [1]. All five patients had excellent early results including low systemic metal ion concentrations, but subsequently developed symptoms and progressively increasing metal ion concentrations in the short-term requiring revision arthroplasty. This paper describes our experience with a novel CoCHR implant.
after detailed discussion with the patient and informed consent. All patients were suitable for HR but had a history of intolerance to metals and tested positive for nickel hypersensitivity on lymphocyte transformation testing. Each patient had normal renal function, with no other metal implants or hardware in the body. The CoCHR device consisted of a cemented femoral head with a metallic base made of cobaltchrome alloy and a solid ceramic coating. This articulated with an ESKA-Ceram (ceramic-composite comprising two thirds polyurethane and one third alumina ceramic) liner (Fig. 1) fitted into a poroussurface Titanium–Niobium acetabular shell through a secure taper locking mechanism. The acetabular component had an articular arc angle of 164 °. Measurements of the retrieved components showed the liner thickness to be 4.4 mm at the pole and 1.4 mm at the periphery. The thickness of the assembled shell-liner construct was 8.2 mm at the pole. The ceramic coating thickness of the femoral component was 0.74 mm. All surgeries were performed by the senior surgeon (DJWM) experienced in MoMHR using a mini-posterior approach. Patients underwent regular clinical, radiological, and metal ion follow-up as per the institution protocol (2 months, 6 months, 1 year, then annually) which included whole blood and urine cobalt and chromium assessments.
Patients and Methods Results Between 2008 and 2009 a CoCHR device (ESKA, Lübeck, Germany) was implanted in five patients (five hips) for primary osteoarthritis No grants or funding have directly been received by any of the authors for the work presented. The Conflict of Interest statement associated with this article can be found at http://dx. doi.org/10.1016/j.arth.2014.10.019. Reprint requests: Mr Joseph Daniel, FRCS, MS (Orth), The McMinn Centre, 25 Highfield Road, Edgbaston, Birmingham, B15 3DP, United Kingdom. http://dx.doi.org/10.1016/j.arth.2014.10.019 0883-5403/© 2014 Elsevier Inc. All rights reserved.
All five patients had an uneventful recovery and excellent early results. The mean acetabular component inclination and anteversion was 39.8 ° (range 34 °–47 °) and 14.2 ° (range 10 °–18 °) respectively. After up to 3 years of symptom-free hip function all patients developed symptoms (including clicking, discomfort, and pain) and progressively increasing systemic metal ion concentrations requiring revision surgery at a mean of 3.0 years (Table 1). All patients had highly elevated metal
G.S. Matharu et al. / The Journal of Arthroplasty 30 (2015) 416–418
Fig. 1. ESKA Ceram hip resurfacing components.
ion levels in whole blood (Fig. 2) and urine (median urine cobalt 971 μg/24 h and chromium 59.2 μg/24 h) prior to revision. Blood inflammatory markers were normal in all cases. Four patients were revised at this centre by the same surgeon using the same surgical approach. One patient (patient 5 in Table 1) had her revision surgery at another institution. All four patients revised at this centre had evidence of metallosis and effusions intraoperatively with black-stained periprosthetic tissues and jet black fluid (Fig. 3). In three of the four cases the ceramic liner was fractured. The ceramic femoral head coating was worn through to the metal base in all. None of the implants removed were loose, with no evidence of deep infection or softtissue destruction in any case. Revision was achieved with primary total hip implants with ceramic-on-polyethylene bearings used in all four cases. Histology demonstrated reactive changes with extensive metallosis, metal-laden macrophages and fibrosis, but no evidence of ALVAL. Microbiological samples sent from revision were all negative for infection. At a mean follow-up of 18 months following revision all patients were asymptomatic with no complications or need for surgical re-intervention. Systemic metal ion concentrations normalized in all cases after revision (Fig. 2). Discussion This represents the first case series in the literature of the outcomes of a modern CoCHR device. CoCHR was used in patients who were suitable for HR but had hypersensitivity to nickel, in order to avoid the risk
417
of ARMD. After an initial symptom-free and low metal ion release period, all patients developed symptoms and significantly raised blood and urine metal ion concentrations requiring revision. This was due to the development of an unintended metal-on-ceramic or metal-on-metal articulation by one of two mechanisms: (1) early ceramic liner fracture resulting in third body particle release, or (2) accelerated wear of the ceramic femoral head coating. Both these processes led to exposure of the underlying metal in the femoral component and subsequent catastrophic metal wear. We have subsequently discontinued the use of this CoCHR device. We are only aware of one case report describing a patient with metal allergy undergoing CoCHR subsequently developing metallosis requiring early revision [7]. The clinical presentation and intraoperative findings were similar to those described here with accelerated wear of the ceramic femoral head coating [7]. We are unaware of any published reports of the former mechanism of CoCHR failure caused by a fractured ceramic liner. Such liner fractures have been observed in early reports of ceramic-on-ceramic total hip arthroplasties (CoC THAs) [8] but are now less common with newer materials. In recent years CoC THAs have shown promising ten-year results in young patients with hip arthritis [9]. In contrast, HR with the bearing couple used in this series demonstrated poor short-term results, even when implanted by an experienced surgeon with excellent results in MoMHR [1]. It is important to note the ceramic used for the liners in this series was a novel polyurethane and alumina composite material. This is different to the ceramic used in current CoC hip bearings which are Alumina, Zirconia, or Alumina/Zirconia sintered ceramics. The spread of cup inclination and anteversion (Table 1) demonstrates that these were within the optimal range, therefore it is suspected that device positioning was not a problem. The failure mechanism is likely to be multi-factorial and related to the materials used and/or design features. It is possible the clearance between the liner and the shell was not adequate to allow it to fully lock. Furthermore the flexible liner material could have provided insufficient rigidity for secure fixation in the taper lock, leading to possible sliding and uncoupling of the liner within the shell. In addition, there are uncertainties about the fracture-resistance and wear-resistance of the materials under in-vivo loading conditions. Therefore these results cannot be generalized to all types of CoC hip implants [4,8]. As further research into alternative HR bearings continues we should be wary of unexpected failure modes.
Table 1 Details of Five Patients With Failed Ceramic-on-Ceramic Hip Resurfacings.
Age (years) at resurfacing/gender Body mass index (kg/m2) Acetabular/femoral component size (mm) Initial cup inclination (°) Initial cup anteversion (°) Presentation and symptoms Time to revision (years) Pre-revision ion concentrations Blood cobalt (μg/l) Blood chromium (μg/l) Urine cobalt (μg/24 h) Urine chromium (μg/24 h) Intraoperative findings
Revision performed Follow-up period after revision (years) Complications after revision Ion concentrations at latest follow-up after revision Blood cobalt (μg/l) Blood chromium (μg/l) Urine cobalt (μg/24 h) Urine chromium (μg/24 h)
Patient 1
Patient 2
Patient 3
Patient 4
Patient 5
39/F 31.6 50/42 47 18 Hip pain, Limp, clicking 1.9
50/F 21.5 52/44 42 13 Hip pain, clicking 2.4
42/F 28.3 56/48 34 10 Clicking, hip giving way 3.2
56/F 27.3 52/44 35 18 Occasional clicking 3.6
38/F 26.2 52/44 41 12 Clicking, hip discomfort 3.9
120 8.86 3.89 1.07 Liner spin out and edge fractured, head worn through, metallosis CoP THA 1 None
155 10.4 971 59.2 Liner edge fractured, head worn through, severe metallosis CoP THA 2 None
208 17.5 2783 125 Liner edge fractured, head worn through, severe metallosis, osteolysis CoP THA 2 None
53.1 13.1 1661 135 Ceramic head worn through, severe metallosis CoP THA 1 None
3.93 1.57 77.3 13.6 Ceramic head worn through, severe metallosis CoC THA NA NA
0.42 0.83 1.45 0.42
0.33 0.40 1.60 1.60
1.22 2.85 7.60 17.1
0.71 2.36 7.12 12.8
NA NA NA NA
CoP THA = ceramic-on-polyethylene total hip arthroplasty; CoC THA = ceramic-on-ceramic total hip arthroplasty; F = female; NA = data not available.
418
G.S. Matharu et al. / The Journal of Arthroplasty 30 (2015) 416–418
Fig. 2. Whole blood metal ion concentrations before and after the ceramic-on-ceramic hip resurfacing and revision procedures. Plots illustrate the mean and standard deviation.
Fig. 3. Intraoperative photograph showing effusion of black metal-stained fluid and the components retrieved at operation (fractured ceramic liner and femoral component with ceramic femoral head coating worn through).
In conclusion, we observed high early failure rates when using a novel CoC bearing for HR. We therefore recommend this particular type of CoC bearing is not used for HR. Acknowledgments All the work presented here was carried out by the four listed authors, and therefore there are no additional acknowledgments to be declared. References 1. McMinn DJ, Daniel J, Ziaee H, et al. Indications and results of hip resurfacing. Int Orthop 2011;35:231.
2. Holland JP, Langton DJ, Hashmi M. Ten-year clinical, radiological and metal ion analysis of the Birmingham Hip Resurfacing: from a single, non-designer surgeon. J Bone Joint Surg (Br) 2012;94-B:471. 3. Scholz J, Grundei H, Klingbeil K. ESKA-Ceram — a new material in hip endoprosthetics. Biomed Tech (Berl) 2000;45:377. 4. Dickinson AS, Browne M, Wilson KC, et al. Pre-clinical evaluation of ceramic femoral head resurfacing prostheses using computational models and mechanical testing. Proc Inst Mech Eng H 2011;225:866. 5. National Joint Registry for England and Wales: tenth annual report 2013. http://www. njrcentre.org.uk. [Accessed 4 October 2014]. 6. Knahr K, Salzer M, Plenk Jr H, et al. Experience with bioceramic implants in orthopaedic surgery. Biomaterials 1981;2:98. 7. Atrey A, Waite J, Hart A, et al. Failure of a ceramic-on-ceramic hip resurfacing due to metallosis. A case report. JBJS Case Connect 2014;4:e28. 8. Jeffers JR, Walter WL. Ceramic-on-ceramic bearings in hip arthroplasty: state of the art and the future. J Bone Joint Surg (Br) 2012;94-B:735. 9. Milošev I, Kovač S, Trebše R, et al. Comparison of ten-year survivorship of hip prostheses with use of conventional polyethylene, metal-on-metal, or ceramic-on-ceramic bearings. J Bone Joint Surg (Am) 2012;94-A:1756.
