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BIRMINGHAM HIP

Resurfacing System

BHR Birmingham Hip Resurfacing

Overview

BHR is the global market leading Hip Resurfacing system with over 180,000 implantations worldwide since the introduction in 1997. Features of the BIRMINGHAM HIP Resurfacing System include:

  1. Bone conservation
  2. Global long term clinical outcomes
  3. Metallurgy and Design

This successful, bone conserving, hip resurfacing system is well documented through independent clinical and laboratory studies. Additional clinical evidence supporting our BIRMINGHAM HIP Resurfacing System is published in multiple registries. This bone conserving procedure, combined with the virtual elimination of dislocation and excellent survivorship make the BIRMINGHAM HIP Resurfacing ideal for the informed active male patient. For additional information, contact your local sales rep.

 

BHR product image


References

1.  FDA Review Memo, BHR Important Medical Information, Page 59.
2.  Back DL, Dalziel R, Young D, Shimmin A. Early results of primary BIRMINGHAM HIP resurfacings - An independent prospective study of the first 230 hips. J Bone Joint Surg Br, 2005, 87(3):324-9.
3. Treacy RB, McBryde CW, Pynsent PB. BIRMINGHAM HIP resurfacing arthroplasty. A minimum follow-up of five years. J Bone Joint Surg Br (2005 Feb) 87(2):167-70.
4. Nishii T, Sugano N, et al. Five-year results of metal-on-metal resurfacing arthroplasty in Asian patients. JOA (2007) Vol. 22 No. 2.
5. Steffen RT, Pandit HP, Palan J, Beard DJ, Gundle R, McLardy-Smith P, Murray DW, Gill HS. The five-year results of the BIRMINGHAM HIP arthroplasty – An independent series. J Bone Joint Surg Br (2008 Apr); 90-B:436-41.
6. Richardson JB, et al. Minimum 7-year outcome of the BIRMINGHAM HIP Resurfacing. A review of 1,345 cases from the 2007 international register. Presented at the 2007 British Orthopaedic Association.
7. Nelson K, Dyson J. Wear simulation of a metal-on-metal resurfacing prosthesis. AEA Technology Group, Harwell, UK. 1997.
8. Que L. Effect of heat treatment on the microstructure, hardness and wear resistance of the as-cast and forged cobalt-chromium implant alloys. Presented at the Symposium on cobalt-based alloys for biomedical application. Nov 3-4, 1998, Norfolk, Virginia, USA.
9. Varano R, Bobyn JD, Medley JB, Yue S. Does alloy heat treatment influence metal-on-metal wear? Poster #1399 presented at the 49th Annual meeting of the Orthopaedic Research Society. New Orleans, LA, USA. 2003.
10. Cawley J, Metcalf JEP, Jones AH, Band TJ, Skupien A. A tribological study of cobalt chromium molybdenum alloys used in metal-on-metal resurfacing hip arthroplasty. Wear, 255 (2003) pp. 999-1006.
11. Ahier S, Ginsburg K. Influence of carbide distribution on the wear and friction of Vitallium. Poc Inst Mech Eng, 1966; 181:127-9.
12. Clemow AJT, Daniell BL. The influence of microstructure on the adhesive wear resistance of a Co-Cr-Mo alloy. Wear, 1980; 61:219-31.
13. Wang KK, Wang A, Gustavson LJ. Metal-on-metal wear testing of chrome cobalt alloys. In: Digesi JA, Kennedy RL, Pillar, eds. Cobalt based alloys for bio-medical applications, ASTM STP 1365: Wear Characterization. West Conshohocken, PA 1999; 135-44.
14. McMinn DJW. Ten year Kaplan-Meier survival analysis of McMinn Corin hip resurfacings.
Journal Of Engineering In Medicine, 2005, Proceedings Institute of Mech Engineers, Part H.
15. McMinn D. Development of metal/metal hip resurfacing. Hip International. 2003; 13(1) suppl 2.
16. McMinn DJW, et al. Friction testing in metal-on-metal bearings with different clearances using blood as lubricant.  52nd Annual Meeting of the Orthopaedic Research Society, 2006. Paper No. 0500.
17. Kamali A, Daniel JT, Javid SF, Youseffi M, Band T, Ashton R, Hussain A, Li CX, Daniel J, McMinn DJW. The effect of cup deflection on friction in metal-on-metal bearings, AAOS, 5-8 March 2008, Poster Exhibit.
18. McMinn DJW. BHR lecture, BOA Manchester 2004.
19. Unsworth A, Vassiliou K, Elfick APD, Scholes SC. The effect of “running-in” on the tribology and surface morphology of metal-on-metal hip resurfacing devices in simulator studies. JEIM Part H 2.

Clinical Data

Global Long-Term Clinical Outcomes 

 Paper

 Site

n

 Quoted Survivorship (%)

 Years Follow-up

 De Smet. Hip Intl, 2005

Ghent, Belgium

200

99.5

1.5

 Daniel et al. JBJS, 2004

Birmingham, UK

446

99.8

4

 Treacy et al. JBJS 2005

Birmingham, UK

144

99.0

5

 Hing et al. JBJS 2007

Melbourne, Australia

230

99.1

5

 McBryde et al JBJS 2010

Birmingham, UK, 10 surgeons

2,123

97.5

5

 Nishii et al. JOA 2007

Osaka, Japan

50

96.0

5

 Su at al. JOA 2014

5 multi centre study, USA

265

97.6 (M: 98.6, F: 94.7)

5

 Reito et al. Intl. Orth. (SICOT) 2011

Tampere, Finland

144

96.7

6

 Heilpern et al. JBJS 2008

Kent and Sussex, UK

110

96.3

6

 Pollard et al. JBJS 2006

Bristol, UK

54

94.0

6

 Steffen et al. JBJS 2008

Oxford, UK

610

95.1

7

 Madhu et al. JOA 2010

Hull, UK

117

91.5

7

 Khan et al. JOA 2008

Global, 58 surgeons

653

95.7

8

 Witzleb. Minerva Ortop Trauma, 2009

Dresden, Germany

100

95.0

8

 Robinson, et al. Oswestry Register 2008

Oswestry, UK

518

95.4

10

 

 Carrothers et al. JBJS 2010

Oswestry, UK

5,000

96.4

10

 

 Treacy et al. JBJS 2011

Birmingham, UK

144

93.5 (M: 98%)

10

 

 Holland et al. JBJS 2012

Newcastle, UK

100

92.0 (M: 94.6%)

10

 

 Murray et al. JBJS 2012

Oxford, UK

379

95 (males only)

10

 

 Shimmin et al. JBJS 2012

Melbourne, Australia

230

94.5 (M: 97.5)

10

 

 Treacy et al.  Intl Orth. (SICOT) 2013

Birmingham, UK

180

96.4% (≥65 years, males 98.9%)

10

 

 De Smet. ISTA 2011

Ghent, Belgium

149

93.1

12

 

 McMinn et al. Intl. Orth. (SICOT) 2011

Birmingham, UK

3,095

96 (<55 years OA 98)

13

 

DeSmet et al,  Bone Joint J 2013

Ghent, Belgium

202

92.4

13.2

 

McMinn et al,  Bone Joint J 2014

Birmingham, UK

1000

95.8 (M: 98)

13.7 mean

 

Treacy et al.  Bone Joint J 2013

Birmingham, UK

447

100% males <50

14

 

Treacy et al. SICOT 2015

Birmingham, UK

 

95.8% (overall survivorship  designing surgeons)

15

 

  • The Australian Orthopaedic Association National Joint Replacement Registry Annual Report 20151 showed BHR survivorship of 90.2% at 14 years follow-up, the longest of any resurfacing device.
  • BHR continues to be the most implanted resurfacing device world-wide and is the only hip resurfacing device with 14 years of registry data
§

 

Clinical Evidence: Reference

1.Australian Orthopaedic Association National Joint Replacement Registry Annual Report. Adelaide: AOA; 2015


 


Design and Technology

The BIRMINGHAM HIP◊ Resurfacing System now has over eighteen years of clinical history and utilizes an as-cast cobalt chrome metal on metal bearing with a highly polished finish. As Cast CoCr components have shown superior wear resistance compared to other forms of the alloy. This is because the As Cast process maintains the block carbides integrated throughout the metal structure. These carbides are harder than the metal substrate and reduce wear, especially at startup.

Metallurgy

The BHR is produced using the investment casting process from high carbon cobalt chrome in the As Cast micro-structural condition. The First Generation Metal-on-Metal bearings manufactured in the 1950s and 1960s were produced by the investment casting process (Ring and McKee Farrar prostheses). From these devices we have recorded the longest benign clinical history of cobalt chrome alloys with extremely low linear wear rates.

Forensic studies of these successful first generation Metal-on-Metal bearings were conducted to determine the material chemistry, micro-structural condition, bearing clearance, and evidence of the wear mechanism. These implants were typically produced from the investment casting process from high carbon Cobalt Chrome in the As Cast condition. The material contained large block carbides.

The BHR◊ is produced using the investment casting process from high carbon cobalt chrome in the As Cast micro-structural condition.  Wear studies have shown that Cobalt Chrome in its As Cast form has superior wear resistance to other forms of the alloy. 1, 2, 3 

Heat treating, which includes hot isostatic pressing (HIP), solution heat treatment (HT), wrought forging or sintering modifies the microstructure, reducing the block carbides in both quantity and quality. This directly affects the wear resistance of the metal, as shown in diagram A. 4, 5, 6

The importance of carbide structure has been demonstrated in independent testing with other devices. A publication highlighted the difference in the wear rates of heat treated and As Cast products. The cumulative linear wear rate data showed substantially more wear with the heat treated metallurgy when compared to the As Cast devices. 7

First generation Metal-on-Metal implant retrieved after 26 years. 

first generation metal on metal

Diagram A: Micro-abrasive Wear of Cobalt Chrome Alloys. 6. 

BHR micro-abrasive wear chart

Diagram B: Linear Wear of As Cast device compared to HIP & HT device. 7

BHR linear wear

Typical Microstructures of First Generation Metal-on-Metal

BHR microstructures of first generation MoM

This image shows a cross-section micrograph through the articulating surface and shows the coarse primary, block carbide in the Cobalt Chromium matrix. The BHR has a hemispherical cup design with a cast-in porous ingrowth surface called POROCAST. This ingrowth surface does not require a heat treatment to attach the beads and therefore preserves the carbide structure. 

BHR product image

Clearance

Clearance is the term used to describe the effective gap between the femoral head and acetabular cup in a Metal-on-Metal bearing. It is calculated by subtracting the radius of the femoral head from the radius of the acetabular cup. This difference in radii is used to describe the gap at the equatorial position on the bearing when the femoral head is in contact with the acetabular cup in a polar orientation. Polar bearings operate with a large apparent contact surface area. However the real contact surface area is very small. It is at this point where the articular surfaces interact creating friction and wear.

What is clearance?

BHR clearance

 

Generation of fluid film

BHR fluid film

 

A fluid film is present when the two articulating surfaces are separated by the lubricant.  It is the clearance (entrainment) angle and motion which generates the fluid film.

Optimal Clearance

Factors such as bone density, implant position and post- surgery may all affect the ability of the bearing to generate a fluid film. As well as a value of the difference between head and cup radii, clearance can be expressed as a ratio to head diameter. There is an optimal clearance associated with each head diameter. Although low clearances work well in laboratory conditions, there may be an issue in the clinical environment. Factors such as bone density, implant position and post surgery may all effect the ability of the bearing to generate a fluid film. With low clearances, there is reduced tolerance for correct function in less than perfect implantation or patient conditions.

As a Metal-on-Metal bearing is not in continuous motion, it operates in a mixed lubrication regime and its longevity is linked to its ability to generate and sustain a fluid film. Laboratory evidence confirms the BHR generates fluid film lubrication. Small clearances increase friction and may cause micro motion in the cup. This may hamper bony ingrowth resulting in impaired fixation. 8

The Stribeck Curve is a graphical representation of the measured frictional forces occurring in a bearing. From the shape of the curve, deductions can be made concerning the lubrication operating conditions of the bearing.

Results of friction testing of the BHR are shown below in Graph A. The friction tests suggest boundary lubrication pre-testing but at 1 million cycles, a mixed lubrication regime was evident. By 2 million cycles, the classical Stribeck curve had formed indicating a considerable contribution from fluid film, which continued to be evident at 3 million cycles. 9

Stribeck Curve Graph A 

Stribeck curve graph A

Changes in Friction and Lubrication during a 3 Million-cycle weat test on a CoCrMo/CoCrMo Hip Resurfacing Device.

Unsworth, K Vassiliou, APD Elfick, SC Scholes Centre for Biomedical Engineering, University of Durham, England.

 

Surface Finish

It was clear that some of the early McKee/Farrar failures were due to poor manufacturing. In the modern era of metal on metal joints the highest possible technology is employed to achieve near perfect bearings. 

BHR factory picture 1

BHR manufacturing 2

BHR manufacturing

BHR manufacturing

Design and Technology: References 

1. Ahier S, Ginsburg K. Influence of carbide distribution on the wear and friction of Vitallium. Poc Inst Mech Eng 1966; 181:127-9. 

2. Clemow AJT, Daniell BL. The influence of microstructure on the adhesive wear resistance of a Co-Cr-Mo alloy.Wear 1980; 61:219-31. 

3. Wang KK, Wang A, Gustavson LJ. Metal-on-Metal wear testing of chrome cobalt alloys. In: Digesi JA, Kennedy RL, Pillar, eds. Cobalt-based alloys for bio-medical applications, ASTM STP 1365: Wear Characterization. West Conshohocken, PA 1999; 135-44. 

4. Que L. Effect of heat treatment on the microstructure, hardness and wear resistance of the as-cast and forged Cobalt-chromium implant alloys. Presented at the Symposium on cobalt-based alloys for biomedical application. Nov 3-4, 1998, Norfolk, Virginia, USA. 

5. Varano R, Bobyn JD, Medley JB, Yue S. Does alloy heat treatment influence metal-on-metal wear? Poster #1399 presented at the49th Annual meeting of the Orthopaedic Research Society. New Orleans, Los Angeles, USA. 

6. J. Cawley, J.E.P Metcalf, A.H. Jones, T.J. Band, A. Skupien, A Tribological Study of Cobalt Chromium Molybdenum Alloys Used in Metal-on-Metal Resurfacing Hip Arthroplasty. Wear, 255 (2003) pp. 999-1006.

7. Nelson K., Dyson J., 'Wear Simulation of a Metal-on-Metal Resurfacing Prosthesis.' AEA Technology Group, Harwell, UK. 1997.

8. McMinn BHR lecture, BOA Manchester 2004.

9. The Effect of “Running-in” on the Tribology and Surface Morphology of Metal-on-Metal hip Resurfacing Device (BHR) in Simulator Studies. (Submitted for publication) JEIM Part H 2 Unsworth et al. 

 






Indications

The BIRMINGHAM HIP™ Resurfacing (BHR™) System is a single use device intended for hybrid fixation: cemented femoral head component and cementless acetabular component.

The BHR System is intended for use in patients requiring primary hip resurfacing arthroplasty due to:

  • Non-inflammatory arthritis (degenerative joint disease) such as osteoarthritis, traumatic arthritis, avascular necrosis, or dysplasia/DDH, or
  • Inflammatory arthritis such as rheumatoid arthritis.

The BHR System is intended for patients who, due to their relatively younger age or increased activity level, may not be suitable for traditional total hip arthroplasty due to an increased possibility of requiring future ipsilateral hip joint revision.

Contraindications

  • Patients who are female
  • Patients with infection or sepsis
  • Patients who are skeletally immature
  • Patients with any vascular insufficiency, muscular atrophy, or neuromuscular disease severe enough to compromise implant stability or postoperative recovery
  • Patients with bone stock inadequate to support the device including:
    • Patients with severe osteopenia or patients with a family history of severe osteoporosis or severe osteopenia
    • Patients with osteonecrosis or avascular necrosis (AVN) with >50% involvement of the femoral head (regardless of FICAT Grade).
    • Patients with multiple cysts of the femoral head (>1cm).
    • Note: In cases of questionable bone stock, a DEXA scan may be necessary to assess bone stock status.
  • Patients with known moderate to severe renal insufficiency
  • Patients who are immunosuppressed with diseases such as AIDS or persons receiving high doses of corticosteroids
  • Patients who are severely overweight
  • Patients with known or suspected metal sensitivity (e.g., jewelry)

FAQs

1. Is the BIRMINGHAM HIP Resurfacing implant clinically proven?

The BIRMINGHAM HIP  Resurfacing implant is not a new implant or technique. It has been in use worldwide since 1997.

2. Who is a candidate for the BIRMINGHAM HIP Resurfacing System?

The typical patient will be a physically active male, under 60 years of age, and suffering from hip arthritis. The implant can be used in male patients over 60 whose bone quality is strong enough to support the implant.

3. How long will the BIRMINGHAM HIP Resurfacing implant last?

It is impossible to say how long the implant will last because so many factors play into the lifespan of an implant. In the case of resurfacing, for instance, the metal-on-metal bearing surfaces of the new joint may extend its life longer than that of a traditional total hip replacement, but failure to comply with the physical rehabilitation regime may cause the implant to fail within months. A clinical study showed the BIRMINGHAM HIP Resurfacing implant had a survivorship of 95.4% at the 10 year mark, which is comparable with the survivorship of a traditional total hip replacement in the under-60 age group, and 98.6% are pleased to extremely satisfied with BHR. 1
1.  Minimum 10 Year Outcome of Birmingham Hip Resurfacing (BHR)

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