Active Articulation E1

Transcription

1 Active Articulation E1 Dual Mobility Hip System Design Rationale Knees Hips Extremities Cement and Accessories PMI Trauma Technology

2 Active Articulation E1 Dual Mobility Hip System Dual Mobility: Not a New Concept Dual mobility was introduced in the mid-1970s by Professor G. Bousquet for use in total hip replacement with the goal of preventing chronic dislocations. 1 This goal was successfully achieved 1,2,3 by combining two fundamental principles: the first is the concept of low friction arthroplasty as described by J. Charnley, where by a small head articulating against a polyethylene liner has a low risk of failure due to low wear 4 ; the second is the McKee-Farrar concept, which recommended the use of large diameter bearings to minimize the risk of dislocation. 5 The secondary motion occurs between the E1 bearing and the acetabular cup when a larger range of motion is required (Figure 2). The bearing acts as a large femoral head articulating in the metal cup. Motion 2 Principle 1 (pertaining to the ID) The smaller the head the lower the wear rates. 4 (Charnley) + Principle 2 (pertaining to the OD) The larger the head the greater the joint stability. 5 (McKee-Farrar) = Dual Mobility Biomet has a wealth of experience successfully combining these two principles in dual mobility constructs. The clinically proven AVANTAGE hip system 6 has been a market leader in Europe for over fifteen years. The Active Articulation E1 Hip System merges Biomet s engineering experience in dual mobility with the benefits of Antioxidant Infused Bearing Technology. Large range of motion The dual mobility biomechanical concept is simple. The first motion occurs between the 28 mm femoral head and the inner concave surface of the E1 bearing, until the neck of the femoral stem comes into contact with the E1 bearing (Figure 1). The significant shell-to-neck ratio of the large diameter E1 bearings provide for excellent range of motion (ROM). The ROM for the smallest Active Articulation construct is 161 degrees. 7 Range of Motion (Degrees) Figure 2 Range of Motion Potential for Acetabular Constructs 7 161º 165º AP ROM Motion Max-Rom 36 mm Liner Max-Rom + 40 mm Liner Max-Rom + 44 mm Liner Active Articulation 44 mm Cup Active Articulation 66 mm Cup Figure 3 Figure 1

3 Reduced risk of dislocation The incidence of hip dislocation is gradually increasing, and is currently the fourth largest indication for hip revision at 16%. 8 Large diameter heads have been shown to improve joint stability and increase dislocation resistance. 9,10 The Active Articulation E1 hip bearing ranges from size 38 to 60 mm. Additionally, the retentive properties of the inner-diameter of the E1 bearing can greatly minimize the risk of femoral head dislocation from the E1 bearing. E1 Antioxidant Infused Technology Changing patient demographics show that higher levels of demand are placed on acetabular components related to increased patient activity and longevity. In order to address these evolving patient needs, E1 Antioxidant Infused Technology was developed to surpass the limitations of first generation highly crosslinked polyethylenes and offer an alternative bearing that provides ultra-low wear, maintains mechanical strength and demonstrates remarkable oxidative stability. 7 Revolutionary processing E1 bearings are made from the same isostatically compressed molded polyethylene barstock as Biomet s clinically proven ArCom polyethylene. 11 The bars are then gamma irradiated to induce a high level of crosslinking. Vitamin E is subsequently infused into the highly crosslinked polyethylene to neutralize residual free radicals present after irradiation. Some manufacturers have developed different manufacturing methods in the attempt to reduce the risk of oxidation after crosslinking. One method, remelting, consists of heating the material above its melting temperature. This process reduces the amount of free radicals, which increases the oxidation resistance of the material. 12 However, recent research has demonstrated in vivo oxidation of remelted highly crosslinked bearings. 13,14 Additionally, remelting reduces the strength of the material. 12 Another manufacturing method involves annealing the crosslinked material below the melting temperature. Although annealed materials maintain their strength, the process does not fully eliminate or neutralize all the free radicals which can lead to oxidation. 12 Oxidation in acetabular bearings has been shown to lead to increased wear, decreased strength, material degradation and fracture. 12,13,15,16 Oxidative Stability Cyclic loading, combined with the in vivo environment, may potentially induce cracks in polyethylene. This phenomenon is referred to as environmental stress cracking (ESC). Researchers now believe that oxidation of highly crosslinked UHMWPE may be a result of the absorption of lipids from the synovial fluid and/or cyclic loading, 17 similar to that seen in environmental stress crack testing. 7,18 E1 samples, along with sequentially crosslinked and annealed samples, were tested to determine their resistance to ESC by stressing the samples while subjecting them to adverse aging conditions that lead to oxidation. E1 Antioxidant Infused Technology protects polyethylene from oxidation and cracking during environmental stress crack testing. 19 Oxidation levels were detectable in the sequentially crosslinked and annealed samples and increased with loading. One study demonstrated that vitamin E antioxidant infused material...protect[ed] against lipid-initiated oxidation. 20 Oxidation Index (Absorbance Units) Top Surface Oxidation Profile 7 After ESC testing Center Sequentially Crosslinked and Annealed Loaded Sequentially Crosslinked and Annealed Control E1 Material Loaded E1 Material Control Figure 4 Bottom Surface 1

4 Active Articulation E1 Dual Mobility Hip System Ultra-low wear Laboratory testing was conducted on the Active Articulation E1 Hip System to test wear during suboptimal cup position. Cups were placed at 60 degrees of inclination and the system still yielded ultra-low wear rates after five million cycles Wear Rates for Acetabular Constructs 7 High strength Biomet has carried out extensive testing to compare the mechanical properties of E1 material with both ArCom and other highly crosslinked polyethylenes. The ultimate tensile and yield strengths of the E1 material are similar to those of ArCom polyethylene and greater than those of the remelted polyethylenes (Figure 6). 7,21,22 Tensile Strength Wear Rates 5 Million Cycles % wear reduction over 36 mm ArCom liners 7 62% wear reduction over 44 mm E1 liners 7 Tensile Strength (MPa) mm ArCom Liner (45º Inclination) 44 mm E1 Liner (45º Inclination) Figure 5 60 mm Active Articulation E1 Bearing (60º Inclination) 0 ArCom 7 Polyethylene E1 Unaged Material 7 E1 Aged Material 7 100kGy Remelted 21 50kGy Remelted 22 Yield Strength Yield Strength (MPa) ArCom 7 Polyethylene E1 Unaged Material 7 E1 Aged Material 7 100kGy Remelted 21 50kGy Remelted 22 Figure 6 2

5 Cup Design The Active Articulation Hip System utilizes the clinically proven M 2 a-magnum cup. 23 The M 2 a-magnum cup is an as-cast, high carbon cobalt chrome molybdenum (CoCrMo) alloy, press-fit design, with a titanium PPS Porous Plasma Spray outer surface and a highly polished inner geometry. The exterior geometry contains four pairs of peripheral fins to enhance rotational stability and aid initial fixation (Figure 7). The outer diameter of the cup is fully hemispherical (180 ), with four rim indentations for the stable attachment of the locking impaction device. The inner diameter is designed with up to 165 degrees of acetabular-head coverage to help maximize range-of-motion and minimize subluxation. The interior geometry is honed and buffed to a high polish to achieve a strict spherical tolerance of 200 micro-inches. Proven Fixation PPS Porous Plasma Spray Coating Biomet was the first orthopedic company to introduce a plasma-sprayed prosthesis with the release of the PPS coated Taperloc hip stem in The M 2 a-magnum cup features Biomet s PPS coating, a proprietary process that is instrumental to our clinical success. Biomet s process not only helps guard against osteolysis but allows both immediate and long-term fixation Biomet s proprietary plasma spray application is unique in that only the titanium powder used to create the coating is heated, while the implant s substrate is retained at near ambient temperatures. This unique process enables the implant to maintain its mechanical properties. Figure 7 In order to resist deformation forces, the cup is manufactured with a 6 mm thickness at the dome and an average of 3 mm thickness at the rim (Figure 8). This design is specific to the M 2 a-magnum component and allows for the maximum head-to-cup ratio. Figure 9: Titanium PPS Porous Plasma Spray being applied through a heated plasma arc. The heating effect of the PPS process is transient (lasting only for milliseconds). Therefore, the substrate material remains virtually unaffected, fatigue properties are maintained such that small femoral components are possible with this process and, importantly for M 2 a-magnum articulation, the carbide structure is unaffected. Figure 8 3

6 Active Articulation E1 Dual Mobility Hip System Biomet s PPS coating has irregularly shaped molten titanium particles that splatter upon impaction with the substrate surface. This generates a random distribution of pore size between 100 and 1,000 microns providing a larger contact area between particles and substrate (Figure 10). The larger distribution of pore size in conjunction with the enhanced biocompatibility of titanium, allows immediate fixation via mechanical interlocking and longterm fixation. Straightforward Instrumentation The Active Articulation Hip System utilizes an established and straightforward instrument platform. In fact, it is the same instrumentation used with Biomet s clinically proven, fully-hemispheric M 2 a-magnum cup 23 that has been in use since The system was designed to help facilitate and simplify acetabular preparation, cup and head trialing and cup positioning. The only additional instruments are a bearing press which secures the 28 mm head to the E1 bearing (Figure 11) and a head impactor that is specifically designed to impact the E1 bearing. This instrument platform can be used with all traditional and minimally invasive total hip arthroplasty approaches. See the Active Articulation Dual Mobility Hip System surgical technique for more information. Figure 10: The irregularly shaped titanium particles sprayed onto the substrate result in a wide pore size distribution. Biomet s PPS coating has been clinically proven for over 20 years as seen in a variety of published clinical papers Figure 11 4

7 References 1. Leclercq S, et al. Charnley-Kerboull-Bousquet hybrid THR after 10 years. Total Hip Arthroplasty; 3rd International Symposium, Aubriot P, Lesimple S. Study on Cementless Bousquet Type Cup in One Hundred Hybrid Total Hip Replacements (Femoral Stem Cemented Charnley Type) Average Follow-up 5 Years. Acta Orthopaedica Belgica. 59: Farizon F, de Lavison R et al. Results with a Cementless Alumina Coated Cup with Dual Mobility, a Twelve Years Follow up Study. Int Orthop. 22(4) : , Charnley, J. Long Term Results of Low Friction Arthroplasty of Hip as Primary Intervention, Journal of Bone and Joint Surgery (Br). 54: 61 76, McKee, G., Farrar, J. Replacement of Arthritic Hips by the McKee- Farrar Prosthesis. Journal of Bone and Joint Surgery. 48(2): , Tarasevicius, S. et al. Dual Mobility Cup Reduces Dislocation Rate After Arthroplasty for Femoral Neck Fracture. BMC Musculoskeletal Disorders.11: , Data on File at Biomet. Bench test results not necessarily indicative of clinical performance. 8. Joint Registry for England and Wales 6th Annual Report. P. 66, Beaule, et al. Jumbo Femoral Head for the Treatment of Recurrent Dislocation Following Total Hip Replacement. Journal of Bone and Joint Surgery. 84-A (2): , Burroughs BR, et al. Range of Motion and Stability in Total Hip Arthroplasty with 28, 32, 38, and 44mm Femoral Head Sizes: An in vitro Study. The Journal of Arthroplasty. 20: 11 19, Ritter MA. The Anatomical Graduated Component Total Knee Replacement-A Long Term Evaluation with 20 Year Survival Analysis. Journal of Bone and Joint Surgery (Br) , Kurtz, S. UHMWPE Biomaterials Handbook Second Edition, Currier, et al. In Vivo Oxidation in Remelted Highly Cross-linked Retrievals. JBJS (92) , Rowell, S. et al. Ex vivo stability loss of irradiated and melted UHMWPE. ORS Poster No Bhambri, S. et al. The Effect of Aging on Mechanical Properties of Melt-Annealed Highly Crosslinked UHMWPE. Crosslinked and Thermally Treated Ultra-High Molecular Weight Polyethylene for Joint Replacements , Wang, A. et al. Wear and Structural Fatigue Simulation of Crosslinked UHMWPE for Hip and Knee Bearing Applications. Crosslinked and Thermally Treated Ultra-High Molecular Weight Polyethylene for Joint Replacements , Multi-Center Study. Data on file at Biomet. 24. Keisu, K. et al. Primary Cementless Total Hip Arthroplasty in Octogenarians: Two to Eleven-Year Follow-Up. Journal of Bone and Joint Surgery. 83: 359, McLaughlin, J. et al. Total Hip Arthroplasty in Young Patients. 8- to 13- Year Results Using an Uncemented Stem. Clinical Orthopaedics and Related Research. 373: , Parvizi, J. et al. Prospective Matched-Pair Analysis of Hydroxyapatite- Coated and Uncoated Femoral Stems in Total Hip Arthroplasty. Journal of Bone and Joint Surgery. 83: 783 6, McLaughlin, J. et al. Total Hip Arthroplasty with an Uncemented Femoral Component. A Long Term Study of the Taperloc Stem. Journal of Arthroplasty. 19(2): 151 6, Meding, K. et al. Minimum Ten-Year Follow-up of a Straight- Stemmed, Plasma-Sprayed, Titanium-Alloy, Uncemented Femoral Component in Primary Total Hip Arthroplasty. Journal of Bone and Joint Surgery. 86: 92 7, McLaughlin, J. et al. Total Hip Arthroplasty with an Uncemented Femoral Component: Excellent Results at Ten Year Follow-Up. Journal of Bone and Joint Surgery. 79B: 900 7, Hozack, W. et al. Primary Cementless Hip Arthroplasty with a Titanium Plasma Sprayed Prosthesis. Clinical Orthopaedics and Related Research. 333: , Head, W. et al. A Titanium Cementless Calcar Replacement Prosthesis in Revision Surgery of the Femur: 13-Year Experience. Journal of Arthroplasty. 16(8): 183 7, Head, W. et al. The Proximal Porous Coating Alternative for Primary Arthroplasty. Orthopedics. 22(9): 813 5, Currier, B.H. et al. Evaluation of Oxidation and Fatigue Damage of Retrieved Crossfire Polyethylene Acetabular Cups. Journal of Bone and Joint Surgery. 89: , Besong, A.A. et al. A study of the combined effects of shelf ageing following irradiation in air and counterface roughness on the wear of UHMWPE. Biomed Mater Eng. 7: 59 65, Muratoglu, O., et al. Ex Vivo Stability Loss of Irradiated and Melted Ultra-High Molecular Weight Polyethylene. The Journal of Bone & Joint Surgery. 92: , Nabar, S. et al. Comparison of Second Generation Highly Crosslinked Polyethylenes Under Adverse Aging Conditions. ORS Poster No FDA Cleared Claim. See biomet.com/e1 for complete claim language. 20. Oral, E., et al. Protection of UHMWPE against lipid-initiated oxidation by antioxidants. 56th Annual Meeting of the Orthopaedic Research Society. Paper No. 234.

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