Converge® Clinical Experience
Building on Long -Term Success with CSTi-Coated Shells
Clinical History
The Converge System evolves from the clinically successful APR Acetabular Cup System, which has been in use for 15 years.
A recent survivorship analysis2 of Dorr’s series of 110 APR cups revealed that the acetabular components implanted without additional screw fixation had a 99.1% percent survival at 12 years.
Ingrowth Fixation
In a postmortem analysis employing backscattered electron imaging, a series of seven porous acetabular components harvested at 10 to 64 months showed consistent and uniform biologic ingrowth into the CSTi surface.
Contact microradiographs of all seven components revealed that an average of 84% (+/- 9; range 72% to 93%) of the periprosthetic bone was in direct apposition to the porous coating. This study also found that the volume fraction of bone in the porous coating corresponded to the volume fraction of bone measured in human cancellous bone.
| 7 to 11.9-Year Results for CSTi Porous-Coated Press-Fit Shell without Screw Fixation1 |
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Patient Population: 110 hips, 103 patients 132 hips initially -16 hips lost to death at an average of 4.8 yrs -6 hips lost to follow-up at an average of 3.3 yrs Average age 61 yrs Average follow-up 10.2 yrs Results: 1 revised for aseptic loosening 3 had non-progressive radiolucencies at final follow-up, not revised 12-yr survivorship (Kaplan-Meier analysis): 99.1% (Revision or recommended revision for aseptic loosening as the endpoint) 95.4% (Revision of cup for any reason as endpoint) |
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| 73-year-old osteoarthritic female with CSTi porous-coated cup 10 year post-op | CSTi /bone interface | Retrieved CSTi coated shell (cross-section through screw holes) |
Industry Leading Locking Mechanism
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Compared to the findings of an independent study³ by The Orthopaedic Research Laboratories at The Mt. Sinai Medical Center (Cleveland, Ohio), Converge scored the highest cup-liner congruency and oush-out resistance; and the second highest lever-out resistance of all the systems tested. |
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Maximum Insert Thickness
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The 3.5mm to 3.75mm shell thickness minimizes the stiffness of the implant in the acetabulum while maximizing possible insert thickness. |
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Initial Stability
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With With a broad range of six different shell styles, the Converge
System enables a 1.0mm, 1.5mm, or 2.0mm press-fit option depending on
surgeon preference and bone quality. During in-house laboratory testing using cancellous foam blocks, hemispherical Converge shells inserted with a 1.5mm press-fit showed significantly higher lever-out resistance than shells inserted with a 1.0mm press-fit. |
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Durasul
Highly Crosslinked Polyethylene
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In rigorous laboratory testing, the wear levels of Durasul highly crosslinked polyethylene could not be measured even after 27 million cycles on a hip simulator.6 Independent lab tests have verified that the wear rate of Durasul is near zero and is less than any competitive polyethylene.7,8 |
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Metasul
Metal-On-Metal
| Metasul has passed the test of time: In a unique retrieval study involving 177 explants that had been in situ for up to 10 years4 , Rieker et. Al. found that the average volumetric wear rate for Metasul was 200 times lower after the “run-in” period than typically observed in conventional metal-on-poly couplings. |
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In Situ Wear Study
In a study of 118 explants, the average wear rate for Metasul components was found to be about 3µm/year after the “run-in” period.5 Conventional polyethylene is known to wear 100µm to 200µm per year. 4
References
1 Dorr LD, 7 to 11.9 year results on APR porous-coated press-fit shell without screw fixation, In press for J Bone Joint Surg, 2002.
2 Bloebaum RD, Mihalopoulus NL, Jensen JW, Dorr LD. Postmortem analysis of bone growth into porous-coated acetabular components. J Bone Joint Surg, 79A, 1997, pp. 1013-1022.
3 Testing performed by the Orthopaedic Research Laboratories at The Mt. Sinai Center in Cleveland, Ohio. Data on file with Centerpulse Orthopedics.
4 Rieker C, Shen M, Kottig P. In-Vivo Tribological Performance of 177 Metal-on-Metal Hip Articulations, World Tribology Forum in Arthroplasty, Rieker C, Oberholzer S, Wyss U (ed.), Hans Huber, Bern 2001.
5 Sieber HP, Rieker CB, Kottig P. Analysis of 118 second-generation metal-on-metal retrieved hip implants, J Bone Joint Surg Br, 1998; 80:46-50.
6 Testing performed by Massachusetts General Hospital Biomechanics Lab. Data on file with Centerpulse Orthopedics.
7 D’Lima D, Hermida JC, Chan PC, Colwell CW. Evaluation of Wear of Two Different Cross-Linked Polyethylene Materials in a Hip Simulator, AAOS 2001 Poster Session.
8 Li S. Comparison of Four Highly Crosslinked UHMWP, Harvard Hip Course, Boston, Mass., October 2001.
