CSTiTM Bibliography
Clinical Experience
Udomkiat P, Dorr LD, Wan Z.
Cementless hemispheric porous-coated sockets implanted with press-fit
technique without screws: average ten-year follow-up. J Bone Joint
Surg Am. 2002 Jul;84-A(7):1195-1200. Reprint available: Part
#1001-45-042
Link to abstract via Medline
This study followed 103 patients (110 hips) with APR acetabular cups an average of 10.2 years. All of the cups were implanted without screw fixation, employing an under-ream of 1-3 mm for initial stability and ingrowth into the CSTi coating for long-term stability. The 12-year rate of survival of the acetabular cup was 99.1%. On self-assessment questionnaires, 88% of patients rated their outcome as excellent or very good, 10% as good, and 2% as fair. The researchers state, “We have confidence in this method of fixation because of the low prevalence of radiolucent lines, particularly progressive radiolucent lines.” (Note: The APR cup was a predecessor of the current Converge CSTi Porous Acetabular Cup, which is also a hemispherical cup with CSTi porous coating.)
Hofmann AA, Evanich CJ, Ferguson RP, Camargo MP. Ten- to
14-year clinical followup of the cementless Natural-Knee system. Clin
Orthop. 2001 Jul;388:85-94. Reprint available: Part #1001-01-045
Link to abstract via Medline
This study followed 141 patients (176 knees) with the Natural-Knee CSTi porous-coated total knee system an average of 12 years. The researchers found a long-term survivorship of 95.1% when focusing on bony attachment; this does not include the three revisions associated with infection or the five revisions due to late posterior cruciate ligament failure. At ten years, the femoral and tibial components demonstrated survivorship of 99.1% and 99.6, respectively. The metal-backed patellar component had a survivorship of 95.1%. At last follow-up, the HSS knee scores were 97.8±4.7 points.
Hofmann AA, Feign ME, Klauser W, VanGorp CC, Camargo MP.
Cementless primary total hip arthroplasty with a tapered, proximally
porous-coated titanium prosthesis. J Arthroplasty. 2000
Oct;15(7):833-9. Reprint available: Part #1001-22-041
Link to abstract via Medline
87 consecutive patients (100 hips) received the Natural-Hip stem with proximal CSTi porous coating. Six patients were lost to follow-up, and four died during the follow-up period of reasons unrelated to surgery. The average Harris Hip Score at latest follow-up was 94. The researchers observed no femoral subsidence. There was no femoral component loosening and thus no revision for femoral loosening.
Evanich CJ, Tkach TK, Von Glinski S, Camargo MP, Hofmann AA.
6- to 10-year experience using countersunk metal-backed patellas. J
Arthroplasty. 1997 Feb;12(2):149-54. Reprint available: Part
#1000-02-076
Link to abstract via Medline
Of 302 consecutive knee arthroplasties employing the CSTi-coated metal-backed Natural-Knee patella, 212 were available for 6-10 follow-up evaluation. (Fifty-nine patients had died, and 31 were lost to follow-up.) At last follow-up, the mean HSS knee score was 98 points. Overall patellar survivorship was found to be 96%.
Baldwin JL, El-Saied MR, Rubinstein RA. Uncemented total
knee arthroplasty: Report of 109 titanium knees with cancellous-structured
porous coating. Orthopedics. 1996 Feb;19(2):123-30
Link to abstract via Medline
This study followed 109 Natural-Knee arthroplasties 3-5 years. 96% of patients had good or excellent results. 82% demonstrated no radiolucencies. The researchers found no complete radiolucencies under any implant, and none of the knees were revised for loosening.
Hofmann AA, Murdock LE, Wyatt RW, Alpert JP. Total knee
arthroplasty two- to four-year experience using an asymmetric tibial tray
and a deep troclear-grooved femoral component. Clin Orthop. 1991
Aug;(269):78-88
Link to abstract via Medline
This study followed 183 Natural-Knee arthroplasties 2-4 years. 96% of patients had good or excellent results. There was no revision for component loosening. Six components were obtained for analysis at the time of revision, and three were obtained postmortem. These demonstrated bone ingrowth into the CSTi porous coating of up to 40% at 27 months.
Please refer to the following definitions of terms commonly used in retrieval studies of porous coatings.
- ABI (appositional bone index): A measure of the percent of bone in direct contact with the porous surface.
- Ingrowth: The percent volume of bone in the total volume of pores available. This is determined through BSE (backscattered electron microscopy).
Hofmann AA, Bloebaum RD, Bachus KN. Progression of human
bone ingrowth into porous-coated implants. Acta Orthop Scand.
1997 Apr;68(2):161-6
Link to abstract via Medline
This study found that ingrowth of human cancellous bone into porous coating plateaus at about 9 months postoperatively.
Bloebaum RD, Bachus KN, Jensen JW, Scott DF, Hofmann AA.
Porous-coated Metal-backed Patellar Components in Total Knee Replacement.
A Postmortem Retrieval Analysis, J Bone Joint Surg Am.
80(4):518-28, 1998
Link to abstract via Medline
In this study of CSTi-coated metal-back patellas, an average ABI of 86% and ingrowth of 13% were found.
Bloebaum RD, Rhodes DM, Rubman MH, Hofmann AA. Bilateral
tibial components of different cementless designs and materials.
Clin Orthop. 268:179-87, 1991
Link to abstract via Medline
In this study, two cementless tibial components (one Natural-Knee CSTi-coated component and one cobalt-chrome beaded component) underwent postmortem analysis. The CSTi implant had been in place for 19 months and the CoCr-beaded for 25 months. The ABI for the CSTi and CoCr-beaded implants were 67% and 9% respectively. The CoCr-beading implant showed no bone within the pores, while the CSTi was 22% ingrown.
Bloebaum RD, Mihalopoulus NL, Jensen JW, Dorr LD.
Postmortem analysis of bone growth into porous-coated acetabular
components. J Bone Joint Surg Am. 1997 Jul;79(7):1013-22
Link to abstract via Medline
Seven CSTi-coated hemispherical shells were retrieved postmortem for analysis. These had an average ABI of 84% and ingrowth of 12%.
Bloebaum RD, Bachus KN, Jensen JW, Hofmann AA.
Postmortem analysis of consecutively retrieved asymmetric porous-coated
tibial components. J Arthroplasty. 1997 Dec;12(8):920-9
Link to abstract via Medline
Postmortem analysis was preformed on eight consecutively retrieved Natural-Knee tibial components with CSTi porous coating. The ABI averaged 73%, with no radiolucencies in the series.
Related Technical Information
Warren LD, Chowdhary PR. Comparison of the
electrochemical properties of various orthopedic porous metals.
Biomed Mater Eng. 1992 Fall;2(3):107-13
Link to abstract via Medline
This paper describes potentiodynamic corrosion testing which was used to compare various porous metals on solid substrates. The researchers found that all pairings tested, including CSTi and CoCr beads on titanium and CoCr alloy substrates, had similar corrosion scans.
Bobyn JD, Pilliar RM, Cameron HU, Weatherby GC. The
optimum pore size for the fixation of porous-surfaced metal implants by
the ingrowth of bone. Clin Orthop. 1980 Jul-Aug;(150):263-70
Link to abstract via Medline
This study concludes that the minimum pore size for successful bone ingrowth is 50-400µm.
