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Wear and Fixation of the acetabular component: in vivo evaluation of different polyethylenes and modes of fixation in total hip arthroplasty
Umeå University, Faculty of Medicine, Department of Surgical and Perioperative Sciences, Orthopaedics.
2004 (English)Doctoral thesis, comprehensive summary (Other academic)Alternative title
Verschleiβ und Verankerung der Pfanne von Hüftendoprothesen : In vivo Beurteilung von unterschiedlichen Polyethylenen und Fixationsarten (German)
Abstract [en]

Polyethylene wear and micromotion of the implant play an important role in multifactorial etiology of osteolysis leading to aseptic loosening of the acetabular components. Despite excellent results in primary total hip arthoplasty in a 10-15 year perspective there are still unsolved problems. The weakest link is the longevity of the actabular component. Young and active patients have a clearly worse outcome than older patients. Consequences of polyehtylene wear and ways to reduce wear have therefore been in focus during recent years. Radiostereometry (RSA) is the golden standard in measuring in vivo micromotions. In 4 clinical studies including 332 patients we used therefore RSA to record the efficacy of fixation of cemented and uncemented cups. The amount of wear of old and newly designed polyethylenes (PE) was related to cup stability and radiological and clinical measures of outcome.

This study showed that cementless cups inserted with pressfit technique do not need additional augmentation. Screws and pegs increase the risk for radiolucencies and osteolystic lesions but are helpful tools in cases where primary stability is jeopardized. In the second decade clinically silent osteolysis is common for the porous coated Harris Galante cup with unsealed screw holes. The locking mechanism of the PE liner in this cup is unsatisfactory and an increase of liner dissociations is expected. EtO sterilized PE displayed high in vivo wear and we do not recommend its continued use but close monitoring of patients with earlier inserted EtO sterilized implants. The substantially reduced wear in cemented highly cross-linked PE cups without any negative in vivo tradeoffs might have a substantial impact on choice of material and operating technique in the near future. However, we still recommend its restrained use in controlled series until longer follow-up data is available. Nevertheless, the short term in vivo results of modern highly cross-linked PE look promising and ight improve the outcome of cemented and uncemented hip arthroplasties by reducing complication and revisions.

Place, publisher, year, edition, pages
2004. , 150 p.
Series
Umeå University medical dissertations, ISSN 0346-6612 ; 879
Keyword [en]
Surgery, total hip arthroplasty, acetabular component, wear, fixation, osteolysis, Radiostereometry, RSA
Keyword [sv]
Kirurgi
National Category
Surgery
Research subject
Orthopaedics
Identifiers
URN: urn:nbn:se:umu:diva-230ISBN: 91-7305-614-6 (print)OAI: oai:DiVA.org:umu-230DiVA: diva2:142756
Public defence
2004-04-29, Betula Sal, 6M, Norrlands Universitetssjukhus, 901 85 Umeå, 13:00
Opponent
Supervisors
Available from: 2004-04-13 Created: 2004-04-13 Last updated: 2010-08-11Bibliographically approved
List of papers
1. Increase in early polyethylene wear after sterilization with ethylene oxide: radiostereometric analyses of 201 total hips.
Open this publication in new window or tab >>Increase in early polyethylene wear after sterilization with ethylene oxide: radiostereometric analyses of 201 total hips.
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2003 (English)In: Acta Orthopaedica Scandinavica, ISSN 0001-6470, Vol. 74, no 5, 531-541 p.Article in journal (Refereed) Published
Abstract [en]

We evaluated polyethylene wear by measuring femoral head penetration in 201 THA (median age 62 (31-81) years, 117 women) extracted from 5 randomized studies aimed to assess various fixation principles. There were 30 cemented all-polyethylene Lubinus cups sterilized by gamma irradiation in a reduced oxygen environment, 65 porous-coated Trilogy cups with liners gamma-sterilized in inert gas. Moreover, 37 cemented cups were sterilized with ethylene oxide (Reflection all-poly) and 69 porous-coated cups had liners sterilized in ethylene oxide (Reflection). 28 mm femoral heads were used in all cups. The patients were followed with repeated radiostereometric measurements (RSA) up to 2 years. The activity level of the patients was evaluated by a questionnaire. After 2 years, cups with polyethylene sterilized in EtO had almost twice the proximal and 3D penetration rates, as compared with gamma-sterilized polyethylene. The penetration did not differ between the gamma-irradiated designs. Using stepwise linear regression analysis, we found that the type of sterilization, age and weight were the most important predictors and that they determined the direction of the proximal penetration rate. Activity score, male gender and proximal migration of the cup had little effect. The accelerated wear observed with the EtO-sterilized polyethylene causes concerns about long-term problems and especially in younger patients.

National Category
Medical and Health Sciences
Identifiers
urn:nbn:se:umu:diva-3864 (URN)10.1080/00016470310017910 (DOI)14620972 (PubMedID)
Available from: 2004-04-13 Created: 2004-04-13 Last updated: 2010-08-11Bibliographically approved
2. In vivo wear and migration of highly cross-linked polyethylene cups a radiostereometry analysis study
Open this publication in new window or tab >>In vivo wear and migration of highly cross-linked polyethylene cups a radiostereometry analysis study
2005 (English)In: The Journal of Arthroplasty, ISSN 0883-5403, E-ISSN 1532-8406, Vol. 20, no 4, 409-413 p.Article in journal (Refereed) Published
Abstract [en]

In 50 cemented hip arthroplasties, wear and migration of the polyethylene (PE) cups were measured with radiostereometric analysis for a period of 2 years. Twenty had a normal gamma-in-air-sterilized PE, another 20 had a PE sterilized with 30000 Gy followed by heat stabilization (Duration; Stryker Orthopaedics, Mahwah, NJ), and 10 had highly cross-linked PE cups irradiated with 100000 Gy (Crossfire; Stryker Orthopaedics). In the initial 2 months, head penetration (creep) was 63 microm on average for the 3 groups. From 2 to 24 months, the mean proximal head penetration (wear) was 156 microm for standard PE, 138 microm for stabilized PE (P = .45), and 23 microm for highly cross-linked PE (P < .001; analysis of variance). The low in vivo wear rate for highly cross-linked cups was not at the expense of higher migration or less favorable clinical outcome and looks promising.

Keyword
wear, migration, cross-linked, polyethylene, THA
National Category
Medical and Health Sciences
Identifiers
urn:nbn:se:umu:diva-23498 (URN)10.1016/j.arth.2004.09.040 (DOI)16124954 (PubMedID)
Available from: 2009-06-22 Created: 2009-06-22 Last updated: 2017-12-13Bibliographically approved
3. Effect of augmented cup fixation on stability, wear and osteolysis: a 5-year follow-up of total hip arthroplasty with RSA
Open this publication in new window or tab >>Effect of augmented cup fixation on stability, wear and osteolysis: a 5-year follow-up of total hip arthroplasty with RSA
2004 (English)In: The Journal of Arthroplasty, ISSN 0883-5403, E-ISSN 1532-8406, Vol. 19, no 8, 962-971 p.Article in journal (Refereed) Published
Abstract [en]

To evaluate different modes of cementless fixation of hemispherical cups, we operated on 87 hips in 81 patients using 4 different means of cup fixation. The hips were randomly assigned to fixation with press-fit technique only (PF), or with augmentation with screws (S), pegs (P), or hydroxyapatite (HA) coating. The patients were evaluated with radiostereometric analysis (RSA) for cup migration and wear, conventional radiography for osteolysis, and Harris Hip Score for clinical outcome over 5 years. The fixation of the cups did not differ between the groups, but HA showed a tendency to decrease proximal migration. HA-coated cups displayed the best interface with hardly any signs of radiolucent lines, indicating a superior sealing effect of the HA coating. Cups with screws or pegs had more radiolucent lines and osteolytic lesions than the other groups. Radiolucent lines were correlated to higher proximal migration, young age, and female gender (r2=.2). The wear rate of the ethylene oxide-sterilized polyethylene liner was high (0.2 mm/y) but did not differ between the groups. Two cups with a perioperative fracture of the acetabular rim showed large initial migration but stabilized thereafter.

Keyword
hip arthroplasty, fixation, cup
National Category
Medical and Health Sciences
Identifiers
urn:nbn:se:umu:diva-23496 (URN)10.1016/j.arth.2004.06.024 (DOI)15586331 (PubMedID)
Available from: 2009-06-22 Created: 2009-06-22 Last updated: 2017-12-13Bibliographically approved
4. Porous-coated cups fixed with screws.: A 12-year clinical and radiostereometric follow-up study of 50 hips.
Open this publication in new window or tab >>Porous-coated cups fixed with screws.: A 12-year clinical and radiostereometric follow-up study of 50 hips.
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2006 (English)In: Acta Orthopaedica, ISSN 1745-3674, E-ISSN 1745-3682, Vol. 77, no 3, 393-401 p.Article in journal (Refereed) Published
Abstract [en]

BACKGROUND: Excellent mid-term results have stimulated the use of hemispherical porous-coated cups in hip replacement. With longer follow-up, there have been problems related to polyethylene wear and liner fixation, and osteolysis has been documented in reports of selected cases. We evaluated the clinical and radiographic results of 50 patients followed for 12 years. PATIENTS AND METHODS: 58 consecutive patients (58 hips), mean age 55 years, were operated with Harris-Galante (HG) I or II cups using line-to-line fit and additional screw fixation. Polyethylene linersgamma-sterilized in air and 32-mm ceramic heads were used. 8 patients died within 12 years, leaving 50 patients with a complete 12 year follow-up. 23 of the cups were also evaluated with radiostereometry (RSA) for migration, liner stability, and wear. RESULTS: All metal shells were still in situ after 12 years. 4 hips had been revised due to femoral loosening. In these revisions, the liner had been exchanged due to wear and/or instability, resulting in a cup survival rate of 89%. 28 cups displayed osteolytic lesions, mainly in relation to screws. RSA revealed minimum translations, but in many cases there were pronounced liner rotations suggesting unstable liners within the metal shell. The annual proximal wear was 0.09 mm and the three-dimensional wear was 0.16 mm. INTERPRETATION: RSA can predict the long-term performance of cup fixation. Low migration during the initial years after implantation indicates excellent long-term results regarding fixation of the metal shell. The main problem with this design appears to be liner instability and osteolysis, factors that are probably interrelated. Because these phenomena are clinically silent, we recommend regular follow-up of patients with HG cups to avoid sudden loosening and complicated revisions.

National Category
Medical and Health Sciences
Identifiers
urn:nbn:se:umu:diva-10306 (URN)10.1080/17453670610046316 (DOI)16819677 (PubMedID)
Available from: 2008-08-11 Created: 2008-08-11 Last updated: 2016-02-09Bibliographically approved

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