| 1. |
- Dahl, Jon, et al.
(author)
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Less wear with aluminium-oxide heads than cobalt-chrome heads with ultra high molecular weight cemented polyethylene cups : A ten-year follow-up with radiostereometry
- 2012
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In: International Orthopaedics. - : Springer Science and Business Media LLC. - 0341-2695 .- 1432-5195. ; 36:3, s. 485-490
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Journal article (peer-reviewed)abstract
- Purpose Wear is a major contributor to osteolysis and aseptic loosening of total hip replacements (THR). Both alumina (Al2O3) and cobalt-chrome (CoCr) femoral heads are commonly used. We investigated wear comparing alumina heads to cobalt-chrome heads against conventional cemented polyethylene (PE) cups for up to ten years. Methods Linear wear was measured with radiostereometry (RSA). Our material was derived from two prospective randomised trials that investigated fixation of femoral stems, not wear, and was evaluated retrospectively (Level III). Results The mean (95% CI) proximal head penetration was 0.96 mm (0.68-1.23) in the cobalt-chrome group and 0.42 mm (0.30-0.53) in the alumina group at ten years (P=0.001). The mean (95% CI) 3D penetration was 1.07 mm (0.79-1.35) and 0.53 mm (0.38-0.63), respectively, at ten years (P=0.001). Conclusion Alumina heads performed better than cobalt-chrome heads in this study after ten-year follow-up.
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| 2. |
- Digas, Georgios, et al.
(author)
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Increase in early polyethylene wear after sterilization with ethylene oxide : radiostereometric analyses of 201 total hips.
- 2003
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In: Acta Orthopaedica Scandinavica. - : Medical Journals Sweden AB. - 0001-6470. ; 74:5, s. 531-541
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Journal article (peer-reviewed)abstract
- 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.
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| 3. |
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| 5. |
- Otten, Volker T C, et al.
(author)
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Stability of Uncemented Cups - Long-Term Effect of Screws, Pegs and HA Coating : A 14-Year RSA Follow-Up of Total Hip Arthroplasty
- 2016
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In: The Journal of Arthroplasty. - : Elsevier BV. - 0883-5403 .- 1532-8406. ; 31:1, s. 156-161
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Journal article (peer-reviewed)abstract
- Screws, pegs and hydroxyapatite-coating are used to enhance the primary stability of uncemented cups. We present a 14-year follow-up of 48 hips randomized to four groups: press-fit only, press-fit plus screws, press-fit plus pegs and hydroxyapatite-coated cups. Radiostereometric migration measurements showed equally good stability regardless cup augmentation. The mean wear rate was high, 0.21mm/year, with no differences between the groups. Seven hips had radiographical osteolysis but only in hips with augmented cups. Cups without screw-holes compared with cups with screw-holes resulted in better clinical outcome at the 14-year follow-up. Thus, augmentation of uncemented cups with screws, pegs, or hydroxyapatite did not appear to improve the long-term stability compared with press-fit only.
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| 6. |
- Röhrl, Stephan, et al.
(author)
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In vivo wear and migration of highly cross-linked polyethylene cups a radiostereometry analysis study
- 2005
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In: The Journal of Arthroplasty. - : Elsevier BV. - 0883-5403 .- 1532-8406. ; 20:4, s. 409-413
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Journal article (peer-reviewed)abstract
- 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.
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| 7. |
- Röhrl, Stephan M, et al.
(author)
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No adverse effects of submelt-annealed highly crosslinked polyethylene in cemented cups : an RSA study of 8 patients 10 years after surgery
- 2012
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In: Acta Orthopaedica. - : Informa Healthcare. - 1745-3674 .- 1745-3682. ; 83:2, s. 148-152
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Journal article (peer-reviewed)abstract
- Background and purpose Highly crosslinked polyethylene (PE) is in standard use worldwide. Differences in the crosslinking procedure may affect the clinical performance. Experimenatal data from retrieved cups have shown free radicals and excessive wear of annealed highly crosslinked PE. We have previously reported low wear and good clinical performance after 6 years with this implant, and now report on the 10-year results. Patients and methods In 8 patients, we measured wear of annealed highly crosslinked PE prospectively with radiostereometry after 10 years. Activity was assessed by UCLA activity score and a specifically designed activity score. Conventional radiographs were evaluated for osteolysis and clinical outcome by the Harris hip score (HHS). Results The mean (95% CI) proximal head penetration for highly crosslinked PE after 10 years was 0.07 (-0.015 to 0.153) mm, and the 3D wear was 0.2 (0.026 to 0.36) mm. Without creep, proximal head penetration was 0.02 (-0.026 to 0.066) mm and for 3D penetration was 0.016 (-0.47 to 0.08) mm. This represents an annual proximal wear of less than 2 mu m. All cups were clinically and radiographically stable but showed a tendency of increased rotation after 5 years. Interpretation Wear for annealed highly crosslinked PE is extremely low up to 10 years. Free radicals do not affect mechanical performance or lead to clinically adverse effects. Creep stops after the first 6 months after implantation. Highly crosslinked PE is a true competitor of hard-on-hard bearings.
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| 8. |
- Röhrl, Stephan Maximilian, 1966-
(author)
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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
- 2004
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Doctoral thesis (other academic/artistic)abstract
- 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.
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| 9. |
- Rörhrl, Stephan M, et al.
(author)
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Very low wear of non-remelted highly cross-linked polyethylene cups : an RSA study lasting up to 6 years.
- 2007
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In: Acta Orthopaedica. - Basingstoke : Taylor & Francis. - 1745-3674 .- 1745-3682. ; 78:6, s. 739-745
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Journal article (peer-reviewed)abstract
- Background and purpose: Highly cross-linked polyethylenes (PEs) all appear to reduce wear dramatically in laboratory studies, although there is substantial variation in this respect between manufacturers. Nonremelted cross-linked PE is almost as tough as unirradiated PE, but is not completely stable and can oxidize in vivo, as has been shown in recent retrievals studies. We had reported low wear and good clinical performance after 2 years for 10 non-remelted highly crosslinked PE cups compared to 16 conventional PE cups sterilized by gamma-in-air. Method: Because of possible degradation by free radicals, we followed up both cohorts for 5 years (conventional PE) and 6 years (highly cross-linked PE). Result: Mean (CI) proximal head penetration over the observation time was linear and measured 0.08 (0.02–0.13) mm for cross-linked PE and 0.42 (0.23–0.62) mm for conventional PE, and total penetration was 0.23 (0.1–0.35) mm and 0.75 (0.05–1.4) mm respectively. After subtracting creep, the annual wear for non-remelted highly cross-linked PE was below 6 µm. The cups had equally low migration and few radiolucencies. Interpretation: The theoretical possibility of oxidation in non-remelted highly cross-linked PE may not show clinically. However, it may be that cemented cups with their thicker PE are more forgiving than metal-backed cups with thin PE moving in the locking mechanism. So far, we can conclude that the Crossfire highly crosslinked polyethylene cups performed very well clinically, with extremely low wear even after almost 6 years. This is reassuring, but care should be taken in extrapolating these results to other cross-linked PEs or uncemented cups where toughness of PE is more of an issue.
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| 10. |
- Söderlund, Per, et al.
(author)
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10-year results of a new low-monomer cement Follow-up of a randomized RSA study
- 2012
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In: Acta Orthopaedica. - : Medical Journals Sweden AB. - 1745-3674 .- 1745-3682. ; 83:6, s. 604-608
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Journal article (peer-reviewed)abstract
- Background and purpose The properties and performance of a new low-monomer cement were examined in this prospective randomized, controlled RSA study. 5-year data have already been published, showing no statistically significant differences compared to controls. In the present paper we present the 10-year results. Methods 44 patients were originally randomized to receive total hip replacement with a Lubinus SPII titanium-aluminum-vanadium stem cemented either with the new Cemex Rx bone cement or with control bone cement, Palacos R. Patients were examined using RSA, Harris hip score, and conventional radiographs. Results At 10 years, 33 hips could be evaluated clinically and 30 hips could be evaluated with RSA (16 Cemex and 14 Palacos). 9 patients had died and 4 patients were too old or infirm to be investigated. Except for 1 hip that was revised for infection after less than 5 years, no further hips were revised before the 10-year follow-up. There were no statistically significant clinical differences between the groups. The Cemex cement had magnitudes of migration similar to or sometimes lower than those of Palacos cement. In both groups, most hips showed extensive radiolucent lines, probably due to the use of titanium alloy stems. Interpretation At 10 years, the Cemex bone cement tested performed just as well as the control (Palacos bone cement).
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