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Effects of hydroxyapatite coating on survival of an uncemented femoral stem: A Swedish Hip Arthroplasty Register study on 4,772 hips
Uppsala University, Disciplinary Domain of Medicine and Pharmacy, Faculty of Medicine, Department of Surgical Sciences, Orthopaedics.
Uppsala University, Disciplinary Domain of Medicine and Pharmacy, Faculty of Medicine, Department of Surgical Sciences, Orthopaedics.
2011 (English)In: Acta Orthopaedica, ISSN 1745-3674, E-ISSN 1745-3682, Vol. 82, no 4, 399-404 p.Article in journal (Refereed) Published
Abstract [en]

Background and purpose: Hydroxyapatite (HA) is widely used as a coating for uncemented total hip arthroplasty components. This has been suggested to improve implant ingrowth and long-term stability. However, the evidence behind the use of HA coating on femoral stems is ambiguous. We investigated survival of an uncemented, tapered titanium femoral stem that was available either with or without HA coating (Bi-Metric).

Patients and methods: The stem had been used in 4,772 total hip arthroplasties (THAs) in 4,169 patients registered in the Swedish Hip Arthroplasty Register between 1992 and 2009. 59% of the stems investigated were coated with HA and 41% were uncoated. Kaplan-Meier survival analysis and a Cox regression model with adjustment for age, sex, primary diagnosis, and the type of cup fixation were used to calculate survival rates and adjusted risk ratios (RRs) of the risk of revision for various reasons.

Results: The 10-year survival rates of the HA-coated version and the uncoated version were about equal when we used revision for any reason as the endpoint: 98% (95% CI: 98-99) and 98% (CI: 97-99), respectively. A Cox regression model adjusting for the covariates mentioned above showed that the presence of HA coating did not have any influence on the risk of stem revision for any reason (RR = 1.0, 95% CI: 0.6-1.6) or due to aseptic loosening (RR = 0.5, CI: 0.2-1.5). There was no effect of HA coating on the risk of stem revision due to infection, dislocation, or fracture.

Interpretation: The uncemented Bi-Metric stem showed excellent 10-year survival. Our findings do not support the use of HA coating on this stem to enhance implant survival.

Place, publisher, year, edition, pages
2011. Vol. 82, no 4, 399-404 p.
National Category
Medical and Health Sciences
Identifiers
URN: urn:nbn:se:uu:diva-159485DOI: 10.3109/17453674.2011.597699ISI: 000294851100002OAI: oai:DiVA.org:uu-159485DiVA: diva2:445312
Available from: 2011-10-03 Created: 2011-10-03 Last updated: 2017-12-08Bibliographically approved
In thesis
1. Form and Finish of Implants in Uncemented Hip Arthroplasty: Effects of Different Shapes and Surface Treatments on Implant Stability
Open this publication in new window or tab >>Form and Finish of Implants in Uncemented Hip Arthroplasty: Effects of Different Shapes and Surface Treatments on Implant Stability
2013 (English)Doctoral thesis, comprehensive summary (Other academic)
Abstract [en]

The design of an uncemented hip arthroplasty implant affects its long-term survival. Characteristics such as the form and the finish of the implant are crucial in order to achieve the best possible conditions for long-term implant survival. In this thesis we hypothesized that different shapes of stems and cups used in primary and revision total hip arthroplasty (THA), and their finish with hydroxyapatite (HA) coating affect implant stability and thus long-term survival.

In 2 prospective cohort studies the clinical outcome, the stability measured with radiostereometric analysis (RSA), and the periprosthetic changes in bone mineral density (BMD) measured with dual-energy x-ray absorptiometry (DXA) were investigated in 2 uncemented THA implants – the CFP stem and the TOP cup. In 3 register studies the effect of HA coating on uncemented THA implants used in primary and revision arthroplasty was investigated.

Both implants investigated in the prospective cohort studies showed an excellent short-term clinical outcome with good primary stability, but neither their novel form nor the finish with HA protected the implants from the proximal periprosthetic demineralization that usually occurs around other uncemented THA implants.

The register studies revealed that HA coating on cups used in primary and revision THA is a risk factor for subsequent revision of the implant. The use of HA coating on the stem in primary THA did not affect long-term survival. Additionally, the shape of an implant plays a crucial role for implant stability and survival.

In conclusion, this thesis highlights that the finish of implants with HA coating does not prevent periprosthetic proximal femoral bone loss and can even enhance the risk of revision of both primary and secondary cups. Importantly, the shape of uncemented THA implants affect their stability, showing that the implant form is a crucial factor for the long-term survival.

Place, publisher, year, edition, pages
Uppsala: Acta Universitatis Upsaliensis, 2013. 74 p.
Series
Digital Comprehensive Summaries of Uppsala Dissertations from the Faculty of Medicine, ISSN 1651-6206 ; 845
Keyword
Form, Finish, Total hip arthroplasty, Swedish Hip Arthroplasty Register, Hydroxyapatite, RSA, DXA, BMD, Stability.
National Category
Orthopedics
Research subject
Orthopaedics
Identifiers
urn:nbn:se:uu:diva-185299 (URN)978-91-554-8549-8 (ISBN)
Public defence
2013-01-11, Grönwallsalen, Akademiska sjukhuset, Akademiska sjukhus, Uppsala, 09:00 (Swedish)
Opponent
Supervisors
Available from: 2012-12-21 Created: 2012-11-21 Last updated: 2013-08-06Bibliographically approved

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