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Comparison of the Accuracy of Total Hip Arthroplasty Component Placement between Cemented and Uncemented implants

Chawda, Mayur N. , Whitehouse, Sarah L., English, Hugh , Crawford, Ross W., & Donnelly, William J. (2007) Comparison of the Accuracy of Total Hip Arthroplasty Component Placement between Cemented and Uncemented implants. In Australian Orthopaedic Association 67th Annual Scientific Meeting, 7/12 October 2007, Gold Coast, Queensland. (Unpublished)

Abstract

Introduction & Aims

Data from recent AOANJRR shows a higher incidence of acetabular revision for dislocation of THA in uncemented compared to cemented THA (RR-1.59). We hypothesized that a difference in accuracy of component placement may be a factor. We aimed to assess any difference in accuracy between these 2 types of THAs.

Material and Methods

Patients undergoing navigated THA were prospectively recruited. Choice of uncemented or cemented THA was based on individual surgeon’s routine practice and preference and no adjustments were made for this study. 2 senior surgeons (HE and BD) experienced in cemented and uncemented THA, performed all surgery.

All THAs (Cemented Exeter-17 and uncemented Trident/Secur fit-17) were performed through a posterior approach. In each case the surgeon nominated an “ideal target” component position. Based upon the position of a trial acetabular component and femoral broach the surgeon then attempted to implant the definitive implants to the “target” position with the assistance of navigation.

Results & Statistical analysis:

Measurement of final cup inclination & version were compared against the target trial positions. Femoral stem version, varus and flexion were compared against the broach positions. A comparison of target position versus final implant position was made. Deviation from the target position of 5 degree or more was considered to be significant. The mean and standard deviation were analysed using ANOVA. Levine statistic was used for variability.

Cemented acetabular implant target position was achieved more consistently. Uncemented cups deviated from target position by 5 degrees or more in 23% of cases compared to none in the cemented group. The difference in cup version reached statistical significance (P<0.05) however difference in cup inclination did not reach significance level.

On the femoral side, difference found in stem version was not statistically significant. Cemented stem deviation of more than 5 degrees of varus or flexion occurred more frequently than in the uncemented group. These findings did not reach statistical significance.

Ability to achieve target leg length as per navigation was compared between the groups. Deviation from target position by 5 mm or more was found in 26% of uncemented cases compared to 5.8% of cemented cases. This difference was statistically significant (p<0.05).

Conclusion:

Statistically significant reduced accuracy of cup placement and control of leg length have been demonstrated with uncemented compared to cemented implants.

It is harder to control implant positioning in uncemented implants than cemented implants. This may be significant in terms of higher risk for revision for dislocation with uncemented implants.

Impact and interest:

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ID Code: 10196
Item Type: Conference Paper
Additional Information: For more information, please refer to the publisher’s website (see hypertext link) or contact the author.
Additional URLs:
Subjects: Australian and New Zealand Standard Research Classification > MEDICAL AND HEALTH SCIENCES (110000) > CLINICAL SCIENCES (110300) > Orthopaedics (110314)
Divisions: Past > QUT Faculties & Divisions > Faculty of Built Environment and Engineering
Current > Institutes > Institute of Health and Biomedical Innovation
Copyright Owner: Copyright 2007 (please consult author)
Deposited On: 17 Oct 2007
Last Modified: 11 Aug 2011 00:01

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