Improved technique dramatically reduces the incidence of femoral loosening and supports the authors’ confidence in resurfacing hips with risk factors (small size and cystic degeneration)
J Arthroplasty. 2007 Jun;22(4):481-9.
Amstutz HC
Le Duff MJ
Campbell PA
Dorey FJ.
The purpose of the present study was to determine the effectiveness of modifications in the surgical technique on loosening of the femoral component in the first 600 consecutive Conserve® Plus metal-on metal hybrid resurfacings. These modifications were gradually introduced over time but all the changes were implemented after the first 300 hips. Average age of the patients was 48.9 years and 74% were male. Average follow-up was 70.5 months for the first 300 hips and 42.4 months for the second 300 and there was a significant improvement (p=0.016) of the second 300 hips over the first 300 in a time-dependant analysis using as an end point the time to appearance of a radiolucency suggesting potential femoral component loosening. There were 18 revisions in 17 patients for definite femoral loosening. All but one of these femoral component loosenings (hip #340) happened in the first group. None of the components with cemented stems showed femoral radiolucencies or were revised for aseptic loosening. Adding fixation holes in the dome and chamfered areas and cleansing and drying using a suction tip in the dome hole were significantly related to the improvement of the results. Positioning the femoral component in a more valgus position did not show any effect as an independent variable.
This table shows the prevalence of radiolucencies and femoral loosenings sorted by generation of femoral fixation technique.
A rigorous comparison between generations of surgical technique can only be made through a time-dependant analysis to make a fair assessment of the progress if any. This was made in this publication demonstrating the improvement between 1st and 2nd generation technique, using the time to appearance of a metaphyseal stem radiolucency as end point. Our initial publications identified the risk factors for femoral loosening, essentially related to the size of the area of fixation between bone and cement, and quality of the bone (size of femoral defects). The immediate application of the progress made in the quality of the initial fixation is an advantage for the patients presenting the previously highlighted risk factors as illustrated in the following figure, which shows the difference in survivorship between 1st and 2nd generation technique in patients with poor bone quality (femoral defects >1cm).
Femoral loosening
|
Stem radiolucencies
|
Total
|
Follow-up (months)
|
|
1st generation (n=300)
|
17 (5.7%)
|
11 (3.7%)
|
28 (9.3%)
|
97 (84-124)
|
2nd generation (n=371)
|
2 (0.5%)
|
2 (0.5%)
|
4 (1.1%)
|
64 (36-84)
|
3rd generation (n=329)
|
0 (0%)
|
0 (0%)
|
0 (0%)
|
20 (7-36)
|
Copyright 2005 Joint Replacement Institute Los Angeles, CA · (213) 484-7600 · JRIinfo@dochs.org
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