Abstract
Purpose of the study
to verify, after a period of 5 years, that no particular complication overshadows the benefits of a large diameter metal-on-metal articulation in combination with a conventional femoral stem with regard to stability and functional result.
Patients and methods
Between October 2003 and May 2005, 100 hips in 99 patients were treated with an uncemented Emeraude stem and a Durom Resurfacing Cup made from cobalt-chrome with high carbon content. Mean age at time of surgery was 60 years. 80 of the operated patients were reviewed after a follow-up of 5 years and two months: the results are expressed according to Merle d'Aubigné and Harris, by means of the UCLA and the WOMAC scores. The radiographs were reviewed by independent observers. The patients underwent a chrome and cobalt test in whole blood. Of the 20 patients lost to follow-up, 13 had died, 1 could no longer be located, 1 had been revised because of a peri-prosthetic fracture and the remaining 5 were unable to show up for the follow-up examination. A telephone interview and the WOMAC did not reveal any complication in their cases.
Results
The mean Merle d'Aubigné and Harris scores increase from 9.8 to 16.3 and from 37.4 to 79.9, respectively. The UCLA score improves from 4.2 to 6.5. The corrected WOMAC is 77.2%. But the results after 1 year show a distinct difference between the first 30 patients (Harris score of 58.2) and the subsequent patients (Harris score of 82.4). The radiographic analysis does not show any migration; the observed radiolucencies, whether around the fixation wings or at the level of the surface coating, are not progressive; mean cup inclination is 52°.
The mean values for chrome are 1.95 μg/l and for cobalt 2 μg/l.
Discussion and conclusion
This study confirms the relevance of this concept with regard to stability (no dislocations) and functional result, and reveals no particular complication. The less good clinical results are to be attributed to the pain previously noted in the first 30 cases, before our technical experience led us to impact an undersized cup in respect to the last used rasp. This technique enables a better centering of the cup, ensures that the latter does not protrude nor expose it to excessive equatorial compression, which seems to cause pain. We have no doubt that it is this technical modification that has spared us the complications that have led some of our colleagues to abandon this type of implant.
