Abstract
Purpose of the study. The aim of the study is to evaluate the results achieved after the replacement of a loosened or broken cemented cup by another cemented cup and to specify conditions under which such procedure may be successful.
Material. In the period of 1992-1997, 158 revision surgeries of total hip arthroplasty were performed at the authors' Department.
In 69 patients (57 women, 12 men) the cemented cup was replaced by another cemented cup and the original femoral monocomponent with the 32 mm head diameter the surface of which was not damaged was left in place. Methods.
The indication for operation was loosening of Degree 2 or 3 of the classification after Krbec et al. The surgery was performed from the Watson-Jones or Bauer approach.
The cup was always revised with the use of the Palacos cement in combination with antibiotics by the cementing technique of 2nd generation. Augmentation was used in 11 cups.
The original femoral component was always returned to the original cemented bed and a cement mantle was added in the proximal part in 15 patients. Poldi cups were replaced in all patients of the followed up cohort (63times loosening - 91%, 6times breakage - 9%) using 3 types of cups for revision surgery (Poldi - 44times, Ultima - 20times, SPC - 5times).
During the period of March through December 2001, 48 patients were followed up in the out-patient department. The clinical condition was evaluated on the basis of the Harris Hip Score and a radiograph was made to monitor changes in the position of the cup, linear wear, the presence and size of the radiolucent zone.
Results. The results were evaluated in 48 patients (40 women and 8 men) with the average interval of 63 months after revision of the cup (range, 46 to 112 months).
However, the clinical and radiograph evaluation of the condition was made only in 45 patients. Three patients re-operated on in 2001 were not included in the evaluation.
The Harris Hip Score was on average 78 points (range, 51 to 97 points). Radiographs did not show any change in the position of the cup.
The linear wear up to 1 mm was revealed in 4 cups and above 1 mm in 1 cup (11% of the evaluated patients). The radiolucent line in zone III after DeLee and Charnley was present in 4 cups, in zones II and III in another 4 patients, i. e. in total in 8 of 45 cups (18%).
Discussion. The group of 45 followed-up patients may be considered a sufficiently representative sample of the original 69-member cohort (minimally 7 patients died in the follow-up period, 3 patients were not included in the evaluation).
With regard to the average follow-up of 63 months the results may be considered as medium-term. The average interval between primary total hip arthroplasty and revision of 130 months is comparable with the results of similar studies by other authors.
The results of the clinical evaluation on the basis of Harris Hip Score are not convincing (range, 51 to 97 points, average 78 points). Radiographs showed a radiolucent zone in 8 cups (18%).
Another 3 patients were at the time of evaluation after a repeated revision of the cup for loosening (at the interval of 22 to 34 months). Conclusion.
A good integration of the cemented cup used in revision of the loosened cemented cup of total hip arthroplasty was evident only in infrequent cases of a perfectly preserved acetabulum both from the viewpoint of shape and structure. The evaluation of other patients of the followed-up cohort, however, produced rather unconvincing results.
On this basis and also on the basis of their experience in the use of cementless cups in revision of total hip prostheses the authors recommend to prefer a cementless implant in the revision of the cup.