[Spotorno CLS Cup in Revision Arthroplasty of the Hip.]

PURPOSE OF THE STUDY Revision surgery for the loosening of total hip arthroplasty with the use of cemented implants does not guarantee good long-term results. The current trend prefers the use of cementless implants, particularly of the press-fit type. In our group of patients with aseptic loosening of the acetabular cup with a preserved acetabular bone stock without segmental defects we used for the revision surgery a Spotorno CLS cementless cup. MATERIAL The group comprised 33 patients, 29 women and 4 men, of the average age of 66 years, with the loosened acetabular component, of which 31 had originally a cemented Poldi cup and 2 a cementless threaded Walter-Motorlet cup. Cup revision only was performed in 25 cases, both components (cup and stem) were replaced in 8 cases. METHODS We used a standard cementless Spotorno CLS cup. In case of a preserved circular bone stock of acetabular rim the cup was implanted in the standard position. Cavity defects were filled by cancellous bone grafts. In case of poor anatomical bone stock the cup was implanted deeper in acetabular cavity usually in a more varus position and rarely in valgus position depending on the localisation of segmental defect. RESULTS The average follow-up was 38 months (range, 16-63 months). In one case there occurred aseptic loosening after 12 months and the second revision surgery was necessary in order to replace the implant by the same type of a greater size. In one case after 6 months there developed a hematogeneous infection and the implant was replanted by a two-stage procedure. In the remaining cases osteointegration took place in the course of 12 months after the operation. In 7 cases the cups were implanted in a slightly varus/valgus position necessitated by the acetabular bone stock, without any impact on the osteointegration or function. DISCUSSION The disadvantage of cemented implants in the revision surgery consists in the limited possibility of the integration of cemented mantle and the destructed bone interface. The advantages of cementless implant in the revision surgery of a loosened cup is confirmed by a number of authors but they relate mainly to press-fit cups. The data on the use of Spotorno CLS expansion cup in the revision surgery are rare. Our group with a short follow-up demonstrates that the integration and the function of the CLS cup as a revision implant seems to be reliable. The main prerequisite, however, is a good acetabular bone stock without greater segmental defects. Cavity defects may be filled in by autologous or homologous cancellous bone grafts. The CLS cup may be fixed, if necessary, in a slightly non-anatomical position without any impairment of the function. It includes mainly the cases of the ovoid shape of acetabulum when the cup is implanted in the acetabula roof in greater varus slope than recommended by the author of implant. CONCLUSIONS The Spotorno CLS cementless expansion cup as a revision implant in the right indication brings good short term results on condition of a good primary stability of the implant and a spherical acetabulum without great segmental defects.

THA, revision surgery, cementless CLS cup.