In acetabular revision press-fit cups usually are used in smaller defects and contact to the host bone should be more than 50 %. Due to the thin wall thickness and the surface design the cementless press-fit cup Allofit S has a specific characteristic during implantation. Therefore this cup was used for revision with greater acetabular defects and analysed in a prospective study. The press-fit in these cases was 4 mm and additional 2 or 3 screws into the Os ilium were used.

64 cups were were followed prospectively for 38.3 months with a minimum of 24 months and examined clinically (Harris-Hip-Score) and radiographically for migration (Method of Nunn et al.) and loosening (Method of Delee and Charnley). Corresponding to Nunn et al. and Blum et al., cup migration was defined to be a change of position greater than 3 mm or referring to Cordero-Ampuero et al. and Dickob et al. a change of inclination greater than 5 degrees. There were 25 revisions of the cup and 39 complete exchanges of the prosthesis due to 54 aseptic and 10 septic loosenings (two-step revision with spacer and cementless reimplantation). There were acetabular defects of type Paprosky 2A in 12 cases, of type 2B in 15 cases, type 2C in 19 cases, type 3A in 16 cases and type 3 B in 2 cases. The average age of the patients was 70.9 ± 8.9 years.

The Harris-Hip-Score increased from 45.4 ± 14.9 points preoperatively to 81.8 ± 17.5 points one year and 82.3 ± 17.1 points two years postoperative. There was no loosing or significant migration of the cups.

The Allofit S press-fit cup shows good result in cup revisions with greater acetabular defects when using a press-fit of 4 mm and additional 2 or 3 screws. In these cases it seems to be a good and cheeper alternative to specific implants like trabecular metal cups.

Aim: The aim of this prospective study was to analyse the rate of sinking and the clinical results of the new cementless modular revision stem Revitan curved concerning the length of fixation of the implant and the technique of implantation (endofemoral compared with transfemoral).

Material and Methods: 51 cementless modular curved revision stems (Revitan curved) were implanted 17 times endofemoral and 34 times transfemoral. All operations were performed by the first author with 24 times a total exchange of the hip implants and 27 times an exchange of the stem. Patients were followed every 3 months in the first postoperative year and then every 6 months. Because sinking of a cementless implant occurs during the first postoperative year the minimum follow-up was 12 months (average follow-up was 22.5 + −12.6 months). Patients were evaluated clinically using the Harris Hip-Score and length of fixation of the implant as well as implant sinking was evaluated radiographically.

Results: The Harris Hip-Score increased from 45.7 preoperatively to 86.7 twelve months postoperative in endofemoral implanted stems and from 41.6 preoperatively to 81.2 twelve months postoperative in transfemoral implanted stems. The patients with transfemoral implanted stems had a significant higher amount of limping and positive Trendelenburg sign after the operation. With time the percentage decreased and reached nearly the same level as in patients with endofemoral implanted stems. 2 endofemoral and 1 transfemoral (with a fixation length of less than 3 cm) implanted stems showed a sinking of 5 mm. 2 transfemoral implanted stems had to be revised because of aseptic loosening. In both stems the fixation length was less than 3 cm in the first revision due to operative technical reasons.

Conclusion: The curved cementless revision stem Revitan shows encouraging results using the endofemoral and transfemoral technique. In transfemoral implantation a secure fixation can be reached with a fixation length of more than 3 cm (which is less than the usually recommended fixation length of 4 to 6 cm for cementless revision stems). Transfemoral implanted stems need a longer time of rehabilitation than endofemoral implanted stems