Purpose of the study: The authors evaluate the mid-term results and their experience with the cementless total hip replacement Beznoska type S.F. "Slavík, Fencl" in a group of 40 patients.
Material: During 2002, a total of 46 patients underwent implantation of a cementless total hip replacement (THR) type S.F. Six patients failed to come to the final follow-up at 5 years after surgery. Coxarthritis was the indication for primary surgery in the majority of the patients. The average age of the group, which comprised 20 men and 20 women, was 63 (50-75) years.
Methods: At the end of 2007, 40 patients were evaluated at an average follow-up of 62.5 months. The patients' age, gender, body mass index, physical activity, diagnosis on which indication for surgery was based, size of each cementless component and intra- and post-operative complications were recorded. The objective outcome was assessed using the Harris Hip Score (HHS), signs of secondary stability were evaluated on radiographs at 3, 6 and 12 months, then at 3 and 5 years after the primary THR.
Results: The primary fixation of all components was always good. In the post-operative period there was no THR dislocation and no loosening of the polyethylene acetabular liner from the titanium shell. One patient suffered a periprosthetic fracture following a fall. At 5-year follow-up, no evidence of acetabular loosening was found one patient required polyethylene liner exchange for excessive wear. Thirty-eight stems were evaluated as stable, with three stems showing ingrowth of a fibrous intermediate layer. Only one femoral component was assessed as unstable with a suspected late haematogenous infection. The mean HHS value was 45.6 before THR and 90.3 at 5 years after the primary surgery. The results were excellent in 24, very good in 12, fair in two and poor in two patients.
Discussion: If the correct surgical procedure is observed, a perfect press-fit fixation of both components can always be achieved. The S.F. type implant can also be used for a dysplastic acetabulum in this case a deeper reaming of the acetabular bed in preferred to acetabular augmentation (acetabuloplasty). The excessive polyethylene wear in one patient can be accounted for by the patient's overdone daily exercise the imperfect secondary osteointegration of three stems was probably due to the selection of a smaller femoral component than it was appropriate. When an undersized stem is used, insufficient implant osteointegration and a higher incidence of pain symptoms should be expected. The findings of signs of stress shielding were in accordance with those reported in the literature. CONCLUSIONS The mid-term clinical results and evidence of good osteointegration of both components five years after primary implantation of the THR type S.F. in 40 patients are very satisfactory. This group of patients will be followed up for another 5 years and evaluated.