Cementless stem stability in dysplastic osteoarthritis of the hip--12 years' experience.

BACKGROUND The aim of this paper is a retrospective assessment of artificial hip joint function and stability of cementless stems of varied design used in the treatment of deformative and degenerative dysplastic changes in the hip. MATERIALS AND METHODS The study enrolled 182 patients treated by cementless total hip arthroplasty. The average age of the patients was 44 years and the follow-up time ranged from 2 to 22 years (16.7 years on average). The following features were assessed: endoprosthesis survival judex according to Kaplan-Meier's criteria, functional outcome of the treatment on the Harris Hip Score (HHS) and endoprosthesis stability and changes in periprosthetic bone tissue over time, according to McGovern, Callaghan and Engh. RESULTS The study revealed a considerable importance of the method chosen for matching the type of endoprosthesis to the anatomy of the dysplastic hip. The highest probability of long endoprosthesis survival time, correct implant placement and good stability in the femoral canal was obtained in the group with anatomical stem implants. The function of the operated hip in the study group had improved three times by the third year of follow-up. CONCLUSIONS In dysplastic arthrosis, in which the proximal part of the femur has a narrow canal, the intertrochanteric area is often deformed and the angle of antetorsion greatly increased, better stability and osteointegration as well as a considerable functional improvement and extension of survival time can be obtained through using the so called anatomical stem, with anteflexion and antetorsion, fitted in the intertrochanteric area of the bone.