Poor outcome of a spherical pressfit cup with a modern ceramic liner: a prospective cohort study of 181 cups.

A spherical pressfit cup with a new ceramic liner was introduced in a clinical trial in order to improve range of motion and reduce wear induced problems. The early clinical and radiological outcome was assessed.In a prospective cohort study 181 hips received a seleXys TH+ cup (Mathys, Bettlach, Switzerland) in combination with a third generation ceramic liner (ceramys, Mathys, Bettlach, Switzerland). The Harris Hip Score (HHS), pain (VAS) and range of motion (ROM) were recorded, cup migration and inclination were measured. Experience of any noise was documented.Fourteen hips were radiologically loose, seven of them were revised. Two-year survival of the cup was 92% with radiological loosening as the endpoint. There was no correlation between head size and ROM, no patient had a dislocation. There were no ceramic fractures. Two patients experienced squeaking and three clicking at final follow-up.Reasons for loosening might have been multifactorial but the rate of failure was unacceptably high. The use of large heads did not improve the ROM and development of noise could not be prevented with the modern ceramic. We abandoned the use of this implant system.