Movement pattern of the Exeter femoral stem A radiostereometric analysis of 22 primary hip arthroplasties followed for 5 years

Background The design of the Exeter stem may facilitate distal migration, but radiostereometric analysis (RSA) studies have been limited to 2 years of follow-up. Patients and methods We followed migration of the Exeter femoral stems in 22 primary hip arthroplasties for 5 years with RSA. Results All stems migrated distally and the median migration at 2 years was 1.34 mm, while at 5 years it was 1.77 mm. 7 stems migrated above accuracy between 3 and 5 years. (RSA) evaluation of the cement mantle could be performed in 14 cases, and in 5 slight migration was found. Most of the stems rotated towards retroversion and the median rotation at 2 years was 1.2°, while at 5 years it was 1.6°. We found 1 patient with impending clinical failure but no deviation in the RSA migration pattern, and 1 patient with unstable migration pattern but no clinical symptoms. Interpretation We found a greater distal migration of the Exeter stem for longer periods of time than seen with other types of cemented implants.