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.


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 degrees, while at 5 years it was 1.6 degrees. 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.


CONCLUSIONS
We found a greater distal migration of the Exeter stem for longer periods of time than seen with other types of cemented implants.
Stefánsdóttir
Anna
A
Department of Orthopedics, Hässleholm-Kristianstad County Hospital, Sweden. anna.stefansdottir@ort.lu.se
Franzén
Herbert
H
Johnsson
Ragnar
R
Ornstein
Ewald
E
Sundberg
Martin
M
D000328:Adult; D000368:Aged; D001696:Biomechanical Phenomena; D005260:Female; D005500:Follow-Up Studies; D005548:Foreign-Body Migration / Q000000981:diagnostic imaging*; D006622:Hip Prosthesis; D006801:Humans; D008297:Male; D008875:Middle Aged; D015207:Osteoarthritis, Hip / Q000000981:diagnostic imaging* / Q000601:surgery*; D011474:Prosthesis Design; D011475:Prosthesis Failure; D011859:Radiography; D013997:Time Factors