[Measurement of migration of acetabular components in cementless hip replacement].
OBJECTIVE
Migration measurements of acetabular components using a special computer aided method (EBRA = abbreviation for the German term "Ein-Bild-Röntgenanalyse") were performed to evaluate early results of the implants and predict aseptic loosening.


METHODS
Standard ap-radiographs of the pelvis were marked, specific points were digitised. Simulating the spatial situation the programme computes longitudinal and vertical migration of the cup. 74 acetabular components in 71 patients could be studied by migration measurements.


RESULTS
14 patients showed migration of more than 1 mm, which is the confidence limit of this method. Each of these patients showed diverse reasons for the migration, i.e. osteoporosis of the acetabular bone stock or problems concerning the surgical technique which means malposition of the cup or insufficient reaming of the bone. There were some patients with severe congenital dysplasia of the hip and in some cases the inclination angle of the cup was too great.


CONCLUSIONS
The technique applied for measuring migration of acetabular components can be useful for evaluating early instability of the implant and can be helpful in detecting problems concerning the surgical technique.
Eckardt
A
A
Klinik für Orthopädie, Johannes Gutenberg-Universität Mainz.
Karbowski
A
A
Schwitalle
M
M
Vogel
J
J
Bodem
F
F
Seeleitner
C
C
Schunk
K
K
Mayrhofer
P
P
D000077:Acetabulum / Q000000981:diagnostic imaging; D000328:Adult; D000368:Aged; D019644:Arthroplasty, Replacement, Hip / Q000009:adverse effects* / Q000379:methods; D001843:Bone Cements; D016001:Confidence Intervals; D005260:Female; D005500:Follow-Up Studies; D005548:Foreign-Body Migration / Q000000981:diagnostic imaging*; D006622:Hip Prosthesis; D006801:Humans; D008297:Male; D008875:Middle Aged; D010024:Osteoporosis / Q000000981:diagnostic imaging / Q000209:etiology; D011183:Postoperative Complications; D011474:Prosthesis Design; D011857:Radiographic Image Interpretation, Computer-Assisted / Q000379:methods*; D012680:Sensitivity and Specificity
D001843:Bone Cements