Migration characteristics and early clinical results of a novel-finned press-fit acetabular cup.
BACKGROUND
Ana Nova® is a novel-finned press-fit acetabular cup which showed superior biomechanical characteristics in an experimental set-up. Using Einzel Bild Röntgen Analyse (EBRA) measurements should offer the opportunity to predict implant survival at an early stage. The purpose of this study was to assess migration and clinical outcome 2 years after total hip replacement by a novel-finned press-fit acetabular cup.


METHODS
In this study, migration and clinical results of the implant were prospectively assessed in 67 patients. Clinical outcome was assessed using the Harris hip score (HHS). Migration analyses were performed using the computer assisted EBRA system. Data were analyzed for normal distribution using the Kolmogorov-Smirnov test. Group comparisons were performed using the analysis of variance (ANOVA) test. P-values less than 0.05 were considered statistically significant.


RESULTS
At 2 years after surgery, none of the implants needed revision and HHS increased from 39.7 up to 92.2. In contrast to the beneficial clinical outcome, 17 of 44 patients showed increased total migration ( 1 mm/2a).


CONCLUSIONS
Adverse migration data in this study might predict aseptic loosening and decreased survival of the implant. According to previous studies, it is possible that this effect occurred because of limited accuracy of the EBRA system. In our opinion, migration analyses may not be recommended as a screening tool in a 2 year follow-up.
Orthopaedic Department, Barmherzige Brüder Hospital, Johannes von Gott-Platz 1, 7000, Eisenstadt, Austria, martin.kaipel@bbeisen.at.
Martin
M
Kaipel
Anton
A
Prenner
Sebastian
S
Bachl
Sebastian
S
Farr
Günter
G
Sinz
D000077:Acetabulum / Q000601:surgery*; D000328:Adult; D000368:Aged; D019644:Arthroplasty, Replacement, Hip / Q000009:adverse effects*; D019544:Equipment Failure Analysis; D005260:Female; D005271:Femur Head Necrosis / Q000150:complications / Q000000981:diagnostic imaging / Q000601:surgery*; D006622:Hip Prosthesis / Q000009:adverse effects*; D006801:Humans; D007593:Joint Instability / Q000000981:diagnostic imaging / Q000209:etiology* / Q000601:surgery*; D008297:Male; D008875:Middle Aged; D015207:Osteoarthritis, Hip / Q000150:complications / Q000000981:diagnostic imaging / Q000601:surgery*; D010865:Pilot Projects; D011312:Pressure; D011474:Prosthesis Design; D011475:Prosthesis Failure; D017755:Prosthesis Fitting / Q000009:adverse effects; D011859:Radiography; D012086:Reoperation; D016896:Treatment Outcome