The Nordic Arthroplasty Register Association: a unique collaboration between 3 national hip arthroplasty registries with 280,201 THRs.
OBJECTIVE
The possibility of comparing results and of pooling the data has been limited for the Nordic arthroplasty registries, because of different registration systems and questionnaires. We have established a common Nordic database, in order to compare demographics and the results of total hip replacement surgery between countries. In addition, we plan to study results in patient groups in which the numbers are too small to be studied in the individual countries.


METHODS
Primary total hip replacements (THRs) from 1995-2006 were selected for the study. Denmark, Sweden, and Norway contributed data. A common code set was made and Cox multiple regression, with adjustment for age, sex, and diagnosis was used to calculate prosthesis survival with any revision as endpoint.


RESULTS
280,201 operations were included (69,242 from Denmark, 140,821 from Sweden, and 70,138 from Norway). Females accounted for 60% of the patients in Denmark and Sweden, and 70% in Norway. Childhood disease was the cause of 3.1%, 1.8%, and 8.7% of the operations in Denmark, Sweden, and Norway, respectively. Resurfacing of hips accounted for 0.5% or less in all countries. The posterior approach was used in 91% of cases in Denmark, 60% in Sweden, and 24% in Norway. Cemented THRs were used in 46% of patients in Denmark, in 89% of patients in Sweden, and in 79% of patients in Norway. Of the 280,201 primary THRs, 9,596 (3.4%) had been revised. 10-year survival was 92% (95% CI: 91.6-92.4) in Denmark, 94% (95% CI: 93.6-94.1) in Sweden, and 93% (95% CI: 92.3-93.0) in Norway. In Denmark, 34% of the revisions were due to dislocation, as compared to 23% in Sweden and Norway. Replacement of only cup or liner constituted 44% of the revisions in Denmark, 29% in Sweden, and 33% in Norway.


CONCLUSIONS
This unique common Nordic collaboration has shown differences between the countries concerning demographics, prosthesis fixation, and survival. The large number of patients in this database significantly widens our horizons for future research.
Havelin
Leif I
LI
The Norwegian Arthroplasty Register, Department of Orthopaedic Surgery, Haukeland University Hospital, Bergen, Norway. leif.havelin@helse-bergen.no
Fenstad
Anne M
AM
Salomonsson
Roger
R
Mehnert
Frank
F
Furnes
Ove
O
Overgaard
Søren
S
Pedersen
Alma B
AB
Herberts
Peter
P
Kärrholm
Johan
J
Garellick
Göran
G
D000293:Adolescent; D000328:Adult; D000368:Aged; D000369:Aged, 80 and over; D019644:Arthroplasty, Replacement, Hip / Q000009:adverse effects / Q000592:standards*; D002648:Child; D016208:Databases, Factual; D003718:Denmark; D005260:Female; D005271:Femur Head Necrosis / Q000601:surgery; D006801:Humans; D008297:Male; D008875:Middle Aged; D009664:Norway; D015207:Osteoarthritis, Hip / Q000601:surgery; D017063:Outcome Assessment, Health Care; D011475:Prosthesis Failure; D012042:Registries; D012086:Reoperation; D013548:Sweden; D055815:Young Adult