Higher revision risk for unicompartmental knee arthroplasty in low-volume hospitals.
OBJECTIVE
Some studies have found high complication rates and others have found low complication rates after unicompartmental knee arthroplasty (UKA). We evaluated whether hospital procedure volume influences the risk of revision using data from the Norwegian Arthroplasty Register (NAR).


METHODS
5,791 UKAs have been registered in the Norwegian Arthroplasty Register. We analyzed the 4,460 cemented medial Oxford III implants that were used from 1999 to 2012; this is the most commonly used UKA implant in Norway. Cox regression (adjusted for age, sex, and diagnosis) was used to estimate risk ratios (RRs) for revision. 4 different volume groups were compared: 1-10, 11-20, 21-40, and > 40 UKA procedures annually per hospital. We also analyzed the reasons for revision.


CONCLUSIONS
We found a lower risk of revision in hospitals performing more than 40 procedures a year than in those with less than 10 UKAs a year, with an unadjusted RR of 0.53 (95% CI: 0.35-0.81) and adjusted RR of 0.59 (95% CI: 0.39-0.90). Low-volume hospitals appeared to have a higher risk of revision due to dislocation, instability, malalignment, and fracture than high-volume hospitals.
Kysthospital in Hagevik , Hagavik.
Mona
M
Badawy
Birgitte
B
Espehaug
Kari
K
Indrekvam
Leif I
LI
Havelin
Ove
O
Furnes
D000328:Adult; D000368:Aged; D000369:Aged, 80 and over; D019645:Arthroplasty, Replacement, Knee / Q000706:statistics & numerical data*; D005260:Female; D061846:Hospitals, Low-Volume / Q000706:statistics & numerical data*; D006801:Humans; D007720:Knee Prosthesis / Q000706:statistics & numerical data; D008297:Male; D008875:Middle Aged; D009664:Norway / Q000453:epidemiology; D011183:Postoperative Complications / Q000453:epidemiology* / Q000601:surgery*; D016016:Proportional Hazards Models; D011475:Prosthesis Failure; D012086:Reoperation / Q000706:statistics & numerical data; D012307:Risk Factors