We studied the effects of
antibiotic prophylaxis, systemically and in
bone cement, on the revision rate of cemented
total hip arthroplasties (
THAs) in data from the Norwegian
Arthroplasty Register during the period 1987-2001. To have comparable groups, only
THAs performed because of primary
osteoarthritis, using cemented implants with documented good results, and high-viscosity cement were included. If systemic
antibiotic prophylaxis had been given, only operations with
cephalosporin or
penicillin were selected. Cox-estimated survival relative revision risks (RR) are presented with adjustment for differences among groups in gender, age, cement brand, type of systemic
antibiotic prophylaxis, type of
prosthesis, type of operating room, and duration of the operation. Of 22,170
THAs studied, 696
THAs (3.1%) were revised, 440 (2.0%) for aseptic loosening and 102 (0.5%) for deep
infection. We found the lowest risk of revision when the
antibiotic prophylaxis was given both systemically and in the cement (15,676
THAs). Compared to this combined regime, patients who received
antibiotic prophylaxis only systemically (5,960
THAs) had a 1.4 times higher revision rate with all reasons for revision as endpoint (p = 0.001), 1.3 times higher with aseptic loosening (p = 0.02) and 1.8 times higher with
infection as the endpoint (p = 0.01). With the combined
antibiotic regime, the results were better if
antibiotics were given 4 times on the day of surgery (2,194
THAs), as compared to once (1,424
THAs) (p < 0.001), twice (2,680
THAs) (p < 0.001), or 3 times (5,522
THAs) (p = 0.02). Those who received systemic prophylaxis a single day 1, 2 or 3 times, as compared to 4 times, had a revision rate 1.8-3.5 times higher with all reasons for revision as endpoint, 1.5-3.1 times higher with aseptic loosening, and 2.7-6.8 times higher with
infection. When we compared systemic prophylaxis 4 times in 1 day, no further improvement resulted in those given systemic prophylaxis for 2 days (1,928
THAs) or 3 days (717
THAs). In a subset of data including only the Charnley
prosthesis, we obtained similar results. This observational study shows that the best results were recorded when
antibiotic prophylaxis was given both systemically and in the
bone cement, and if the systemic
antibiotic was given 4 times on the day of surgery.