A search in the local operation register provided 522 operations under the study period. Twenty-eight operations in 24 patients were excluded from further analysis. 5 patients had been diagnosed with polymyalgia rheumatica, 10 with osteoarthritis, 1 with calcium pyrophosphate arthritis, 1 with spondyloepiphyseal dysplasia, and in 7 cases data regarding rheumatic diagnosis could not be found. After exclusions, data was collected from 494 operations in 395 individual patients (Fig. 1). 92 patients had undergone more than one operation.
Patient characteristics are described in Table 2. A majority of cases were female (76%) and the mean age by time of surgery was 62 years (range 18–89). TKA comprised 51% of procedures (n = 245). A majority of cases had RA (69%) followed by juvenile idiopathic arthritis (JIA) (12%). The most used DMARD was methotrexate (55,5%), followed by a TNF-alpha inhibitor (31.8%). 18.2% of patients were on both methotrexate and a TNF- alpha inhibitor. Details on treatment is summarized in Table 3.
Table 2
Patients characteristics. Values are number (percentage) unless otherwise indicated.
All | 494 |
Female | 377 (76.3) |
TKA1 | 254 (51.4) |
THA2 | 240 (48.6) |
Age, years, by time of surgery, mean (range) | 62.4 (18–89) |
ASA3, valid no 451 | |
ASA 1 | 9 (2) |
ASA 2 | 268 (59.4) |
ASA 3 | 172 (38.1) |
ASA 4 | 2 (0.4) |
BMI4, kg/m^2, valid no 474, mean(range) | 26.5(14.9–44.6) |
Diagnosis | |
Rheumatoid arthritisa | 341 (69) |
Psoriatic arthritis | 35 (7) |
Spondyloarthritis incl. ankylosing spondylitisb | 29 (5.9) |
Juvenile idiopathic arthritisc | 59 (11.9) |
Other diagnosisd | 30 (6.1) |
1 Total knee-arthroplasty, 2Total hip-arthroplasty, 3American Society of Anesthesiologists (ASA) Physical Status, 4Body mass index
a Seropositive rheumatoid arthritis (n = 283), seronegative rheumatoid arthritis (n = 58)
b Ankylosing spondylitis (n = 21), other specified inflammatory spondylopathies (n = 6), inflammatory spondylopathy, unspecified (n = 2)
c juvenile arthritis (n = 40), juvenile arthritis with systemic onset (n = 7), juvenile polyarthritis (seronegative) (n = 6), juvenile arthritis, unspecified (n = 4), pauciarticular juvenile rheumatoid arthritis (n = 2)
d Inflammatory polyarthropathy (n = 1), polyarthritis, unspecified (n = 4), other specified arthritis (n = 4), monoarthritis, not elsewhere classified (n = 2), systemic lupus erythematosus, unspecified (n = 5), systemic lupus erythematosus with organ or system involvement (n = 3), adult-onset Still disease (n = 2), Crohn´s disease (n = 1), ulcerative colitis (n = 1), polymyositis (n = 1), systemic sclerosis (n = 2), other overlap syndrome (n = 1), arthritis unspecified (n = 1), systemic involvement of connective tissue, unspecified (n = 2)
Table 3
Exposure. Values are number (percentage) unless otherwise indicated.
Prednisolone | 214 (43.3) |
Prednisolone, dose mg/d, mean (valid no 489) | 5.5 |
Number of ongoing DMARDs1 | |
0 | 109 (22.1) |
1 | 243 (49.2) |
2 | 132 (26.7) |
3 | 10 (2) |
cDMARD2 | 343 (69.4) |
Methotrexate | 274 (55.5) |
Methotrexate dose, mg/w, mean (valid no 488) | 16 |
cDMARD2 other than methotrexatea | 69 (14) |
bDMARD3 | 193 (39.1) |
TNF- alpha inhibitorb | 157 (31.8) |
bDMARD3, other than TNF- alpha inhibitorc | 36 (7.3) |
Methotrexate and prednisolone | 124 (25.1) |
Methotrexate and TNF- alpha inhibitor | 90 (18.2) |
Methotrexate and prednisolone and TNF- alpha inhibitor | 40 (8.1) |
1 Disease-modifying antirheumatic drug
2 Conventional disease-modifying antirheumatic drug
3 Biologic disease-modifying antirheumatic drug
a azathioprine (n = 9), sulfasalazine (n = 30), hydroxychloroquine (n = 26), mycophenolate mofetil (n = 3) and leflunomide (n = 1)
b etanercept (n = 93), golimumab (n = 5), certolizumab (n = 12), infliximab (n = 15), adalimumab (n = 32)
c abatacept (n = 6), rituximab (n = 16), anakinra (n = 5), tocilizumab (n = 14) One patient did bilateral THA at the same session and was treated with both anakinra and rituximab
The total incidence of SSI was 3.8% (n = 19). Of these, 12 were superficial SSI; the rate of superficial SSI being 2.4%. All of these healed after wound debridement and/or antibiotic treatment.
There were seven PJI; the one-year rate of PJI being 1.4%. All PJI occurred after TKA and there was a statistically significant difference in the rate of PJI depending on operating site (p = 0.015). One of the patients suffering a PJI had a hematogenous infection 11 months after surgery, but is according to the design of the study counted as a SSI .
One patient with PJI was treated with the TNF-alpha inhibitor etanercept, and 4 patients were treated with methotrexate. There was no statistically significant difference in the rate of infection between patients treated with a TNF-alpha inhibitor and those not, (p = 0.44) or those treated with methotrexate (p = 1.00). No association could be found between PJI and prednisolone (p = 0.25), combination of TNF-alpha inhibitor and methotrexate (p = 1.0), combination of methotrexate and prednisolone (p = 1.0), combination of TNF-alpha inhibitor, methotrexate and prednisolone (p = 1.0), BMI (p = 0.21) or ASA-score (p = 0.44) (Table 4).
Table 4
Periprosthetic joint infection(PJI) and total surgical site infections(SSI) in various subgroups.
| total(n) | PJI(n) | p-value | total SSI (n) | p-value |
Female | 377 | 3 | | 14 | |
Male | 117 | 4 | 0.06a | 5 | 0.78b |
Procedure | | | | | |
TKA1 | 254 | 7 | | 11 | |
THA2 | 240 | 0 | 0.015a | 8 | 0.33b |
BMI3, valid no 474 | | | | | |
< 30 | 368 | 4 | | 12 | |
≥ 30 | 106 | 3 | 0.19a | 7 | 0.16 b |
ASA4, valid no 448 | | | | | |
≤ 2 | 277 | 3 | | 10 | |
≥ 3 | 174 | 4 | 0.44a | 8 | 0.60 b |
Treatment | | | | | |
Methotrexate | 274 | 4 | 1.0a | 12 | 0.49b |
TNF-alpha inhibitor | 157 | 1 | 0.44a | 5 | 0.60b |
Prednisolone | 214 | 5 | 0.25a | 10 | 0.40b |
Methotrexate and prednisolone | 124 | 2 | 1.00a | 4 | 0.79a |
Methotrexate and TNF-inhibitor | 90 | 1 | 1.00a | 3 | 1.00a |
Methotrexate, TNF- inhibitor and prednisolone | 39 | 0 | 1.00a | 0 | 0.39 a |
1 Total knee-arthroplasty, 2Total hip-arthroplasty, 3Body mass index 4American Society of Anesthesiologists (ASA) Physical Status.
a Fisher´s exact test
b Chi-square test
No correlation could be found between the total number of SSI and medical treatment (Table 4).
Five out of 7 PJI healed after treatment with debridement and antibiotics. Details on patients suffering PJI, including outcome are described in Table 5.
Table 5
, Periprosthetic joint infection (PJI), individual cases
Diagnosis | Age | Sex | Type of surgery | Anti-rheumatic treatment | Infectious agents | Treatment of PJI | Outcome |
RA1, seronegative | 65 | Female | TKA3 | Methotrexate, prednisolone | S. aureus | Debridement and exchange of tibial insert | Healed (26 months later re-infected with the same bacteria) |
RA1, seropositive | 66 | Male | TKA3 | Etanercept, methotrexate | coagulase negative staphylococcus (CNS) | Two-stage revision | Healed |
RA1, seropositive | 70 | Male | TKA3 | Prednisolone, azathioprine | S. aureus | Debridement and exchange of tibial insert | Failure (chronic infection treated with suppressive antibiotics) |
RA1, seropositive | 69 | Female | TKA3 | Methotrexate, prednisolone | B. fragilis | Antibiotics | Failure, amputation |
RA1, seropositive | 66 | Female | TKA3 | Methotrexate, sulfasalazine, hydroxychloroquine, prednisolone | S. mitis, S. hominis | Debridement and exchange of tibial insert | Healed |
RA1, seropositive | 67 | Male | TKA3 | Prednisolone | coagulase negative staphylococcus (CNS) | Debridement and exchange of tibial insert | Healed |
PsA2 | 44 | Male | TKA3 | None | coagulase negative staphylococcus (CNS) | Debridement and exchange of tibial insert | Healed |
1 Rheumatoid arthritis, 2psoriatic arthritis.
- after consultation with a specialist in infectious diseases, all patients received treatment with antibiotics for a minimum of three months according to antimicrobial resistance pattern.
Four out of seven of patients with a PJI were male, although only 24% of the operations were performed on male patients. However, there was no statistically significant difference in the rate of PJI between men and women (p = 0.06) (Table 4).
Six patients died within one year of surgery. One patient died 20 days after surgery due to a gastrointestinal bleeding. Three patients died due to acute coronary syndrome, one due to a subarachnoid hemorrhage and one due to progressive dementia (Pick's disease). None of the deaths within one year of surgery could be linked directly to surgery or PJI.
Four patients underwent reoperation within one year from surgery. One patient was reoperated because of joint instability, two because of aseptic loosening of the prosthesis and one patient due to fracture after resurfacing hip arthroplasty.