TABLE 1.
Characteristics of the study subjects
| Characteristic | Valuea for subjects with: |
Pb | |
|---|---|---|---|
| Prosthetic joint infection (n = 104) | Aseptic failure (n = 125) | ||
| Median age (IQR), yr] | 66.5 (25, 92) | 67 (26, 87) | 0.825 |
| Male gender | 61 (59) | 66 (53) | 0.375 |
| Type of prosthetic joint | 0.013 | ||
| Hip | 31 (30) | 16 (13) | |
| Knee | 55 (53) | 85 (68) | |
| Shoulder | 11 (10) | 12 (10) | |
| Elbow | 7 (7) | 12 (10) | |
| Reason for primary arthroplasty | 0.618 | ||
| Osteoarthritis | 66 (64) | 86 (69) | |
| Fracture or trauma | 23 (22) | 28 (22) | |
| Rheumatoid arthritis | 5 (5) | 5 (4) | |
| Avascular necrosis | 0 (0) | 1 (1) | |
| Fibromyalgia | 1 (1) | 1 (1) | |
| Tumor | 3 (3) | 2 (2) | |
| Unknown | 6 (6) | 2 (2) | |
| Presence of sinus tract | 23 (22) | 0 (0) | <0.0001 |
| Visible purulence at implant site | 79 (76) | 0 (0) | <0.0001 |
| Acute inflammation in periprosthetic tissue [no./total (%)] | 55/86 (64) | 0/117 (0) | <0.0001 |
| Presence of clinical symptoms or signs | |||
| Pain | 92 (89) | 119 (95) | 0.059 |
| Local signs of infectionc | 48 (46) | 4 (3) | <0.0001 |
| Fever | 8 (8) | 2 (2) | 0.025 |
| Radiolucent lines present | 33 (32) | 49 (39) | 0.241 |
| Preoperative laboratory findings [no./total (%)]d | |||
| Blood leukocyte count >10 × 109/liter | 21/97 (22) | 15/110 (14) | <0.0001 |
| Erythrocyte sedimentation rate >30 mm/h | 58/98 (59) | 16/116 (14) | <0.0001 |
| Serum C-reactive protein concn >10 mg/liter | 72/100 (72) | 22/116 (19) | <0.0001 |
| Synovial fluid leukocyte count >3 × 109/liter | 38/50 (76) | 14/56 (25) | <0.0001 |
| Synovial fluid neutrophils >80% | 31/50 (62) | 6/56 (11) | <0.0001 |
| Positive synovial fluid culture | 27/57 (48) | 2/63 (3) | <0.0001 |
| Antibiotics received 4 weeks prior to surgery | 38 (37) | 10 (8) | <0.0001 |
| Surgical procedure | <0.0001 | ||
| Revision (including one-stage exchange) | 26 (25) | 102 (82) | |
| Resection (including insertion of a spacer) | 78 (75) | 23 (18) | |
| No. of tissue cultures [median (IQR)] | 4 (2, 10) | 3 (2, 10) | <0.0001 |
| Timing from prosthesis implanted to surgery (mo) | <0.0001 | ||
| <3 | 19 (18) | 1 (1) | |
| 3–12 | 26 (25) | 19 (15) | |
| >12 | 59 (57) | 105 (84) | |
a
Values are no. or no./total (%) unless interquartile range (IQR) is specified.
b
Age as a continuous variable was compared using the Wilcoxon rank sum test, and categorical variables were compared using Fisher's exact test.
c
Local signs of infection included redness and swelling around the surgical site.
d
Blood leukocyte count was the result within 1 week preoperative; other laboratory findings were the latest results within 6 months.