Risk factors for revision due to prosthetic joint infection following total knee arthroplasty based on 62,087 knees in the Finnish Arthroplasty Register from 2014 to 2020

Abstract

Background and purpose: Periprosthetic joint infection (PJI) is the commonest reason for revision after total knee arthroplasty (TKA). We assessed the risk factors for revision due to PJI following TKA based on the Finnish Arthroplasty Register (FAR).

Patients and methods: We analyzed 62,087 primary condylar TKAs registered between June 2014 and February 2020 with revision for PJI as the endpoint. Cox proportional hazards regression was used to estimate hazard ratios (HR) with 95% confidence intervals (CI) for the first PJI revision using 25 potential patient- and surgical-related risk factors as covariates.

Results: 484 knees were revised for the first time during the first postoperative year because of PJI. The HRs for revision due to PJI in unadjusted analysis were 0.5 (0.4-0.6) for female sex, 0.7 (0.6-1.0) for BMI 25-29, and 1.6 (1.1-2.5) for BMI > 40 compared with BMI < 25, 4.0 (1.3-12) for preoperative fracture diagnosis compared with osteoarthritis, and 0.7 (0.5-0.9) for use of an antimicrobial incise drape. In adjusted analysis the HRs were 2.2 (1.4-3.5) for ASA class III-IV compared with class I, 1.7 (1.4-2.1) for intraoperative bleeding ≥ 100 mL, 1.4 (1.2-1.8) for use of a drain, 0.7 (0.5-1.0) for short duration of operation of 45-59 minutes, and 1.7 (1.3-2.3) for long operation duration > 120 min compared with 60-89 minutes, and 1.3 (1.0-1.8) for use of general anesthesia.

Conclusion: We found increased risk for revision due to PJI when no incise drape was used. The use of drainage also increased the risk. Specializing in performing TKA reduces operative time and thereby also the PJI rate.

Figure 1

Directed acyclic graph (DAG) constructed under following assumptions:

1. TKA “revision for infection” is dependent on “patient age,” “sex,” “bilaterality,” “ASA class,” “BMI,” “diagnosis,” “hospital volume,” “education of surgeon,” “bleeding,” “drain,” “duration,” “intraoperative complications,” “previous operations,” “antimicrobial incise drape,” “anesthesia,” “antibiotic prophylaxis,” and type of TKA “fixation.” Choice of “side,” “education of assistant,” “surgical approach,” “antithrombotic prophylaxis,” “antifibrinolytic medications,” and “kinematic alignment” are not expected to affect “revision for infection” due to clinical suspicion.

2. “Fixation” is dependent on “age” and “sex” because older and female patients have probably received a cemented or hybrid TKA due to poorer bone quality. ASA class is partly dependent on age by definition. “Bilaterality” is dependent on “age” and “ASA class,” because both knees are seldom operated on in elderly or high ASA class patients.

3. “BMI” may affect “duration” and “intraoperative complications” due to more difficult operation with high BMI. “Duration” and “bleeding” may be dependent on “education of surgeon” due to the experience factor. “Bleeding,” “duration,” and “previous operations” may be dependent on clinical basis.

4. “Anesthesia” is dependent on “ASA class” and “age,” because general anesthesia is usually avoided in elderly patients. “Drain” is dependent on “bleeding” and vice versa.

Figure 2

Flowchart of patients.