The most feared complication of arthroplasty after septic arthritis (active or quiescent) on a degenerative joint is septic failure, but this risk is difficult to assess. The aim of the present study was to analyze the results of arthroplasties after septic arthritis of native knee and hip joints, in terms of functional results and infection control and to seek eventual risk factors of failure.

Fifty-three cases of septic arthritis treated by arthroplasty (31 knees and 22 hips) were retrospectively included. In case of evolutive septic arthritis (30 cases: 17 knees and 13 hips) failing to react to conservative treatment, arthroplasty was performed in a 2-stage procedure (a mean interval of 6 weeks between stages, and an associated antibiotic therapy for a mean 3 months were routinely respected). In case of previous arthritis considered to be cured (23 cases: 14 knees and nine hips), arthroplasty was performed with a 1-stage procedure, observing a mean interval of 5 years after the initial septic arthritis, and antibiotic therapy maintained until definitive microbiological results were obtained from joint cultures samples at surgery. No patients were lost to follow-up; minimum follow-up was 2 years, for a mean of 5 years. The final results were assessed in terms of functional outcome (on PMA functional score for hips and IKS score for knees) and successful eradication of infection.

Two-stage arthroplasty was successful in 26 of the 30 cases of evolutive septic arthritis (87%), while the 1-stage procedure was successful in 22 of the 23 cases of quiescent septic arthritis (95%) (NS). Functional results were very good. No significant difference in functional outcome or successful eradication of infection was found between the 1- and 2-stage procedures. No significant difference in final outcome in terms of infection eradication was found between knees and hips. No clinical, microbiological or treatment-related criteria emerged as risk factors for septic failure.

Arthroplasty after septic arthritis of the knee or hip using the present protocol (2-stage implantation in case of evolutive septic arthritis and a 1-stage procedure in case of quiescent septic arthritis) achieved very good functional results with a success rate of 87% for sepsis control in evolutive septic arthritis and of 95% in quiescent septic arthritis.

Level IV retrospective or historical series.