Factors influencing the outcome of deep infection following total knee arthroplasty

• We searched the factors related to the outcomes of cases with infection after TKA.
• Short onset time after primary TKA is related to good clinical outcome.
• Undergoing primary TKA in an arthroplasty center is related to good clinical outcome.
• Infection with methicillin-resistant organisms is related to poor clinical outcome.

BackgroundWhereas clinical studies have revealed a number of important risk factors for postoperative infection following total knee arthroplasty (TKA), it is unclear which factor influences clinical results. A multicenter study was therefore performed by reviewing 51 patients with deep infection after TKA and seeking for the factors related to clinical outcomes.MethodsFifty-one deep infections after TKA were treated from 2000 to 2011 at the multicenter including a university or three arthroplasty centers. Among them, two clinical outcome measures including retention of prosthesis at initial treatment and functional prosthetic knee were assessed for several factors such as age, sex, primary diagnosis, onset time after primary TKA, type of hospital where the primary TKA was performed and the organism's resistance to methicillin using the logistic regression analysis model.ResultsAmong the factors, type of hospital where the primary TKA was performed and onset time after primary TKA had higher multivariable-adjusted odds ratios (ORs) for retention of primary prosthesis (ORs 35.21 and 11.69, respectively.). The cases which primary surgery were performed in arthroplasty centers had higher multivariable-adjusted ORs for functional prosthetic knee (OR 4.9). Thirty-one infection cases with non-methicillin-resistant organisms were all able to keep functional prosthetic knee after the operation, whereas 13 out of 20 infection cases with methicillin-resistant organisms lost their knee function after the operation.ConclusionsOnset time after primary TKA, type of hospital where the primary surgery was performed and the organism's resistance to methicillin are important factors influencing the clinical outcomes after infected TKA.Level of EvidenceLevel 3. Retrospective comparative study.