Paper of the week: Risk Factors for Failure After 1-Stage Exchange Total Knee Arthroplasty in the Management of Periprosthetic Joint Infection. Citak M, Friedenstab J, Abdelaziz H, Suero EM, Zahar A, Salber J, Gehrke T. J Bone Joint Surg Am. 2019 Jun 19;101(12):1061-1069. doi: 10.2106/JBJS.18.00947.

Summary by Dr Sreeram Penna

In this case control study researchers analyzed the causes of and risk factors for failure following 1-stage exchange total knee arthroplasty. In this study cases consist of total knee joints treated for periprosthetic joint infection with 1 stage exchange arthroplasty that subsequently had revision procedures. These were matched with controls who had 1 stage exchange arthroplasty that did not require further revision. Cases included 91 patients, of these patients reason for failure was infection (n = 42), aseptic loosening (n = 37), patellar problems (n=3), periprosthetic fracture (n=3) and knee dislocation (n=1). Risk factors associated with reoperation in 1 stage procedure included weight more than 100, history of DVT, more than 4 prior procedures, history of poly microbial infection, prior one stage exchange, prior two stage exchange, extensive osseous defects requiring tantalum cones, surgical time more than 4 hours, persistent wound drainage, and isolation of enterococcus. Further bivariate analysis of infection subgroup showed all above risk factors except extensive osseous defect. It also identified two additional risk factors including isolation of streptococcus and wound revision due to healing disorders. Please see table below for odds ratios (OR).