The ongoing debate on fixation in
total knee arthroplasty (TKA) has become increasingly relevant with its increased use in a younger patient population and the advent of novel cementless
prostheses. Recent literature suggests modern cementless implants are comparable to their cemented counterparts in terms of survivorship and functional outcomes. What has not been well-assessed is whether the two modalities differ with respect to
infection rates which was the purpose of this study. Specifically, a propensity score matched study population was used to compare: (1) overall
infection; (2) prosthetic joint
infection (PJI); and (3)
surgical site infection (SSI) rates between cementless and cemented TKAs. Using a large institutional database, 3,180 consecutive primary TKAs were identified. Cementless and cemented TKA patients were propensity score matched by age (p = 0.069), sex (p = 0.395), body mass index (BMI; p = 0.308), and Charlson's comorbidity index (CCI) score (p = 0.616) in a 1:1 ratio. Univariate analysis was performed to compare 2-year overall
infection rates.
Infections were further analyzed separately as PJIs (deep joint
infections requiring surgery) and SSIs (skin/superficial
wound infections). Multivariate logistic regression was performed to evaluate
infection incidences after adjusting for procedure-related factors (i.e.,
operative time, hospital volume, and surgeon volume). There were no significant differences between the matched cohorts in terms of overall
infection rates (3.8 vs. 2.3%, p = 0.722), as well as when PJI (p = 1.000) and SSI (p = 1.000) rates were analyzed separately. Multivariate analysis revealed no significant differences in overall postoperative
infection rates (p = 0.285), PJI rates (p = 0.446), or SSI rates (p = 0.453) even after adjusting for procedure-related factors. There is increasing literature investigating various outcomes demonstrating the comparable efficacies of cementless versus cemented TKAs. To the best of the author's knowledge, this was the first matched case-control study to directly compare their post-operative
infection rates. The findings from this study show that post-operative
infection rates were similar between fixation modalities even after accounting for a range of patient- and procedure-related factors.