Septic vs. aseptic revision knee arthroplasty: are scoring systems effective in communicating the nuances?

In comparison to primary TKA, outcomes of revision TKA will always appear inferior. When trying to assess outcomes of revision TKA for PJI, a group of aseptic revisions can serve as a reliable control, as compared to primary TKA. Our primary aim was to compare functional outcomes of septic versus aseptic revisions by using 5 scoring systems.

We retrospectively reviewed 45 revision knee arthroplasty cases. Of the 45 cases, 17 belonged to the septic group and 28 to the aseptic group. The scores obtained were assessed for differences between the two groups using the Mann-Whitney U test. Pearson correlation coefficient (r) was calculated to assess the correlation between the PCS and MCS of the SF-36 score vs. other scores.

The mean WOMAC score in the septic group was 38.88 ± 6.35 and in the aseptic group was 44.96 ± 10.07. With regards to the SF-36 score, the RE component (role limitations due to emotional problems) showed a significant difference, being poorer in the septic group (51.06 ± 31.57) as compared to the aseptic group (69.18 ± 28.62). We found a higher incidence of rest pain and nocturnal pain in the septic group. None of the scoring systems showed correlation with the SF-36 score.

In our study, there was a significant difference in the outcome of revision TKA based on etiology only with regards to the WOMAC score. Moreover, our study brings to the fore the importance of not just surgical management of patients with septic failure but also the importance of paying heed to the emotional and social problems encountered by these patients which has an impact on their outcome as a whole and diminishes their perception of benefit from revision surgery in spite of equivocal knee scores as compared to their counterparts.