Preoperative mental health status measured by the SF12 questionnaire correlates with patient reported outcomes one year after total knee arthroplasty

Preoperative mental health status affects the clinical outcome of total knee arthroplasty (TKA). The first objective of our study was to investigate whether the mental health component of the SF12 questionnaire (SF12-MCS) could predict clinical outcomes one year after TKA. The second objective was to determine the influence of the questionnaire on postoperative Oxford and WOMAC scores one year after surgery. A prospective study of patients who received the same model of total knee arthroplasty was conducted at a single surgical center. The SF12, Oxford and WOMAC questionnaires were used to evaluate patient-reported outcome measures (PROMs). The statistical analysis included Wilcoxon rank-sum test, Pearson's correlation method and regression analysis via R project software. A total of 138 patients were included in the final analysis; the preoperative SF12-MCS score was moderately correlated with the Oxford score one year after surgery (r = 0.39, p value < 0.05). All patients improved their clinical status as measured by PROMs, regardless of their preoperative SF12-MCS score, but patients with a higher SF12-MCS score had higher scores on the final evaluation of the Oxford and WOMAC questionnaires. The difference in the measured outcomes was not significant between the groups with or without depression. The SF12-MCS proved to be a useful tool for identifying patients who obtained lower PROM scores after TKA. A lower preoperative score on the SF12-MCS does not preclude significant improvement after TKA.