Discussion
hip arthroplasty, TKA
DISORDERS
The most important findings of this study were the significant positive/negative association of dispositional optimism/pessimism with post-operative functional outcome after TKA measured via the KOOS-12 score. Optimistic patients showed significant higher KOOS-12 scores pre-operative as well as 3, 6 and 12 months post-operative, while pessimistic patients had significant lower scores at all survey points compared to their respective counterparts.The findings of higher post-operative function in optimistic than in pessimistic patients are in line with other literature, showing better outcome in optimistic patients after total hip arthroplasty [Nevertheless, the significant higher post-operative functional scores in optimistic patients could be derived by the influence of pre-operative functional score levels on post-operative score values as this has been shown previously [Besides the overall higher satisfaction in life and after surgery in optimists [Even though the KOOS-12 is a widely used instrument in patient-reported outcome measurements (PROMs), one has to take into consideration that PROMs might not be the right instrument when measuring outcome in optimists and pessimists. Scherer et al. [When considering the study results, the question about the practical significance for orthopedic surgeons remains, especially as the MCID of the KOOS-12 was not reached at every post-operative survey point in this study, probably due to the large sample size. Nevertheless, our findings suggest considering every patient’s individual personality traits when he or she is admitted to surgery. This would allow the treating physicians to detect pessimistic patients, who tend to have worse outcomes and potentially react to their special needs and pessimistic expectations prior to surgery. A redirection of these pessimistic patients to a cognitive–behavioral intervention or an intervention on pessimism-predicting variables (e.g., preexisting mental disorders, lack of social support) prior to surgery could help to reduce pessimism and increase optimism and optimistic expectations in those patients, and thus could improve post-operative outcome.