New-onset Fibromyalgia After Total Knee Replacement in Patients With Osteoarthritis: A Propensity-score-matched Cohort Study in the United States.

Background/aim: The risk of new-onset fibromyalgia after total knee replacement (TKR) in osteoarthritis patients is not well-established. This study aimed to assess the risk of developing fibromyalgia post-TKR, considering potential variations across age and sex.

Patients And Methods: Utilizing a multicenter retrospective cohort design and data from the TriNetX research network, electronic health records of osteoarthritis patients who underwent TKR and the same number of matched controls were analyzed. Propensity-score matching was performed by matching critical confounders. Hazard ratios were evaluated to assess fibromyalgia risk in the TKR cohort compared to non-TKR controls.

Results: The hazard ratio of future fibromyalgia for the TKR cohort was 2.08 (95% confidence interval=1.74-2.49) for 1 year after the index date, 1.81 (95% confidence interval=1.62-2.02) for 3 years, and 1.69 (95% confidence interval=1.54-1.86) for 5 years compared with non-TKR controls. The significant association remained in sensitivity models and stratification analyses in different age and sex subgroups.

Conclusion: Clinicians should be vigilant about the potential for fibromyalgia development post-TKR and consider tailored interventions; our findings emphasize the need for further research to elucidate underlying mechanisms and identify modifiable risk factors.