Depressive symptoms influence progression to total knee arthroplasty in patients with early knee osteoarthritis: Evidence from the Osteoarthritis Initiative database

Purpose: Several factors can influence progression to total knee arthroplasty (TKA) in knee osteoarthritis (OA) patients. Among these, psychological aspects can play a relevant role. The aim of this study was to quantify the influence of depressive symptoms on the progression to TKA in a large population of patients affected by knee OA. Methods: A total of 912 patients were selected from the Osteoarthritis Initiative (OAI) database. The data collected included demographic data, Kellgren–Lawrence (KL) OA grade, Visual analogue scale (VAS) for pain, Center for Epidemiologic Studies Depression Scale (CES-D) and the number of patients progressing to TKA. Patients with KL 2, 3 or 4 and with symptomatic knee OA (VAS ≥ 3) were included and followed up to 9 years. Results: At 9 years, 22.9% of patients underwent TKA. Overall, no significant differences of CES-D were found between patients who progressed to TKA and patients who did not. However, in patients with KL grade 2, those who progressed to TKA had a significantly higher CES-D compared to those who did not (6.9 ± 6.6 vs. 5.4 ± 5.2, p = 0.018) and the CES-D score significantly associated with the risk of undergoing TKA (hazard ratio = 1.042, p = 0.015). The pairwise comparison of KL 2 patients showed a significant difference in terms of progression to TKA between patients having a CES-D > 6 and patients having a CES-D ≤ 6 (p = 0.001). None of these differences were statistically significant in the KL 3 and 4 groups. Conclusion: This study showed that even minor psychological symptoms related to the depression spectrum, well below the threshold of what commonly considered the level at risk for developing clinical depression, are significantly correlated with the trajectory towards TKA in knee OA patients. However, this correlation was observed only in early KL 2 knee OA patients, but not in the more advanced KL 3 and 4 stages of the disease. Level of Evidence: Level III.