The mind matters: Psychological factors influence subjective outcomes following unicompartmental knee arthroplasty-A prospective study

Purpose: This study aimed to investigate how psychological factors, including pain catastrophizing (PC), anxiety and depression affect preoperative and postoperative subjective outcomes in patients undergoing unicompartmental knee arthroplasty (UKA).

Methods: A prospective comparative study was performed among 150 patients undergoing medial or lateral UKA for isolated unicompartmental osteoarthritis. Patients were categorized based on their preoperative PC and Hospital Anxiety and Depression Scale, stratifying them into groups with PC, anxiety or depression, and those without these psychological factors. Patient-reported outcomes, including the Knee Injury and Osteoarthritis Outcome Score-Physical function Short form (KOOS-PS), 5-level EQ5D Visual Analogue Scale (EQ5D-VAS), Forgotten Joint Score (FJS) and Numeric Rating Scale for pain (NRS-pain) were compared between groups preoperatively and at 6-, 12-, and 24-month follow-up.

Results: At 24 months, PC patients had inferior outcomes in KOOS-PS (66.9 ± 16.5 vs. 77.6 ± 14.7, p = .008), EQ5D-VAS (63.5 ± 19.9 vs. 78.9 ± 20.1, p = .003) and FJS (73.7 ± 14.3 vs. 84.6 ± 13.8, p = .003). Anxiety was associated with inferior KOOS-PS (65.4 ± 15.2 vs. 78.2 ± 14.5, p = <.001), EQ5D-VAS (64.2 ± 23.2 vs. 79.3 ± 19.4, p = .002), FJS (75.7 ± 16.8 vs. 84.6 ± 13.4, p = .008) and NRS-pain (27.4 ± 24.6 vs. 13.7 ± 19.3, p = .023) at 24 months. Depression consistently resulted in inferior outcomes in KOOS-PS, EQ5D-VAS, FJS and NRS-pain across all follow-up assessments (p = <.05). Additionally, patients with anxiety and depression experienced longer length of hospital stay compared to those without these psychological factors (anxiety: 2.3 ± 2.3 vs. 0.8 ± 0.8 days, p = .006; depression: 2.3 ± 2.4 vs. 0.8 ± 0.8 days, p = .017).

Conclusions: Preoperative PC, anxiety and depression are associated with inferior subjective outcomes both prior to and following UKA. Among these factors, depression seemed to exert the most substantial adverse impact on outcomes following UKA. Patients with anxiety and depression had an extended duration of hospitalization lasting over twice as long as patients without these psychological factors. It seems that inferior outcomes primarily stem from the suboptimal preoperative condition rather than an inherent inability to benefit from UKA.

Level of evidence: Level II, prospective study.