Multijoint osteoarthritis increases pain burden but does not impair early outcomes after total knee arthroplasty

Previous studies have demonstrated inferior medium- and long-term PROMs in patients with multijoint arthritis, the influence of concomitant painful joints on short-term postoperative outcomes remains unclear. A retrospective comparative analysis was performed on prospectively collected PROMs from 110 consecutive patients undergoing primary unilateral TKA between November 2024 and September 2025 at a tertiary academic center. Patients were divided into a single arthritic joint group (SAJ; n = 59) and a multiple arthritic/painful joint group (MAJ; n = 51). PROMs included the Oxford Knee Score (OKS), Knee Injury and Osteoarthritis Outcome Score for Joint Replacement (KOOS-JR), EQ-5D, overall health score, general health score, and single-item back pain severity score. Outcomes were assessed preoperatively and at 6 weeks postoperatively. There were no significant differences in baseline demographic characteristics between groups. Preoperative PROMs were comparable between the SAJ and MAJ cohorts. Postoperatively, patients in the MAJ group reported significantly greater pain in other joints (2.12 vs. 0.84, p < 0.001) and higher back pain severity scores (1.39 vs. 0.56, p = 0.018). Despite this increased pain burden, no significant differences were observed in postoperative OKS (33.9 vs. 34.0, p = 0.75), KOOS-JR (7.1 vs. 7.3, p = 0.40, raw unconverted scores), EQ-5D (9.4 vs. 8.4, p = 0.13), overall health score (79.6 vs. 74.0, p = 0.31), or general health score (2.4 vs. 2.7, p = 0.08). All observed differences remained below established minimal clinically important difference thresholds. Patients with multijoint arthritis and concomitant back pain demonstrated a greater overall pain burden but achieved comparable early postoperative PROMs following primary TKA compared to patients with isolated knee osteoarthritis. Concurrent painful joints did not appear to adversely influence short-term knee-specific or global postoperative outcomes at 6 weeks. These findings suggest that early perceived recovery after TKA may be primarily driven by improvement in the operated knee rather than total body pain burden.