Background <p>Medial compartment knee osteoarthritis is common. Unicompartmental knee arthroplasty (UKA) offers a bone-preserving alternative to total knee replacement. Despite its advantages, patient dissatisfaction remains a concern. This study aimed to identify factors associated with dissatisfaction following UKA.</p> Methods <p>Methods A retrospective analysis was conducted on 978 patients who underwent UKA between January 1, 2017 and December 31, 2023. Postoperative outcome data were collected via telephone and outpatient follow-up (mean follow up 49.6 months, range 20–102 months). Only unilateral UKA cases were included. Dissatisfaction was defined as a response of “neutral”, “dissatisfied”, or “very dissatisfied” on a 5 point Likert scale.</p> Results <p>Among 978 patients, 811 (82.9%) were satisfied and 167 (17.1%) were dissatisfied. Multivariate logistic regression identified kneeling difficulty (OR=0.128, 95%CI: 0.079–0.206), stair-related pain (OR=8.783, 95%CI: 5.588–13.803), walking pain (OR=9.463, 95%CI: 5.591–16.014), and knee instability (OR=3.988, 95%CI: 2.179–7.298) as independent factors associated with dissatisfaction.</p> Conclusions <p>Patient dissatisfaction after UKA is independently associated with walking pain, stair-related pain, knee instability, and inability to kneel fully. Surgeon experience, prosthesis type, and preoperative patellar morphology (Wiberg III) were associated with satisfaction in univariate analysis but were not identified as independent factors in multivariate regression.Preoperative counseling should address these modifiable factors.</p> Trial registration <p> Retrospectively registered. No trial registration number is applicable.</p>