BACKGROUND: Minimum clinically important difference (MCID) values are commonly used to measure treatment success for total knee arthroplasty (TKA). MCID values vary according to calculation methodology, and prior studies have shown that patient factors are associated with failure to achieve MCID thresholds. The purpose of this study was to determine if anchor-based 1-year Knee Injury and Osteoarthritis Outcome Score Joint Replacement (KOOS-JR) MCID values varied among patients undergoing TKA based on patient-specific factors. METHODS: This was a retrospective review of patients undergoing TKA from 2017-2018. Patients without baseline or 1-year KOOS-JR or Patient-Reported Outcome Measurement Information System Global Health data or that underwent procedures other than primary TKA were excluded. MCIDs were calculated and compared between patient groups according to preoperative characteristics. RESULTS: Among the included 976 patients, 1-year KOOS-JR MCIDs were 26.6 for men, 28.2 for women, 30.7 for patients with a diagnosis of anxiety and/or depression, and 26.7 for patients without a diagnosis. One-year MCID values did not differ significantly according to gender (P = .379) or mental health diagnosis (P = .066), nor did they correlate with body mass index ( β = -0.034, P = .822). Preoperative KOOS-JR decile demonstrated an inverse relationship with 1-year MCID values and attainment of MCID. CONCLUSIONS: The proportion of patients attaining KOOS-JR MCID values demonstrated an inverse relationship with preoperative baseline function. Future investigation may identify patient factors that allow surgeons to better capture patient satisfaction with their procedure despite failure to attain a 1-year MCID.