AbstractAn updated understanding of unicompartmental knee arthroplasty (UKA) utilization is needed. The purpose of this study was to evaluate temporal trends in volume and utilization of UKA among early-career surgeons and to examine the influence of fellowship training status on utilization of UKA. The American Board of Orthopaedic Surgery (ABOS) Part-II database was queried from 2010 to 2019 to identify candidates who reported ≥1 total knee arthroplasty (TKA) or UKA. Self-reported history of fellowship training experiences was recorded. “High-volume” surgeons were defined as performing ≥7 UKA over the ABOS Part-II collection period. Trends were evaluated with the Cochrane–Armitage test and generalized linear models. From 2010 to 2019, a total of 2,045 candidates (28.1%) reported ≥1 TKA, while 585 candidates (8.0%) reported ≥1 UKA. The number of candidates reporting ≥1 UKA significantly increased (p = 0.001). An increase in UKA volume was observed over the study period (p < 0.001). Rates of utilization of UKA relative to TKA did not change significantly over the study period (p = 0.11). Sixty-three (2.4%) candidates met the study definition for high-volume UKA utilization. UKA procedure volume increased among ABOS Part-II candidates over the study period; however, rates of UKA utilization relative to TKA volume remained unchanged. Increasing volume of UKA performed by early-career surgeons is likely secondary to an increased number of surgeons trained in adult reconstruction. Only 2.4% of candidates who reported performing at least one knee arthroplasty procedure met the threshold for a high-volume UKA practice. Early-career surgeons should remain conscientious of UKA volume in their practice.