The most impactful resolutions of the Patient Protection and Affordable Care Act (ACA) took effect on January 1, 2014. The clinical and economic effects are widely experienced by orthopaedic surgeons, but are not well quantified. We proposed to evaluate the effect of the ACA on the timing of MRI for knee pathology before and after implementation of the legislation. We conducted a retrospective analysis of all knee MRIs done at our institution from 2011 to 2016 (3 years before and after ACA implementation). The MRI completion time was calculated by comparing the dates of initial clinical evaluation and MRI completion. The groups were subdivided based on insurance payer status (Medicare, Medicaid, and commercial payers). The cohorts were compared to determine differences in average completion time and completion rates at time intervals from initial clinic visit before and after ACA implementation. MRI scans of 5,543 knees were included, 3,157 (57%) before ACA implementation and 2,386 (43%) after. There was a 5.6% increase in Medicaid cohort representation after ACA implementation. Patients waited 14 days longer for MRIs after ACA implementation (116 versus 102 days). There were increased completion times for patients in the commercial payer (113 versus 100 days) and Medicaid (131 versus 96 days) groups. Fewer patients had received MRI after ACA implementation within 2, 6, and 12 weeks of their initial clinic visits. The time between initial clinical evaluation and MRI scan completion for knee pathology markedly increased after ACA implementation, particularly in the commercial payer and Medicaid cohorts. Additional studies are needed to determine the effect of longer wait times on patient satisfaction, delayed treatment, and increased morbidity. As healthcare policy changes continue, their effects on orthopaedic patients and providers should be closely scrutinized. Level III-Retrospective cohort study.