Background: The utilization of total hip arthroplasty (THA) and total knee arthroplasty (TKA) increased after Medicaid expansion under the U.S. Affordable Care Act (ACA), suggesting a potential unmet need for THA and TKA. We examined the timing of THA and TKA in patients after obtaining Medicaid expansion insurance coverage. We hypothesized that patients with Medicaid expansion insurance would undergo a surgical procedure sooner than patients in traditional Medicaid populations.
Methods: We used administrative data from a Medicaid managed care company to determine the timing of primary THA and TKA in patients who were 18 to 64 years of age in 4 states with Medicaid expansion (Illinois, Ohio, Oregon, and Washington) and 4 states without Medicaid expansion (Louisiana, Mississippi, Texas, and Wisconsin) from 2008 to 2015. The insurance types were Medicaid expansion, Medicaid plans for Supplemental Security Income (SSI), or Temporary Assistance for Needy Families (TANF). Roughly, these 3 groups correspond to relatively healthy childless adults, relatively unhealthy disabled adults, and parents of children with Medicaid insurance. The main outcome measure was time from enrollment to the surgical procedure. The primary exposure of interest was insurance type. We used a generalized linear regression model to adjust for patient age, sex, social deprivation, surgeon supply and reimbursement, and state-level Medicaid enrollment.
Results: In the unadjusted analysis of 4,117 patients, there was a significantly shorter time from enrollment to THA and TKA for the expansion group (median, 7.5 months) relative to the SSI group (median, 16.1 months; p < 0.0001) and the TANF group (median, 12.2 months; p < 0.0001). In the adjusted analysis, the time from enrollment to THA and TKA was significantly shorter in the expansion group (β, -1.21 [95% confidence interval (CI), -1.35 to -1.07]; p < 0.001) compared with the TANF group (β, -0.27 [95% CI, -0.38 to -0.17]; p < 0.001) and the SSI group (reference). Compared with the SSI group, these coefficients are equivalent to a 70% shorter time to the surgical procedure in the expansion group and a 24% shorter time to the surgical procedure in the TANF group.
Conclusions: Our findings suggest an unmet need for THA and TKA among newly enrolled Medicaid expansion beneficiaries. This need should be considered by surgeons, hospitals, and policymakers in ensuring access to care. Furthermore, consideration should be given to existing insurance-based disparities in access to orthopaedic care, as these may be exacerbated by an increased demand for THA and TKA from Medicaid expansion beneficiaries.