OBJECTIVES: Total knee arthroplasty (TKA) is one of the most common procedures in the US with high costs for both surgeries and rehabilitation. Center for Medicare and Medicaid Services (CMS) plans to implement comprehensive care for joint replacement model (CJR), which makes hospitals responsible for rehabilitation costs after surgeries. The objective of this research is to investigate how post-acute care (PAC) costs differ by initial discharge status.    METHODS: This research used 5% Medicare fee for services (FFS) claim data in 2013. Discharge status is defined as the first Medicare claim 7 days after TKA surgeries. It includes the following categories: inpatient rehabilitation (IRF), outpatient rehabilitation (CORF), skilled nursing facilities (SNF) home health (HHA), ambulatory care (AMB), inpatient hospital (INP) and no medical service (NONE). PAC costs are defined as all medical care costs 90 days after TKA surgeries.  RESULTS: A total of 8,801 TKA surgeries were identified. The average age was 71.6 (standard deviation (SD) 7.9). The distribution of the discharge status is as follows: IRF (7.7%), SNF (35.0%), HHA (35.7%), CORF (1.3%), AMB (15.5%), INP (0.6%) and NONE (4.1%). The total costs 90 days after surgeries were $22,921 (SD 12,722) for IRF, $15,489 (SD 8,164) for SNF, $6,620 (SD 8,164) for HHA, $3,709 (SD 4,485) for CORF, $4,123 (SD 6,689) for AMB, $21,416 for INP (SD 13,678) and $3,241 for NONE (SD 6,179). T tests show that IRF, HHA and SNF all have costs significantly higher than the cost of AMB (p<0.001). Patients discharged to IRF and SNF were generally older and sicker than patients discharged to HHA, CORF and AMB.  CONCLUSIONS: There are significant PAC cost differences among patients who were discharged to different rehabilitation settings after TKA surgeries. Significant savings may be achieved by moving patients discharged to high cost rehabilitation settings to lower cost rehabilitation settings.