Moore MG, et al. - A total of 325 consecutive unilateral primary TKAs conducted on individuals who finished the Perioperative Surgical Home (PSH) preoperative optimization pathway within a single hospital system were retrospectively analyzed in order to recognize preoperatively ascertained factors correlated with hospital length of stay (LOS) for the same-day discharge (SDD) and inpatient TKA described by Medicare’s two-midnight rule benchmark. Lower BMI and fewer self-notified allergies were related to SDD. The Risk Assessment and Prediction Tool (RAPT) alone outperformed by the SDD model. Elderly age, higher BMI, lower RAPT score, and later surgery start time were correlated with inpatient discharge. The RAPT alone was outperformed by the inpatient model. Hence, preoperatively discovered factors related to SDD as BMI and allergies and inpatient TKA as age, BMI, RAPT score, and surgery start time were determined. Furthermore, for TKA episode planning, hospitals, providers, patients, families, and payers could use this data.