INTRODUCTION: To collect and analyse clinical and functional variables of patients undergoing rehabilitation after total knee arthroplasty (TKA), in order to identify which amongst them could influence the post-operative length of hospital stay (LOS). METHODS: We conducted a retrospective analysis of prospectively collected data of 1,082 consecutive patients (746 females and 336 males) who underwent primary TKA and rehabilitation in our Orthopedic Institute between January 2013 and July 2017. Clinical and anthropometric data were analysed using a multivariate linear regression model. RESULTS: The average LOS was 5.08 ± 2.52 days in the Department of Orthopedic Surgery, and 12.67 ± 5.54 days in the Rehabilitation Unit. Age, female sex and the presence of comorbidities were predictive of a longer stay. The presence of caregiver assistance at home was associated with shorter LOS. There was no evidence of a statistically significant positive association between BMI and LOS. CONCLUSION: An in-depth and early knowledge of these factors may enable the whole multidisciplinary team to plan a patient-tailored rehabilitation path and a better allocation of resources to maximize patients' functional recovery, while reducing LOS and the overall cost of the procedure.