Background: Formal rehabilitation programs are often assumed to be required after total knee arthroplasty to optimize patient recovery. Inpatient rehabilitation is a costly rehabilitation option after total knee arthroplasty and, in Australia, is utilized most frequently for privately insured patients. With the exception of comparisons with domiciliary services, no randomized trial has compared inpatient rehabilitation to any outpatient based program. The Hospital Inpatient versus HOme (HIHO) study primarily aims to determine whether 10 days of post-acute inpatient rehabilitation followed by a hybrid home program provides superior recovery of functional mobility on the 6-minute walk test (6MWT) compared to a hybrid home program alone following total knee arthroplasty. Secondarily, the trial aims to determine whether inpatient rehabilitation yields superior recovery in patient-reported function. Methods/Design: This is a two-arm parallel randomized controlled trial (RCT), with a third, non-randomized, observational group. One hundred and forty eligible, consenting participants who have undergone a primary total knee arthroplasty at a high-volume joint replacement center will be randomly allocated when cleared for discharge from acute care to either 10 days of inpatient rehabilitation followed by usual care (a 6-week hybrid home program) or to usual care. Seventy participants in each group (140 in total) will provide 80% power at a significance level of 5% to detect an increase in walking capacity from 400 m to 460 m between the Home and Inpatient groups, respectively, in the 6MWT at 6 months post-surgery, assuming a SD of 120 m and a drop-out rate of <10%.The outcome assessor will assess participants at 10, 26 and 52 weeks post-operatively, and will remain blind to group allocation for the duration of the study, as will the statistician. Participant preference for rehabilitation mode stated prior to randomization will be accounted for in the analysis together with any baseline differences in potentially confounding characteristics as required.Discussion: The HIHO Trial will be the first RCT to investigate the efficacy of inpatient rehabilitation compared to any outpatient alternative following total knee arthroplasty.Trial registration: U.S. National Institutes of Health Clinical Trials Registry (http://clinicaltrials.gov) ref: NCT01583153.