Study design: Replication of previously developed prognostic model. Objectives: In motor complete injuries at admission to rehabilitation, perform; (1) replication analyses of the relationships between ISNCSCI motor level and motor scores and SCIM and (2) novel analyses to determine if age and/or sex moderate relationship between neurological impairment and function. Setting: Admission to initial inpatient rehabilitation in the United States. Methods: Post-Hoc analyses of data collected as part of a separate study. Replication analyses: (1) Pearson’s correlation assessed relationship strength between neurologic impairment and function. (2) Multiple linear regression assessed if center or age influenced functional outcome. Novel analyses: (1) Moderated multiple regression assessed if age and/or sex moderated the lesion level-function relationship. Results: Of the 406 datasets, 161 were motor complete injuries, and included in the analyses. Median time post injury at admission to rehabilitation was 19 days. Our replication analyses confirmed the neurologic and functional value of each spinal segment reported by the EM-SCI group (all p ≤ 0.018). We failed to confirm their reported age effect (p = 0.05) and non-effect of center (p = 0.037). Our novel analyses indicated that age coded as above/below 50 moderated the relationship between neurologic impairment and function (p = 0.038) in cervical injuries only, but that age coded as above/below 35 (all p ≥ 0.510) and sex (all p ≥ 0.465) did not. Conclusions: The neurological and functional value of each segment is consistent across very different healthcare settings in early and late sub-acute stages and minimally impacted by age and sex. Differences related to centers and age may confound efficacy trials. Sponsorship: The Miami Project to Cure Paralysis; The Craig H. Neilsen Foundation (83492).