From Injury to Independence: Longitudinal Locomotor Recovery Patterns Following Traumatic Brain Injury - a TBI Model Systems Study

Background/Objectives: Traumatic Brain Injuries (TBIs) affect more than 50 million individuals worldwide each year. Approximately 90% of individuals survive and experience persistent motor, cognitive, and emotional deficits, substantially contributing to a reduced quality of life and a global economic burden. TBI mechanisms are a foundational determinant of long-term recovery. The objective of this study was to examine long-term trends in functional locomotion ability over extended follow-up durations (>10 years) across distinct TBI mechanisms. The researchers hypothesized that TBIs caused by falls or violent mechanisms would be associated with poorer functional locomotor abilities and, subsequently, lower item scores than those sustained through automotive or recreational activities. Methods: Data were obtained from the Traumatic Brain Injury Model Systems (TBIMS) database at Craig Hospital in Englewood, Colorado, the largest longitudinal TBI data repository in the world. Functional locomotion was assessed using the Functional Independence Measure (FIM) Locomotion item as the primary outcome measure. To enhance measurement precision and ensure interval-level scaling, raw FIM scores were converted into logit-based estimates of latent functional ability using Rasch modeling. Longitudinal changes of these Rasch-transformed scores were analyzed using linear mixed-effects regression, accounting for individual-level variability and unbalanced follow-up data. Results: The findings demonstrated a clinically meaningful decline in functional ability among individuals with TBIs from violent mechanisms, particularly assault-related injuries and gunshot wounds, which were associated with chronic medical complications and limited functional independence. Conversely, TBIs from bicycling, unclassified vehicular incidents, and winter sports showed significant positive estimates, possibly reflecting higher premorbid physical fitness. Motor vehicle, motorcycle, pedestrian, and fall-related TBIs demonstrated steep early gains, followed by a period of recovery stabilization and plateau. In contrast, violence-related mechanisms were characterized by consistently low median scores, with minimal long-term improvement. Falls, gymnastics, track & field, and water sports did not exhibit meaningful changes in the context of the primary hypothesis. Conclusions: TBI mechanisms play a vital role in shaping long-term functional locomotion outcomes, with violence-related TBIs associated with poorer long-term functional independence. The results have clinically important implications, supporting earlier identification of high-risk populations and the development of targeted rehabilitation strategies during periods of heightened neuroplasticity. Rasch analysis integrated with linear mixed-effects modeling yields a robust analytic framework that uncovers subtle but meaningful differences in recovery trajectories across TBI mechanisms.