Automated quantification of spinal axis distortion for behavioral assessment after spinal cord injury in mice

Spinal cord injury (SCI) causes persistent locomotor deficits that are commonly evaluated in mouse SCI models using observational scoring systems such as the Basso Mouse Scale, which primarily assesses hindlimb function. Here, we established an automated behavioral analysis pipeline using DeepLabCut to quantify spinal axis distortion, a characteristic feature of locomotor impairment after SCI, during open-field locomotion in mice. By tracking multiple anatomical landmarks along the spine and tail, this approach enabled the extraction of locomotor parameters, including speed, travel distance, and segmental angular measurements of rostrocaudal spinal alignment. SCI mice in the acute phase showed reduced locomotor speed and travel distance, and exhibited significant spinal axis distortion compared with intact controls. Furthermore, Y-27632 treatment was associated with a reduction in one segmental spinal axis angle, and spinal axis angles showed weak-to-moderate associations with BMS scores across animals. These results support spinal axis distortion as an objective quantitative metric that complements conventional locomotor scoring systems for the assessment of functional impairment and recovery after SCI.