Quantitative Gait Analysis in a Sheep Model of In-Utero Spina Bifida Repair

Objective

To evaluate quantitative gait analysis in a sheep model ( Ovis aries ) of in-utero spina bifida repair.

Method

Using a 3D marker-based motion capture system, we quantified spatiotemporal gait parameters and hindlimb joint angles in a sheep model of in-utero spina bifida repair and normal controls. A linear support vector machine classifier, trained and tested on subject-disjoint partitions with individual gait cycles as the unit of analysis, evaluated the relationship between hindlimb joint angles and clinician-assigned Texas Spinal Cord Injury Scale scores. Linear mixed-effects models compared spatiotemporal parameters, hoof height, and hip drop across 3- to 6-month evaluations and between groups.

Results

In treated (n=14) and control (n=3) lambs, front- and hindlimb gait speed differed by timepoint (both p=0.025). Across 1,632 left and 1,661 right hindlimb gait cycles, held-out classification accuracy was 85.9% and 88.6% (Cohen’s κ=0.78 and 0.84) for left and right hindlimbs, respectively, against majority-class proportions of 76.5% and 75%. Left hindlimb hip drop differed between treated lambs and controls (Δ=0.8 cm, p=0.027). Between-group contrasts were considered exploratory given the small control group.

Conclusion

Quantitative gait analysis was feasible in an in-utero spina bifida repair model. Hindlimb kinematic profiles classified clinical ambulation scores above the majority-class baseline.

What’s already known about this topic?

• Independent walking is a major benefit of in-utero spina bifida repair surgery and a driver of treatment innovation.

• Ambulation after in-utero repair is typically assessed using subjective clinical assessments, which limits the ability to evaluate the effect of treatment.

• Instrumented gait analysis enables precise evaluation of ambulatory function in three-dimensional movements but has not yet been implemented in models of in-utero spina bifida repair.

What does this study add?

• We objectively quantified spatiotemporal gait parameters and hindlimb kinematic profiles over serial assessments in an established sheep model of in-utero spina bifida repair using a three-dimensional motion capture system.

• Hindlimb kinematic profiles classified clinician-assigned Texas Spinal Cord Injury Scale scores with 85.9%–88.6% accuracy, above the 75%–76.5% majority-class baseline. Pastern kinematics contributed most to classification.

• Treated lambs’ gait deviated from controls mainly during swing and mid-stance phases (exploratory).