3D gait analysis

Cameras track reflective markers on the body while force plates measure ground reaction forces. The output is joint angles, moments, timing and loading through the full gait cycle, in three dimensions, with a precision the eye cannot reach.

The clinically important output is not the walking pattern itself but the cause of it — distinguishing a compensation from the primary problem. A patient may limp because of hip weakness, ankle stiffness, pain, or leg length difference, and the four look similar and need different treatment.

Cerebral palsy, where it informs surgical decision-making and orthotic prescription. Post-stroke gait. After amputation, for alignment and socket assessment. After joint replacement and lower limb surgery. Persistent unexplained pain in a limb. Return-to-sport assessment.

In cerebral palsy specifically, gait analysis before multilevel surgery changes the surgical plan in a substantial proportion of cases, which is the strongest argument for doing it 1.

Treating the compensation instead of the cause is the single most common reason gait rehabilitation fails, and the compensation is usually the thing that is visible.

The session takes around an hour, and the analysis changes the plan often enough to justify it. We provide the report and the data, not just a conclusion.

Joint angles, forces and timing measured across the gait cycle, producing a description of walking that observation cannot match. It identifies which joint is producing a compensation and which is suffering from it.

Its clinical value is in decisions: which muscle to inject for spasticity, whether an orthosis is doing what it should, whether surgery would change the pattern. Measured without such a question, it produces data nobody uses.

In the studies that have tested it, yes. A 2020 systematic review found that 3D gait analysis changes treatment plans, increases clinicians’ confidence in their decisions and increases agreement between clinicians 2. In a randomised trial in children with cerebral palsy, when the laboratory advised against a planned procedure, surgeons who had the gait report changed the plan more often than those who did not: 48% against 27% 1. Outcomes after surgery improved only when the gait data were available and the recommendations were followed 2.

The review is also candid about the gaps: of more than 2,700 studies of the method, over 99% concerned its technical, diagnostic or predictive performance, and only a handful tested its effect on patients 2. One of those, a population-based study, found that the incidence of severe crouch gait fell from 25% to 4% after practice changes that included adding gait analysis, so the fall cannot be credited to gait analysis alone 2.