# The effect of bilateral knee osteoarthritis on spatiotemporal gait parameters during incline walking: implications for gait rehabilitation

## TL;DR

This study finds that people with bilateral knee osteoarthritis walk with shorter steps and more stability during incline walking, even after adjusting for walking speed.

## Contribution

The study reveals a novel adaptive gait strategy in bilateral knee osteoarthritis patients during incline walking, characterized by a quadratic trend in gait variability.

## Key findings

- Bilateral KOA patients had shorter step and stride lengths and longer double support times compared to controls during incline walking.
- KOA patients showed a U-shaped trend in gait variability during incline walking, unlike controls.
- WOMAC physical function scores correlated with gait parameters like double support time and step length.

## Abstract

Gait alterations in knee osteoarthritis (KOA) patients are well documented; however, there is a paucity of research examining how bilateral KOA patients adapt to incline walking, a common real-world activity. Since KOA patients typically walk slower than healthy adults, it is essential to know if gait differences persist when walking speed is accounted for as a covariate.

The aim of this study was to compare spatiotemporal adaptations and gait variability in bilateral KOA patients versus healthy controls over multiple inclines when controlling for walking speed as a covariate.

Fifteen bilateral KOA patients and fifteen healthy controls were recruited. Gait parameters were collected using a three-dimensional motion analysis system while walking at a self-selected speed on a treadmill at five inclines (+6%, +3%, 0%, −3%, and −6%). A mixed two-way repeated measures Analysis of Covariance (ANCOVA) was used with walking speed as a covariate. Pearson correlations were used to assess the relationship between Western Ontario and McMaster Universities Osteoarthritis Index (WOMAC) score and spatiotemporal parameters.

The ANCOVA revealed a significant group-by-incline interaction for several spatiotemporal parameters. Despite speed being a covariate in the ANCOVA, bilateral KOA patients had significantly shorter step and stride lengths at all inclines and longer double support times during inclined walking (predominantly downhill) compared to the control group. Additionally, KOA patients showed a significant quadratic, U-shaped trend in gait variability such that variability increased during both uphill and downhill walking, while variability linearly decreased in the control group as the incline increased. WOMAC physical function correlated positively with double support time and negatively with step and stride length.

Bilateral KOA patients take a safety-first approach to walking characterized by shorter steps and prolonged double support times to ensure stability and load distribution even at the cost of gait efficiency. The distinct quadratic modulation of gait variability in bilateral KOA patients may represent a novel adaptive motor control strategy for managing the mechanical demands of inclined surfaces. This work could have implications for the rehabilitation of downhill walking in KOA patients.