Teng, Phillis Soek Po

Background Biomechanics of knee osteoarthritis (KOA) patients have been extensively studied using motion capture systems, but less have explored standing knee joint angles with the walking parameters, particularly in Asians. We aim to determine gait biomechanical differences between healthy and KOA participants in an Asian population using One-dimensional Statistical Parametric Mapping (SPM1D) and explore if they are associated with standing joint angles.

Methods
A total of 20 KOA and 24 healthy stood upright and walked 10 m at self-selected speeds. The standing angles, walking kinematic and kinetic parameters of the ankle, knee, hip and trunk were analysed. Lower limb muscle excitation was measured via electromyography. SPM1D was used to compare the healthy group with the KOA group, and for further subgroup analysis.

Results
The all KOA group had significantly greater standing knee flexion angles (KFA) (p < 0.001), standing ankle dorsiflexion angles (ADA) (p < 0.001), walking KFA during terminal stance (p = 0.001) and terminal swing (p = 0.02) and walking ADA during terminal stance (p = 0.02) and mid-swing to terminal swing (p = 0.001). Knee adduction moment (p = 0.04) and knee flexion moment (p = 0.03) were higher in severe KOA. A positive correlation was found between standing KFA and initial KFA (R2 = 0.579), and mean walking KFA (R2 = 0.801) in the KOA group.

Conclusion
The increase in standing KFA was associated with an increase in walking KFA in the KOA group. Static joint angles remain as an essential parameter, although further studies need to be carried out to determine if the increase in standing joint angles can be recommended as an adjunctive measure during gait analysis of KOA using motion capture.

Background: Stair climbing tests are pivotal when assessing physical performance in knee osteoarthritis patients, yet the biomechanical strategies that underpin poor stair climbing ability are heterogeneously reported. Single step tasks emulate a step-by-step gait pattern, an approach associated with knee pain when stair climbing. The objective of this study is to analyse the biomechanics and electromyography activity of both the leading and trailing limbs during single Step-up and Down tasks in knee osteoarthritis patients.

Methods: Three-dimensional motion analysis captured biomechanical data of twenty participants with knee osteoarthritis (n = 20) and twenty four (n = 24) age matched controls completing isolated Step-Up and Step-Down tasks. Data was collected from both the leading and trailing limbs and analysed continuously using One-dimensional Statistical Parametric Mapping (α = 0.05).

Findings: During Step-Up, knee osteoarthritis participants demonstrated kinematic (p < 0.001), kinetic (p = 0.045), and electromyography (p < 0.001) variance compared to control participants, whilst Step-Down induced elevated external knee adduction moments (p = 0.042). Across both tasks, knee osteoarthritis participants stood with increased lower limb flexion in quiet standing and spent a proportionally elevated time in transitional double stance during Step-Up (p = 0.02).

Interpretation: Our study reveals that knee osteoarthritis patients display distinctive biomechanical strategies during single Step-Up and Down tasks, that deviate depending on whether the osteoarthritic knee is leading or trailing. Single-step tasks are a safer and practical alternative to other stair climbing tests. We hope that clinicians can use these findings to guide treatments that promote less effortful step and stair ambulation in knee osteoarthritis patients with advanced disease.