"Balance, Gait, and Motion Analysis in Multiple Sclerosis"

Multiple Sclerosis (MS) is a chronic immune-mediated disease of the central nervous system characterized by demyelination and neurodegeneration. Impairments in balance and gait are among the most common manifestations of the disease and are associated with reduced mobility, increased risk of falls, decreased independence, and lower quality of life. Accurate assessment of these impairments is essential for clinical decision-making and the development of effective rehabilitation interventions.

Clinical functional assessments are widely used to evaluate balance, gait, and physical performance in individuals with Multiple Sclerosis. In parallel, advances in motion analysis technology have enabled the objective quantification of movement characteristics through kinetic and kinematic measurements. Although both approaches are commonly used in clinical and research settings, the relationship between objective biomechanical parameters and functional clinical outcomes remains insufficiently understood.

The purpose of this cross-sectional observational study is to investigate the associations between kinetic and kinematic measures of balance and gait obtained through three-dimensional motion analysis using the Vicon system and functional performance outcomes in people with Multiple Sclerosis. By examining these relationships, the study aims to identify biomechanical indicators that are most closely related to functional abilities and mobility limitations.

Participants will undergo a comprehensive laboratory-based assessment including biomechanical analysis of balance and gait, standardized functional performance testing, patient-reported outcome measures related to fear of falling and fatigue, and assessment of lower-limb spasticity. Correlation analyses will be conducted to explore the relationships between biomechanical and functional measures.

The findings of this study may contribute to a better understanding of the biomechanical determinants of functional performance in people with Multiple Sclerosis and support the selection of clinically meaningful assessment tools for rehabilitation practice and future research.

Primary outcomes

• Kinetic and Kinematic Analysis [Single laboratory session (~40 minutes per participant)]: Three-dimensional gait and balance analysis will be performed using a Vicon Nexus version 2.16 motion-capture system (12 Vero cameras, 200 Hertz \[Hz\]) synchronized with two Bertec force plates (1000 Hz). Reflective markers will record spatial coordinates for gait speed, step length, joint angles, and Center-of-Pressure (CoP) displacement. This setup enables precise kinetic and kinematic quantification of balance and gait parameters and allows correlation with clinical functional tests in individuals with Multiple Sclerosis (MS).
• Balance Assessment-Postural Control: Mini Balance Evaluation Systems Test (mini-BESTest) [Single laboratory session (~10 minutes per participant)]: The mini Balance Evaluation Systems Test (mini-BESTest) assesses dynamic postural control across four domains: anticipatory adjustments, reactive responses, sensory orientation, and dynamic gait. It includes 14 items scored on a 3-point scale (0 = severe impairment, 2 = normal performance); total = 28. Higher scores indicate better balance. It is validated and reliable for detecting fall risk in neurological populations, including Multiple Sclerosis and its Greek cross-cultural adaptation has further confirmed the scale's reliability and validity within Greek-speaking clinical cohorts.
• Gait Assessment: Functional Gait Assessment (FGA) [Single laboratory session (~10 minutes per participant)]: The Functional Gait Assessment (FGA) evaluates dynamic balance and gait adaptability under varying conditions. It consists of 10 walking tasks (e.g., head turns, obstacle negotiation, pivot turns), each rated 0-3 (0 = severe impairment, 3 = normal). Total = 30; higher scores indicate better functional gait performance and lower fall risk. Demonstrates strong reliability and validity in neurological and Multiple Sclerosis populations living. The Greek version of the scale will be employed in the present study.

Secondary outcomes

• Balance Assessment-Fear of Falling: Fall Efficacy Scale-International (FES-I) [Single laboratory session (~5 minutes per participant).]: The Fall Efficacy Scale-International (FES-I) assesses fear of falling and confidence in performing daily activities. It consists of 16 self-report items, each rated 1-4 (1 = not at all concerned, 4 = very concerned). Total score 16-64, with higher scores indicating greater fear of falling. The Greek validated version will be used. It is reliable and widely applied in Multiple Sclerosis and older-adult populations.
• Assessment of Physical Performance and Endurance: Short Physical Performance Battery (SPPB) [Single laboratory session (~10 minutes per participant)]: The Short Physical Performance Battery (SPPB) evaluates lower-limb function through three components: (1) standing balance, (2) 4-meter gait speed, and (3) repeated chair stands. Each component is scored 0-4 based on performance time or ability, for a maximum total of 12 points. Higher scores indicate better physical performance. The SPPB is validated for assessing mobility, endurance, and fall risk in individuals with Multiple Sclerosis.
• Assessment of Physical Performance and Endurance: 2-Minutes Walk Test [Single laboratory session (~5 minuites per participant).]: The 2-Minutes Walk Test (2MWT) measures walking endurance and fatigue by recording the total distance walked in 2 minutes on a flat 12-meter walkway at a self-selected pace. Results are expressed in meters. Higher distances reflect better walking endurance and lower fatigue. The test is validated for patients with Multiple Sclerosis and correlates with physical fitness and perceived fatigue.
• Fatigue Assessment: Fatigue Severity Scale (FSS) [Single laboratory session (~5 minutes per participant).]: The Fatigue Severity Scale (FSS) quantifies perceived fatigue through 9 self-report items, each scored 1-7 (1 = strongly disagree, 7 = strongly agree). The mean of all items represents the final score; higher values indicate greater fatigue severity. It is reliable, simple, and sensitive to changes in energy levels in Multiple Sclerosis and other neurological populations.
• Spasticity Assessment: modified Ashworth Scale (mAS) [Single laboratory session (~5 minutes per participant).]: The modified Ashworth Scale (mAS) assesses muscle tone and spasticity during passive movement of specific joints. Each muscle group is rated on a 6-point ordinal scale (0 = no increase in tone; 1, 1+, 2, 3, 4 = progressively increasing resistance or rigidity). Higher scores indicate greater spasticity. The scale demonstrates strong intra- and inter-rater reliability in Multiple Sclerosis.

Sex: All, ages: 18 Years to any

Inclusion Criteria:

* Adults (≥ 18 years) with confirmed diagnosis of Multiple Sclerosis
* Expanded Disability Status Scale (EDSS) score <6
* Ability to ambulate independently without the use of assistive devices
* Absence of significant orthopedic or neurological conditions affecting mobility
* Ability to understand and follow verbal instructions.

Exclusion Criteria:

* History of injury or surgical intervention to the lower limbs or spine within the past year
* Any musculoskeletal, neurological, cardiovascular, or other medical condition, other than Multiple Sclerosis, that may significantly affect gait or balance or compromise participant safety during testing.
* Severe balance impairment or high risk of falling that prevents safe participation in single-leg stance, gait analysis, or obstacle negotiation tasks.

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• Sofia Lampropoulou, PT, MSc, PhD, Principal investigator, Department of Physiotherapy, University of Patras