The purpose of this study is to develop and validate a novel video-based postural evaluation tool designed to objectively measure the quality and dynamics of the Sit-to-Stand (STS) motion in stroke patients, specifically allowing physical therapists to monitor patient progress remotely via tele-evaluation. Since stroke survivors often face difficulties attending regular in-clinic assessments, this tool addresses a critical unmet need. The core question this study aims to answer is whether this new video-based measurement can accurately and consistently assess standing ability when compared against established standards. To confirm the tool's trustworthiness, we will first test its reliability by assessing if different experts achieve the same results (Inter-rater reliability) and if the same expert achieves the same results across multiple trials (Intra-rater reliability). We will then confirm the tool's accuracy (validity) by examining if its derived scores correlate strongly with established clinical measures (e.g., Trunk Impairment Scale, TIS) and patient-reported outcome measures. Finally, we will verify its scientific precision by comparing the tool's detailed kinematic measurements (including total STS time and joint angles) against the gold-standard data derived from the Kinovea motion analysis software.

1. Rationale and Context

   - Stroke remains a leading global cause of long-term functional disability. While early functional recovery is rapid, many patients require sustained long-term rehabilitation. Access to adequate rehabilitation is often compromised by geographical and institutional barriers, highlighting a critical unmet need in clinical practice. Tele-rehabilitation, utilizing Information and Communications Technology (ICT) via devices such as smartphones and tablets, is presented as a vital alternative to enhance accessibility and provide continuous, systematic care without the need for physical travel. The success of tele-rehabilitation fundamentally depends on the availability of assessment tools that can objectively and reliably measure functional changes from a distance.

2. Scientific Focus: Sit-to-Stand (STS) Movement

   - The Sit-to-Stand (STS) task is a foundational activity of daily living, demanding complex coordination of lower extremity strength, balance, posture control, and weight shifting. Post-stroke, patients exhibit significant limitations in STS due to asymmetric weight-bearing, decreased strength, and impaired postural control, which increases the risk of falls. Therefore, the assessment of STS must extend beyond simple quantitative measures (e.g., time or repetition counts, such as FTSTS or TUG) to capture the qualitative characteristics (e.g., symmetry, compensatory strategies) essential for guiding therapeutic intervention. This study addresses the current limitation of existing qualitative tools that require direct, in-person observation by developing a tool suitable for non-face-to-face video analysis.

3. Assessment Tool Development Methodology

   • The study utilized a multi-stage process for tool construction, ensuring both clinical relevance and theoretical soundness:
   • Initial Item Generation: The preliminary tool items were compiled based on a comprehensive literature review and clinical books related to stroke patient posture and balance assessment, with a specific focus on alignment and movement analysis during STS. The tool ultimately adopted concepts from Raine et al.'s Bobath concept theory.
   • Item Structuring: The STS movement was segmented into five functional phases (including a preparation phase added later). The items, totaling 29 items, are structured for observation from both the frontal and sagittal (affected side) planes, and scored on a 5-point Likert scale for most items.
   • Validation Procedures (Content/Face Validity): The preliminary tool underwent rigorous validation. Face validity was assessed by a panel of expert physical therapists. Content validity was verified by 10 neurological rehabilitation therapists with over 10 years of experience, following established procedures. This iterative process led to the deletion, modification, and addition of items, ensuring the tool's clinical relevance and comprehensiveness.
   • Video Recording Protocols: To minimize observational bias and establish remote feasibility, the assessment guidelines mandate that the STS movement be recorded from the patient's front (coronal view) and affected side (sagittal view). The videos are then edited to allow simultaneous viewing of both perspectives, ensuring full visibility from head to toe.

4. Study Procedures for Reliability

   • The final version of the tool was tested using video recordings of STS movements from 10 chronic stroke patients. The assessments were conducted by 10 neurological physical therapists with over three years of experience.
   • Inter-Rater Reliability: Measured the consistency of scoring among the 28 different evaluators using the same video recordings. The ICC(2,1) model was applied for this analysis.
   • Intra-Rater Reliability: Measured the consistency of individual evaluators by having the same 10 evaluators assess the identical video recordings two times, separated by an interval of approximately 6 months. The ICC(3,1) model was applied for this analysis.

5. Statistical Analysis The consistency of measurements (Reliability) was quantified using the Intraclass Correlation Coefficient (ICC). The interpretation of the ICC values followed standard guidelines (e.g., ICC ≥0.90 is considered 'excellent', 0.75-0.90 is 'good', 0.50-0.75 is 'moderate').

Inclusion Criteria:

• Patients diagnosed with stroke resulting in motor impairment.
• Patients in the chronic phase, defined as being more than one year post-diagnosis.
• Patients capable of performing the Sit-to-Stand (STS) movement independently without the use of walking aids or physical assistance.
• Patients who fully understand the study purpose and procedures and have voluntarily provided written informed consent.

Exclusion Criteria:

• Exclusion criteria included individuals with visual, auditory, or vestibular impairments, cognitive dysfunction, more than two episodes of stroke, or other neurological impairments.

The study population consists of stroke patients currently admitted to H Hospital located in Namyangju-si, Gyeonggi-do, South Korea.