Early Detection of Functional Impairment in Knee Osteoarthritis: Combining the Early Osteoarthritis Questionnaire and Y-Balance Test

Background Knee osteoarthritis (KOA) is a degenerative disease that causes pain and functional decline, making early detection difficult. Recently, the Early Osteoarthritis Questionnaire (EOAQ) has been used to screen for early symptoms of KOA, but it lacks objective assessment of knee function. The Y-balance test (YBT), which provides objective measurement, may help detect early functional deficits that are difficult to identify with the EOAQ alone. Purpose This study aimed to compare YBT performance and frontal knee angulation (FKA) during YBT between EOAQ and non-EOAQ group. Study design Cross sectional study Methods This cross-sectional study included 20 recreational badminton players aged 20–50 years who played at least twice per week over the past year. Participants were classified into an early KOA risk group (EOAQ group; 6 male, 4 female) and control group (non-EOAQ group; 7 male, 3 female) based on their responses to the EOAQ. The YBT was used to assess dynamic balance, with normalized reach distances and composite scores calculated. FKA during YBT was measured using 2D video analysis with reflective markers and Kinovea software. Group differences in YBT performance and FKA were analyzed using independent <italic>t</italic>-tests (<italic>p</italic>&lt;0.05). Results There were no significant differences in age, height, or weight between the EOAQ and control groups. YBT performance did not differ significantly between groups in any reach direction or in the composite index (<italic>p</italic>&gt;0.05). However, FKA during the YBT was significantly greater in the EOAQ group than in controls across all directions: anterior (<italic>p</italic>&lt;0.001), posteromedial (<italic>p</italic>&lt;0.001), and posterolateral (<italic>p</italic>=0.006). Conclusions This study suggests that individuals at risk for early KOA, as identified by the EOAQ, exhibit increased FKA during dynamic balance tasks despite no differences in YBT performance. This study highlights the importance of assessing FKA by demonstrating that the YBT can complement the EOAQ in detecting early functional impairment related to knee osteoarthritis. Quantitative movement analysis using the YBT may help detect early functional changes before structural damage occurs, supporting its use alongside subjective screening for early diagnosis and targeted intervention.