Y-Balance Test Asymmetry and Frontal Plane Knee Projection Angle During Single-leg squat as Predictors of Patellofemoral Pain in Male Military Recruits.

OBJECTIVES:Investigate prospectively whether dynamic balance and frontal plane knee projection angle (FPKPA) are risk factors for the development of patellofemoral pain (PFP) in male military recruits. STUDY DESIGN:Prospective cohort. SETTING:Military training center. PARTICIPANTS:135 male military recruits were followed prospectively for six weeks and the incidence of PFP was documented. MAIN OUTCOMES:Baseline measures of the Y-Balance test (YBT) and two-dimensional FPKPA during single-leg squatting were recorded. Mann-Whitney U tests and logistic regression analysis were utilized to identify possible variables associated with the development of PFP. RESULTS:A total of 14 male recruits developed PFP during the follow up period. The PFP group had significantly greater asymmetry on the YBT posterolateral direction (mean difference = 3.44 ± 0.57 cm; 95% Confidence Interval [CI] = 2.38-4.51 cm) and greater FPKPA during single-leg squat (mean difference = 5.55°±1.78°; [CI] = 1.81-9.28°) at baseline when compared to controls. Binary logistic regression models revealed that YBT posterolateral asymmetry ≥4.08 cm (Nagelkerke R2 = 0.304; X2 = 21.63; p < 0.001; OR = 5.46; [CI] = 4.47-8.06) and FPKPA ≥ 4.81° (Nagelkerke R2 = 0.249; X2 = 17.46; p < 0.001; OR = 4.65; [CI] = 3.32-9.06) were significantly associated with PFP. CONCLUSIONS:Male military recruits with greater asymmetry on the YBT posterolateral direction and FPKPA were at a greater risk of developing PFP.