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.

Relationship of hip and ankle range of motion, trunk muscle endurance with knee valgus and dynamic balance in males.

OBJECTIVES: Investigate the relationship of hip internal rotation (IR) and ankle dorsiflexion (DF) range of motion (ROM), trunk flexor, extensor, and lateral flexor muscle endurance with frontal plane knee projection angle (FPKPA) and Y-balance test (YBT). STUDY DESIGN: Cross-sectional study. SETTING: Armed Force training site. PARTICIPANTS: 121 healthy male militaries with no history of musculoskeletal injury in the last 6 months. MAIN OUTCOMES: FPKPA was evaluated during single-leg squat. YBT was assessed on the anterior, posterolateral and posteromedial directions. Passive hip IR ROM and weight-bearing ankle DF ROM were measured with a digital inclinometer. Trunk muscle endurance was measured as the time the participant could hold the positions. RESULTS: FPKPA was predicted by ankle DF ROM and hip IR ROM (r2 = 0.340; P = 0.009). For YBT anterior, ankle DF ROM was the only predictor (r2 = 0.32; P < 0.001); whereas trunk extensor endurance predicted YBT posterolateral (r2 = 0.273; P < 0.001) and YBT posteromedial (r2 = 0.033; P = 0.045). CONCLUSION: The results suggest that increasing hip stiffness and ankle mobility might help to control dynamic knee alignment. In addition, the dynamic balance could be improved increasing ankle DF ROM and trunk extensor endurance.