Patellar tendon mechanical properties change with gender, body mass index and quadriceps femoris muscle strength

Objective: The purpose of this study is to assess the effect and correlation of gender, body mass index (BMI) and quadriceps femoris (QF) muscle strength on patellar tendon (PT) thickness and stiffness in healthy sedentary individuals. Methods: This study was carried out with 67 (36 female, 31 male) healthy sedentary individuals between the ages of 18-44 (28.0 ± 7.5 years). The individuals included in the study were divided into two groups according to their gender and BMI (18.5 < BMI < 25 and 25 < BMI). The body composition was determined with Tanita Body Composition Analyser. PT thickness and stiffness was measured with ACUSON S3000 Ultrasonography Device using 9L4 ultrasonography probe. QF concentric muscle strength of the individuals was measured with Biodex® System 4 Dynamometer at 60°/sec angular speed. Results: It was found that PT stiffness was higher in males compared to females (p < 0.001). It was found that PT stiffness was lower in obese individuals compared to individuals with normal weight (p = 0.017). A negative and weak correlation was found between BMI and PT stiffness (r=-0.26, p = 0.032), whereas a negative and moderate correlation was found between fat percentage and PT stiffness (r = -0.50, p < 0.001). A moderate correlation was found between BMI and PT thickness (r = 0.54, p < 0.001). It was found that peak torque at 60°/sec angular speed had a moderate correlation with PT stiffness (r = 0.44, p < 0.001) and PT thickness (r = 0.45, p < 0.001). Conclusions: PT stiffness is correlated and affected by gender, BMI and QF muscle strength whereas PT thickness is correlated and affected only to BMI and QF muscle strength.