Correlation between BMI and Static Biomechanical Lower Extremity Kinetic Chain Variables in Overweight Young Adults: A Cross-sectional Study

Introduction: Lower Extremity Alignment (LEA) is a main influencing cause in the active motion of the human body. Changes in the lower limb kinetic chain can be pushed by Body Mass Index (BMI). The gait may be impacted, which may result in more energy usage. However, little is known about how BMI and other static alignment parameters such as Quadriceps (Q)-angle, tibial torsion and plantar arch index are related.

Aim: To determine the correlation between BMI and lower extremity kinetic chain variables such as pronated feet, femoral anteversion, Q-angle, tibial torsion, plantar arch index, angle of toe and pelvic inclination.

Materials and Methods: The present cross-sectional study was conducted in the Department of Physiotherapy, Santosh Hospital Ghaziabad, Uttar Pradesh, India, from January 2021 to December 2021. A total of 160 participants age ranged between 18 years and 30 years with a BMI between 25 kg/m2 and 29 kg/m2 were included in the study. The following parameters were measured: pronated foot, angle of toe, plantar arch index, pelvic inclination, femoral anteversion, Q-angle and tibial torsion. Correlation between BMI with the seven static alignment parameters mentioned above was statistically analysed by using Pearson’s correlation coefficient and Spearman’s correlation test.

Results: The mean age of the subjects was 23.82±2.021 years and mean BMI of the participants was 26.37±1.501 kg/m2. There was significant correlation between BMI and pronated foot of both sides (r-value=0.256, 0.199, p-value=0.001, 0.012), BMI and plantar arch index of both sides (r-value=0.198, 0.161, p-value=0.013, 0.043). However, no significant correlation was found between BMI and Q-angle (r-value=0.137,0.144, p-value=0.087, 0.72), BMI and tibial torsion (r-value=0.024, 0.066, p-value=0.766, 0.413), BMI and anteversion (r-value=0.111, 0.134, p-value=0.164, 0.92), BMI and angle of toe (r-value=0.127, 0.139, p-value=0.111, 0.081) and, BMI and pelvic inclination (r-value=0.012, 0.013, p-value=0.885, 0.870).

Conclusion: BMI was positively correlated with the pronated feet and plantar arch index, and this relationship was statistically significant. However, no statistically significant relationship between BMI and pelvic tilt, femoral anteversion, Q-angle, tibial torsion and angle of toe.