Effects of hip joint kinematics on the effective pelvis stiffness and hip impact force during simulated sideways falls

• Published in: Journal of biomechanics Vol. 162; p. 111885
• Main Authors: Choi, J W, Park, J W, Choi, W J
• Format: Journal Article
• Language: English
• Published: United States Elsevier Limited 01-01-2024
• Subjects: Experiments; Fractures; Hip; Hip joint; Impact loads; Impact prediction; Kinematics; Motion capture; Pelvis; Rotation; Stiffness; Variables; Variance analysis; Young adults; United States > US; Falls; Hip fracture risk; Femur orientation; Hip joint kinematics; Pelvis stiffness
• ISSN: 0021-9290; 1873-2380
• DOI: 10.1016/j.jbiomech.2023.111885

Improved understanding is required on how hip fracture risk is influenced by landing configuration. We examined how hip impact dynamics was affected by hip joint kinematics during simulated sideways falls. Twelve young adults (7 males, 5 females) of mean age 23.5 (SD = 1.5) years, participated in pelvis release experiments. Trials were acquired with the hip flexed 15° and 30° for each of three hip rotations: +15° ("external rotation"), 0°, and -15° ("internal rotation"). During falls, force-deformation data of the pelvis were recorded. Outcome variables included the peak hip impact force (F
) and effective stiffness of the pelvis (k
, k
, and k
) determined with different methods suggested in literature, and predicted hip impact force during a fall from standing height (F
, F
and F
). The two-way repeated-measures ANOVA was used to test whether these variables were associated with hip joint angles. The F
, k
and F
were associated with hip rotation (F = 5.587, p = 0.005; F = 9.278, p < 0.0005; F = 5.778, p = 0.004, respectively), and 15 %, 31 % and 17 % smaller in 15° external than internal rotation (848 versus 998 N; 24.6 versus 35.6 kN/m; 2,637 versus 3,170 N, respectively). However, none of the outcome variables were associated with hip flexion (p > 0.05). Furthermore, there were no interactions between the hip rotation and flexion for all outcome variables (p > 0.05). Our results provide insights on hip impact dynamics, which may help improve a hip model to assess hip fracture risk during a fall.