Joint contact force

Purpose: The negative heel rocker shoes help reduce the plantar pressure in patients with
diabetes, but their effects on the other lower limb joints are unknown. Accordingly, the current
study aimed at evaluating the effect of negative heel rocker shoes on the moment and the contact
forces applied on lower limb joints of diabetic patients while walking.
Methods: A total of 10 patients with diabetes mellitus and 10 healthy individuals were enrolled
to this quasi-experimental study. Musculoskeletal system modeling was initiated using OpenSIM
and Visual 3D. After noise elimination and data processing, the independent t test was done. The
statistical analyses were done by SPSS 19 and significance level was considered at less than 0.05.
Results: Vertical contact force of hip joint in the experimental group (1.17 Newton/body
weight) was significantly higher than that of the control group (P=0.04). In the experimental
group, the anterior-posterior contact forces of hip joint (P=0.01), knee joint (P=0.01), and ankle
joint (P=0.04) were 1.3, 1.5, and 0.47 N/BW, respectively, which were significantly higher than
those of the control group. In the experimental group, the internal-external contact forces of
hip joint (P=0.01) and knee joint (P=0.01) were 1.31 and 0.15 N/BW, respectively; which were
significantly lower than those of the control group.
Conclusion: Using negative heel rocker shoes is associated with decrease in the vertical contact
force of ankle joint. Heel rocker shoes increase vertical and anterior-posterior forces of proximal
lower limb joints (hip and knee). The increased contact force in proximal lower limb joints,
especially hip joint, may increase the risk of joint injury and disruption. Thus, more attention
should be paid to prescribe negative heel rocker shoes for the patients with diabetes.