The literature is devoid of complete descriptions of hip biomechanics
during gait. We present for the first time simultaneously acquired in
vivo acetabular contact pressures, ground reaction forces, kinematics,
hip torques, and electromyographic (EMG) activity during gait with an
d without a cane from an 85-year-old male with a left instrumented fem
oral head prosthesis. Highest acetabular contact pressures occurred in
all gait trials at the posterosuperior acetabulum, just prior to peak
EMG, adductor torque, and ground reaction force during late stance ph
ase. Contralateral cane use reduced both peak acetabular contact press
ure and gluteus medius EMG but not adductor torque or ground reaction
force. These data identify a small area of high acetabular and femoral
head stress that could occur during each of human's millions of gait
cycles annually and indicate that muscle activity, rather than solely
body weight, drives hip loading. Clinicians who desire to limit hip lo
ads should reduce both hip muscle contraction and weight bearing in la
te stance.