Quantitative determination of the contact pressure distribution in the hip joint during gait

The objective of this investigation was the experimental determination of the contact pressures in the hip joint for characteristic phases of the gait cycle. The joint forces determined in vivo with telemetric endoprosthesis by Bergmann et at. (1993) were converted into a pelvic reference system, based on kinematic gait analysis. In eight cadaveric hip joints (age 18-75 yrs.) the reaction forces were applied corresponding to four phases of the gait cycle (heel strike, mid-stance, heel off, toe off) and the pressure distribution determined with FUJI pressure sensitive film. We found maxima of 10 MPa during mid stance. The areas of highest pressure were located in the ventro-superior aspect of the acetabulum (anterior part of the acetabular roof) and in the dorso-inferior aspect of the lunate surface. The pressure distribution was relatively constant during the four phases and the maxima did not vary proportional to the applied load. The normal pressure distribution in the hip appears to be determined by the physiological incongruity of the articular surfaces and the inhomogeneous bony support of the acetabulum, During operative interventions this normal load transfer should be restored as accurately as possible.