Quantitative determination of the contact pressure distribution in the hipjoint during gait

The objective of this investigation was the experimental determination of t he 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, ba sed on kinematic gait analysis. In eight cadaveric hip joints (age 18-75 yr s.) the reaction forces were applied corresponding to four phases of the ga it cycle (heel strike, mid-stance, heel off, toe off) and the pressure dist ribution determined with FUJI pressure sensitive film. We found maxima of 1 0 MPa during mid stance. The areas of highest pressure were located in the ventro-superior aspect of the acetabulum (anterior part of the acetabular r oof) and in the dorso-inferior aspect of the lunate surface. The pressure d istribution was relatively constant during the four phases and the maxima d id not vary proportional to the applied load. The normal pressure distribut ion in the hip appears to be determined by the physiological incongruity of the articular surfaces and the inhomogeneous bony support of the acetabulu m, During operative interventions this normal load transfer should be resto red as accurately as possible.