Background: The stabilising effect of atmospheric pressure on the hip joint was first described by the brothers Eduard and Wilhelm Weber in 1836. Later in 1837, they conducted an experiment in which they examined a weight-bearing cadaveric hip joint in an evacuable container and could repeatedly demonstrate dislocation of the femur head due to the significant reduction of surrounding pressure and its repositioning by normalisation of the pressure. In our study we aimed to honour the contribution of the Weber brothers, to reflect on the historical argument about the hip stabilising effect of atmospheric pressure they initiated, to repeat the famous experiment they did in 1837 using advanced sensors and radiological equipment and to demonstrate the consequences of the effect on total hip arthroplasty.
Method: A weight-bearing human cadaveric hip joint was placed in a radiolucent evacuable container, in which the pressure was reduced with a vacuum pump and normalised by opening a valve. Pressure and dislocation distance were measured continuously by sensors. The state of the hip joint was documented both by X-ray as well as by permanent fluoroscopy with video recording.
Results: Conforming to the experiments published in 1837 we demonstrated dislocation of the hip joint as a result of a significant reduction of pressure. Normalisation of the pressure caused joint reduction. The ability of the cadaveric hip to bear weight depended to a great extent on its quality. Reduction of the pressure harmed the cadaveric hip and reduced the number of possible experiments.
Conclusion: The stabilising effect of atmospheric pressure on the hip joint is a fact, which was proved in 1836/37 by the Weber brothers, who conducted convincing experiments with human cadaveric hip joints. Nevertheless, the investigation into this relationship continues until today. We repeated and reproduced their experiment published in 1837 which irrefutably proved the stabilising effect of atmospheric pressure on the hip joint. The surgical application is of the utmost importance in the field of hip arthroplasty. Careful handling and reconstruction of the capsula, the use of size-adapted large hip balls as well as the intra-articular drainage provide the basis for maintaining the optimal mechanical environment and avoiding postoperative dislocation. Due to the variation in quality and anatomic characteristics of cadaveric hip specimens, we decided to use standardised model joints for further experiments.