PELVIX: Development of a physiologically relevant, biomechanical test setup considering internal muscle forces for the investigation of complex pelvic ring fractures

Status:

ongoing

Aims:

The human pelvis is a ring-shaped bone structure, designed to transfer the load of the upper body to the lower extremities. The forces are applied along the pelvic ring at different positions (right and left hip joint, sacrum and different positions of muscle origins and attachments), so that torques result from the action of the lever arms. In addition, during walking, the alternating application of forces to the left and right hip joints induces an alternating load that the pelvis must absorb.

Fractures of the pelvis can lead to disruptions of the ring-shaped structure which results in mechanical destabilization. The forces and moments described can then no longer be completely transmitted by the pelvis. In order to address the existing instability, fractures of the pelvic ring require a mechanically stable osteosynthetic treatment. A variety of different methods are available for this treatment. Their mechanical stability is usually determined in biomechanical studies. However, previous studies do not fully consider the complex loading situation at the pelvis, so that there is still a lack of knowledge about the mechanical stability of the different osteosynthetic treatments.

The aim of this project is to investigate the currently most common treatment strategies used for complex pelvic ring fractures in a novel test bench. The test bench is designed to apply the dynamic loads that occur during walking on human specimens and artificial pelvises. When walking, the weight of the upper body is alternately transferred to the legs via the right and left hip joints. In addition, powerful muscles originate at the pelvis, which counteract a tilting of the pelvis during walking. The forces that these muscles exert on the pelvis should be considered.

During the period between surgery and healing, a patient’s pelvis is loaded several thousand times. The aim is to assess the stability of different treatment strategies for complex pelvic ring fractures under such dynamic everyday loading.

Activities/Methods:

The physiological, alternately loading situation at the pelvis during walking is determined via literature research. Forces that are considered are forces acting at the hip joints and the sacrum, as well as forces of big muscle groups that originate at the pelvis and are active during walking.

Subsequently, a concept of a mechanical test bench is being developed and realized. This test bench is used to load pelvises similar to the loading situation that occurs during gait.

To compare the effectiveness of different treatment strategies the fracture gap movement can be determined via optical measurement.

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