**1. Introduction**

According to the World Health Organization (WHO), back pain of the lower spine has reached epidemic proportions, being reported by about 80% of people at some time in their life [1]. Hoy notes that lower back pain causes more global disability than any other condition [2]. The causes of back pain are manifold. Reasons may be degenerative changes of intervertebral discs, spinal stenosis, spondylolisthesis, spinal stenosis, traumatic injury, skeletal irregularities, and osteoporosis. But there is also a correlation between increased body weight and low back pain [3–5]. These overloads may result in sequelae such as instability or dysesthesia with narrow‐ ing of the spinal canal and compression of the associated nerve roots may be a consequence. If

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a conservative treatment does not achieve a pain relief anymore, only a surgically induced stabilizationlike a therapeuticoptionremains.Mayer[6]indicates thatnovalidatedresults exist aboutthe successoftheseoperationsover aperiodoftwoyears, andthusprovide clear evidence ofreduced adjacent segment degeneration. Furthermore, statements aboutthe sustainability of clinical and radiological results with respect to a reconstruction of the segmental mobility are still missing. A modern non-invasive method for assessing the effect of medical operational measures is theloaddeterminationinvarious spinal structuresbymeansof computermodeling.

To capture the load distribution of the lumbar spine, highly developed so-called finite-element (FE) models [7–11] can be used which allow a very detailed calculation of force and torque transmission—both in the rigid bones and in the elastic proportions as intervertebral discs, ligaments, and implants. The complexity of the models, however, requires high computing times for each load case. Is the aspect of the holistic approach of the human movement in the focus of interest, the multibody simulation (MBS) is a suitable simulation method? Due to the highly efficient short computation times, even complex motion sequences can be simulated.
