Activities of Everyday Life with High Spinal Loads

Abstract

Activities with high spinal loads should be avoided by patients with back problems. Awareness about these activities and knowledge of the associated loads are important for the proper design and pre-clinical testing of spinal implants. The loads on an instrumented vertebral body replacement have been telemetrically measured for approximately 1000 combinations of activities and parameters in 5 patients over a period up to 65 months postoperatively. A database containing, among others, extreme values for load components in more than 13,500 datasets was searched for 10 activities that cause the highest resultant force, bending moment, torsional moment, or shear force in an anatomical direction. The following activities caused high resultant forces: lifting a weight from the ground, forward elevation of straight arms with a weight in hands, moving a weight laterally in front of the body with hanging arms, changing the body position, staircase walking, tying shoes, and upper body flexion. All activities have in common that the center of mass of the upper body was moved anteriorly. Forces up to 1650 N were measured for these activities of daily life. However, there was a large intra- and inter-individual variation in the implant loads for the various activities depending on how exercises were performed. Measured shear forces were usually higher in the posterior direction than in the anterior direction. Activities with high resultant forces usually caused high values of other load components.

Lumbar annulus fibrosus biomechanical characterization in healthy children by ultrasound shear wave elastography

“…It consists of a gelatinous central zone, the nucleus pulposus, surrounded radially by the fibro-cartilaginous layers of the annulus fibrosus and confined below and atop by the cartilage endplates of the adjacent vertebral bodies [1]. This highly specialized structure allows the spine to be flexible while withstanding high compressive, torsional and shearing loads [2].…”

Methods for Avoiding or Reducing High Spinal Loads in Everyday Life

“…The force was calculated from the three force components and was always positive. The force components perpendicular to the longitudinal spinal axis were generally much smaller than the axial component [20]. In those cases, the magnitude of the resultant force was always similar to that of the axial compressive force.…”

“…This flexion was ranked 7 th among the everyday-life exercises with the highest resultant forces [20]. Flexion of the upper body should be avoided shortly after surgery whenever possible.…”

“…These activities are among the ten activities of everyday life that cause the highest resultant implant forces [20]. VBR forces of nearly 1000 N were measured.…”

“…Placing the hand on a stair-rail led to only slightly lower forces on the VBR. Staircase walking was ranked 5 th among the everyday-life exercises with the highest resultant forces [20].…”