Soft tissue artefacts of the human back: comparison of the sagittal curvature of the spine measured using skin markers and an open upright MRI.

Soft tissue artefact affects the determination of skeletal kinematics. Thus, it is important to know the accuracy and limitations of kinematic parameters determined and modelled based on skin marker data. Here, the curvature angles, as well as the rotations of the lumbar and thoracic segments, of seven healthy subjects were determined in the sagittal plane using a skin marker set and compared to measurements taken in an open upright MRI scanner in order to understand the influence of soft tissue artefact at the back. The mean STA in the flexed compared to the extended positions were 10.2±6.1 mm (lumbar)/9.3±4.2 mm (thoracic) and 10.7±4.8 mm (lumbar)/9.2±4.9 mm (thoracic) respectively. A linear regression of the lumbar and thoracic curvatures between the marker-based measurements and MRI-based measurements resulted in coefficients of determination, R2, of 0.552 and 0.385 respectively. Skin marker measurements therefore allow for the assessment of changes in the lumbar and thoracic curvature angles, but the absolute values suffer from uncertainty. Nevertheless, this marker set appears to be suitable for quantifying lumbar and thoracic spinal changes between quasi-static whole body postural changes.

The spinal curvature of three different sitting positions analysed in an open MRI scanner.

Sitting is the most frequently performed posture of everyday life. Biomechanical interactions with office chairs have therefore a long-term effect on our musculoskeletal system and ultimately on our health and wellbeing. This paper highlights the kinematic effect of office chairs on the spinal column and its single segments. Novel chair concepts with multiple degrees of freedom provide enhanced spinal mobility. The angular changes of the spinal column in the sagittal plane in three different sitting positions (forward inclined, reclined, and upright) for six healthy subjects (aged 23 to 45 years) were determined using an open magnetic resonance imaging (MRI) scanner. An MRI-compatible and commercially available office chair was adapted for use in the scanner. The midpoint coordinates of the vertebral bodies, the wedge angles of the intervertebral discs, and the lumbar lordotic angle were analysed. The mean lordotic angles were 16.0 ± 8.5° (mean ± standard deviation) in a forward inclined position, 24.7 ± 8.3° in an upright position, and 28.7 ± 8.1° in a reclined position. All segments from T10-T11 to L5-S1 were involved in movement during positional changes, whereas the range of motion in the lower lumbar segments was increased in comparison to the upper segments.

Imaging-based planning for spine surgery.

The planning of decompressive and reconstructive spine surgery is based on clinical findings and diagnostic imaging. The evaluation of segmental instability, but also of the risk of destabilization following a needed decompression of the spinal canal and/or neural foramina make complex spine surgery a challenge, bearing in mind the risk of failures in case of an inadequate operation. The insufficient correlation between imaging and clinical symptoms originating from the spine and its nerve roots has been frustrating for some decades. This review focuses on the new upright, dynamic-kinetic, i.e., "functional" MRI and its ability to detect load- and motion-dependent disc herniations, stenosis, instabilities, and combinations of these pathologies not seen during recumbent imaging.

The Wilhelm tell technique for anterior lumbar interbody fusion. Technical note.

Experience indicates that stand-alone cages may lack the necessary stability to secure highly unstable motion segments at the lumbosacral junction. The authors have designed a special carbon fiber composite interbody cage that allows additional screw placement in anterior lumbar interbody fusion procedures performed at the lumbosacral junction.