Video raster stereography

The video raster stereography ( VRS for short ; Latin. Videre = “see” / Greek στερεος stereos = “space / spatial, fixed” / γράφειν, graphein = “draw”, “write, describe”) is a computer-aided light - optical process that is used in the Medical diagnostics is used to measure and three-dimensional surface representation of the spine in order to record and document its course and the position of the pelvis .

The VRS is occasionally offered as a radiation-free supplement to the X-ray during follow-up checks. According to an analysis by IQWiG , however, there is insufficient scientific evidence for its use and the values determined do not agree with those of X-rays, so that it is not an alternative to X-rays and can possibly lead to incorrect treatments.

application

functionality

technical functionality of video grid stereography (VRS)

The VRS is physically based on the principle of triangulation .

The measuring system consists of a light projector that projects a line grid onto the patient's back, which is recorded by a camera unit . A software analyzes the line bends and generates therefrom by photogrammetry a three-dimensional image of the surface, as it were a virtual plaster cast. Using the surface curvature and the automatic detection of anatomical fixed points, the spatial course of the spine and the position of the pelvis can be reconstructed. In contrast to X-ray examinations, the VRS provides information about the entire body statics and posture , such as spinal curvature (lateral and frontal), vertebral body rotation or pelvic position, in just one measurement process . Even muscular imbalances can be read from the curvature of the back surface.

Measuring process

For a three-dimensional spine measurement, the patient stands with the undressed back at a distance of approx. 2 meters from the stereo base with the projection and recording device. The patient assumes his natural posture, the knee joints should be relaxed. Using an additional simulation platform, it is possible to immediately compensate for any pelvic asymmetries or leg length differences. For the recording, the room should be darkened slightly so that the line projection on the patient's back is clearly visible and free of interference. The measurement itself only takes a few seconds and is easy to carry out. Using the data obtained, a three-dimensional surface analysis of the shape of the spine and the pelvic position is carried out.

Schematic representation of a patient during a video raster stereographic examination

Clinical application

Video grid stereography is occasionally used without sufficient scientific evidence in:

Scolioses , and also when making corsets
Postural deficits and bad posture (including hyperlordosis , hyperkyphosis )
Pelvic inclination and pelvic torsion
Real and functional leg length differences
Craniomandibular dysfunction (malfunction of the temporomandibular joint)
Muscular posture weaknesses ( posture test according to Matthiass )
For monitoring the progress of "posture-correcting" insoles
Control of medically based training therapy
Checks after surgical interventions, e.g. B. after insertion of a hip or knee joint prosthesis and after operations on the spine

Alternatives

Like the VRS, the principle of optrimetry is based on a representation of the patient's back by means of video recording, which, however, is evaluated manually after the surface rotation. For this purpose, the strips of the slide projection on one side of the patient's back are marked at several different, clinically interesting places and followed along the surface of the back. From the starting point on one side of the patient's back and its end point on the other side, a straight line can be represented, the angle of which to the horizontal allows a statement to be made about the rotation of the body at this point. In order to assess the course of the spinous processes , these must be masked off manually with markers in the patient, which in contrast to the VRS is done by automatic detection. In addition, unlike the VRS, the optrimetry method does not allow the analysis of vertebral body rotations and the pelvic position (twisting) or the representation of a vertebral body center line comparable to the X-ray image. A 3D reconstruction of the spine itself is also not possible with this method.

history

The basis for video raster stereography was developed in the 1980s at the Westfälische Wilhelms-Universität Münster by the department for experimental biomechanics under the direction of Eberhard Hierholzer and Burkhard Drerup. The background to this was the search for radiation-free methods for monitoring the progression of patients with scoliosis.

Initially, it was about non-contact and radiation-free measurement and at the beginning of the 1990s, the DIERS formetric, the first medically certified VRS measuring device, came onto the market.

Individual evidence

↑ ^a ^b Arne Hillienhof: Video raster stereography: No alternative to x-rays in scoliosis Deutsches Ärzteblatt 2019, Volume 116, Issue 49 of December 6, 2019, page A2278, link accessed on December 15, 2019 at 8:38 p.m. CEST
↑ ^a ^b W. Frobin, E. Hierholzer: Rasterstereography: A photogrammetric metric method for measurement of body surfaces . In: Photogrammetric Engineering & Remote Sensing No. 47, 1981, pp. 1717–1724 PMC 6853417 (free full text)
↑ W. Schupp, I. Säckler: Checking the occlusion in a craniomandibular dysfunction with manual medical diagnostics and formetric measurement , in: Manual Medicine No. 43, 2005, pp. 331–341. doi: 10.1007 / s00337-005-0381-5
↑ Marcel Betsch, Michael Wild, Pascal Jungbluth, Simon Thelen, Mohssen Hakimi: The rasterstereographic-dynamic analysis of posture in adolescents using a modified Matthiass test . In: European Spine Journal . tape 19 , no. 10 , October 1, 2010, ISSN 0940-6719 , p. 1735–1739 , doi : 10.1007 / s00586-010-1450-6 ( springer.com [accessed August 31, 2017]).
↑ J. Schröder et al .: Immediate effects of a sensorimotor insert on the shape of the spine and the activity of postural muscles in splayfoot , in: Orthopädische Praxis No. 19, 2010, pp. 1735–1739
↑ L. Hackenberg et al .: Rasterstereographic back shape analysis in idiopathic scoliosis after posterior correction and fusion , in: Clinical Biomechanics No. 18, 2003, pp. 883-889. PMC 14580831 (free full text)

[hillienhof-1] Arne Hillienhof: Video raster stereography: No alternative to x-rays in scoliosis Deutsches Ärzteblatt 2019, Volume 116, Issue 49 of December 6, 2019, page A2278, link accessed on December 15, 2019 at 8:38 p.m. CEST

[Photogrammetric_Engineering-2] W. Frobin, E. Hierholzer: Rasterstereography: A photogrammetric metric method for measurement of body surfaces . In: Photogrammetric Engineering & Remote Sensing No. 47, 1981, pp. 1717–1724 PMC 6853417 (free full text)

[3] W. Schupp, I. Säckler: Checking the occlusion in a craniomandibular dysfunction with manual medical diagnostics and formetric measurement , in: Manual Medicine No. 43, 2005, pp. 331–341. doi: 10.1007 / s00337-005-0381-5

[4] Marcel Betsch, Michael Wild, Pascal Jungbluth, Simon Thelen, Mohssen Hakimi: The rasterstereographic-dynamic analysis of posture in adolescents using a modified Matthiass test . In: European Spine Journal . tape 19 , no. 10 , October 1, 2010, ISSN 0940-6719 , p. 1735–1739 , doi : 10.1007 / s00586-010-1450-6 ( springer.com [accessed August 31, 2017]).

[5] J. Schröder et al .: Immediate effects of a sensorimotor insert on the shape of the spine and the activity of postural muscles in splayfoot , in: Orthopädische Praxis No. 19, 2010, pp. 1735–1739

[6] L. Hackenberg et al .: Rasterstereographic back shape analysis in idiopathic scoliosis after posterior correction and fusion , in: Clinical Biomechanics No. 18, 2003, pp. 883-889. PMC 14580831 (free full text)