Pelvic orthosis has a direct impact on the SI joints

A comprehensive study on the effect of the SacroLoc has revealed that it has a clear impact on the sacroiliac (SI) joints. Computer simulations have also shed some light on fundamental questions regarding the anatomy and biomechanics of the ligaments in this area.

For a long time, the sacroiliac (SI) joints, which form the main link between the sacral and iliac bones, tended to be pushed to the sidelines of medical research. They have begun to attract more and more scientific interest only in the past few years. Until now, however, relatively little was known about the exact anatomical conditions of the ligament structures around the SI joints, as conventional measurement techniques did not offer enough scope for investigating this area.
For researchers at Leipzig University and Chemnitz University of Technology, this was reason enough to attempt to close this gap in research and, using state-of-the-art investigation methods, to get to the bottom of the effect of the SacroLoc orthosis on the SI joints and the pelvis.

Rotation of the sacral bone reduced by more than 40 percentt

The study was carried out at the Institute of Anatomy at Leipzig University and led by anatomist Dr. Niels Hammer. As well as looking into anatomical and biomechanical aspects, the study examined clinical issues regarding the stability and mobility of the pelvic ring under the influence of the SacroLoc.
Using the finite element method (FEM), a computer model was developed into which geometric and mechanical data relating to the anatomy of the pelvis was incorporated. This made it possible to measure slight movements of the SI joints in simulations.
One of the groundbreaking results from this study was that, overall, the movements of the SI joints turned out to be significantly smaller than previously assumed. Another important finding was that use of the pelvic orthosis altered the nutation of the SI joints considerably. In numerical terms, the rotational components were reduced by more than 40 percent. The transverse tilt of the iliac bone part of the hip bone increased by 65 percent, leading to a slight straightening of the pelvis. According to the researchers involved in the study, this sophisticated effect of the pelvic orthosis, which alters the range of movement in a complex way rather than restricting it in isolation, is a new finding for the scientific community.

Innervation of the SI joint ligaments

Thanks to the complex way in which it changes the range of movement of the SI joints, the SacroLoc relieves the strain on the local ligament structures to a measurable extent – especially the ligaments inside the SI joints and the sacrospinous and sacrotuberous ligaments. This influences the kinematics of the pelvis, has a stabilizing effect, and in most cases helps to relieve pain. In fact, in the clinical part of the study, some of the patients with chronic SI joint symptoms reported immediate relief from pain when wearing an orthosis.
There is also a direct link between this and the innervation conditions in the SI joint area. One of the findings shown by anatomical studies using plastinated specimens, which formed the basis for the computer simulations, was that the SI joint region is densely innervated up to the joint space. This means that applying the SacroLoc so that it encircles the pelvic ring not only relieves pressure on the ligaments, but also has an impact on the interaction between the ligaments and nerves.

Ref. Soisson O, Lube J, Germano A, Hammer K-H, Josten C, Sich­ting F, Winkler D, Milani T , Hammer N. PLOS ONE 10.1371/journal.pone.0116739. published 17 Mar 2015. Pelvic belt effects on pelvic morphometry, muscle activity and body balance in patients with sacroiliac joint dysfunction. (www.plosone.org)

Images: Dr. Hammer, Bauerfeind