Sacroiliac Joint

Several researchers have contributed to foundational literature in trunk control including Richardson, Snijders, and Hull. One study of interest completed by these authors and other colleagues assessed sacroiliac joint stability with contraction of the transversus abdominis muscles compared to contraction of all the lateral trunk muscles.

In this experiment, 13 healthy subjects without a history of low back pain participated in the tests. Eight men and five women with a mean age of 26 and who were able to complete the required muscle activations participated in the study. The subjects were positioned in prone, and electromyographic recordings as well as ultrasound imaging were used to verify the muscle activation patterns. To measure sacroiliac joint stiffness or laxity, Doppler imaging of vibrations was utilized. The theory of using vibration to measure joint stiffness includes that a transfer of vibration across a joint is best when the joint is more stiff, according to the authors.

The results of the study include a decrease in laxity (or an increase in stiffness) in the sacroiliac joint when either muscle patterns were used, however, when the transversus only was activated, laxity was decreased more than during a more global contraction.

Research in trunk and pelvic control has typically divided the muscles into local or global muscles, with inclusion of the the more superficial, larger muscles that control trunk movement grouped into the global muscles. Local muscles in this study describe the deeper, smaller muscles more apt to act as stabilizers of the lumbar spine and sacrum such as the transversus abdominis and multifidus. While this description is not inclusive of all or of more recent models, for the purposes of this study, these descriptions may be found useful.

The authors acknowledge that the role of the pelvic floor in creating sacroiliac joint stiffness, having not been measured, is not known in this study. The research does support the body of work that describes use of specific training for treating patients with low back pain, rather than global exercises without an emphasis on local muscle activation.

Many of you are aware of the various "camps" and beliefs about trunk and pelvic rehabilitation and activation, and more than likely, as with most issues in life, the truth lies in the middle. Do some patients simply need to correct their breathing patterns, trunk alignment, or gait patterns? Sure, and other patients may require a focus on inhibiting a very painful muscle, bringing awareness to that area, and learning how to "turn on" the muscle and incorporate the muscle pattern into routine activities. Herein we find, in my opinion, the art of rehabilitation. Researchers and therapists will continue to work towards clinical prediction rules and guidelines for best practice, yet we are left with understanding the theories and tools that drive the research and clinical practice so that we can apply individual plans of care for patients. If you find yourself "stuck" with the same "core" exercises and feel that you would like to improve your skills in sacroiliac rehabilitation, therapists have been raving about Peter Philip's sacroiliac joint course, where you can learn very specific palpation, testing, and rehabilitation principles. The next opportunity to take this course is in January!