Since its creation in 1925, the sacro-occipital technique (SOT) has grown to become one of the most commonly used chiropractic techniques. Essentially, the system screens patients into one of three categories according to a set of physical findings suggested by the techniques creator, DeJarnette. The second SOT category (Cat II) is based on the concept of sacroiliac joint separation during standing posture which can be expressed as a loss of joint stiffness. To the present authors' knowledge no study has attempted to measure objectively the functional aspects of joint separation in patients screened as Cat II. Therefore the objective of the present project was to investigate if there is any difference in sacroiliac joint stiffness between Cat II and non-Cat II subjects in the weightbearing posture.
Specific measures were used to select a test group and evaluators were considered to be "expert SOT practitioners." Twenty-one subjects were categorized as Cat II and 19 as non-Cat II. The means of SIJ stiffness at each load (100, 150, 200, and 250 N) were compared between the three different subject postural positions within the Cat II and Non-Cat II groups using the paired i -test for related designs.
The present study demonstrated that there was no significant difference in sacroiliac stiffness within or between SOT Cat II and non-Cat II subjects in left-, right- and two-legged postures. This does not in any way challenge the effectiveness of prescribed SOT procedures or management, but merely underlines the need for more experimental and clinical trials in order to reconsider the basic principles underlying the clinical results observed.