A very common but frequently overlooked cause of pain in the low back is a result of leaning forward without adequately supporting the anterior pelvis. This allows the innominates to rotate slightly downwards on the sacrum with fixation and an apparent increase in the length of the legs, which in turn irritates the sciatic nerve. This commonly occurs bilaterally but may occur on just one side. Flexion of the innominate(s) on the sacrum restores function to the sacroiliac joint, causes an apparent shortening of the legs and gives excellent relief of pain in the low back and sciatic pain.J Orthop Sports Phys Ther 1979;1(1):23-35.