The upside-down flexion back brace.

For a brace to be effective, it must be comfortable so that the patient will wear it. The lordotic low back can be changed to an active flat back by training (Fig. 1, left & center). To acquire an active flat back, the role of the abdominals and their deep crease at navel level is important. The lumbar spine from the lum­ bosacral area upward has a considerable arc range compared with that of the sacrum downward from the lumbosacral center. The lumbosacral area moves backward in space. The Williams brace (Fig. 2 ) concentrates on pushing the sacrum for­ ward, pressing round the relatively unyielding pelvis, using the long lever arm for power, not to follow range, and simulating the effect particularly of the gluteus maximus. With a tack in the rear, a firm elastic band round the pelvis can also give active withdrawal from discomfort. There is a pivot point quite high on the Williams brace; it might as well be off the top band directly and does very little moving anteroposteriorly. If a pivot point is located low (Fig. 1, right), near the lumbosacral level, it will float backward