With my book "Regulatietherapie vanuit de voet"(Tijdstroom, 1991) I introduced a new, integral therapeutic, way of thinking: the Quadrant Theory.
Starting from a 3-D observation: longitudinal, transversal and sagittal, I subdivided the body in 16 small squares corresponding with the two times 8 squares at the plantar side of both feet.
I further assume that:
- Our body must provide continuous resistance against gravity. Since we became a biped our struggle is to remain upright, where we tend to 'fall' forward.
- Each displacement of a part gravity point leads to a compensatory displacement of another part gravity point and always to an adjustment of the central body gravity point in front of S 2.
- watching a standing person we see a 'mirrored reaction': a displacement under L 3 gives an opposite reaction above L 3. This all takes place within the 3 dimensions. These displacements and compensations lead to a related pressure on our feet and so to related ground reaction forces.
Conclusion: displacement of a part gravity point forward, leads to an increased pressure in the corresponding foot square.
My Quadrant Theory is based on three dimensions. This appears to be logical, but is still not common practice in medicine. In case of a scoliosis for example people often speak from a lateral curvature. The simple fact that standing we create a closed kinematic chain implies an adjustment in the third dimension: the sagittal plane.
Our feet are a very complex part of the body. They bear our weight and keep us mobile. The pressure sensitive receptors of the glabrous skin of the foot sole continuously transmit information to the brains during stance and gait, in particular to the cerebellum. This together with the optical information makes us keeping our balance. Huson (*) suggested that there was as good as no movement possible in the sub-talar joint and spoke of a kinematic chain reaction of foot and lower leg. In his opinion pro-and supination is a process in the foot. My earlier suggestion that going from pronation to supination creates a torsion *** around the length axis of the foot, at the height of the Lisfranc joint, seems to be agreed (**). This process takes place three dimensionally in the foot itself, thus also in the sagittal plane. Later research shows that there is (some) movement in the subtalar joint.
Summary: the Quadrant Theory explains how forward displacement of the body center of gravity is generally projected to the plantar loading of the feet (see diagram). When we can see that the postural balance is directly related to the loading of the feet, we can also understand the very important role of the intrinsic foot muscles. Nineteen out of twenty intrinsic foot muscles lie in the longitudinal direction of the foot! It is therefore quite surprising that scientific interest is only recent. The Quadrant Theory can provide a stepping stone to other, posture and foot -related visions.
Attention: it is tempting to als o fit in the foot sole reflex therapy. However, the plantar side of the foot is motor innervated from L 5 to S 2. This means that there are no impulses, at least directly, above this level!
(*) Auteur(s): Lagerberg A., Lulofs R. Titel: Passieve bewegingskoppelingen tussen onderbeen en voet, Jaargang: 7, Jaartal: 1989, Nummer: 1, Oorspronkelijke paginanummers: 9-32.
(**) Rugklachten, je moet er maar mee leren leven... Peter W.B.Oomens, De Driehoek Amsterdam, 1993, ISBN90-6030-527-2.
(***) The effects of shoes on the torsion and rearfoot motion in running