Forefoot Varus is a rigid deformity that requires the STJ to compensate into a pronated position. During this process of compensation over compensation usually occurs which leads to ground reactive forces causing dorsiflexion of the midfoot. This frequent dorsiflexion eventually causes the midfoot to remain in a supinated position secondary to soft tissue accomidation, particularly shortening of the posterior tibialis. The PT shortening causes the TN joint to remain supinated, decreasing the overall ROM of the midfoot.
Rearfoot Varus is when the STJ has decreased pronatory ROM. During push off the lateral column comes off the ground first due to the limited time available to bring the foot into a rigid supinated position causing a dorsiflexory force to the medial midfoot leading the supinatus. During gait the heel strike occurs with the foot in a more inverted position causing the foot to have to pronate very quickly to get the forefoot to the ground causing a high GRF to the medial column as it slams into the ground.
Requested 1986 Forefoot Supinatus article from JAPMA
Random exerts from "The Foot Book":
Forefoot Supinatus:
o Fixed supinated position of the forefoot due to SOFT TISSUE ADAPTATION
o One would see MTJ total ROM DECREASED (different from Forefoot Varus)
o Example: Calcaneal Eversion Forefoot supination via GRF soft tissue adaptation
supinatus Decreased MTJ ROM
Supinatus?
YES!
If FF varus is 4 degrees and STJ pronatory ROM is 9 degrees.
o STJ will pronate to END ROM
o FF 4 degree varus will become SUPER-COMPENSATED
o STJ extra 5 degrees of pronation will JAM THE MEDIAL Forefoot into
the ground Inversion Soft Tissue adapation SUPINATUS
Soft tissue defects are often an affect not a cause of MSK deformity. Examples are equinus,
supinatus
Supinatus: soft tissue adaptation about the MTJ causing the supinatus; due to 1) rearfoot varus (the
STJ compensatory pronation jams the 1st ray into the ground, causing the soft tissue adaptation) and 2) forefoot varus (STJ compensatory pronation will pronate to end ROM which will probably jam the 1st ray into the ground causing soft tissue adaptation and, thus, the supinatus)
Supinatus with a RF Varus: the STJ doesn’t pronate enough to jam the 1st
met into the ground to cause the soft tissue adaptation leading to supinatus – this actually still happens because the lateral column raises FASTER than the STJ pronates, so the 1
st still slams into the ground leading to the soft tissue adaptation
Plantarflexory force on 1st ray to cast out supinatus
Cotton indicated.
Supinatus
General Cause of Supinatus (see below for details on exactly how): PRONATION OF THE STJ! #1 cause is a compensated RF varus or it could also be due to over-compensated forefoot varus –when you pronate past where you need to to be able to fully compensate for the FF Varus deformity
Supinatus occurs at the TN joint (talo-navicular joint)
It occurs when the TN joint SUPINATES to allow the 1st
ray to dorsiflex during hyperpronatory gait so that the 1st ray doesn’t get slammed into the ground
It is a “FLEXIBLE forefoot varus” type of a deformity, so soft tissue is causing the problem
o Since it’s flexible, it can in theory be manually reduced by rotating the navicular about the
talus such that the forefoot inversion problem corrects itself
The only soft tissue that can cause the navicular to have a problem is the PT tendon because it’s theonly one that attaches to the navicular
Supinatus occurs when the PT tendon becomes functionally shorter that it’s supposed to be –
here’s how that happens: when you have a forefoot varus (rigid deformity), you pronate at the STJ
to compensate for it. In theory, you compensate (pronate the STJ) so that you stop pronating when the 1st ray hits the ground (so that it doesn’t go through the ground). Catch-22 is that when you pronate to compensate, you basically always pronate past full compensation to have an “overly
compensated” forefoot varus. Well, since the ground doesn’t permit the 1st ray to go through the ground, you get SUPINATION at the TN joint to allow the 1st ray to elevate so that you can keep
pronating without crushing your sesamoids and 1st metatarsal. THIS SUPINATION OF THE TN JOINT when the STJ pronates past full forefoot varus compensation causes the PT tendon to become functionally shorter, so the PT tendon then “holds” the navicular in the inverted position leading to the supinatus deformity
DO NOT plantarflex the first ray (yes you Californians are probably throwing up a little…), why create an artificially high medial arch that often cannot be tolerated by pts? When plantarflexing the first ray you are not effectively removing supinatus, only flexing the met-cuneiform joint. Supinatus is due to contracture of soft tissues at the level of the mid foot not the first ray. To cast out supinatus you must rotate out the supinatus at the T-N joint by pressing down on the navicular. By plantar flexing the 1st ray you can actually create a more supinated foot that will eventually lead to a weakened peroneus longus and possible HAV.
