Written by Northwest Podiatric Laboratory’s Medical Director, Timothy Messmer, DPM, and originally appearing in the Fall 2021 newsletter for AAWP (American Association for Women Podiatrists). Click here to learn more about AAWP and its mission to develop female podiatric physicians.

As podiatrists and their staff work through the daily flow of the office schedule, certain cases or situations might cause some pause.  For those of you in the typical podiatric practice, you know that the ‘orthotics’ patient can often be challenging.

Not only are no two patients’ feet exactly the same, but different pathologies often present with varying degrees of challenges.  Obtaining quality negative casts or digital scans in the patient with a significant equinus deformity can bring many difficulties.

We know from the anatomy as well as the clinical presentation, that patients with a tight Achilles tendon (whether it is isolated gastrocnemius or gastroc-soleus) present with the foot/ankle in a relatively plantarflexed position, and/or their deformity produces an excessive plantarflexory force when they are placed into proper position to cast or image the foot.

A few positioning tips (specific to supine casting technique) should help to ease the frustration that often is experienced in trying to obtain good quality plaster casts or digital images from these patients.

•   Patients need to be reminded that relaxing is key to this working well!
•   The knee should be flexed slightly with a bump/pillow under the knee or a step/raise (such as https://www.amazon.com/Step-Aerobic-Platform-Black-Risers/dp/B000BO8AAC ) under the calf being utilized.  (Both of these techniques will help to relax the proximal tightness by negating the pull of the gastroc muscle as it originates off the distal femur.)
•   Hip position – asking the patient to lie flatter (fully supine with hip neutral) rather than sitting up in the treatment chair (with hip flexed) will help to reduce the tightness in the hamstrings, which is often seen coinciding with a tight Achilles tendon.
•   You will also want to avoid asking the patient to ‘fight off’ the equinus by actively dorsiflexing their ankle, because this will invariably lead to firing of their tibialis anterior tendon and result in dorsiflexing the 1^st metatarsal, leading to inversion of the forefoot and a ‘false FF varus.’

If you keep the above suggestions in mind when positioning your equinus patient for casting/scanning, you will make it much easier for both you and your patient to comfortably and reliably obtain high-quality images for the making of the best custom foot orthoses.

Northwest Podiatric Laboratory is an industry leader in custom foot orthotic and related technologies. Dennis Brown, a retired British soldier, elite athlete and natural-born inventor founded the company in 1964 and was joined by a biomechanics pioneer, Dr. Chris Smith, in 1974. With an exclusive blend of science, craftsmanship and innovation, the partners have built a company that utilizes proprietary production techniques and technology to produce orthotics with a unique shape and unparalleled performance. Northwest Podiatric Laboratory has helped over a million people suffering from foot pain to lead better, pain-free lives. Learn more at www.nwpodiatric.com.

Northwest Select Orthotics™ make ordering custom orthotics for a variety of activities and types of foot pain as simple as checking a box.

Unsure what to order? Worried about “over ordering?” Looking for ordering ideas?  Interested in a Northwest-exclusive specialty design?

Select from a variety of clearly named configurations, each based on successful patient outcomes achieved by thousands of healthcare professionals over 55 years.

Options for Northwest Select Orthotics™ are broken into two categories: Activity/use and Foot pain/pathology.

Activity/use

Athletic – Low profile shoes

Athletic – Standard/high profile shoes

Athletic – Standard/high profile shoes + lateral stability

Accommodative – Control + comfort

Accommodative – Comfort

Dress – Heel below 1.5″

Dress – Heel above 1.5″

Everyday

Child

Ski/Skate/Cycle

Foot pain/pathology

Adult Acquired Flatfoot (AAF) / Posterior Tibial Tendon Dysfunction (PTTD)

Plantar fasciitis

Heel spurs

Amputee

Sesamoiditis / hallux limitus

Lateral ankle instability / peroneal tendonitis

Gait plate – Adult, promote in-toe

Gait plate – Adult, promote out-toe

Gait plate – Child, promote in-toe

Gait plate – Child, promote out-toe

NWPL is a fully custom orthotic lab so, beyond the solutions provided by Northwest Select Orthotics™, we craft orthotics for all common types of foot pain: Achilles tendinitis, Achilles tendon rupture, Bone spurs, Bunions, Bursitis, Flatfeet, Haglund’s deformity, Hammertoe and mallet toe, Metatarsalgia, Morton’s neuromoa, Tarsal tunnel syndrome, Tendinitis and more.

For healthcare professionals who prefer ultimate control over every detail, the You Build Orthotics™ line keeps traditional “a la carte” ordering unchanged.

Order Northwest Select Orthotics™ using NWPL’s print Rx form or the SmartCast® app.

Northwest Podiatric Laboratory is an industry leader in custom foot orthotics and related technologies. Dennis Brown, a retired British soldier, elite athlete and natural-born inventor founded the company in 1964 and was joined by a biomechanics pioneer, Dr. Chris Smith, in 1974. With an exclusive blend of science, craftsmanship and innovation, the partners have built a company that utilizes proprietary production techniques and technology to produce orthotics with a unique shape and unparalleled performance. Northwest Podiatric Laboratory has helped over a million people suffering foot pain to lead better, pain-free lives. Learn more at www.nwpodiatric.com.

The range of motion and direction of motion of the STJ are important considerations.

The end point of pronation of the Subtalar Joint is important. The overwhelming majority of calcanei do not evert past the perpendicular to the transverse plane. (Rearfoot Varus is a very common commodity). While this is seemingly an outrageous remark, it can readily be demonstrated by placing a patient prone on the examining table, flexing the knee to 90 degrees and maintain the lower leg perpendicular to the tabletop in both the sagittal and frontal planes. With the ankle joint dorsiflexed to 90 degrees, maximum eversion of the calcaneus will place the heel bone approximately perpendicular to the tabletop. This can be visually demonstrated on almost any patient.

Consider the Relaxed Calcaneal Stance Position and determine if the Calcaneus is truly everted. In reality, the appearance of the everted rearfoot is an illusion due to fat pad displacement as the rearfoot and midfoot shifts medially as illustrated below. Disregarding the lateral fat pad and carful palpation of the medial and lateral borders of the central portions of the posterior surface of the Calcaneus (avoid the plantar lateral tubercle of the heel) will demonstrate that the calcaneus is approximately perpendicular to the transverse plane (+/- 2 to 3 degrees). The medial displacement of the midfoot and rearfoot is actually due to the unlocking (abnormal pronation) of the Midtarsal Joint. The forefoot cannot abduct due to the weight bearing friction and therefore the rearfoot and midfoot adduct.

The bottom line is that the Calcaneus always attempts to reach vertical and generally this is accomplished. If the Calcaneus is maximally pronated at the moment of heel contact then there is no shock absorption within the Subtalar Joint but inverting the Calcaneus by four degrees at the moment of heel contact will permit the Subtalar Joint to pronate and absorb shock. This seemingly small range of Subtalar Joint motion has a profound effect upon the function of the pelvis.

Posting has a significant effect upon the ability of the hip to flex and extend as well as prevent shock at heel contact.

Written by Chris Smith, DPM, Former Vice President and Medical Director of Northwest Podiatric Laboratory and Professor Emeritus of Biomechanics at the California School of Podiatric Medicine (CSPM) at Samuel Merritt University.

Skiing is a sport with no swing phase of gait i.e., the foot is in contact with the supporting surface at all times.

Skating, however, has a “swing phase” where the basic foot function is one of “position” and not of motion (not pronation followed by supination). In skating there is no change in foot position during the “swing’ to “stance”.

Both sports rely on the position of the foot to the supporting surface.

Little or no motion occurs within the foot; motion within the foot is not a consideration. Posting is not indicated because motion is not paramount within the foot (posting positions the rearfoot at heel contact only and there is no heel contact with these sports).

The rigid forefoot extension (it flexes to the transverse plane on weight bearing) keeps a constant pressure on the plantar surface of the toes creating a bio-feed back through the proprioceptors in the skin on the plantar surface of the toes. This feedback causes the posterior leg muscles to contact. (Stand up, then lean forward and notice that the posterior muscles of the leg contract to prevent you from falling on your nose. Now, stand up, then lift your toes off the floor and then lean forward and you will fall on your face).

This feedback enhances skiing and skating.

Good alignment of the rearfoot and midfoot enable greater plantarflexion of the first metatarsal into the supporting surface for increased inside edge control for skiing and more powerful propulsion for skating.

Northwest Podiatric Laboratory is an industry leader in custom foot orthotic and related technologies. Dennis Brown, a retired British soldier, elite athlete and natural-born inventor founded the company in 1964 and was joined by a biomechanics pioneer, Dr. Chris Smith, in 1974. With an exclusive blend of science, craftsmanship and innovation, the partners have built a company that utilizes proprietary production techniques and technology to produce orthotics with a unique shape and unparalleled performance. Northwest Podiatric Laboratory has helped over a million people suffering from foot pain to lead better, pain-free lives. Learn more at www.nwpodiatric.com.

When it was introduced in the early 1960’s, the rearfoot post was intended to invert the rearfoot of the orthotic (and the foot) a specific number of degrees enabling the subtalar joint to function around its neutral position. A rearfoot varus of nine degrees was given a varus post of nine degrees. (See Fig. 1). In theory, at heel contact the calcaneus would be inverted to the floor by nine degrees – so long as the lateral platform of the post was bearing the majority of body weight. (See Fig. 2). The subtalar joint would subsequently pronate as the weight shifted from the lateral platform to the medial platform. (See Fig. 3). The medial platform of the post was angled four to six degrees relative to the lateral post to facilitate physiologic pronation of the subtalar joint. When the medial platform was fully engaged with the supporting surface it acted as a terminal brake and subtalar joint rotation would cease. After this initial physiologic pronation ended the foot would subsequently resupinate to neutral and beyond producing a stable foot in preparation for propulsion.

This paradigm is erroneous. In the example above, when the medial platform is fully engaged in weight bearing, the distal medial aspect of the orthotic plate is five degrees inverted to the floor, a mechanical impossibility. (See Fig. 3).

With time, the high degrees of rearfoot posting steadily reduced to the customary four degrees (and sometimes 6 degrees) because of the potential for inversion sprains with the higher postings. Today, most rearfoot posts have a four degree varus lateral platform with a four degree medial grind off (See Fig. 4) to allow four degrees of rearfoot eversion at heel contact. (See Fig. 5). This means that resupination starts at the heel vertical position and is not dependent upon weight bearing of the medial platform. This change in perception requires some explanation.

In order to understand why resupination is not dependent on the medial platform of the post but rather the vertical position of the heel, consider the foot during the first 25% of stance as the foot contacts the floor. The foot contacts the supporting surface in the following sequence: lateral heel, then lateral forefoot, then medial forefoot and finally medial heel. (See Fig. 6). Medial forefoot contact and medial heel contact are almost simultaneous. Notice that the forefoot is everted on the rearfoot (locking the midtarsal joint) by the reactive force of gravity pushing upwards through the lateral forefoot. The same sequence occurs with the functional device: lateral platform of the heel, followed by the lateral forefoot and finally, the medial platform of the post. Thus, the eversion of  the forefoot on the rearfoot ultimately shifts the weight to the medial platform of the posts. The end-point of the eversion of the rearfoot is determined by the contact of the distal-medial aspect of the orthotic plate with the transverse plane and not by the medial platform engaging the supporting surface. In reality, the heel vertical position is the termination point of heel contact pronation no matter what degree of post is applied to an orthotic plate.

Increasing the value of the rearfoot post may be counterproductive. With higher degrees of posting a more inverted position is possible at the initial portions of heel contact but the subtalar joint must pronate further to reach the vertical end point. Remember the end point is determined by the distal medial aspect of the orthotic plate rather than the medial platform of the post. In other words, increasing the value of the rearfoot post increased the amount of pronation of the rearfoot at heel contact.

As stated before, most rearfoot posts will theoretically invert the rearfoot by four degrees and this is quickly followed by pronation to the vertical. Such a post theoretically mandates four degrees of motion that terminates with a vertical heel at the end of the first 25% of stance. An unposted device has no such mandate for motion and may not undergo the desired four to six degrees of motion at heel contact.

Rearfoot posts should be utilized with most functional orthotics to assure physiologic pronation as well as shock absorption. This is especially true for any foot that is maximally pronated at the moment of heel contact such as heel spur syndrome and sinus tarsi syndrome. In the latter case, a higher degree of motion may be desirable because the symptomatology is dependent on the impact of body weight onto an immobilized subtalar joint. Controlled motion is the best long-term therapy for this syndrome.

Written by Chris Smith, DPM, Former Vice President and Medical Director of Northwest Podiatric Laboratory and Professor Emeritus of Biomechanics at the California School of Podiatric Medicine (CSPM) at Samuel Merritt University.