In 1971, podiatrist and professor, Merton Root, literally wrote the book on foot disorders that have a biomechanical cause. His Normal and Abnormal Function of the Foot revolutionized our understanding of the biomechanics of the foot and ankle during walking and running, and also identified the single most destructive mechanical factor in the pathogenesis of foot disorders – ankle equinus – or the inability to freely dorsiflex the ankle.
In the half century since Dr. Root’s book was published, the list of foot problems associated with ankle equinus became so long, and the condition so notoriously destructive and hard to treat, that foot and ankle surgeons began to call it “the Root of all evil”, in a nod to the man – Dr. Root – who’d first described it’s malevolent influence.
How Equinus hurts the feet
When we walk, the ankle above the foot on the ground needs to dorsiflex to allow our bodies to proceed forward in space. If dorsiflexion does not easily occur, our bodies will employ one or more compensatory workarounds to move our bodies forward over our planted foot. Typically, these compensations are relatively effective – we will continue to be able to walk – but each compensation style will produce destructive forces that will inevitably result in injury, pain and/or eventual disability.
If the ankle doesn’t bend freely, some people will simply lift their heels prematurely during the gait cycle. This produces a characteristic bouncy gait, as the person is almost walking on their toes, and because their weight is on the balls of their feet earlier than normal, and so stays there longer than normal, they tend to develop problems with their toes and the balls of their feet – including hammer toes, neuromas and stress fractures – as these areas are chronically overloaded.
This compensation is akin to toe walking, which is relatively common in small children. Some kids grow out of toe-walking, others go on to develop ankle equinus in adulthood. Ankle Equinus literally means “horse ankle”, referencing the fact that horses (and almost all other quadrupeds) walk on their “toes.”
Other people with ankle equinus compensate for it by excessively pronating at the joint just below the ankle – the subtalar joint. “Hyperpronation” is a commonly understood word nowadays, and equinus is probably the most common cause of it. Hyperpronation is not always a bad thing, but when it occurs as a compensation for ankle equinus, it allows the middle part of the foot – the midfoot – to bend upwards. So instead of the ankle joint dorsiflexing, the midfoot bends in that direction instead, producing a kind of pseudo-dorsiflexion.
This compensatory midfoot dorsiflexion can be profoundly destructive, and leads to plantar fasciitis, strain and sprain of the tibialis and peroneal muscles and tendons, jamming and eventual destruction of the big toe joints (hallux limitus and rigidus), and in some cases precipitates the catastrophic and disabling breakdown of the arch of the foot, a condition known as adult acquired flatfoot.
Other people with ankle equinus will turn their feet out when they walk, which essentially shortens the foot and reduces the need for dorsiflexion during walking. This might be the least destructive compensation, but does contribute to postural disorders that may carry a cost later in life.
The Evil of Equinus is not confined to the feet
It’s easy to see why podiatrists call equinus the “Root of All Evil”, but it’s actually worse than foot doctors think! Podiatrists are limited by their scope of practice to treating only ailments below the knee. But because the ankle joint is so close to the ground, limitations in movement there can and do affect everything above it. And so the evil of ankle equinus spreads beyond the ankle to the entire body.
If the ankle does not have the ability to freely dorsiflex, every joint in the body above the foot – the knee, the hip, the sacroiliac joint, the 100+ joints of the spine, even the skull – will have to compensate for the ankle limitation by moving in ways that are suboptimal and potentially injurious.
The Back Squat as a model of ankle Equinus
To illustrate the effect ankle equinus has on the joints above it, we can use the squat exercise taught and practiced in gyms all around the world (above). Partly to protect the knees and the spine, the squat is almost always taught nowadays with an emphasis on restricting how much the ankles bend. Most people are taught to not allow their knees to move past their toes, which greatly restricts ankle dorsiflexion.
This is actually not the natural way to squat, and when the ankles are restricted from dorsiflexing in this way, the knees and hips must bend more to compensate. In addition, limiting the ankle’s motion pushes the body’s center of gravity backward, and to maintain balance over the feet the lower back arches (extends), the chest lifts up in front and the chin lifts and juts forward.
This way of squatting represents a fundamentally faulty movement pattern. A person with ankle equinus will demonstrate very similar patterns in everything they do.
By contrast, adequate ankle dorsiflexion range of motion allows for a deep functional squat that is actually therapeutic:
Stairs are tricky and dangerous for those with ankle equinus
Climbing and descending stairs and hills can be particularly difficult for someone whose ankles don’t bend freely. Going up and down stairs is a bit like repeated single-leg squats.
In order to smoothly descend stairs, the ankle must dorsiflex far enough that the other foot can reach the next stair. If this isn’t possible, we will employ one or more of the compensatory patterns outlined above – we will lift our heels prematurely, going down the stairs essentially balanced on the balls of our feet (which is bad for the knees); or we will pronate our feet and allow our knees to buckle inward, which results in tremendous strain on the joints of the feet, ankles, knees and hips. Some young people with ankle equinus develop the habit of bouncing down stairs quickly, a strategy that avoids their ankle range of motion limitations, but could become problematic down the road.
Going up stairs can also be tricky. Without enough ankle dorsiflexion range of motion, people tend to lean forwards, arch their backs, and pull themselves upward by jutting their heads – almost like they are pulling their whole body up with their chin – a movement style that produces spinal strain and excess tension in the back and neck muscles.
It sounds crazy, but In essence, people with ankle equinus climb stairs with their neck and back muscles more than their leg and hip muscles.
Exorcising Equinus
But recall that ankle equinus is called the “Root of all evil” not just because of the destructive compensations required to get around it, but also because it is a difficult problem to resolve.
In pediatric and orthopedic surgery practices, equinus is often addressed surgically. Surgical lengthening of the calf muscles and/or the achilles tendon are sometimes performed at the same time as surgery to fix whatever problem/pain that brought the patient to the doctor. For instance, if a neuroma (inflamed, enlarged nerve) in the ball of the foot must be removed, the surgeon may also lengthen the calf muscles or the achilles tendon during the same surgery, because he or she knows that without correcting the cause (equinus), the problem (neuroma) and symptom (pain) may come back again.
But these surgeries – known as gastrocnemius (long calf muscle) recession or percutaneous achilles tendon lengthening procedures – have lengthy recovery times, and patients do not always regain full function and strength afterward.
Stretching?
In physical therapy, ankle equinus has traditionally been treated with stretching exercises for the calf muscles, and/or ankle joint manipulation or mobilization.
In some cases, hands-on ankle mobilization can dramatically improve ankle range of motion. In these cases, motion at the ankle joint itself, or at the nearby tibio-fibular joints, is stuck, and skillful manual therapy can quickly resolve the problem by unjamming the stuck joints. But if mobilization or manipulation does not improve ankle range of motion in two or three tries, it is unlikely to ever do so, as the problem is probably contracture or hyperactivity of the calf muscles, and not restriction in the joints.
This is most often the case, and so the go-to physical therapy intervention for many years has been stretching, either performed actively by the patient or passively by a device, such as the Strasbourg Sock, worn during sleep.
But although these stretching interventions are the go-to in most cases of equinus, research actually shows that they are of very limited effectiveness. Even diligent daily stretching tends to produce minimal range of motion improvements, and cessation of stretching usually results in rapid return of the original movement limitation.
Why doesn’t stretching work?
Well, traditional stretching exercise is a rather primitive endeavor. We naturally tend to assume that stretching our muscles results in them becoming longer, like what happens if we pull out a piece of taffy. But the effect of stretching is actually not physical – the muscle tissue itself does not change with stretching, even with diligent stretching carried out over many months.
Rather, the effect of stretching exercise is neurological. Research has shown that stretching increases a muscle’s “stretch tolerance.” That is, stretching a muscle makes a muscle more tolerant to stretching. In other words, when we practice stretching our muscles, we become better at stretching them.
But unfortunately, a muscle that has become good at stretching does not automatically function like a longer muscle when walking or running. Calf muscles that have become good at stretching will often tighten right back up when walking or climbing stairs.
Why?
The answer here seems to be twofold:
- The reason the calf muscles are tight in the first place, is because of the way we use them. Unless we change the way we use them – change our posture and movement patterns – they will continue to return to their habitually shortened state soon after we’ve stopped stretching them.
- Although “stretch tolerance” is increased by stretching, teaching a muscle to get longer while performing a stretching exercise is not the same thing as teaching it to run and climb stairs in that lengthened position. In other words, traditional stretching is not teaching or communicating the right thing to the tight calf muscles. If we think of stretching as a form of communication with our bodies, it is the wrong message, said the wrong way.
Neuromuscular Reeducation
One of the fundamental and original insights of the Postural Restoration method of physical therapy, is that calf muscle tightness and ankle equinus nearly always co-exist with common postural and movement pattern aberrations. Calf muscle tightness coincides with patterns of muscle tension from head to toe.
In people with ankle equinus, the muscles of the low back and neck are usually as short and tight as the calf muscles.
These patterns of muscle tension produce and maintain patterns of movement that rely on them:
Walking on our toes with a bouncy gait requires our calf muscles to function in a tight and short state. It also requires an overall postural pattern that supports and perpetuates the short and tight calf muscles. Specifically, bouncing along with overactive calf muscles requires a forward head posture (and with it tight neck muscles), a lifted and stiff chest (and with it, underactive abdominal oblique muscles and poor breathing), and an anteriorly tilted pelvis (and with it, tight low back and hip flexor muscles).
Producing lasting improvements in ankle dorsiflexion range of motion requires lasting change in the way the calf muscles function, which in turn requires lasting change in the way the neck muscles function; in our chest and pelvic posture; and in the way our abdominal, low back, and hip flexor muscles function.
All Four Belly Lift Walk from the Postural Restoration Institute
To illustrate, above is a Postural Restoration exercise called the All Four Belly Lift Walk, that is commonly taught at FuncPhysio. It looks like yoga’s downward dog, but is quite different. It is one of the most effective exercises to inhibit (turn down the volume of) the calf muscles, and its effectiveness relies on several factors:
- The entire back side of the body is elongated. Research has shown that all of the muscles on the back side of our body, from head to toe, are anatomically and neurologically connected. For instance, in one study, massage of the muscles at the base of the skull reduced tension in the calf muscles.
- In this exercise, as in all Postural Restoration exercises, deep breathing emphasizing a full and complete exhale is used. This pattern produces diaphragmatic breathing, which inhibits the neck, low back, hip flexor and diaphragm tension that coincides with calf muscle hypertonicity. Breathing diaphragmatically is easy in this position, because the hooped posture facilitates a full and complete exhale. In addition, the partially inverted position allows the abdominal organs to slide toward the chest and support the domed shape of the diaphragm from below.
- At the end of the exhale, the abdominal oblique and transverse abdominis muscles naturally engage, and that engagement furthers and perpetuates all of the positive effects mentioned above. (Breathing with the abdominal oblique muscles turned on, and with the dome of the diaphragm maintained, is one definition of diaphragmatic breathing.)
- Following performance of this exercise, the body is prepared to walk with the heels rooted in the ground, with ankles dorsiflexing, with the pelvis in a neutral position; with the chest relaxed instead of lifted, and with the head balanced atop the spine, rather than jutting ahead.
Patients walk differently after doing this exercise, spontaneously demonstrating posture and gait mechanics that support and reinforce greater dorsiflexion range of motion, and reduced tone in the calf muscles. Practicing 4-5 times per week can produce profound and lasting changes, particularly when combined with other Postural Restoration exercises, which become more challenging – and crucially, more directly resemble walking, running or doing stairs – as a patient progresses in their plan of care.
Lasting improvements in the way our bodies move and function can be difficult to achieve. In general, a sophisticated approach – one that changes our standing posture, the way we breathe, and our way of walking and running – is necessary to produce a positive feedback loop that facilitates, maintains and reinforces the changes we are making.
Ankle equinus, a problem so common, destructive and persistent as to be called “the Root of all evil”, requires such an intelligent, whole-person approach to be lastingly exercised. Postural Restoration, as practiced at FuncPhysio, is one such approach.
