The Mighty Mighty Peronei

As discussed in 'Reciprocal Implications At Play In Gait', we need to have a good foot-ground relationship to create a biomechanically appropriate blueprint for movement. Quite frequently aberrant development in the womb and in the first 4 years of life leaves the adult with a few bony malalignments or functional insufficiencies. When these deviations from ideal are in the foot, leg, or hip they can greatly disturb the foot-ground relationship and set off a cascade of poor neuromuscular control.

Here is a pedograph of a poor foot-ground relationship. We see an uncompensated forefoot varus, increased pronation, and slew of other findings in the foot.

There are two obvious ways to solve this problem.

 1) Orthotic therapy to allow the ground to meet the foot in a better way.

 2) Improve neurologic control of the foot to meet the ground in a better way.

The hotly debated topic of foot orthotics will be discussed in a later post, but for now lets focus on improving the control of the foot.

When a patient cannot achieve a firm base of support under the 1^st mpj they will be at risk for hallux abducto-valgus, bunion formation, hyper-pronation injuries, and the list goes on. One of the muscles that helps to create the medial tripod is peroneus longus. The peroneus longus plantar flexes and everts the ankle, and based on its distal attachment also strongly plantar flexes the first mpj to support the medial tripod. When this muscle is not functioning properly we see a weak medial tripod, hyper pronation, genu valgum, and increased occurrence of inversion ankle sprains.

To test if the strength of the peroneus longus- completely plantarflex, abduct and evert the foot. While bracing the calcaneus and contacting the lateral foot, try to invert and adduct the foot against the patient’s resistance.

A great exercise we use to get the peroneus longus firing is called the peronei pump and is demonstrated in the video below.

This exercise requires the patient to put the peroneus longus muscle into its shortest and strongest position (plantarflextion/abduction/eversion of the foot with plantarflexion of the 1^st mpj). The foot is then slowly pumped between full plantarflexion and full dorsiflexion while all other values are maintained. If done correctly, the patient will feel a deep ache in the lateral leg as the peronei musculature clears fascial restrictions, activates full contraction, and eventually fatigues. This is typically achieved within the first 10-20 repetitions or within 1 minute. By doing a peronei pump exercise a few times daily, the muscle becomes easier to access in all phases of gait. This is not a perfect representation of the peronei function during gait, so further “gait training” may be needed to incorporate the mighty mighty peronei.

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Reciprocal Implications At Play In Gait

A gait analysis can range anywhere from a quick glance to confirm ataxia or evaluate a limp, to an ultimate screen to assess full-body function. Although there is little debate when someone says, “that limp may be causing your low back pain”, few follow and understand the full implications of a gait finding. What is really needed is a way to know if a gait finding is important in a clinical presentation: whether this finding is causing pathology or symptomology, resulting from pathology or symptomology, or an artifact that is seemingly unrelated.

Three quotes to drive this discussion:

1.  “Posture follows gait like a shadow” – Sherington
2.  “Gait assessment is the most challenging functional assessment” – Chaitow
3.   “Simplicity is the key to brilliance” –Bruce Lee

 

3 ways to look at a gait finding:

1.      Ground up
2.      Brain down
3.      Feedback loop

Ground Up

The way your foot forms a relationship with the ground sends a blueprint to your brain to determine how all following movements need to occur. I can tell you as a former carpenter that a bad blueprint will destroy a house quicker than any wear and tear. When the knee crashes medially creating strain on the meniscus, MCL, ACL, etc. it is simply the brain doing its best job to build off of a bad blueprint. The brain is not to blame! Every muscle that you focus on with activation techniques, every joint you mobilize, every pattern you groove, will eventually deteriorate if the foot is sending the wrong information to the brain, because the brain ALWAYS wins.  The brain is an excellent builder and quickly creates the best myofascial pattern from information it receives from sensory input. We need a better blueprint.

Thus, a gait finding can be responsible for any pain or dysfunction in the body.

Brain Down

When there is a lesion in the musculoskeletal or nervous systems, an adaptation must be made to complete a task around the lesion. If the head of the femur begins to deteriorate, the brain automatically writes a new program to protect and avoid the weak structure. Typically a coxalgic gait pattern is written, which uses the torso  to lean the body weight over the injured hip. This de-stresses the gluteus medius, a major compressor of the hip joint and slows the hip degeneration. This is an example of a brain down gait finding because structurally there is nothing that causes the torso to lean over the injured joint, it is instead a compensatory decision of the brain. Perhaps a better example of a brain down gait finding is that of ataxia, where a brain lesion directly creates a change in the gait. A goal of the practitioner should be to determine if the gait finding is caused by the foot or the brain.

Feedback loop

A feedback loop is when two or more elements in a system affect one another. Element A sends a signal to element B, element B adapts to that signal and sends different signal back to element A, which further adapts. This is what we see happen in hyper speed with human biomechanics. A ‘Ground Up’ gait issue will cause a ‘Brain Down’ reaction that creates a new ground up signal that further changes the brain down reaction, etc. This is what we see most frequently in a clinical setting. If we can identify the root cause (ex: Plantar-flexed first ray, impaired stereognosis, etc.) we have the best chance at cutting the poor feedback loop and preventing global degenerations. We must fix the ground up issues AND re-groove the brain down reaction to cut the loop. The best treatment strategies do this simultaneously. This will be expanded upon in the upcoming GRIP Approach Seminars!