Excessive Pronation

Excessive pronation

Excessive pronation

The pronated foot is one in which the heel bone angles inward and the arch tends to collapse, Pro nation flattens the arch as the heel strikes the ground in order to absorb shock. Excessive pro nation can lead to foot pain as well as knee pain, shin pain, Achilles tendonitis, posterior tibial tendinitis, soft tissues over stretching, corns & callus, back & buttock pain and plantar fasciitis or heel pain. This causes the joint surfaces to function at unnatural angles to each other, when this happens, joints that should be stable become very loose and unlocked and ankle sprains can occur. At first, excessive pro nation may cause fatigue. As the problem gets worse, strain on the muscles, tendons, and ligaments of the foot and lower leg can cause permanent problems and deformities.

Excessive pro nation is usually inherited, but may also be acquired as a result of injury, e.g. a broken leg. In such cases, where the legs may be of a differing length the foot of the longer leg will compensate by means of pro nation  to attempt to 'level off' the disparity and make walking easier. Although all the above complaints can result as a direct consequence of excess pro nation, it is unusual to experience more than 1 or 2 symptoms and if you do this can indicate the severity of your poor foot function.
The opposite of pro nation is excessive supination, but this is less common. Excessive supination causes symptoms of pain due to the foot’s inability to be a good shock absorber. Again back pain, knee pain and heel pain can be symptoms.

Treatment

It may be possible to control pro nation using correct footwear. Change your running shoes regularly approximately every 500 miles or 100 hours of wearing and other shoes should be re-heeled or thrown out once they become worn in the soles and uppers. If that doesn't help then orthoses may be required. These are devices which are placed in the shoe and they hold the foot in a more optimal position for heel strike and into foot flat or mid-stance phases of walking or running.

A functional orthotic device will allow normal foot pro nation during gait. At Trinity Podiatry, Jacqui Baggaley, Podiatrist, specialises in custom made functional foot orthoses preferring them to off the shelf one size fits all devices which you can buy from chemists and from magazines. A bit like one size fits all glasses, they are not as good as optician dispensed glasses. Imagine wearing off the shelf false teeth! A custom-fit pair of devices are made following a bio mechanical examination. The podiatrist watches you walking/running (Gait Analysis), takes a range of measurements lying down and the results of which enable her to determine the prescription and type of device to be made. Plaster of Paris non-weight bearing casts of the feet are then taken, these are then sent to a laboratory who specialise in the manufacture of orthoses. (Orthoses made from a standing cast capture the foot in an inappropriate or less than ideal position and can't move it back into an optimal position so are less successful).

Many people suffer with foot problems, leg, knee and spinal conditions, because of the structure, or position of the feet during standing, walking or running.

Gait Analysis

Foot bones detailed analysis of gait is a tool podiatrists use to help with diagnosis and the assessment of the effect foot orthoses (and footwear) have during running and walking. The patient is watched, firstly barefoot, and then sometimes with shoes/trainers and orthoses placed inside the shoe/trainer. Video of the gait enables the practitioner to analyse walking and running in more detail by freeze-framing the film at important stages or the gait cycle.

During gait analysis the practitioner would look for head movement, position of the arms, trunk, pelvis legs and knee rotation. A close inspection of the feet and ankles would also take place.

The foot is composed of 26 bones, 16 intrinsic muscles, 33 joints, dozens of tendons and hundreds of ligaments.
All these components work together to give support, balance and mobility. The foot has to be a stable structure for standing, yet it has to able to adjust quickly during walking and running. During running and walking the foot must adapt to any uneven surfaces, by “unlocking” the bones. Then, in an instant during running and walking (just after mid stance) it has to prepare for the propulsive phase of gait, here it must become a rigid lever, to enable it to propel itself and the lower limb forward.

There is a kinetic chain of events that causes the body to move forward from the impact of landing, to the propulsive phase of gait that involves many bones of the lower limb. In sequence they are; the lumbar spine, pelvis, femur (thigh), tibia and fibula, the rear foot; calcaneus & talus, the mid foot (or tarsus) and finally the forefoot; metatarsals and phalanges, or toes. Joints connect all these segments together, such as the knee which connects the thigh to the leg. There are many joints of the foot – each having a part to play in locomotion.

Bones, muscles, tendons and ligaments (of the lower limb) all work together and act as shock absorbers, by rotation and compressions, and then move in the opposite direction preparing the limb for take-off. Muscles are very important in that they initiate - and stop - the movement and stabilise the limbs.

Walking starts with the heel striking the ground, followed by mid-stance, then propulsion and toe-off. The rest of the time this leg and foot are in the ‘swing phase’.

Walking and running differ, in the main in that there is no double support phase (both feet in contact with the ground at the same time) and with running, both feet are off the ground at the same time and the body becomes airborne. During running the support phase is reduced to 30% of the gait cycle – compared with 60% in walking. Other differences in running include; more vertical movement, more flexion of the arms and at heel strike the foot moves up and toward the leg (dorsiflexion). It moves down in walking!

Injuries are therefore more likely to occur in running than walking due to the increased stresses involved. One of the main reasons injuries happen is due to too much foot motion - pro nation during the stance phase. Pro nation is a necessary and vital part of gait, but too much or too soon, can have a major impact on the other joints and muscles involved in gait. Excess foot pro nation affects many people and is characterised by in-rolling of the feet, low arch height, and out-toeing walking style.

Pro nation Injuries and conditions which may be caused by excessive foot pronation include:

Low back /hip pain
Knee pain
Shin splints
Ankle pains and sprains
Heel pain / plantar fasciitis
Forefoot and toe pain
Bunions and hammer toes
Corns & callus
Orthoses

Functional foot orthoses are devices, worn in shoes to improve foot function. There are many materials, thickness, densities and design variations at the prescriber's disposal. A podiatrist can determine what foot type you have and prescribe a pair of devices best suited for your requirements.

Jacqui Baggaley at Trinity Podiatry has 26 years’ experience in providing custom fitted foot orthoses to professional sports people and to patients with neurological problems alike.
We constantly review the latest technological advances in an ever changing field of podiatry and foot orthoses. In the last year we have studied the merits – and shortcomings of the vast majority of foot orthoses manufacturers and suppliers in the UK.

It is our belief that the orthoses we prescribe to our patients are the most advanced orthoses, being more controlling, comfortable and durable than anything seen before. However, no single type of orthosis (manufacturer) can be ideal for every patients’ needs and activity levels. Therefore, depending on each individual we would prescribe different devices from different manufacturers, using different materials to suit that patient's needs the best.

Foot orthoses, when properly prescribed and manufactured will only be effective whist they are being worn. Depending on the patients’ condition orthoses should form part of an overall treatment plan, which may involve exercises, and other treatment modalities such as dry needling, physiotherapy or osteopathy.
It is essential that the correct shoe gear is worn. There are 3 basic training shoes types; neutral, stability and motion control. The structure of each depends on the curvature and rigidity of the last. Some mid-soles offer more stiffness on the medial side of the shoe to resist any pronatory forces from deforming the shoe. Cushioning is always compromised for control, i.e. a cushioned shoe will offer little support and a motion control shoe will offer little cushioning. If the wrong shoe is worn then the athlete is more susceptible to injury! This is a vital component of treatment and is in our repertoire of expertise which allows us to advise patients, especially if they have a sports related injury.

To claim that orthoses can cure all lower limb ailments is nonsense. Any sources suggesting this is the case should be ignored. There is nothing in any research literature to validate such claims. However, a properly prescribed orthoses and shoe can alleviate many symptoms and reduce risk of injury.

CAD-CAM Orthoses

At Trinity Podiatry, CAD-CAM orthoses - Computer Aided Design – Computer Aided Manufacture are our preferred method of producing orthoses. We regard these devices as the way forward, as they offer more accuracy, have increased patient tolerance, they are more light weight and therefore have reduced space in the shoe compared to hand crafted devices.

The design is obtained by scanning the casts (taken by the podiatrist) of the feet, together with the bio mechanical data and Podiatrist prescription and a numerically correct design is produced.

Using a specialised milling process the orthoses are direct milled from a solid block of high specification polypropylene, where design accommodations may be incorporated.
In some instances, such as gross excessive pro nation, and some sports activities, there may be a need for a more forgiving material may be required. In such cases hand crafted devices, or devices made from a more flexible material (EVA) may be most suitable. The podiatrist will discuss this with you before making a prescription.

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