FLAT FOOT

 

What is a flat foot ?
The most obvious deformity with a flat foot occurs on the inner side of the foot and arch.  However this side of the foot does not exist in isolation and if the arch on the inner side flattens this may result in the following:

  1. Heel moves outwards(valgus)
  2. Front part of the foot ‘sqews’ outwards at the midfoot
  3. The Achilles tendon may also become tight as a result of the heel position
  4. The forefoot may need to rotate inwards to balance the heel position

The correct medical term is a plano-valgus foot. ‘Plano’ refers to the flattened arch, valgus to the heel position away from the midline of the body.

Is a flat foot always a bad thing ?
Not at all.
Your foot may be made this way and in children this can be a normal stage of development.
It is entirely compatible with normal day to day and sporting capabilities.
A ‘good’ flat foot is bilateral, painless, has been present a long time, is not progressing, and is flexible(corrects fully).

How can I tell if my foot corrects fully? (what does it mean?)
When you stand on tip toe you should develop an arch and your heel move inwards.
From this it is possible to say that the joints, tendons and ligaments (which go to form the arch) are all functioning normally when ‘called upon’.  Though it often indicates a clean bill of health it doesn’t always. There may never the less be the early stages of a problem (for example an early tendonitis of the tibialis posterior tendon).


A left sided flat foot




The first two pictures show an abnormal response to going onto tip toes(a heel raise), with the heels remaining facing away from the midline of the body.
The third picture shows the normal response with heels moving to face inwards

When might there be a problem ?

  • If your foot changes to this shape having started off with an arch.
  • If you develop pain where there was none before.
  • If your foot becomes fixed in this position, wheras previously it was flexible .
  • If the flat foot is on one side only (unilateral).


A right sided flat foot, the left side normal.

Are there any other variants of foot shape?
The main other pathological foot shape is the cavo-varus or equino-cavo-varus foot.
Cavus means a high arch. Varus that the heel moves towards the midline of the body and equinus that the foot angles downwards (like a ballerina “en pointe”)




The cavo-varus foot

What makes the arch?
The inner arch of the foot is formed and maintained by:

  1. Bones /joints: The alignment of the bones (calcaneum ,talus ,cuboid,navicular,cuneiforms and metatarsals) and the joints which they make with each other)
  2. Muscle/tendon : The pull of the Tibialis posterior(Tib post) tendon and its balancing muscles(antagonists) the peroneals.
  3. Ligament :tight and unyielding ligaments sitting deep on the inner border of the foot (The spring ligament in particular) and the sole of the foot (the plantar ligaments).

What can cause a flat foot and how ?
The straight forward way to look at this is which of the above factors can malfunction and why?.
The following list is not in order of merit or frequency. Probably the most common cause of a flat foot in the adult is inherent ligamentous laxity (known as a physiological flat foot, and a variation of normal), followed by disease of the Tibialis posterior tendon. The medical conditions mentioned in the following list are to be found in the glossary.

1) Bones /joints :Fractures :By disrupting the normal bony architecture of the arch or/and the way the joints sit

Arthritis: Also by destroying the normal alignment of the joints (and sometimes the tendon and ligament as well). Any form of arthritis may result in this condition. A particular type to watch out for is known as Charcot Arthropathy. This can result in a rapid and very severe, progressive loss of the arch.

Developmental :A condition called Tarsal Coalition exists which results in the bones of the midfoot foot fusing together abnormally and results in a fixed flatfoot deformity .

2) Muscle / tendon: Tibialis Posterior Dysfunction : This tendon lies on the inner border of the foot and has a vital in maintenance of the arch. It lengthens when diseased and inflammed, contributing to a loss of the arch and the appearance of a flat foot.

Polio

Accessory navicular: an additional and longstanding piece of bone occurring at the point of tibialis posterior insertion into the foot. This may become symptomatic and lead to a flat foot deformity.

3) Ligament : Ligamentous laxity(Physiological flat foot)

Spring Ligament rupture : Due to trauma or Inflammatory arthropathy.

What symptoms might I get ?
These will be dependent upon underlying cause to some extent. In a physiological flat foot they may be minimal sympptoms.
Pain and a reduction in weight bearing capacity /mobility.  Usually occurs when standing /walking but may progress to being symptomatic when resting or sleeping.
Feelings of instability when weight bearing.
Pain from a flat foot may occur in several locations :

  1. On the inner side of the ankle (Tib Post)
  2. On the inner/under side of the arch(Tib post ,Spring ligament)
  3. On the top of the foot /inner side of the arch (Talonavicular joint)
  4. On the inner border of the big toe(1st MTP)
  5. On the outer side of the heel(subtalar and calcaneo-cuboid joint , crushing of peroneal tendons )
  1. Eventually arthritic change may occur in the subtalar and midfoot joints and/or in the ankle.

What treatments are available for a painful flat foot?
ORTHOTIC MANAGEMENT
Orthotic treatment may be able to reposition a mobile flat foot and hold it in a corrected position.



The effect is only present when the orthotic is worn in the shoe and ceases if it is not worn. Whatever the cause of the flat foot the techniques used will be essentially the same. These are to resupport the arch with a rigid plastic arch ,

and to reposition the heel by placing a “wedge” under its inner side to tilt it and a heel cup to hold it

Whether orthotic treatment prevents the progression of a deformity is not definitively known, but from basic principles there is no reason why it should not.

In the flexible flat foot orthotics are usually the recommended first line of treatment.
In a rigid and arthritic flat foot orthotics cannot correct the foot position but they may be able to improve symptoms.

OPERATIVE MANAGEMENT
The following refers to the two commonest scenarios which comprise the bulk of operative cases. These are:

  1. A flat foot due to Tibialis posterior dysfunction which an orthotic has failed to treat.
  2. The rigid and painful flat foot.

What happens if I leave my flat foot untreated ?
This will be somewhat dependent upon the cause
With Tibialis posterior dysfunction a progressive deterioration of the rest of the hindfoot and ankle is described. Over what time period this occurs and whether it is inevitable is not definitively known. The stakes are however potentially high as the progression may be to a rigid, painful and arthritic deformity. If an Orthotic controls both the deformity and the pain however this may be all that is required to manage the condition.
The fixed and arthritic flat foot may require at least a triple fusion(see below) and at worst a triple and ankle fusion (or replacement) combined (If the ankle has become involved). This is more extensive and “higher risk” type of surgery than treating early with a tendon reconstruction.

Tibialis posterior reconstruction

How does an unhealthy “Tib Post” lead to a flat foot?
The tendon has unhealthy tissue usually over a portion of its length. In this degenerate and inflammed state it stretches. It is effectively unable to support the arch or resist the pull of the peroneal muscles on the outer aspect of the heel and foot which acting unopposed also flatten the arch and move the heel away from the midline.

What is involved in reconstructing the tendon?
The diseased tendon is excised and a neighbouring tendon moved into its place (the FDL, Flexor Digitorum Longus) to perform its function.

THE INNER(MEDIAL) BORDER OF THE FOOT

Interactive Foot and Ankle 2 2000 Primal Pictures Ltd


The Bio-Tenodesis screw is absorbed by the body once it has served its purpose and the tendon is healed into its new position. After the operation

POSTOPERATIVE STATUS

On the Day
Pain relief
After the anaesthetic has worn off your foot should be largely free of pain ,due to the use of nerve blocks(Femoral and Sciatic). You will be given a course of pain killers and anti- inflammatory tablets .These will be working for you when the nerve blocks wear off by 12 hours or so .
You may also require a PCA analgesic pump.

Your foot
Immediately after the operation you will have a temporary plaster cast. The day following this will be changed into a lightweight fibreglass cast.

Mobility
A physiotherapist will instruct you on the use of crutches the day following surgery. You will be non weight bearing on the operated foot for a period of six weeks.

Length of stay
One or two post-operative days depending upon comfort and mobility.

DVT prophylaxis
Aspirin 150mgs for 6 weeks.

At two weeks
You will require an outpatient assessment and wound review. Self absorbing sutures are normally used .Your lightweight cast will be changed and non weight bearing will continue for another four weeks.

At six weeks
You will require an outpatient assessment and check x-ray to confirm union of the calcaneal osteotomy.
At this stage you will be able to return to the orthotic which by itself has failed to control your foot preoperatively. It may require some adjustment by our orthotist.
This should be worn for all weight bearing activity.

Chance of success

  • The chance of significant reduction in pain and improvement in function is of the order of 85%.
  • The chance of a persisting correction in the alignment of the foot is 70-80%
  • The chance of failure of the surgery to the extent that midfoot fusion is required is 10%.