Adult Acquired Flat Foot

Flat feet can either be flexible (able to reduce / realign the flat position to create and arch profile) or rigid (the foot is not bale to be reduced). A rigid flat foot often develops due to arthritis or a bony coalition (the inappropriate joining of two bones).

A flexible flatfoot collapses when weight bearing. This causes the heel and forefoot to move towards the outside of the foot, the calf muscle / Achilles tendon to become tight and the arch to collapse often with prominence of the head of the ankle bone on the inside of the foot.

The flexible flat foot can produce pain along the arch of the foot as the tendons and ligaments become strained, pain around the outside of the ankle as the soft tissues become compressed, digital deformities, shin splints and even knee pain.

Flat feet may not be problematic to begin with but as the forces continue to be transmitted through the foot the repetitive stress may lead to problems. Management is dependent on the severity of the symptoms and non-surgical care is initially advised, unless there a tear within an important tendon on the inside of the foot called the tibialis posterior tendon.

Non-surgical care includes:

Activity modification: Reducing your activity levels and periods of extended walking or standing

Weight reduction: Reducing your weight can reduce the amount of stress / force that is placed through the foot.

Orthotic devices: These are placed into your shoes and provide support and control to the foot.

Immobilisation: To help reduce painful acute episodes and to allow the tendon to rest a period of immobilisation in a walker boot may be required.

Medications: Analgesia to include non-steroidal anti-inflammatory drugs (NSAIDS) can help ease the pain associated with the condition.

Footwear: Wearing a more supportive shoe can help control the movement and position of the foot.

Surgical management may be required if non-surgical management has failed to ease the symptoms. The range of surgeries is varied and is dependent on how the foot is collapsing and adapting to the ground as well as the patient and their aims and goals of management. More information can be obtained by reading further.

An Adult Acquired Flat foot deformity (AAFFD) commonly develops following a tear within the tibialis posterior tendon causing dysfunction.
The tibilais posterior tendon is a very important tendon and during the walking cycle it locks the foot to create a rigid lever for propulsion and thereby prevents the foot from rolling out beneath the leg. The tendon is located on the inside of the ankle just behind the leg bone (tibia). The tendon progresses from behind the leg bone to insert on the inside of the foot around the arch.

Injury to this tendon can occur through many different reasons: poor position of the foot (flat foot) which increases the stress onto the tendon, diabetes, inflammatory conditions e.g. rheumatoid arthritis, obesity, injury to the tendon e.g. forcefully pushing the foot towards the outside of the body especially if the foot is pointed downwards.

Injury to the tendon generally occurs around the back of the tibia and then progresses towards the arch. The tendon is susceptible to injury in this area due to a reduced blood supply and the acute change in direction from vertical down the leg to horizontal when entering the foot. The injury to the tendon includes: stretching / attenuation and tears along its length.

Symptoms include pain and swelling around the back of the leg and down into the foot. The pain is made worse when standing on tip toes or when trying to bring the foot towards the inside of the body whilst pointed downwards and against resistance. Patients may also notice a reduction in the height of the arch as the foot begins to roll out underneath the leg.

If left untreated the symptoms are likely to worsen as does the position of the foot. Management of this condition should be prompt as if left untreated the damage to the tendon worsens as does the foot position. As the foot position worsens so does the number of joints affected. The longer the condition is left untreated the greater the chance that surgical management would be required.

The condition is graded of which there are four stages. Staging the condition assists in determining the most appropriate management strategy.
Assessment of the condition includes X-ray, ultrasound and MRI.

As the condition worsens the foot goes from a flexible and reducible flat foot to a rigid foot (stage III) and if left to progress further can affect the ankle joint (stage IV).
Surgery is dependent on the grade and if the foot can be corrected manually.

Ritchie Brace
AirLift™ PTTD Brace (DJO Global
An air cast walker boot

Grade I involves inflammation of the tendon sheath often with no damage to the tendon itself. Stage one management is often non-surgical and includes:
• A period of immobilisation in an air cast boot
• Insoles / bracing
• Foot wear alteration
• Activity modification
• Tendon strengthening exercises
• Shock wave therapy / ultrasound
• Steroid injection

On occasion surgery to open the tendon sheath may be required.

In grade II there is damage to the tendon itself and often a poor position of the foot. The foot may respond to conservative care but often surgery is required
Surgery includes:

• Removal of the damaged tibialis posterior tendon
• Transfer of a healthy tendon, present on the inside of the foot, to replace the damaged tendon
• Procedures to reposition the bones of the foot to realign the foot into a more normal position. The types of bony procedures are varied and are related to several factors which would only be determined through assessment of each case. Common procedures include repositioning of the heel bone and fusion of joints within the arch.
• Repair / tightening of ligaments. In this condition the ligaments become stretched and often require tightening and reinforcement. Reinforcement of one of the commonly stretched or torn ligaments can be achieved with an internal brace.

The link below shows an operation (caution recommended) of the procedure with cutting and repositioning the heel bone.

Following grade II surgical repair the foot will be cast immobilized for a period followed by an air cast boot. Walking without the boot would not be possible until six to eight weeks’ post operation and a return to sporting activities or manual type jobs until three months’ post operation.

In grade II tibialis posterior tendon dysfunction every effort would be made to realign the foot whilst not fusing the joints, however in certain cases fusions may be more suitable.

In grade III and IV tibialis posterior tendon dysfunction the foot is in a rigid position and procedures to reposition and fuse the foot and ankle can be performed. The joints addressed are the talonavicular, calcaneocuboid, subtalar joint, and in the case of deformity of the ankle joint. The fusion is held in place whilst the bones heal by screws and plates.

Following fusion operations, immobilisation in a non-weight bearing cast is required. Once the cast is removed there is an extended period of recovery and a return to normality would be around six months. Specific complications include non-union of the bones especially in the case of fusions where the rates of non-union for some of the joints can be up to fifteen percent.