Pes Cavus

General

Pes Cavus is a descriptive term for a foot with a high arch. Patients complain of a variety of symptoms depending on the degree of deformity. In mild cases the toes tend to retract and consequently rub on the upper of shoes. In some the metatarsal heads are prominent and can be painful with overlying calluses. As the arch height increases the ankle can become unstable and for some this is the primary cause for concern.

 

The cause of Pes Cavus needs to identified and can normally be divided into three main categories:

• Neuromuscular conditions affecting nerves and muscles are the most common cause, within this large group Charcot-Marie Tooth disease is the most common. Neuromuscular causes can be static whilst others progress, the rate of which will vary from individual to individual.
• Congenital causes include a residual club foot (talipes equino varus) and idiopathic cases where the condition arises spontaneously.
• Trauma, here the foot becomes malaligned following severe injuries e.g. burns or multiple fractures.

The diagnosis can be made clinically by examining the foot. The severity of the condition is assessed by a variety of means including X-ray, scanning (CT and MRI). In cases where the cause appears to be neuromuscular, extensive neurological testing may need to be undertaken to find the cause and whether the condition is progressive or static.

Treatment options

Conservative care

• Wide fitting shoes / orthopaedic footwear
• Insoles
• Ankle braces
• Palliative care
• Physiotherapy
• Drugs – Anti inflammatory and pain killers

Surgical Management

Surgical intervention occurs when conservative care has failed. The surgery can be divided into three categories depending on the degree of deformity and presenting symptoms:

• The patient’s primary concerns are retraction of the toes and overloading of the balls of the foot.
• Forefoot deformity with instability of the rearfoot although the joints remain mobile with a good range of motion.
• Severe malalignment of the foot and ankle with severe instability. The joints often have marked arthritic changes.

Type 1

The aim is to straighten the toes and reduce the pressure beneath the metatarsal heads. The digits are normally straightened by fusing the toe joints (arthrodesis) and transferring the tendons from the top of the toes to the metatarsals. This elevates them and reduces the pressure beneath the metatarsal phalangeal joints.

Clawing of the hallux with resultant shoe irritation. Straightening the big toe and transferring of one or all of the tendons from the top of the toes to the metatarsals helps improve alignment.

Type 2

Typical appearance on the right side where the toes have been straightened but the heel remains turned in and the ankle is unstable.

Surgically the tibialis anterior tendon would be split and half transferred to the outside of the foot and the heel cut and repositioned to reduce the tilt.

On the left half of the tibialis anterior tendon is cut and on the right picture the cut half is pulled out of a small incision made on the top of the shin.The free tendon is then passed onto the lateral border of the foot and secured to the bone. When tibialis anterior contracts it will the pull the foot up evenly rather than allowing it to twist in.

Type 3

In some cases the arch is fixed in a high position but the foot is otherwise stable. In these circumstances a wedge is removed from the apex of the arch to lower it and increase the surface area of the foot in contact with the ground. This helps to reduce overloading under the heel and the metatarsal heads.

When there is severe fixed malalignment of the foot and ankle, this requires an aggressive approach to provide a flatter foot that is stable on the ground.

A severe deformity on the X-ray, the line diagram shows a fusion of the rearfoot joints to reduce the malalignment, lowering the arch height and the rotated position of the heel and forefoot.

 

Day surgery

These operations are normally carried out on a day care basis. You would be admitted to the hospital on the day of your operation and shown to the ward. Professor Tagoe will confirm your consent form and mark the surgical site.

Before you leave the hospital the physiotherapists will show you how to manoeuvre around on crutches non weight bearing as the operated leg will be in a cast and you will not be able to put the foot to the ground. Post operative painkillers will be dispensed by the nurses.

You should arrange to go home via car or taxi with an escort. You are advised to have someone with you for the first twenty four hours in case you feel unwell.

Anaesthesia

Most patients have their operation carried out under local anaesthetic with sedation, under the care of Dr Nathwani Consultant Anaesthetist.

Anaesthesia is a graduation from sedation through to general anaesthesia. Sedation provides reduced consciousness with most of your reflexes left intact and spontaneous breathing. This means that your airway is secure and there is no need to place a tube into your throat to maintain it. The level of anaesthesia though is not sufficient to perform the operation and so a local anaesthetic block at the level of the knee (Popliteal block) is performed to render the lower leg anaesthetised. This allows us to keep the amount of drugs used to a minimum. As a consequence when the sedation wears off, normally within a few minutes of the end of the operation, there is not the accompanying drowsiness and nausea that is sometimes associated with general anaesthesia. The operation is pain free and patients remember nothing of the operation.

Professor Tagoe will perform the popliteal block. This will be carried out on the ward prior to being put to sleep or after you have been sedated depending on the logistics of your operation. As the anatomy behind the knee varies a little from person to person we use a nerve stimulator to accurately identify the nerves. This sends a small electric current down the needle so that when the nerve is approached it is stimulated. This means that the muscles controlled by that nerve begin to contract and relax causing the foot to ‘flick’. If you are conscious it is a strange sensation, but it is not uncomfortable and helps us to deliver the anaesthetic around the nerve with precision.

Local anaesthetic at the level of the knee not only blocks sensation but also the nerves that enable you to move your foot. This is temporary lasting for 24 to 36 hours and has the advantage of providing long lasting analgesia.

The operation

The operation will probably incorporate several different procedures in order to get a well positioned and functional foot. The surgery normally lasts for about 90 minutes with a cast put on the leg in theatre whilst you are asleep The cast will run from just below your knee to your toes allowing us to maintain correction whilst the your body is healing, reducing the likelihood of damage. Dissolving sutures will be used to close the skin.

Recovery

You must rest with the leg elevated for the first 48hrs (essential ambulation only). It is important that you keep the cast clean and dry. You will be seen for a dressing change 3-6 days post surgery, here the cast will be removed and the wound inspected. An X-ray might be undertaken to ensure position and stable internal fixation. A further change of cast will occur at 4 and 8 weeks post surgery on average. For some patients an additional period of 4 weeks in a cast, partialyl weight bearing is required for full healing.

Once the cast has been removed exercises will be prescribed along with physiotherapy. Returning back to activity and regular footwear is gradual and very much depends on the type of operation, your body’s healing response and the individual’s level of motivation. Once the cast is removed you should be able to return to a supportive shoe e.g. trainers
with driving as soon as you feel you feel safe. On average it takes a year for most patients to fully recovery.

Possible complications

Approximately 900 patients undergo foot surgery annually within the Department of Podiatric Surgery at West Middlesex University Hospital. Most patients have an uneventful recovery. Outlined below are the common problems or those rare complications with serious outcomes. In cases where we don’t have accurate audit, we have used published results from the podiatric literature. These are accompanied by an asterisk *

• Prolonged swelling taking more than 6 months to resolve occurs 1 in every 500 operations*
• Haematoma – a painful accumulation of blood within the operation site. No recorded incidents.
• Thick and or sensitive scar – no audit data is available.
• Screws and plates were removed from 118 patients during a twelve month period. This is often planned but can occur as a result of irritation.
• Adverse reaction to the post operative pain killers. 1 in every 50 patients report that the codeine preparations can make them feel sick.*
• Infection of soft tissue. The incidence is 1 in every 83 operations*
• Infection of bone occurred in 3 out of 916 patients.
• Delayed healing of soft tissue or bone. No audit data is available.
• Circulatory impairment with tissue loss occurred in 3 out of 9000 patients over a 10 year period.
• Loss of sensation can occur although this is usually transient but can take up to a year to resolve.
• Deep vein thrombosis which can result in a clot in the lung is potentially a life threatening condition. Deep vein thrombosis incidence is 1 in every 900 cases.
• Chronic pain syndrome: this is where the nervous system dealing with pain over reacts in a prolonged manner often to a minor incident. This normally requires management by specialists in this condition and doesn’t always resolve. This is a rare complication with no audit data available.
• Reoccurrence of the deformity or failure of the operation: incidence is 1 in every 500 operations.*
• Development of secondary problems including overloading of joints adjacent to the ones operated on occurs in 1 in every 700 operations.*

The risk of having a complication can be minimised when the patient and all those concerned with the operation and aftercare work together. This starts with the pre-operative screening and continues through to the rehabilitation exercises.

Pre operative screening of your health allows us to determine whether you are fit for surgery. It is important that you disclose your full medical history. If there is a query regarding your health, then further investigations or the advice of other surgical and medical specialties will be sought. The surgeon and the theatre team will ensure that the operation is performed effectively and with the minimum of trauma.

You can improve the healing process and reduce the risks of complications by:

• Adhering to the post operative instructions which include resting and elevating the operated leg. Keeping the wound clean and dry until advised otherwise is essential. Please ask the nurse or Professor Tagoe if you are not sure what to do.
• Having a healthy diet is important. This provides the nutrition required for healing.
• Smoking is associated with a 20% increased risk of delayed or non healing of bones.
• Alcohol can interact with the drugs that we will prescribe and in excess can impair wound healing.
• Post-operative exercises and in certain cases physiotherapy will be advised. This helps improve the flexibility, strength and stability of your foot.

Podiatric surgeons evaluate, diagnose, prevent and treat diseases, disorders and conditions affecting the foot and all associated structures. This is carried out in accordance with the individuals, education, training and experience, in accordance with the ethics of the profession and applicable law.

Podiatric Surgical Training

• 3 year: Degree in Podiatry
• 2 year General Podiatric Practice
• 2 year Diploma in the theory of podiatric surgery
• 2 year Surgical training programme (Podiatric Surgical Trainee)
• Final fellowship examinations
• 3 year Specialist training (Podiatric Registrar)
• Accreditation with the Faculty of Podiatric Surgery