MICA Bunion Surgery

David Redfern, creator of the MICA Technique Explains

David Redfern, creator of the MICA Technique Explains


The ‘MICA’ technique was born from a collaboration between British orthopaedic surgeon David Redfern and French surgeon Joel Vernois. They invented and introduced the technique to the UK and France in 2008. Mr Redfern appeared on BBC television demonstrating the technique and also drew attention in the national press. 

Since then, their collaboration has continued and they have designed numerous other percutaneous (minimally invasive) techniques for the treatment of foot and ankle disorders. 

Not only did they introduce these techniques to the UK and France but worldwide and are recognised internationally for their expertise and pioneering contributions in this field. Having introduced these techniques to Germany, Mr Redfern was made a life-long honorary member of the German Foot & ankle Society. 

Between them, Mr Redfern and Dr Vernois have trained hundreds of surgeons worldwide. 

Currently both Mr Redfern and Dr Vernois are introducing their techniques across the USA where their operation is called “ProStep”. 

Mr Redfern has performed over 2,500 MICA / ProStep bunion operations over the last 10 years and has personally trained all UK surgeons who offer this technique. 

More than 50,000 such operations have now been performed worldwide.

What is MICA? 

MICA stands for Minimally Invasive Chevron Akin. This is the name of the keyhole (minimally invasive) operation that Mr Redfern created in conjunction with a French colleague. It is a much less invasive method of correcting bunions and hallux valgus (big toe turning outwards)

Mr Redfern will talk to you about these options and whether surgery is the right option for you. He works closely with several podiatrists and physiotherapists. 

Why have the MICA ProStep surgery?

 Surgery is required when bunions are painful and cannot be adequately managed non-surgically. This is a decision best made with an experienced foot an ankle surgeon such as Mr Redfern who can guide you as to the pros and cons of surgery.

The principle of bunion correction surgery is to realign the bones, abolish the bump and create a straight big toe. This involves cutting and realigning the bones.

Nothing other than surgery can correct a bunion.

What are bunions? 

The term bunion refers to a lump or prominence on the side of the big toe joint. When this occurs, the big toe also tends to lean towards the second toe. The medical term for this condition is hallux valgus. 

A bunion occurs when the bones supporting the big toe drift out of alignment. This is predominantly an inherited risk due to the structure of the bone and joints in the area and is generally not caused by high heeled footwear (although this may accelerate bunion problems). 

Bunions often rub inside shoes, which can cause inflammation (redness) and pain. 

Not all bunions are painful and some people can have large bunions without much pain. The angulation of the big toe can also cause pressure on the second toe, which can also become deformed (a hammer toe). In some cases, the first two toes will cross over, which can then cause a lot of pain in shoes. 

The decision as to whether to operate on a bunion generally driven by pain and limitation of footwear and it is important that you are assessed by an experienced orthopaedic surgeon specializing in these problems. The surgery needs to be delicate and exacting as the mechanics of the foot are very precise and unforgiving.

What causes bunions? 

Hallux valgus tends to run in families. In other words, there is strong genetic link and the majority of people with bunions have a family member with the same problem. Approximately 1/3rd of the population will develop a bunion at some stage in their lives, so it is a very common problem. 

Tight footwear can also be important and it is likely that this contributes to the development of bunions in people who are already genetically at risk. This probably explains why the condition is much more common in females than males. In other words, high heeled and pointed toe shoes are not the main cause of the problem, but such footwear can accelerate the condition. 

Other causes of Hallux valgus include injury, arthritis and muscle imbalance.

What are the alternatives to surgery?

Around half of all bunion sufferers do not need surgery. The aim of non-surgical treatment is to relieve pressure on the bunion and to try to prevent the development of pressure sores and ulcers. 

In some cases, comfortable, well-fitted shoes are sufficient to alleviate pain. In some cases, a podiatrist may be able to help with symptoms by making an inner sole to go inside the shoe. 

There are a lot of splints, pads and cushions sold commercially which may help with symptoms although none of these will correct the bunion. Nothing other than surgery can correct a bunion.

Here is an animation of the MICA (ProStep) keyhole bunion operation that Mr Redfern invented with his French colleague. This operation is now used worldwide for keyhole treatment of bunions and represents state of the art modern surgery.

The main difference between tradition ‘open’ surgical correction of bunions (such as the ‘Chevron Technique’ and ‘SCARF Akin Technique’) and the MICA ProStep technique is the instrumentation used to cut and re-align the bones. 

In traditional open surgery, a large oscillating saw is used to cut the bones which requires a large incision and stripping of the soft tissue from the bone in order to make the necessary bone cuts and re-alignment. 

In Mr Redfern’s minimally invasive technique, a small (2mm) drill is used to cut the bones. As it is so small it can be inserted through tiny incisions and the bones cut under xray guidance without any of the big incisions and soft tissue stripping involved in traditional techniques. This leaves the joint of the big toe unscathed by the surgery and the blood supply intact.  

The bones are cut, realigned, and then held in the correct position using specially designed screws which sit flush with the bone and cannot be felt by the patient. These screws ensure the bones remain in the corrected position whilst they heal.

Bunion surgery has a reputation for being very painful. International studies have shown significantly less pain with the Mr Redfern’s technique (MICA ProStep) than traditional techniques. The majority of patients have very little or no pain following this operation. This is due to a combination of less invasive surgery (substantially less injury to the soft tissues) and specially designed screws to rigidly hold the bones still in their new corrected alignment. Mr Redfern also uses a local anaesthetic block administered in theatre whilst under general anaesthetic and so almost all patients wake up from surgery with no pain.

Minimally invasive surgery in harmony with your body

Minimally invasive surgery in harmony with your body

International studies have shown significantly less pain with the Mr Redfern’s MICA technique than traditional techniques such as the Scarf Akin technique.

MICA General Recovery Information


·      Operation performed under general anaesthetic and / or regional anaesthetic


  • The operated foot must be strictly elevated (above the level of the hip) for the first 2 weeks after surgery

  • The foot should be elevated for 50 minutes out of every hour of every day for the 2 weeks following surgery

  • It does not mean 50 minutes of elevation and then 10 minutes of running around

  • It is good to get up regularly but cumulatively, out of each hour, 50 minutes should be spent with the foot elevated above the hip


  • You are able to walk on the foot immediately on the day of surgery but only in the surgical shoe provided and only slowly with care to protect the foot

  • You must wear the surgical shoe provided at all times when placing the operated foot on the floor, even when going to the toilet at night. Many patients keep the shoe on in bed for the first 2 weeks after surgery 

  • You may notwalk on the foot at all without the surgical shoe

  • The surgical shoe is worn for 6 weeks

  • The foot must be kept dry for the first 2 weeks following surgery until reviewed by Mr Redfern


  • You may notdrive after the surgery for six weeks unless you have an automatic vehicle and only undergone surgery to the left foot


  • You will be provided with a specific bag to cover the operated foot when showering or bathing to keep it dry


  • There will be swelling for 5-6 months after surgery in almost all cases and this can persist in some patients for up to a year


  • The patient can usually return to their own shoes after the review by Mr Redfern at 6 weeks after surgery but the choice of shoes will be limited for some months due to swelling in the foot

  • Generally, trainers are most comfortable initially

Minimally invasive surgery in harmony with your body

Minimally invasive surgery in harmony with your body


  • You will need to discuss this with Mr Redfern

  • You will need at least 2 weeks off work but possibly much longer 

  • If employed in an office role you may be able to return to work from 2 or 3 weeks after surgery although this depends on your occupation and method of commute

  • In general, 6 weeks off is required for work involving standing or walking (The hospital will provide a sick certificate for the first 2 weeks; further sick notes can be obtained from your GP)

  • If you have the facility to work from home then this will be ideal from week 2 onwards until 6 weeks after surgery when most patients (but not all) can manage to return to their usual work role


  • Physiotherapy can be a very useful tool in the recovery of patients from bunion surgery

  • Usually arranged to start after the 6-week review

  • Physiotherapists are able to speed up the recovery process by helping restore a normal walking pattern and mobilization of the foot joints as well as helping to reduce swelling

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Summary Of Post-Operative Instructions

MICA ProStep Bunion / Hallux Valgus Correction

Day 1 - 7

· Foot wrapped in bulky bandage and surgical shoe (heel wedge shoe)

· Start walking on the foot in flat surgical shoe only but remain very sedentary

· Elevate 50 minutes of every hour of every day.

· Simple calf exercises to be performed regularly (anti-DVT)

· DVT stocking on opposite leg (until 2-week review)

· Take pain medication for first 2 days as a precaution (even if no pain present)

· Expect numbness in foot for approximately 10-24 hours

· Blood drainage through bandage can sometimes occur - Do not change bandage

· Do not remove surgical shoe - even at night

DAY 7- 14

· Do not remove surgical shoe - even at night

· Remain very sedentary

· Usually little or no pain. Pain medication if required

· Elevate 50 minutes of every hour of every day

· Keep bandaging dry and do not remove (do not change dressing unless instructed)

Weeks 2 - 6

· Follow-up in the outpatients for wound review & removal stitches at 10 – 14 days usually

· Continue walking on the foot onlyin flat surgical shoe until 6 weeks after surgery

· Important to remain very sedentary until 6 weeks after surgery

· Elevation less important after first 2 weeks but still required sufficient to minimise swelling

· Begin moving the big toe with simple exercises

· Shower and bathing allowed (fine to get foot wet)

· May begin to drive automatic vehicle with caution in surgical shoe IF surgery to left foot ONLY(otherwise return to driving at 6-8 weeks post surgery)

6-8 weeks

· Review in the outpatients with x-ray on arrival

· Remove surgical shoe if satisfactory x-ray

· A regular shoe may be worn (should be well cushioned and supportive such as a trainer)

· Physiotherapy recommended to begin at this stage

Beyond 8 weeks after surgery

· Continue physiotherapy

· Can graduallyincrease daily activity from week to week

· No exercising until 8 weeks after surgery when some gentle cycling and swimming allowed

· No running or racket sports (no impact exercise) until 4 months after surgery or as advised

Minimally invasive surgery in harmony with your body

Minimally invasive surgery in harmony with your body

Main Risks Of MICA Surgery

Mr Redfern undertakes regular detailed audit of his practice. The following is a list of the main risks of surgery and percentages quoted are specific to Mr Redfern’s practice. The main risks include (but not limited to):

Swelling – Initially the foot will be very swollen and needs elevating.  The swelling will disperse over the following weeks and months but will be apparent for up to 6-12 months.

Infection – This is a very small risk with this operation (<1%) You will be given intravenous antibiotics to help prevention.  However, the best way to reduce your chances of acquiring an infection is to keep the foot elevated over the first 14 days as instructed.  If there is an infection, it will likely resolve with a course of antibiotics.

Wound problems – This is a very small risk with this operation (<1%) 

Scar sensitivity – This is a very small risk with this operation (1%) and much more of a concern with traditional open surgery. If the little scars are sensitive following surgery then this usually subsides without treatment. If persistent sensitivity occurs then this can be treated.

Nerve Injury – The risk of the small nerves in the area being directly injured by the surgeon is approximately 1%. However, the nerves can become bruised by the surgery and as a result of the swelling (5%). Whilst this usually recovers, you could end up with some permanent numbness over the big toe area, which might cause irritation but generally doesn’t bother most patients. 

CRPS – This stands for complex regional pain syndrome. It occurs rarely (less than 1%) and is not properly understood. It is thought to be inflammation of the nerves in the foot and it can also follow an injury. It causes swelling, sensitivity of the skin, stiffness and pain. It is treatable but in its more severe form can takes many months to recover.

Under or over correction – The vast majority of patients are happy with the correction achieved by this operation (approximately 95% patients are happy or very happy with the result). Over-correction where the big toe is too straight (with big gap between big toe and second toe) is generally less well tolerated than under-correction and can require more surgery on occasions. The risk of under/over correction occurring is approximately 1%.

These notes are intended as a guide and some of the details may vary according to your individual surgery or because of special instructions from Mr Redfern

Delayed and non union – This is when the bones are either slow to heal / join (delayed union) or fail to do so (non union).  If this is painful then further surgery may be needed.  The risk of delayed union is 3% and usually means that the foot remains swollen and irritable for 6-12 months rather than the usual 5-6 months. The risk of the bones not healing at all (non-union) is approximately 1:500 (much less than 1%) but if this occurs then you are likely to require more surgery.

Deep Vein Thrombosis (DVT) – This is a clot in the deep veins of the leg and the risk of this occurring following forefoot surgery is extremely low (much less than 1% and probably in the region of 1:1000) unless you have had one before or have other risk factors. Mr Redfern will discuss this with you but please let him know if you have had a DVT in the past or have been told that you are at higher risk. The fact that you are mobile after surgery and able to take weight through the operated foot helps to minimise this small risk. However, it is sensible to try and move the toes and the ankle regularly following the surgery and also sensible to avoid a long-haul flight in the first 8 weeks following surgery. If a deep vein thrombosis (DVT) occurs then you will require treatment with blood thinning medication to try and prevent any of the clot travelling to the lungs (pulmonary embolus / PE) which can be much more serious.

Stiffness – The risk of stiffness in the big toe after this surgery is very low (less than 5%) and can be minimised by beginning to move the big toe after 2 weeks from surgery and Mr Redfern will advise you regarding this. Physiotherapy may also be helpful after 6 weeks. Generally patients regain their pre-operative range of motion and if there is some persisting stiffness it usually doesn’t significantly affect function or footwear but could limit height of heel that can be worn.

Recurrence of the bunion – This risk is small in Mr Redfern’s practice but there is a small risk of some recurrence of the bunion and deviation of the big toe. This risk is about 1% in Mr Redfern’s experience over the last 10 years.

Continuing symptoms – Most people (in excess of 90%) are very happy with the results of their bunion surgery but you can appreciate that if some of the above problems occur then this may affect the end result. In most cases however, any persisting or new symptoms can be dealt with by additional treatment although this sometimes requires further surgery.

Further Surgery – This is not usual but can be required for a variety of reasons (some of which have been mentioned above). The commonest cause of requiring further surgery is to remove a symptomatic screw or bony prominence where the bones have healed (8%). In either case, it is a small additional day-case operation with return to normal footwear expected after 24 hours.  The risk of requiring further surgery for any other reason is 1%.