Surgery is a treatment which is frequently necessary in the pathology of the diabetic foot.
If prevention is not sufficient to prevent a wound establishing itself and the treatment of the initial wound is not sufficient to result in healing, a surgical intervention is necessary to resolve the problem.
Surgery can be used in two very different clinical pictures:

• Radical surgery
• Corrective surgery

Radical surgery aims to eliminate a diseased or non-vital part of the foot.
Corrective surgery aims to eliminate certain deformities which pose a high risk of ulcer or which do not allow healing.
In both situations a great deal of professional competence is required to decide on the type and method of intervention, together with a bit of luck ( Figure 47).

Radical surgery

As stated its aim is to eliminate parts of the foot which are diseased and non-vital.
In most cases radical surgery results in amputation of a part of the foot: the term used is minor amputation because this type of amputation and nevertheless allows an erect position to be maintained, with support on both feet, and allows the patient to walk around.
This is the principal aim of the person treating the ulcerated diabetic foot.
If no part of the foot is still vital and it is therefore impossible to carry out a minor amputation, major amputation then becomes essential, namely amputation carried out above the ankle, which does not allow a natural posture on both feet or walking around, which will only be possible if a prosthesis is used.
The reasons behind recourse to surgery are as follows:

• Gangrene: death throughout the thickness (skin, muscles, bone) of one part of the foot
• Infection of the deep tissues
• Bone infection

We must point out that often it is not possible to determine in advance the optimum level of amputation: especially in the case of infected gangrene or abscess what is found on the operating table is often worse than what was visible externally, with this requiring a different level of amputation, generally further back, in comparison with what has been scheduled.

Gangrene is the outcome of ischaemia of one part of the foot which determines the death of all the tissues in that part which do not receive blood; gangrene can be dry or wet.
Gangrene is dry when it is not infected and is clearly delimited: the change of colour of the skin between the gangrenous zone and the healthy zone is clearly demarcated and there are no secretions ( Figure 48).
However we can point out the that gangrenous tissue is an optimum breeding ground for bacterial growth: waiting too long before intervening leads to the risk of dry gangrene turning into wet gangrene.
Gangrene is wet when it is infected and the skin around the black gangrenous zone is inflamed and suppurating ( Figure 49 and Figure 50).
While dry gangrene allows a certain margin of time for scheduling the surgical intervention, wet gangrene is a matter of urgency: the infection aggravates the unhealthy tissues and can extend the dimensions of the gangrene.
Gangrene can affect part of the toe, the toes, the front part of the foot or extend right to the heel and beyond ( Figure 51).

The surgical intervention is aimed at removing the gangrenous parts.
Often it is not easy to accurately establish the level of amputation: attempts to keep the largest possible part of the foot encourages us to carry out amputations very close to the limit of the gangrenous zone on tissues which are in any event unhealthy.
The risk lies in having to carry out a second surgical intervention which extends further back ( Figure 52); all this will be evaluated with the patient, taking into account various factors.
First of all the anaesthesiological risk: in patients with cardiopathy, hypertension, respiratory insufficiency, renal insufficiency, etc., reducing the risk of the second intervention as far as possible will be encouraged.
In patients with a low anaesthesiological risk a very conservative intervention can be risked ( Figure 53).
If there are no fears about a second intervention it is possible to leave a wound open in the hope that debridement and detersion of the tissues may allow subsequent closure without losing part of the foot ( Figure 54).
A second factor is the possibility of an intervention causing deformation of other parts of the foot with a high risk of ulcer caused by the deformity which has been induced.
A typical example is amputation of one toe at its base: the adjacent toes will tend to move in towards each other, which can cause pressure ulcers.
Amputation of the toe extended to the head of the metatarsal avoids this phenomenon ( Figure 55).
The complete healing of a surgical intervention on the foot always requires a great deal of time.
Stitches are removed approximately 21-28 days after the operation, but often small areas remain in which a the stitches have not held (diastasis) and medicated treatment is required, lasting for varying lengths of time, in order to obtain definitive healing ( Figure 56) or even another intervention ( Figure 57).

What happens after a definitive healing? This is the natural question which all patients ask when they are told of the need for a minor amputation intervention.
The question is associated first of all with the possibility of walking, secondly with driving a car, and with the risk of this causing subsequent ulcers of the foot.
We can provide an affirmative response to all these questions: it will be possible to walk, it will be possible to shower and it will be possible to drive a car.
It is also possible for new ulcers to form.
To be able to do all these things and to avoid the formation of new ulcers, as far as possible, it is therefore of primary importance to look after the foot very carefully: examining it every day, washing it and drying it carefully, avoiding anything which might damage it.
Above all it is necessary to wear appropriate shoes which protect the foot from both excessive peaks of pressure and from friction.
With regard to this aspect please refer to the section on prevention; naturally the information provided there must be applied with maximum care by patients who have suffered ulceration.
We have already discussed infection of the deep tissues and osteomyelitis in the section about infection, to which you are referred.
We would like to emphasise the fact that osteomyelitis is an insidious pathology.
It rarely causes pain, and often an ulcer of the soft tissues tends to heal or become minimal.
The danger of osteomyelitis is the progression into the bone in the back of the foot.
If osteomyelitis attacks the astrogalus or calcaneus the risk of major amputation becomes significant.
Obviously this risk is associated with the primary seat of the ulcer and the underlying osteomyelitis: if the phalanges are involved the risk is minimal and prolonged antibiotic treatment may be envisaged together with X-ray monitoring and blood chemistry tests (VESP PCR).
If the metatarsals are involved the need for surgical eradication is pressing; eliminating the infection from the metatarsals puts the bones of the calcaneus at increased risk ( Figure 44).
The surgical intervention can vary in accordance with local and general considerations.
In the event of low anaesthesiological risk it is possible to attempt limited interventions accepting the risk of a subsequent intervention ( Figure 58).

Corrective surgery
In some cases there is an indication to carry out a surgical intervention even in the absence of ulcerative wounds in order to correct specific deformities with a high risk of ulceration.
This type of surgery is indicated for hammer toes, bunions ( Figure 59), flat feet which cannot be corrected with an arch support, disalignment and disarticulation of the bone ( Figure 17).
Excessively flat feet are a very frequent cause of ulceration of the metatarsal heads.
In this case an osteotomy intervention on the first metatarsal can be carried out, for panmetatarsal realignment or a tendon transposition intervention ( Figure 18).
In the event of significant deformity of the foot, either spontaneous or caused by previous surgical interventions, we recommend an intervention which is apparently more radical, such as, for example, transmetatarsal amputation, rather than local resolution of the ulcerative or osteomyelitic pathology, which will worsen the deformity of the foot with the inevitable onset of further wounds within a short period ( Figure 60).

Major amputation
Notwithstanding improved treatments, in some cases major amputation is required: this is essential when, in subjects who cannot be re-vascularised, the pain cannot be relieved and does not allow any rest or in cases in which gangrene has spread throughout the whole foot ( Figure 61).
Although a decision for major amputation must not be too precipitous, it must not be excessively delayed either; the presence of necrotic tissues leads to toxaemia caused by reabsorption and a progressive deterioration of general conditions which aggravate the patient's clinical condition.
Non-vital tissues are then an optimum pabulum for germs and the danger of infection is very high: in some situations it can endanger not just the limb but the patient's actual life.