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Transcript: The Diabetic Foot
The diabetic foot can be defined as the “foot of a diabetic”. There are 150 million people in the world with diabetes mellitus, according to the WHO. When a diabetic with a foot problem comes to Orthopaedics, they usually come because of two reasons:
Remember that when someone comes for foot surgery one must always check the pulses. Take a thorough history and ask about a history of diabetes and other symptoms that may let you think they may be diabetics.
There are basically to ways a foot is affected by diabetes|:-
X ray Changes
On X Rays one can often see the vessels as a "lead pipe" appearance.
When you examine these patients, besides the sensory and routine examination, use a tuning fork. Lack of vibration sense means there is a sensory neuropathy. This is a serious sign! Also use a 10 gauge Semmes Weinstein monofilament needle to check two point discrimination. One should do a good vascular assessment and feel for all pulses, starting with the big ones, the femoral pulse, popliteal pulse and lastly the foot pulses themselves.
The ankle brachial pressure index is not very reliable in diabetic patients. The absence of foot pulses is very significant. If you have somebody with absent foot pulses, basically do not operate, unless for a life or limb saving necessities like amputations, debridements etc. You don't go and perform elective foot surgery on a foot with no pulses- rather send him to the vascular surgeon first. If it is large vessel disease he may be amenable to bypass surgery.
Triple phase bone scanning is not really contributory to treatment.
The X ray signs of penciling of the metatarsals and "vanishing" phalanges on straight x ray. The vessels may also be seen, as mentioned, and Charcot's arthropathy must also be looked for.
Ischemia and the Depth Ischemia Index.
Brodsky has published a classification where he classifies the depth and Ischaemia. Depth is classified from 0 to 3 and then the ischaemia index which is (A) to (D).
Grade 0 : no beak in the skin. Suspicious reddened area only (on the shin)
Grade 1 : there is a superficial ulcer.
Grade 2 : exposed tendons.
Grade 3 : exposed bone.
Distinguish between grade 2 and grade 3 by probing the wound with as metal probe –if you feel bone then it is a grade 3.
Ischaemia can be classified as:
Grade A: - no ischaemia.
Grade B: - ischaemia, but non gangrenous of the toes.
Grade C: - partial foot gangrene – full thickness.
Grade D: - compleeet foot gangrene.
How do we treat these various modalities?
Basically be as conservative as possible! In a Grade 0 or 1, use a total contact shoe or cast. This may have to be left on for several months. Deeper ulcers may take up to a year to heal! For Grade 3 and 4 debridement of the wound will be needed. If there is chronic osteomyelitis partial resection of a phalanx or metatarsal may be necessary.
As far as gangrene is concerned, bypass surgery may limit the extent of later amputations. Partial foot amputations are often successful. For example, if the forefoot is involved a Chopart amputation may be successful. A standard above knee or below knee amputation is thus not always necessary.
Because of a sensory neurapathy the patient then gets an arthritis which is more severe on x ray then the patients feels. The patient always feels some pain, but it is disproportionate to the degree of joint damage seen on X Ray.
Classification of Charcot's joints
Type 1: Midfoot joints. Result in a rockerbottom foot. This results in pressure ulcers in other places.
Type 2: About the subtalar joint including the talo-navicular and calcaneo-cuboid joints. This results in s varus or valgus of the heel.
Type 3: Type 3A is the ankle joint. Type 3B is avulsion of the Tendo Achilles. The bones are very osteoporotic and a “Parrot Beak” type of avulsion may occur. This must not be treated operatively. Treat it non surgically in a boot or plaster.
Charcot's joints are seldom septic. If there are no ulcers or reasons to suspect a septic joint, there is probably no sepsis and the joint itself can be trweated non surgically. Secondary bony prominences resulting from the malalignment may have to be resected. If your patient is walking on the outside border of the foot because of a varys heel, you might have to do a surgical procedure such as subtalar arthrodesis to restore alignment.
Diabetic patient often develop shortening of the Tendo Achilles, check clinically for this always. This results in metatarsal head pressure points. A simple Tendo Achilles lengthening may be all that is required.
Keep away from unnecessary surgery. The role of surgery in the diabetic foot is debridement of ulcers, elimination of pressure points, excision of bones that have developed.chronic ostomyelitis.
Fractures in the Diabetic Foot
Diabetics often come in with ankle and other foot fractures. In the diabetic and especially in one with a pulseless foot, be very wary of doing open reduction and internal fixation of foot and ankle fractures. Costigan in the Journal of foot and ankle surgery, studied 12 diabetic feet that had had ORIF of an ankle farcture, and 10 of these developed complications. The massage is that in the diabetic foot ankle fractures often do badly id opeated on. Treat hem conservatively, especially in the absence of foot pulses. Always ask your patient about diabetes. Rember, before you operate on any foot make sure that there are foot pulses present. If they are not present a vascular consultation is mandatory. Decide together if there is going to be an operation or not.
The diabetic foot is the foot of a diabetic. There can be a sensory neuropathy. Ulcerations can be treated with total contact casts, and other conservative methods. Ulcers may need debridement and sequestectomies of dead bone. Avoid (unnecessary) open reduction and internal fixation on known diabetics especially if they have vascular compromise. The patient will , in the end, do much better if a conservative route is followed.
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