MODULE 3: TREATMENT
Care of the Skin and Nails of the Neuropathic Foot
Care of the skin and nails of the neuropathic foot begins first with an understanding of basic anatomy of skin, the nail, and principles as well as important procedures of foot care.
The Skin
Skin is composed of two main parts:
Epidermis
Serves as a protective barrier against microorganisms Thickest on the palms and soles of the feet Thinner over the surface of the trunk
Dermis (corneum)
Serves as a protective barrier against microorganisms Insulates against heat and cold Helps eliminate body wastes in the form of perspiration Sense receptors enable the body to feel pain, cold, heat, touch, and pressure
Healthy skin is soft and flexible and slightly moist and acidic.
The Nail
Nails are composed of hard keratin, a modification of the horny epidermal cells of the skin. The white crescent shape of the lunula at the proximal end of each nail is caused by air mixed in the keratin matrix. The nail plate originates from the proximal nail fold and attaches to the nail bed. It grows about 1 millimeter per week unless inhibited by disease. Regeneration of a lost toenail occurs over 6 to 8 months.
Facts About Nails
Nails grow approximately 0.1 millimeter per day or 3 millimeters per month Nails grow faster in daytime and summer Fever and serious illness slow growth rates Pregnancy enhances growth Nails grow more rapidly in men and younger people than in women and the elderly Toenails grow 1/2 to 1/3 the rate of fingernails
Skin and Nail Care
Before starting skin and nail care, thoroughly inspect feet and ankles for breaks in the skin. Have a mirror available to examine the heels. Look for ulcers, heel fissures, maceration between the toes, or embedded objects.
When nails are neglected and grow too long, they can break the skin of the neighboring toe. Abnormal nails that are not given routine care can accumulate excess keratin and debris under the nails and in the nail folds, creating an ideal environment for bacteria to grow. Poor hygiene necessitates routine foot care.
Procedure for Basic Foot Care
Wash hands Submerge patient's feet into warm water (not more than 95°F) While wearing gloves, make a paste of baby shampoo (or any mild soap) and baking soda in the palm of your hand and gently massage over the entire foot. (You can also use water that is three parts water and one part vinegar to clean the feet. Vinegar softens the skin and nails. Rinse and wrap feet individually Expose toes and apply cuticle remover Using a curette, gently remove dead skin and loose cuticle from the toes. Rinse Using nail clippers, cut nail straight across. Don't cut what you can't see. Always have good lighting. Thinner, more fragile nails can be cut using smaller cuticle nippers Ingrown toenails are a puncture wound. To prevent them, use an ingrown nail file to smooth sharp corners that can dig into the skin Smooth rough edges of nails with emery board. Patient may take the emery board home for self-care Massage emollient into feet but not between toes. Avoid lotions with fragrance because of drying, alcohol content. Vaseline, lanolin, or even Crisco may be used. Pat excess off with paper towel. Remind patient to use caution when using emollient to prevent slipping and falling. Removing excess and wearing socks help minimize the hazard. Educate patient regarding appropriate footwear.
Other Principles of Care of the Nails
There are nails that are difficult to trim. The safest way to trim the pincer type nail is to file it straight across, rather than risk cutting the skin. Some nails have grown into a "tent" shape, usually formed by being squeezed into tight pointed shoes for years. When trimming this type nail be aware of the skin under the nail at the apex. A condition called onycholysis (separation of the nail plate from the nail bed) can be caused by nail traumas and disorders. If onycholysis has been present for a long time (6 months or more) the structure of the nail bed can change and the nail plate will no longer attach to the nail bed. At this point, the condition becomes permanent. Keep the patient's nails short to prevent the nail from catching on something and tearing off.
Helpful Foot Aids
Tube foam is ideal for protecting bunion deformities, soft corns, and maceration between the toes. Lamb's wool aids in protection between the toes from maceration and provides cushioning. Toe socks help with overlapping toes and controlling maceration in interdigit spaces. Socks that are designed to wick moisture away from the skin are desirable, especially in a foot that sweats excessively. Avoid socks with tight elastic tops.
Care of the Hypertrophic Nail
A hypertrophic nail may be caused by damage to the matrix, fungal infection, age, or circulation problems. 
Hypertrophic nails that have been neglected for a long period need to be thinned to make shoe fit possible and to help prevent secondary infection if the prominent nail is traumatized. The most effective and expedient way to thin the nail is to use a cordless rotary Dremel tool (Dremel, Racine, WI) with an abrasive disc. These discs are easily interchangeable and should be discarded between patients. 
It is important to protect yourself and the patient from airborne dust by wearing a mask and, preferably, hair covering. Using a government-rated high efficiency particulate arrestance (HEPA) air filter device would give added protection to limit the amount of dust in the air.
Procedure for Reducing Hypertrophic Nails
Begin by washing your hands and donning gloves. Examine the skin around the nail for any damage. If there are no signs of broken skin or infection, secure toe to be worked on with the thumb and index finger and move other toes out of the way. Turn Dremel tool on and move sander in a proximal to distal direction in even strokes until nail is thinned. Caution must be exercised when thinning these nails because of unanticipated raised nail beds. Wash and dry thinned nail with water or water/vinegar solution (3 parts water/1 part vinegar) and apply an antifungal cream such as Tineacide (Blaine Labs, Inc., Santa Fe Springs, CA). Use of this, or a similar product, will allow consecutive nail care to be more effective by keeping the nail and surrounding skin conditioned.
Management of Vascular Related Symptoms
Venous Stasis Ulceration
Treatment of venous stasis ulcerations may take many forms.
One form of treatment begins with leg elevation in order to prevent dependent edema.
Another method to reduce venous pooling in the vasculature is to apply superficial compression. The limb must be treated with compression bandages or an Unna boot.
The Unna Boot
This treatment has been used on venous stasis for 100 years. It is a semirigid dressing of gelatin and zinc oxide that is usually applied when wet. Its application protects vulnerable skin from the weeping exudate, especially below the ulcer site. When it dries it forms a nonelastic, nonexpandable, nonshrinkable, porous mold that sticks to the skin.
The Unna boot is a means of controlling edema when it is applied across a joint. The motion of the joint generates a pumping action.
Compression can be ordered to begin at the metatarsal heads and decrease pressure in the calf (neuropathic compression stocking) as an additional assist to the venous system. Most patients do well with compression in the range of 30 to 40 mm Hg at the foot and ankle.
Other Principles of Compression Therapy
When using any type of compression stockings for the patient with neuropathy/dysvascular disease, remember to avoid seams around bony prominences, and never place a zipper over the malleoli. When venous stasis ulceration occurs on one limb, begin compression therapy on the contralateral side. The appearance of small water blisters or weeping is a sign that compression should begin. A prosthetic shrinker sock should be used after a major limb amputation to reduce edema and shape the residual limb. The prosthetic shrinker applies both circumferential and vertical (distal to proximal) compression.
Maceration and Injuries to the Toes
Injury and maceration of the toes is commonly controlled by the use of lamb's wool between the toes or tube foam to space toes and prevent friction.
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A: Lamb's wool pieces are placed between each toe to prevent maceration. They should be replaced after bathing.
B: A custom tube foam toe separator.
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Management of Peripheral Sensory Neuropathy
Paresthesia may be reduced by use of a transcutaneous electronic nerve stimulator (TENS) unit, which generates small pulses of electricity similar to an electric massage. Another method of controlling the discomfort is with topical creams.
Treatment Approaches Based on Risk Categories
In the clinical literature, there is a consensus that several factors can be used to guide the prescription of pedorthic management for patients with neuropathy. These factors are:
sensory dysfunction limited joint mobility foot deformities partial foot amputation presence of ulceration
The Lower Extremity Amputation Prevention (LEAP) program was developed at the Gillis W. Long Hansen's Disease Center for the purpose of reducing the incidence of lower extremity amputations in individuals with diabetes mellitus, Hansen's disease, or any other disorder that results in the loss of protective sensation of the feet.
Treatment recommendations are based upon four risk categories developed by Birke that classify an individual's limb and their risk for amputation:
Treatment Interventions
Foot Orthoses
The patient without protective sensation will not cease ambulating when damage begins to tissues. Patients with feet such as those who walk into the clinic are insensate. They require extra-depth shoes with a total-contact accommodative shoe insert to distribute pressure and reduce forces on areas of potential breakdown.
Design Considerations
The insert may be directly custom molded to the patient's foot or fabricated from a positive model created by a negative impression (cast of the foot). 
The cast does not have corrective forces added, only accommodation of the patient's foot shape. The accommodative insert does not apply correction; it fills only the spaces between the flat shoe and the foot contours. Any corrective force added into the orthosis contour will receive full weight bearing, and breakdown of skin and/or underlying tissues will occur.
Metatarsal or Scaphoid Pads
If the addition of metatarsal head (MTH) pads or scaphoid pads is requested, these pads must be of a soft durometer. Rigid pad additions will cause excess pressure and ulcerations. The MTH pads are placed proximal to the metatarsal heads to redistribute the weight from the heads to the metatarsal shafts.
Treatment of the neuropathic foot requires accommodation, relief of pressure and/or shear forces, and shock absorption. Regardless of materials used for accommodative inserts, the combination of materials must be compressible by 1/2 of the original thickness to accommodate for pressure relief through the gait cycle.
Cellular polyethylene foams such as Aliplast (AliMed Inc., Dedham, MA), Plastazote (Acor Orthopedic, Cleveland, OH), and Pelite are composed of a mass of bubbles in a plastic and gas phase. The bubbles are cells with lines of intersection called ribs or strands, and the walls are called windows.
In closed-cell materials the gases do not pass freely Open-cell material has no windows, leaving many cells interconnected so that gas may pass between cells Cell walls are not totally impermeable to the flow of gases Under a sustained load (especially the heavy patient) gases are squeezed out; when the load is removed, gases are drawn back into the cells Plastazote has a limited effective period of about 2 days Poron (PPT) (Rogers Corporation, Ragers, CT; Langer Biomechanics Group, Inc., Deer Park, NY) remains effective for 6 to 9 months The two materials can be combined for their attributes and perform well as a single unit The Aliplast/Plastazote insert is an immediate preparation and can be provided within a clinic setting, but it has a relatively short life of compressibility (6 to 8 months) Plastazote is a closed-cell polyethylene foam that can be heated to 280°F and molded directly onto the patient's foot
These materials bottom out from compaction of the materials as cells fracture under repetitive stress. The advantages of these foams are:
There are different types of inserts:
cushioning/accommodation improves shock absorption semirigid some cushion/accommodation affords pressure relief rigid hard, single layer of plastic controls abnormal foot and leg motion
By combining materials over a cast model of the foot (positive model), the composite type of insert can achieve all goals of the accommodative insert and provide a life of one year minimum.
Principles of accommodative shoe insert construction
All relief areas of the shoe insert are created on the underlying surface in contact with the shoe, never in contact with the foot. The surface in contact with the foot is always a solid, uninterrupted surface that will not apply edges for the foot to receive shear forces. The figure above diagrams the fabrication of several different layers into an accommodative shoe insert.
Footwear
Shoes for the insensate foot should be of soft leather that will conform to abnormalities on the dorsal surface and allow for the depth of an accommodative insert.
As in the figure above, sometimes modifications to the sole of the shoe may be indicated to accommodate the insensate foot.
Crepe soles are preferred for pressure relief as they are full of air cells and provide pressure relief to the plantar surface.
Leather shoes are also preferred as they will breathe and absorb perspiration.
Features of Appropriate Fitting Shoe
The patient should not depend upon the "feel" of a shoe for correct size. The shoe must be full width and girth and allow 1/2 to 3/4 inch space beyond the longest toe to prevent distal shoe contact through the gait cycle.
Standard modifications of extra-depth shoes for the patient with neuropathy include
Stretching of the soft toe box for clawed toes allows appropriate room to prevent pressure or shear Instep leather should not be taut Flared lateral soles to discourage varus instability Shank/rocker bottom for a partial foot, hallux rigidus, or decreased motion at the metatarsal heads. A rocker bottom should be added to the shoe when metatarsophalangeal extension is to be avoided 
Rocker Bottom Shoe
(www.customfootwear.com)
Shoe Dimension is Important
There are three tests to determine the proper fit of shoes.
Length: Allow 1/2 to 3/4 inch of space in front of longest toe. Ball width: With the patient weightbearing, grasp the vamp of the shoe and pinch the upper material; if leather cannot be pinched, the shoe is too narrow. The ball should be in the widest part of the shoe. Heel to ball length: Measure the distance from the patient's heel to the 1st and 5th metatarsal heads.
The simple addition of shoes, instead of weight bearing and walking barefoot, may correct many deformities. Laced shoes provide the best control, but initially should be worn as part of a wearing schedule. In order to allow the foot to gradually adapt to the new shoes, they must be worn beginning with 2 hours per day and slowly adding time. To evaluate pressures within a shoe, the patient may wear a pressure-sensitive sock that is coated with dye-filled wax capsules. The capsules fracture when a certain pressure threshold is exceeded; leaving dye stains in areas of high pressure provides visual evidence of excessive pressures to the foot.
Overall, the pedorthic treatment of a person with neuropathic feet may involve:
In-depth shoes Protective inserts Custom-molded foot orthoses Biomechanically appropriate shoe modifications
Rocker soles Medial or lateral stabilizers (buttress) Sole spread to widen specific plantar areas of the shoe Dorsum vamp balloon patches
Custom-molded shoes with custom foot orthoses
Let's review a description of each type of treatment and the rationale for its use as a treatment modality.
Off-Loading of Foot Ulcers
In the treatment of foot ulcerations, there must be wound care protocol with debridement/cleansing and simultaneous off-loading of the affected area. This combination has shown optimal results in the healing of wounds. Many patients are given crutches, a walker or a wheelchair, but they must have the upper body strength, cardiovascular reserves, and/or motivation to use assistive devices. Bed rest eliminates the pressures on the foot but may result in deconditioning of the patient.
Other treatment interventions to off load foot ulcers involve a variety of shoe designs, shoe modifications and orthosis designs. Specifically, these treatments are categorized as:
Plastazote healing sandals Wedged shoe Half shoe Surgical/cast shoe
Plastazote Healing Sandals
The custom Plastazote healing sandal contains a molded foot bed and has a rigid rocker sole. The device is lightweight but requires considerable time and experience to fabricate. The Carville sandal has been used as a successful off-loading shoe and interim device after the total-contact cast has been utilized for a treatment period and before definitive footwear is recommended.
Wedged Shoe
The wedged shoe has full contact with the plantar surface of the foot but reduces load forces applied from the ground. The sole angle is designed to shift weightbearing away from the ulcerated area. The wedged shoe is contraindicated when the patient does not have the range of motion to accompany the shoe angle. If the patient has poor proprioception, they may require the use of assistive devices to aid balance and promote safe ambulation.
Half Shoe
Many clinics use the half shoe to suspend the ulcerated area from the ground, providing complete off-loading of the ulcerated area. The forefoot half shoe provides a pressure free area for the forefoot and especially the common ulcerations of the hallux. The heel relief shoe suspends the heel for non-contact. These devices may be contraindicated for the patient with limited ankle motion or balance problems associated with compromised proprioception. Assistive devices may be required to reduce the incidence of falls.
Surgical/Cast Shoe
An inexpensive alternative for wound off-loading would be the postoperative shoe (contains a rigid sole) and cast shoes (contains a rounded sole). These types of shoes contain the ulcerated foot and include an off-loading insert. These shoes allow for some volume variability but do not offer an intimate fit to control foot motion. Usually, these shoes require extensions to Velcro straps and minor modifications. Use of these shoes as off-loading devices requires careful monitoring of the patient.
Shoe Modifications
Modification of a standard-depth shoe
To compensate for varus gait abnormalities, which may develop in persons with neuropathic feet, shoes need to be modified. The modifications required may include:
Persons with neuropathic feet may require greater stabilization or other support of the foot and ankle that shoes or shoe inserts may not fully address. Ankle foot orthoses (AFOs) may be indicated in these cases such as:
Neuropathic walker Orthotic dynamic system splint Total contact AFO Orthopedic type walkers Patellar Tendon Bearing AFO
The following pages will address each of these orthotic interventions.
Neuropathic Walker
The neuropathic walker (also known as a Charcot Restraint Orthotic Walker or CROW) is a combination of an AFO and a boot that is custom designed to provide total contact of the lower limb for weight distribution.
Design is indicated for the patient with changes of Charcot joint in the tarsal and ankle joints, chronic recurrence of Charcot disease, chronic ulcerations, and severe and unstable foot and ankle deformities. Ankle is locked to reduce force through the Lisfranc joint and/or ankle. Orthosis is easily donned and doffed through a bi-valved design Fabricated of a moldable copolymer plastic external shell with a closed-cell lining. A removable insert may be adjusted to reassign weightbearing areas on the plantar surface. The insert may also be formed over areas of the limb where there is chronic breakdown, such as the malleoli, posterior heel, and bunions in order to reduce pressure. A rocker sole allows for easy ambulation, but the contralateral shoe must be adjusted for height.
Special Features Regarding the Neuropathic Walker:
When creating the cast or negative impression for the neuropathic walker, the patient's limb is wrapped and then the foot is placed on a soft foam block until the plaster is set. This allows the plantar surface of the foot to be accommodative -without excessive pressures on bony prominences. Modifications of the positive model include smoothing the plantar surface but never removing plaster. Any area on the positive model where plaster is removed during modification will result in an area of excess pressure in the finished orthosis so care must be taken to minimize plaster removal. The distal end is built up at the medial and lateral metatarsal areas and the length extended 1/2 inch to allow room for the toes during weight bearing and to decrease the chances of maceration.
Orthotic Dynamic System Splint
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The orthotic dynamic system (ODS) splint was developed to take advantage of the casting method of a total-contact cast with the inclusion of a custom-molded insert that could be removed and reliefs modified.
With all of the advantages of the total-contact cast, the advantages added with the ODS splint include the possibilities for daily inspection, regular cleaning/dressings/debridement, and adjustments to areas of excessive pressure and/or friction.
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Procedure for Creation of the ODS Splint
A Plastazote/Aliplast insert is first molded to the patient's foot and trimmed to follow the plantar surface, with 1/4 inch of length added beyond toes. Stockinet is placed on the leg, the insert is positioned, and another stockinet is applied to hold the insert in place. A padded total-contact cast is applied, using fiberglass only. The cast is bivalved, straps are added, edges are finished, and the insert is removed, relieved, and replaced to de-weight the area of ulceration. After the insert is modified, it is replaced within the splint, and the patient may ambulate with a rocker bottom cast shoe worn under the splint. The disadvantage lies with compliance of the patient. The splint design allows donning and doffing by the patient, thus allowing him or her to remove the cast.
Total Contact AFO
Similar to the neuropathic or CROW walker, the total-contact AFO is used for the patient who has an area of trauma in the midfoot or hindfoot. The orthosis includes a custom removable insert and is lined with Plastazote. This orthosis must be fit within a shoe, which may be difficult in standard shoes. The casting procedure is the same as that for the neuropathic walker. The toes are open, and the anterior shell terminates at the midfoot.
Orthopaedic Type Walkers
Short leg walkers and orthopedic walkers have been used by some clinics, but they compromise the total-contact feature. Although prefabricated walkers are not custom made to provide total contact, they contain some features that may assist in reducing movement of the limb within the walker. The walkers can be improved in function with the addition of a wide base, rocker sole, and custom off-loading insert. The low-risk patient does well in the orthosis with a custom insert. The high-risk patient with sensory neuropathy may be better served by a custom total contact orthosis.
Patellar Tendon Bearing AFO
Patellar tendon-bearing (PTB) AFO is considered an axial resist design that is intended to decrease forces on the plantar weight bearing surface of the foot. The design is intended to transmit considerable axial forces from the knee region onto the cast but it may offer limited or no rotary stability. The results offered little effectiveness in reducing the load on the lower leg.
The patellar tendon-bearing design AFO has been used successfully for the calcanectomy, plantar skin graft, and heel ulceration. This orthosis is contraindicated in the patient with vascular impairment because of the excess restriction in the popliteal area of arterial flow.
Orthotic/Pedorthic Material Considerations
By using state-of-the-art foams and room temperature vulcanized silicone elastomers, shear can be reduced in areas of skin grafts, chronic ulcerations, and calcanectomies within more rigid orthoses.
The viscoelastomer gel is a two-part gel that can be adjusted for the durometer desired. The mixture can be used for shock absorption and shear reduction. Scar adherent areas can benefit from a medium durometer mixture. The disadvantage is weight, so it should be used in small areas. Low-density foams can be designed into orthoses, such as toe breaks and forefoot blocks and reliefs. Reliefs for heel pain can be designed into the insert or shoe sole as a solid ankle cushion heel (SACH) heel. SACH heels use soft and medium durometer soling to simulate ankle plantar flexion and provide shock absorption at heel strike.
Total Contact Casts
The total-contact cast (TCC) was introduced in the United States in the 1950s to redistribute walking pressures, prevent direct trauma to the wound, reduce edema, and provide immobilization to joints and soft tissue. The TCC method decreases plantar pressures through increasing weightbearing over the entire lower leg. It has been successful as a treatment for plantar ulcerations but requires careful application, close follow-up and patient compliance with scheduled appointments to minimize complications.
The average healing time for ulcerations treated with the healing cast was 6 weeks. This method has been used for patients with and without evidence of severe peripheral vascular disease. Holes or "windows" should be avoided in the cast, or there may be localized swelling, shear stresses, and eventually a secondary wound. The following are steps for fabrication of the Carville-type TCC:
The ulcer is covered with a thin layer of gauze. Cotton is placed between the toes to prevent maceration. A stockinet is applied. A 1/4-inch piece of felt is placed over the malleoli and anterior tibia. Foam padding is placed around toes. A total-contact plaster shell is molded. The shell is reinforced with plaster splints. A walking heel is attached. A fiberglass roll is applied around the plaster.
The patient is instructed to ambulate only 33% of his/her usual activity. The cast is removed in 5 to 7 days and reapplied. New casts are applied every 2 to 3 weeks. To allow thorough drying, the patient should not stand or walk on the cast for 24 hours. Although not as effective as total contact, a posterior splint covers the posterior lower leg and plantar foot surface and is held in place with elastic wrap. The splint acts to protect the plantar surface.
This casting procedure may be chosen for the patient with a limb compromised by poor circulation or when the patient cannot tolerate the confinement of a cast. There have also been attempts to heal ulcers by using a healing cast shoe molded of plaster. This healing cast shoe must be changed in 3 days and reapplied every 10 days. Results have reported healing of plantar ulcers in 39 days. Contraindications for the use of a healing cast shoe include infection (redness, swelling, warmth, fever) and hypotrophic skin (thin, shiny appearance, marked dependent edema).
The treatment plan for acute Charcot joint is the TCC. The cast must be changed in 1 week to accommodate volume changes. After the period of volume changes, the cast should be changed every 2 to 3 weeks. When the temperature is equal to that of the other limb, the patient may be weaned gradually from the cast to a splint and then to shoes. Follow-up should continue to ensure that there is no recurrence of an episode of Charcot joint.
Wound Healing System
The wound healing system was designed for the practitioner who does not have casting facilities or available support to off-load ulcerations by total-contact casting or ODS splint.
The basic wound shoe provides a base that allows relief of pressure for the dorsum, medial, lateral, and posterior ulceration. The plantar contact system enables the practitioner to off-load plantar ulcerations with four layers of material with varying hardness (multiple durometer).
The system is to be worn until the ulceration has healed. Upon final closure of the wound, a long-term material layer is added, and the wound shoe becomes the casual slipper to be worn at all times when definitive off-loading footwear is not being used. A previous ulceration site is susceptible to breakdown repeatedly and the wound shoe used as a casual slipper ensures that pressure relief is achieved at all times. The patient must never walk barefooted.
Individuals with lower grades (Wagner 0 and 1) use one off-load layer, whereas the higher grades have two off-loading layers available. Upon wound closure, a shock-absorbing layer is to be added to prolong use of the system as a slipper. For nonweightbearing ulcerations (not plantar surface), the double layer upper construction can be trimmed to offload pressure areas without allowing window edema to occur. The off-loading system allows for minimal dressings that usually add excess pressure areas when the patient is weightbearing. The goal of the wound healing system is to allow partial weightbearing while off-loading the high-risk foot with ulcerations.
Surgical Management
The most conservative treatment of foot infections is used to rehabilitate, but antibiotic therapy alone is not always sufficient for treating aggressive virulent foot infections. Surgical intervention may be in the best interest of the patient if conservative therapy is not an option or has proven ineffective. Surgical debridement of all osteomyelitis and nonviable tissue must be completed. The surgeon will preserve as much length and width of the remaining limb as possible to balance the motor function. The goal of amputation is ambulation and reconstruction. Typical locations of partial foot amputations are shown below.
Metatarsal osteotomies can eliminate the intrinsic stresses caused by elongated or plantarflexed metatarsal joints in neuropathic limbs and decrease the number of amputations. Toe resections are the most distal amputation choices available. Expected outcomes of each toe resection are:
First toe (hallux): Interphalangeal disarticulation for an infected distal phalanx gives good balance. When possible a wafer of the proximal phalanx should be left to maintain the position of the sesamoids beneath the first metatarsal head. Second toe: Disarticulation results in loss of lateral support of the first toe. A second ray resection usually is better to avoid secondary hallux valgus. Third or fourth toes: The remaining toes tend to shift to close the gap. All five toes: A long forefoot lever is left with good weightbearing properties.
The advantages of the partial foot amputation are:
Preserves end weightbearing function Preserves proprioception Provides for limited disruption of body image Requires shoe modification/orthosis or limited prosthesis
Limitations of the partial foot amputation are:
Chopart amputation
Selected when a patient retains sensation in the heel pad Metatarsals and tarsals are removed, leaving a very short limb Difficult to suspend a shoe without the aid of an AFO or prosthesis
Transmetatarsal/Lisfranc amputation
Distal Metatarsal amputation
In all partial feet, it is important to watch for an equinus deformity due to the muscle imbalance created by removal of antagonistic muscles.
Implications for Removal of Part of All of the Calcaneus
Whether from trauma or chronic infection, the partial removal of the calcaneus is difficult. The most successful methods of controlling future breakdown have involved the patellar tendon-bearing (axial resist) orthosis or the neuropathic walker. A soft, room-temperature vulcanized foam has been used to fill a void between the orthosis and the heel area.
Deformities interfere with healing because of the mechanical problems they generate. Mechanical problems cause pressure concentrations or attenuation of soft tissues over the deformity, leading to callous formation, bursa formation, ulceration, and osteomyelitis. If the tissues are poorly oxygenated, the patient is at high risk for nonhealing or failed flaps and wound dehiscences after surgery. For wounds to heal and infections to be controlled, 20-fold or greater increases in blood flow and metabolic activity are required. If the examination, Doppler testing, or transcutaneous oxygen measurements indicate that these metabolic requirements are not likely to be met, vascular surgery consultation and angiography are indicated.
Optimal medical management includes addressing the following conditions that have ramifications commonly associated with problem wounds in the neuropathic foot:
Anemias, frequently in patients with diabetes and chronic wounds, especially in association with renal insufficiency. Malnutrition, especially with respect to adequate protein intake. Edema control with attention to fluid retention, chronic venous insufficiency, third spacing of fluids, or contraction of the fluid volume. Cardiac function deficiencies. Challenging wound flora that may require antibiotic combinations and special monitoring for optimizing dosing and avoiding toxicity. Diabetes care with careful control of blood glucose levels.
Most surgeries for managing wounds associated with the neuropathic, diabetic foot can be categorized into five types:
The two types of in-operating-room debridement are:
Excision of ulcers and debridement of underlying bone, cicatrix, and bursa Saucerization, a procedure that involves surgically excising the entire wound base to remove scar tissue and unroof cortical bone to encourage the development of a new healthy granulation tissue base to form. With the establishment of healthy margins, primary closures may be done with reasonable expectations of uncomplicated healing.
In-office correction of deformities is done with joint manipulations and tenotomies for toe deformities. Patients should be instructed in joint manipulations and stretching to be done on a daily basis to maintain corrections or improve the contractures.
Claw and hammer toe deformities are expediently managed in the office with percutaneous tenotomies of the bowstrung tendons and manipulations of the contracted joints to straighten the toes. The in-the-operating-room counterparts of these procedures are Achilles tendon lengthenings (preferably done percutaneously) and correction of deformities by ostectomies and osteotomies by minimally invasive techniques.
Wound Closures
Although wound closures are not usually considered to be in-operating-room procedures, there are office counterparts. These include skin closures with sutures or staples and partial approximations of wound edges with widely spaced sutures. This latter technique is particularly useful for reducing the surface area of the wound and can be done repeatedly as the viscoelasticity of the skin gradually accommodates to the tension of the partially approximating sutures. In the operating room, closures or coverage of wounds can be done with various surgical techniques.
Surgical Complexity:
Simple |
Split thickness skin graft
Full thickness skin graft
Rotation flaps
Advancement flaps
Microvascular flaps
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Complex |
Combination of surgical procedures |
When wounds cannot be covered or closed completely in the operating room, a small portion may be left open to heal by secondary intention. Occasionally the application of negative pressure wound therapy (e.g., The VAC [Vacuum Assisted Closure], KCI International, Inc., San Antonio, TX) may be useful, especially for cavitary wounds, for promoting wound contraction and assisting with the removal of secretions.
Simple amputations such as partial and complete toe removals can be done appropriately in an office setting. By excising skin and joint capsule, the diseased toe can be removed with minimal difficulty. A rongeur can shorten and contour any protruding bone. In general, such amputations are left open to heal by secondary intention or with partially approximating sutures. When formal amputations are indicated, an operating room is required. Two goals should be met:
Adequate resection to achieve a primary tension-free closure Preservation of as much tissue, especially underlying bony support, as possible.
Creativity and unconventional amputations may be needed for the neuropathic foot, such as ray resections, compound amputations in which half the foot is amputated at the forefoot level and the other half at the midfoot level, unconventional flaps such as using the skin of the dorsum of the foot to achieve plantar coverage, subtotal medial and lateral column resections, and very proximal midfoot amputations.
The more proximal the amputation, the more consideration should be given to lengthening the Achilles tendon and temporarily stabilizing the ankle joint with a percutaneous pin. The more unconventional the amputation, the more important the shoe wear prescription.
Treatment Considerations after partial foot amputation
Many foot amputation surgeries involve patients who have already had distal foot bypasses. One should exercise caution in shoe wear fitting any patient with a known distal leg bypass. High-topped shoes or leg orthoses requiring tight elastic stabilizing bands could compromise the bypass.
Procedures for special problems include toenail management in the in-office setting and management of Charcot deformities in the operating room. No patient with a neuropathic foot condition should leave the foot surgeon's office with long, dystrophic, dysmorphic, or fungus-infected toenails. The primary goal for the management of Charcot arthropathy is accommodative shoe wear, up to and including the CROW boot.
Superficial ulcers associated with Charcot arthropathy of the foot usually are successfully managed with bumpectomies and primary closures. When the Charcot arthropathy is "end stage" (a lower limb amputation has been recommended), complex surgical reconstruction, including massive debridement, realignment with or without osteotomies, and temporary stabilization with external fixation, is an option in the strongly motivated, highly compliant patient. A year's postoperative care and convalescence is usually required for this management.
Summary of Surgical Management
Most surgical procedures for the diabetic foot can be done with minimal expenditures of time and equipment and minimally invasive techniques. The management of almost all wound problems of the neuropathic foot has in-office and in-the-operating room counterparts. A team approach to postoperative management is required which includes the primary care physician, medical specialists, and diabetic educators. Patient compliance and family support is required to prevent recurrences or the development of new wound problems. Appropriate shoe wear prescribed by the prosthetist or orthotist is the final common denominator for allowing the patient to resume functional ambulation without undue risk of developing new or recurrent wound problems.
Ulcers
Three interventions have proven effective in reducing risk of ulceration:
For example, when a patient's ulcer is grade 0, preulceration, and the patient can sense the 10 gram monofilament (patient retains protective sensation), he or she will sense pain before damage occurs to the feet. Patients in this category usually do well with a standard shoe of correct sizing and a simple shock-absorbing pad.
Sinacore et al. found that fixed foot deformity prolonged healing of ulcers with total-contact casting when located in the midfoot and rearfoot. Ulcers located in the midfoot healed in 73 ± 29 days, rearfoot ulcers 90 ± 19 days. Individuals without fixed deformities with chronic diabetes mellitus and those with forefoot ulcers healed in 41 days.
Therefore, early detection during the musculoskeletal examination of a fixed foot deformity in a patient with an ulcer located in the midfoot or rearfoot can be used to determine a prognosis that healing time will be significantly longer when a total-contact cast is used as the treatment intervention.
Socks
Socks for the neuropathic limb should have no mended areas or seams over bony prominences. A cotton/acrylic blend will assist in the wicking of perspiration away from the foot. The sock should be fully cushioned and have a nonrestrictive top. Socks for the neuropathic foot should be seamless and without holes or repairs. Tube socks do not contour to the foot without folds that can cause irritation.
The socks should be a blend to wick perspiration and be nonconstricting at the calf. The use of white or light colors enables the patient to easily detect drainage caused by trauma. With a new shoe, the initial wearing or "break-in period" should be completed with two thin socks on each foot. The double socks will allow shear to occur between the socks and decrease the probability of rubbing and subsequent blistering from new leather.
The partial foot sock
Designed of highly elastic fibers Sock shape conforms to partial foot length and shape Single size fits a Chopart amputation, as well as a long transmetatarsal amputation There are no folds or seams to cause friction
Toe socks
Decrease maceration between toes A moist environment between the toes encourages fungal growth and may lead to ulceration and bacterial infection Seamless construction helps reduce overlapping of lesser toes but must be compensated for in shoe size if the socks are to be worn with shoes
The partial foot may require a block or filler within the shoe for the area of amputation. The purpose of a block is to reduce migration of the partial foot and medial/lateral shear for the toe amputation. No block or "prosthetic toe" is to be used for a central digit amputation. The low pressures applied by a block to central digits cause ischemic ulcerations on opposing surfaces.
Medial or lateral amputations (first and fifth toes) may require a block to hold the foot in the correct position within the shoe. The forefoot block holds the shoe leather away from the distal end of the foot and discourages distal migration of the foot. All forms of blocks must have space from the amputation site and be an integral part of the insert, not added to an existing orthotic. Forefoot blocks require a rigid rocker sole to prevent ulceration to distal end.
Treatment Considerations
Postural instability, gait instability, and risk of falling are compounded when the individual has forefoot or digit amputations. However, fillers and rigid soles with or without rocker bottoms are effective in counteracting the potential problems that can arise when walking is resumed with these types of amputations.
Diabetic sensory neuropathy causing inadequate sensory feedback affects the function of the stabilizing muscles that traverse the ankle joint. With loss of fine muscle balance, there is increased postural sway with walking and the generation of shear forces with loading. Currently, nonoperative techniques to manage and prevent wounds in neuropathic feet focus on pressure relief, stabilization, and fillers. Specialized shoe wear must be approached from a hierarchical perspective.
Although most neuropathic foot problems can be managed with nonoperative interventions; surgical interventions must be considered when problems persist or new, impending problems are developing because of deformities, muscle imbalances, or contractures. Proactive surgical procedures to reduce musculoskeletal deformities are practical, tested methods that complement footwear and off-loading strategies. Early surgical interventions can be time efficient and cost-effective managements.
Exercise Prescriptions
Care must be taken with exercise programs. When we walk, each step carries 150% of our body weight; jogging increases the force to 300% of the body weight. The patient with a neuropathic limb would be advised to choose an exercise program that includes aerobics, swimming, cycling, dance, or chair exercises. If walking is considered it should include slow, short steps only and no jogging.
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