Methods of treating plantar ulcers.

The purpose of this article is to describe the indications, precautions, and fabrication techniques for orthotic devices the authors use to facilitate the healing of plantar ulcers. The methods of fabricating and applying three types of orthotic devices developed by the staff at the Gillis W Long Hansen's Disease Center--walking casts, walking splints, and cutout sandals--are described. Patient examples are given for each of the methods. These techniques, in conjunction with patient education and the use of special footwear, provide clinicians with procedures they can use to aid in the healing of plantar ulcers secondary to leprosy, diabetes, or other neuropathic conditions. [Birke JA, Novick A, Graham SL, et al. Methods of treating plantar ulcers. Phys Ther. 1991;71:116-122.]

Key Words: Diabetes mellitus; Diabetic neuropathies; Orthotics/splints/casts, lower extremity; Ulcer; Wound healing.

The majority of plantar ulcers in the United States are secondary to the neuropathic complications of diabetes mellitus. [1,2] Loss of protective sensation and high plantar pressures are considered the primary causes of plantar ulcers. [3-5] Recent literature does not support the common view that diabetic plantar ulcers are caused by poor circulation. [6] These painless wounds are often chronic and resistant to healing because patinets inadvertently walk on the unprotected foot even after medical advice is given to the contrary. It is believed that wound healing is promoted when injurious plantar stresses are reduced by immobilizing the foot and redistributing plantar pressures. [2] When stress-reducing methods are used, diabetic plantar ulcers appear to heal at a rate comparable to that of ulcers seen with other peripheral neuropathic conditions. [7] Poor circulation, however, may in some cases delay wound healing.

For many decades, total contact casts have been used for the treatment of plantar ulcers in patients with leprosy. Brand introduced this cast to the United States in the 1950s, [8] but only recently have walking casts become popular for treatment of plantar ulcers in patients with diabetes and other neuropathies. The casts redistribute walking pressures, prevent direct trauma to the wound, reduce edema, and provide immobilization to joints and soft tissues. [9-11] Casts have been shown to improve the rate of healing when compared with traditional would care techniques [12]; the average healing time of diabetic plantar ulcers using casting methods is approximately 6 weeks (JA Birke, WC Coleman, A Novick, CA Patout; unpublished research). [12-14]

Use of the walking cast has been the treatment of choice for plantar ulcers for many years at the Gillis W Long Hansen's Disease Center (GWLHDC), Carville, LA. We believe, however, that the cast is not indicated in all cases of insensitive foot wounds. By incorporating the principles associated with casting, the walking splint and the cutout sandal were developed. We believe these devices have also been shown to be effective in the treatment of insensitive foot wounds (JA Birke, WC Coleman, A Novick, CA Patout; unpublished research).

     Table.  Ulcer Grades
Grade         Definition
0             Intact skin
1             Superficial ulcer
2             Deep ulcer to tendon, bone
               ligament, or joint
3             Deep abscess or
               osteomyelitis
4             Gangrene of forefoot or
               toes
5             Gangrene of whole foot

This article describes the indications, precautions, and fabrication techniques for the walking cast, the walking splint, and the cutout sandal and provides a case study example for each device. We believe that healing an ulcer, however, should not be considered the final step in the management of the plantar ulcer. We believe the use of interim footwear, monitoring foot temperature and skin condition during progressive ambulation, and the use of definitive footwear are all equally important. [15]

Wound Assessment

Plantar ulcers are often classified using a system described by Wagner [16] (Table). The healing techniques described in this article may be used for all Grade 1 ulcers and most Grade 2 lesions following any necessary surgical debridement. Differentiation between a Grade 1 ulcer and a Grade 2 ulcer can be assessed visually or by determining the wound depth by gently probing the wound with a sterile instrument. [15] Necrotic bone, tendon, fascia, or synovial joint tissue may compromise healing and requires surgical debridement. Grade 3 lesions with deep abscesses often require surgical incision and drainage, as wella s debridement of infected tissue. [16] Following the acute postoperative period when the infection has resolved, casts, splints, or cutout sandals may be beneficial. These devices may still be used following several days of bed rest and antibiotic therapy if cellulitis is present in the soft tissue areas surrounding the wound. Cellulitis is characterized by swelling, redness, and warmth and is evidence of infection. Surgery is the generally recommended treatment for gangrenous lesions of the foot (Grades 4 and 5); however, a walking splint may be useful for immobilization and protection from injury in both the preoperative and the postoperative periods.

The length, width, and depth of the ulcer are measured, and the wound perimeter is traced on sterilized x-ray film. Wound tracings have been shown to be a reliable method of measurement and provide a convenient record for reassessment by the patient and staff. [15,17,18] In our experience, patients are motivated to comply with treatment plans when they are able to see the progress in wound healing.

Wound Care

Overhanging wound edges and heavy callus are trimmed to promote epithelialization and to reduce stresses along the wound margins. [15] Wounds are debrided of necrotic tissue, cleaned with hydrogen peroxide or saline, and covered with light sterile dressings prior to application of the orthotic device. A topical antiseptic appropriate for the wound flora may be used. Convincing evidence, however, is not available to support the general use of any specific topical agent.

Walking Casts

The padding used in walking casts differs from the bulky padding applied for conventional fracture casting. [8,19] A thin cotton stocking provides the innermost layer. Orthopedic felt (0.32 cm [1/8 in] thick) is used to pad the malleoli, navicular, and tibial crest. Adhesive-backed foam-rubber padding (*) encloses the toes and covers the ulcer area (Fig. 1A). The toes are covered to prevent direct trauma or entry of foreign objects. In recent years, we have added cotton cast padding (+) to minimize the risk of secondary lesions from friction within the cast. The cast padding is layered over the less prominent bony areas, such as the posterior heel, base of the fifth metatarsal, and dorsum of the foot (Fig. 1B). To obtain an optimal total contact fit, the inner layers of plaster (1) are applied without stretching and are carefully molded over the contours of the foot (Fig. 1C). The combination of selective padding and molding results in pressure redistribution from the lesion area to the remaining foot and leg. Plaster splints reinforce the posteroplantar and mediolateral aspects of the cast. A 0.64-cm (1/4-in) section of plywood and a rubber walking heel (2) are positioned such that the center of the heel is at a location 40% of the distance from the heel to the toe (Fig. 1D). This heel placement creates a smooth rocking motion during walking. [8,19] The plywood board reinforces the bottom of the cast to prevent the heel from penetrating the plaster. Small pieces of plaster are used to fill the space between the plywood board and the plantar surface of the cast, so that the board appears level when viewed from the side and the front. Additional plaster bandages are used to strengthen the cast and secure the walking heel (Fig. 1E).

Infection, hypotrophic skin, and marked dependent edema are relative contraindications for the use of a cast on patients with insensitive feet. All chronic ulcers contain bacteria, but of concern is infection actively spreading into adjacent tissues (cellulitis) or deep into the compartments of the foot (abscess). Signs of active infection outside the boundaries of the wound are redness, swelling, and warmth and may also include swelling in the groin (lymphadenopathy) and fever. We believe a cast may be safely applied after an active infection is resolved by treatment with antibiotics and bed rest.

Hypotrophic skin, which is characterized by a thin and shiny appearance, is prone to secondary breakdown from cast rubbing. Patients with hypotrophic skin may be better monitored in other devices such as the walking splint or the cutout sandal. Edema is a problem with casting because the cast will usually become loose after several days, resulting in potential skin breakdown. When possible, edema should be reduced before casting by the use of elevation or a Job Extremity Pump [R] (3), and the cast should be replaced if it becomes loose.

The initial cast should be changed 1 week after application because of the concern of loosening attributable to edema reduction. Subsequent casts should be changed at 2-week intervals, unless heavy wound drainage (which often results in maceration of the would and further tissue breakdown) necessitates more frequent cast changes. Other reasons for early removal of the cast include leg or foot discomfort, cast loosess or damage, a lump in the groin, feve, or staining through the cast.

The patient was a 58-year-old woman with a 17-year history of insulin-dependent diabetes mellitus. At the time of referral to the GWLHDC, the patient had a 2-year history of a left third metatarsal head plantar ulcer. Prior treatment included whirlpool, debridement, dressing changes, and use of cast-boot footwear. The ulcer's area was 2 X 1.5 cm, and its depth was 3 mm. The patient had previously been advised by her physician that, because of her diabetes, the ulcer was not likely to heal and the foot would therefore require amputation. Dopler studies showed and ankle ischemic index of .76.

The wound was debrided and dressed, and the patient was fit with a walking cast. The first cast was changed after 1 week, and the ulcer was noted to be smaller but accompanied by heavy drainage, foul door, and maceration of the would area. The would edges were trimmed and redressed, and another cast was applied. Because of the heavy drainage, the patient was instructed in the partial weight-bearing use of a walker after a 24-hour drying period and scheduled for weekly cast changes. By week 3, the drainage had decreased significantly. The patient was subsequently recasted at 2-week intervals until the wound was fully closed (ie, the seventh week). The patient was then fit with molded Plastazoe [R] (#) sandals, instructed to continue partial weight-bearing use of the walker, and measured for extra-depth shoes. (**) At week 9, she was fit with shoes with a molded insole. The patient was progressed slowly to walking activities over the next 4-week period, while skin temperature and condition were monitored. She returned for monthly checkups and remained lesion-free 4 months after treatment.

Walking Splints

In ourt experience, the walking splint is an acceptable alternative to casting and may be preferred over casting in the presence of hypotrophic skin, active infection, or poor circulation. The splint may also be used on patients who are extremely fearful of confinement or who experience secondary injury from casting. The walking splint may also be used by clinicians who are inexperienced with casting techniques.

The walking splint may be preferred when ulcers are associated with poor circulation, so that the clinician can closely monitor the status of the wound. The ratio of the systolic blood pressure in the ankle, foot, or great toe as compared with the arm has been used as an ischemic index. The use of casting for diabetic foot ulcers has been recommended when the ischemic index is greater than .45. [9,14] Other investigators [13,20-22] have found that ulcers and surgical wounds in diabetic feet heal in the presence of even lower ischemic indexes.

The walking splint may also be used, with variations in the padding technique, in the treatment of lesions on nonplanta areas of the foot and ankle. An appealing feature of the splint is the ease with which it may be removed. Easy removal, however, is a clear disadvantages for some patients, who may inappropriately remove the device and walk on the unprotected foot. The walking splint also lacks the snug fit that is provided by the walking cast. A snug fit is considered beeneficial for redistributing walking pressures and minimizing shear stresses at the lesion site. [8]

After applying a light dressing to the wound (or a bulky dressing if there is a large amount of wound drainage), the leg is generously wrapped with cotton cast padding. Relief areas for the posterior heel and plantar lesion are provided with adhesive-backed foam-rubber padding. Bony prominences, such as the malleoli and the navicular, are padded with 0.32-cm (1/8-in) felt (Fig. 2A). The inner shell is made of two sets (five layers each) of plaster splints overlapped in the center (Fig. 2B). The strength of the device is improved by extending the medial and lateral trim lines to the midline of the malleoli and reinforcing the plastic layers with fiberglass casting tape (Fig. 2C). A rubber walking heel (positioned and leveled as described for the walking cast) is secured to the bottom of the splint with a second roll of fiberglass casting tape. The fiberglass casting tape. The fiberglass taping that covers the dorsum of the foot is removed (Fig. 2D). The inner layer of cast padding is cut along the anterior leg and dorsum of the foot to allow removal of the device. An elastic wrap is used to secure the splint to the leg (Fig. 2E). Patients are followed at 1- to 2-week intervals to observe the progress of wound healing.

Case Study 2

The patient was a 54-year-old man with a 15-year history of diabetes melitus, who is currently insulin-dependent. The patient was referred to the GWLHDC for treatment of a right lateroplantar heel ulcer of approximately 2 months' duration. Prior treatment included whirlpool, wound care, topical antibiotics, and non-weight-bearing use of crutches. The lesion measure 9 X 11 mm in area and could be probed to a depth of 4 cm in three separate directions. The ischemic index at the foot was .74.

The lesion was debrided and cleaned with hydrogen peroxide. The patient was fit with a walking cast and instructed to ambulate partial weight bearing with crutches after a 24-hour drying period. The patient returned to the GWLHDC 2 days later with extreme fear of wearing the cast and requested that it be removed immediately. No problems were noted when the cast was removed, but to alleviate the patient's fears, a walking splint was fabricated. He was instructed to remove the splint daily for dressing changes and to continue partial weight-bearing ambulation. During the fourth week of treatment, a small abscess was noted that required additional debridement. The ulcer was fully closed in 7 weeks.

The patient was then fit with molded Plastozote [R] sandals, instructed to continue partial weight-bearing use of crutches, and measured for a pair of extra-depth working boots. The boots were not received until week 11, at which time the patient was fit with molded insoles. He was progressed to normal walking activities over the next several weeks and remained ulcer-free 4 months after the initial treatment.

Cutout Sandal

The cutout sandal is the orthotic device of choice for lesions on the plantar surface of the toes. We do not believe the sandal has been as successful for plantar lesions at other areas of the foot. This lack of success may be due to the inability of the scandal to control movement between the foot and the sandal during walking. This movement likely increases stresses at the lesion site, which could increase healing time.

Construction of the molded Plastazote [R] sandal has been described in detail elsewhere. [22,23] Layers of medium and firm Plastazote [R] are heat-molded to the foot (Fig. 3A). The foot is covered with a cotton sock to provide protection from thermal injury during molding. The materials are then glued and finished on a belt grinder before attaching the straps (Fig. 3B). Plastazote [R] layers are relieved or completely cut our directly beneath and distal to the lesion site to eliminate contact with the ulcer (Fig. 3C). Edges are carefully rounded to minimize edge stresses. The sandal is bound with rigid Plastazote [R] and soled with neoprene crepe (Fig. 3D).

If fabrication of a complete sandal is not possible, one alternative is to mold a Plastazore [R] insert and secure it into a cast boot, a wooden-soled postoperative shoe, or a Darco shoe. (++) The insert can then be relieved similarly at the lesion site.

Case Study 3

The patient was a 52-year-old woman with a 3-year history of diabetes. She was referred to the GWLHDC with a nearly circular 13-mm-diameter lesion on the medioplantar aspect of the left hallux under the interphalangeal joint. Depth of the wound was determined to be 10 mm. The wound was of 9 months' duration. Previous treatment included soaks, debridement, dressings changes, and several courses of antibiotics. The ischemic index at the foot was .86.

The patient was fit with a cutout sandal designed to completely eliminate vertical and shear stresses directly under the lesion while maintaining weight bearing to the remainder of the foot. She returned to the physical therapy department for four follow-up visits during the next 7 weeks. On the fourth follow-up visit, the lesion was found to be healed. She was then progressed to a pair of running shoes with protective insoles. The patient remained ulcer-free 1 year after the in tial treatment.

Bilateral Involvement

Patients with bilateral foot lesions may be managed with any appropriate combination of the three pressure-relieving appliances. When patients are fit bilaterally with walking casts, the walking heels may be reduced in height, cast boots may be applied, or crepe soling may be glued directly to the bottom of the device to improve stability.

Patient Instructions

All patients are instructed in partial weight-bearing ambulation with crutches or a walker to provide additional weight-bearing relief and to increase stability. Advice is given for appropriate style selection and fit of footwear on the uninvolved foot, because the noninvolved foot may be subjected to increased weight-bearing stresses during the healing process. [22] In addition, the following device-specific instructions are provided

Walking Casts/Walking Splints

To allow thorough drying, the patient should not stand or walk on the device for 24 hours. The clinician should be notified immediately if there is leg or foot discomfort, cast looseness or damage, a lump in the groin, fever, excessive drainage, or staining through the cast.

Patients fit with the walking splint are taught how to carefully remove and replace the device for wound-dressing changes and how to inspect the skin for signs of pressure. The splint should be removed twice a day during the first 48 hours for skin inspection. After 48 hours, the splint can be removed daily for dressing changes or even less often if there is minimal drainage. Otherwise, the splint should be worn continuously. A sock should be worn on the opposite leg to protect the skin from abrasions caused by the cast or splint during sleeping. A consent form that includes instructions and precautions is reviewed and signed by eahc patient receiving a cast or splint.

Cutout Sandals

The patient is instructed to remove the sandal at least twice daily and to inspect the ulcer and skin condition. Special attention should be directed to the possibility of skin irritation along the borders of the sandal and straps. The clinical should be notified immediately if there is leg or foot discomfort, damage to the scandal, a lump in the groin, or fewer.

Conclusions

Many physical therapists are involved in the care of plantar ulcers, most commonly seen in the diabetic patient. Traditional treatment methods such as whirlpool and dressing changes alone may be indicated for wounds involving non-weight-bearing areas of the body. In our opinion, however, plantar lesions require immobilization and pressure relief for wound closure. The techniques described in this article are recommended for use in physical therapy wound-treatment programs.

References

[1] Levin ME. The diabetic foot: pathophysiology, evaluation, and treament. In: Levin ME, O'Neal LW, eds. The Diabetic Foot. 4th ed. St. Louis, Mo: CV Mosby Co; 1988:1-50.

[2] Brand PW. Repetitive stress in the development of diabetic foot ulcers. In: Levin ME, O'Neal LW, eds. The Diabetic Foot. 4th ed. St Louis, Mo: CV Mosby Co; 1988:83-90.

[3] Ctereteko GC, Dhanendran M, Hutton, WC, et al. Vertical forces acting on the feet of diabetic patients with neurophatic ulceration. Br J Surg. 1981;68:608-614.

[4] Birke JA, Sims DS Jr: Plantar sensory threshold in the insensitive foot. Lepr Rev. 1986; 57:261-267.

[5] Boulton AJ, Hardesty CW, Betts RP, et al. Dynamic foot pressure and other studies as diagnosis and management aids in diabetic neuropathy. Diabetes Care. 1983;6:26-33.

[6] Sims DS Jr, Cavanagh PR, Ulnrech JS. Risk factors in the diabetic foot: recognition and management. Phys Ther. 1988:1887-1902.

[7] Hampton GH, Birke JA. Treatment of wounds caused by pressure and insensitivity. In: McCullough J, ed. Comteporary Perspective in Rehabilitation: Wound Healing Philidelphia, Pa: FA Davis Co; 1990:196-219.

[8] Coleman WC, Brand PW, Birke JA. The total contact cast: a therapy for plantar ulceration on insensitive feet. J Am Podiatr Med Assoc. 1984;74:548-552.

[9] Mooney V, Wagner FW. Neurocirculatory disorders of the foot. Clin Orthop. 1977; 122:53-61.

[10] Pollard JP, LeQuesne LP, Tapping JW. Forces under the foot. J Biomed Eng. 1983;5:37-40.

[11] Birke JA, Sims DS Jr. Bufford WL. Walking casts: effect on plantar foot pressure. J Rehabil Res Dev. 1985;22:18-22.

[12] Mueller MJ, Diamond JE, Sinacore DR, et al. Total contact casting in treatment of diabetic plantar ulcer: comtrolled clinical trial. Diabetes Care. 1989;12:384-388.

[13] Sinacore DR, Mueller MJ, Diamond JE, et al. Diabetic plantar ulcers treated by total contact casting: a clinical report. Phys Ther. 1987;67:1543-1549.

[14] Walker SC, Helm PA, Pullium G. Total contact casting and chronic diabetic neuropathic foot ulcerations: healing rates by wound location. Arch Phys Med Rehabil. 1987;68:217-221. [15] Birke JA, sims DS Jr. The insensitive foot. In: Hunt GC, ed. Physical Therapy of the Foot and Ankle. New York, NY: Churchill Livingstone Inc; 1988:133-168.

[16] Wagner FW: the dysvascular foot: a system for diagnosis and treatment. Foot Ankle. 1981;2:64-122.

[17] Bohannon RW, Pfaller BA. Documentation of wound surface area from tracings of wound perimeters: clinical report on three techniques. Phys Ther. 1983;63:1622-1624.

[18] Diamond JE, Mueller MJ, Delitto A, Sinacore DR. Reliability of a diabetic foot evaluation. Phys Ther. 1989;69:797-802.

[19] The Total Contact Cast: Instructional Videotape. Carville, La: Training Branch, Gillis W Long Hansen's Disease Center; 1983.

[20] Ramsey DE, Manke DA, Summer DS. Toe blood pressure: a valuable adjunct to ankle pressure measurement for assessing peripheral arterial disease. J Cardiovasc Surg. 1981;24:43-48.

[21] Barnes RW, Thornhill B, Nix L, et al. Prediction of amputation would healing. Arch Surg. 1981;116-80-83.

[22] Coleman WC. Footwear in a management program of injury prevention. In: Levin ME, O'Neal LW, eds. The Diabetic Foot. 4th ed. St Louis, Mo: CV Mosby Co; 1988:293-309.

[23] Coleman WC, Plaia A. Soft molded sandals for insensitive foot care. Clin Pros Orth. 1988;12:67-73.

(*) 0.96-cm (3/8-in) Sifoam, Knit-Rite, 2020 Grand Ave, PO Box 208, Kansas, MO 43694.

(+) Webril, The Kendall Co, Hospital Products, 1 Federal St, Boston, MA 02110.

(1) Gypsona, National Patent Development, PO Box 423, Dayville, CT 06241.

(2) Zimmer Ray Associates, PO Box 53202, New Orleans, LA 70153.

(3) Jobst Institute Inc, PO Box 653, Toledo, OH 4369-0653.

(#) Bakelite Xylonite Ltd, London, England, distributed by AliMed Inc, 297 High St. Dedham, MA 02026.

(**) PW Minor & Son Inc, PO Box 687, Batavia, NY 14021-0678.

(++) AliMed Inc, 297 High St, Dedham, MA 02026.

J Birke, MS, PT, is Director of Physical Therapy, Gillis W Long Hansen's Disease Center, Carville, LA 70721 (USA). Address all correspondence to Mr. Birke.

A Novick, MA, PT, is Research Therapist, Paul W Brand Biomechanics Laboratory, Gillis W Long Hansen's Disease Center.

S Graham, MS, PT, is Staff Physical Therapist. Alaska Native Medical Center, PO Box 107741, Anchorage, AK 95510-7741.

W Coleman, DPM, is Staff Podiatrist, Ochsner Clinic, 1514 Jefferson Hwy, New Orleans, LA 70121

D Brasseaux, BS, PT, Staff Therapist, Gillis W Long Hansen's Disease Center.