A Helpful Primer On Total Contact Casts

Neuropathic foot ulcers are the most common precursor of lower–extremity amputation in patients with diabetes.1 In the podiatry literature, as well as other wound care literature, the total contact cast (TCC) has long been considered the gold standard for treating non-infected, neuropathic foot ulcerations.2 The TCC heals wounds by reducing weightbearing pressure and shear force to the plantar aspect of the foot. The unique well-molded, minimally-padded construct of the cast allows it to maintain “total contact” with the foot and lower leg. Clinical results overwhelmingly validate the use of TCC in healing neuropathic foot wounds. A study by Armstrong, et. al., involved 63 patients with non-infected neuropathic plantar foot ulcers and compared the TCC with a removable cast walker and a half shoe.3 All patients were followed for 12 weeks and had weekly visits for wound care and debridement. The ulcer healing rate for the TCC patients was 89.5 percent, compared with 65 percent for patients treated with the removable cast walker and 58.3 percent for patients treated with a half shoe. Mueller et. al., also compared the TCC with another treatment modality.4 Patients were randomized to receive TCC treatment or to avoid weightbearing and use sterile saline wet-to-dry dressings. Ninety percent of the TCC group healed within 42 ± 29 days, whereas only 67 percent of the non-TCC group healed within 65 ± 29 days. Myerson et. al., reviewed previous reports of TCC therapy and found a combined average healing rate of 75.5 percent after an average of 38.7 days in the cast.5 In their study, 90 percent of 71 ulcers were healed at a mean of five and a half weeks. We have used TCC extensively in our wound care clinic over the past 10 years and have applied more than 2,100 casts in the past three years alone. Despite the efficacy of the TCC, it is a modality that is still not widely used. One of the main reasons for this is the lack of standardization in application technique and materials. With this in mind, we’ve provided a thorough overview of the TCC, including detailed explanations of its application and removal. We hope to not only illustrate that the TCC is a beneficial addition to any wound care practice, but dispel some of the myths impeding its use. Reducing Peak Plantar Pressures Ambulatory short leg casts were first introduced by Kahn and Paul, who developed the technique in the 1930s to treat lepers in India.6,7 In the 1950s, Brand and colleagues embraced the walking cast technique. They reduced the amount of padding and brought it to America.8,9 Today, physicians around the world employ the TCC to treat pedal ulcers related to Hansen’s disease, diabetes and other ailments resulting in insensate feet. The TCC facilitates ulcer healing by effectively reducing plantar pressures. Birke, et. al., reported that a TCC reduced pressure at the metatarsal heads in six normal subjects by up to 84 percent.10 Hartsell et. al., found a 65 percent reduction in forefoot plantar pressures when comparing the TCC to a running shoe.11 The same study showed excellent reproducibility of load redistribution with TCC applications spaced one week apart and performed by the same technician. Shaw, et. al., demonstrated that the TCC allows one to transfer approximately 30 percent of the weightbearing load directly to the cast wall.12 Several mechanisms contribute to the reduction of peak plantar pressures in the TCC. The TCC is molded to the foot and lower leg in order to redistribute pressures over a larger surface area, including the transmission of body weight to both the heel and the lower leg. This allows for the “cone effect” by which an inverted cone (the leg) makes total contact with a conical receptacle (the cast). In order to ensure that the load bearing forces are effectively transmitted to the walls of the cast, the patient must be casted in this position. The intimate contact of the cast with the foot and leg also reduces shear forces normally present between the foot and shoe. The TCC alters the patient’s gait by requiring a shortened stride length and a decreased walking velocity. The TCC also eliminates sagittal plane ankle joint motion and the propulsive phase of gait, thereby reducing the forefoot pressures that normally occur with toe-off. A Review Of Indications And Contraindications One should consider the TCC as first-line therapy for non-infected, neuropathic, plantar foot wounds. This includes the treatment of postoperative delayed primary closures as well as pre-ulcerative conditions. Be sure to debride ulcers prior to instituting cast therapy as well as at weekly intervals when you change the cast. Also obtain weekly measurements and/or photographs so you can document the progression of healing. The TCC is also indicated for treating the acute stage of Charcot neuroarthropathy. By eliminating the stresses of weightbearing, the TCC allows the condition to consolidate. In these cases, cast the patient at two-week intervals for three to six months or until you see clinical and radiographic evidence of coalescence. Absolute contraindications for TCC include infection and severe arterial insufficiency. Proper wound debridement to healthy, bleeding tissue helps in making an early identification of an abscess or osteomyelitis. If you suspect an infection, you must eradicate it prior to employing a TCC. Involvement or exposure of deeper structures (tendon, joint capsule or exposed bone) should also be considered a contraindication. Total contact casting is contraindicated for patients who do not have an adequate vascular status for healing. Therefore, one must document adequate vascular supply either by direct palpation of pedal pulses or via a Doppler ultrasound. You should also assess the patient’s skin quality prior to initiating cast therapy. Any patients with active dermatoses or contact allergies to any cast components should not be casted. As with any treatment plan, carefully consider patient compliance. Patients must be able to comply with the cast care instructions, including the need to keep the cast dry and returning for scheduled appointments for recasting. Relative contraindications include blindness, ataxia, obesity and claustrophobia. In these cases, individual circumstances should guide the decision to employ casting. Key Points For Patient Education Before initiating cast therapy, you should sit down with the patient and discuss the role of TCC in wound healing in detail. During the discussion, it’s important to make the patient aware of possible complications of casting. A patient instruction handout on appropriate cast care can be very helpful in this regard. Patient instructions should include the following key points. • If the cast is loose or rubbing or causing pain, call the doctor as the cast may need to be changed. • The first cast change will take place two to three days after the initial cast has been applied. • Subsequent cast changes will range between twice a week to every other week. • If you develop a fever, chills, nausea or vomiting, the cast must be changed in order to ensure there is no underlying infection. • Keep the cast dry. If the cast gets wet, it must be changed. • If the cast is removed in a hospital or emergency room, the cast technician must be notified that there is only padding on the front over the shin, on the ankles and over the foot and toes. These are the only places they can cut with a saw to remove the cast. • You will need to wear a cast for at least two additional weeks after the wound has healed in order to allow your skin to return to normal thickness. • If you have any questions, call me or have me paged. Pertinent Pearls On Casting And Recasting In addition to the points above, the patient must be able to comply with regularly scheduled appointments for debridement and recasting. After you have debrided the wound and applied any topical agents (if desired), cast the patient in the prone position (see “Fourteen Steps To Applying A Total Contact Cast” below). Casting the patient in the prone position prevents the development of edema in the foot during application and relaxes the gastrocnemius muscle to allow a more intimate fit to the distal lower extremity.8,12 When the patient is in the prone position, one can also allow any excess soft tissue to shift toward the knee. Doing so facilitates maximum use of the cone effect. As we noted above, after the first TCC application, the patient should return in two to three days for the first cast change. This is critical to preventing cast abrasions or new ulcers as the initial decreases in leg volume from the cast may allow the leg to “piston” in the cast. After the first cast change, the time between cast changes is determined at your discretion. It is our practice to see patients with ulcers at weekly intervals. When treating patients who have Charcot neurarthropathy without wounds, we do the cast changes every two weeks. The time may vary depending on the amount of leg atrophy between visits. Prior to removing the cast, one should note the amount of “pistoning” present and make any adjustments to the cast change interval if necessary. We have shown that a patient visit for a cast change takes an average of 29 minutes. Preparation of the cast can be done by trained office staff and takes an average of seven minutes and 34 seconds. An average of 13 minutes and 55 seconds is required for the patient to remain non-weightbearing while the cast dries. The actual amount of time that a physician spends applying the cast on average is seven minutes and 32 seconds.13 Fourteen Steps To Applying A Total Contact Cast 1. Apply a foam dressing to the ulcer area and secure the dressing with paper tape. If the sterile package appears to be compromised, do not use it. 2. Place the stockinette over the foot, extending to the knee. Pull the stockinette forward to cover the toes and fold approximately two to four inches over the dorsum of the foot. Trim the excess and secure with plastic tape. 3. Place a strip of felt along the anterior crest of the tibia with flaps covering the malleoli. 4. Fold adhesive foam lengthwise to cover the toes completely, with the top and bottom sticking to the stockinette. Trim the excess from each side. 5. Place the patient in a prone position with the leg flexed at the knee. Apply webril around the leg, overlapping slightly at the shin area. 6. Maintain the foot in a neutral position with the ankle as close to 90 degrees as possible. Be sure not to crimp materials in toes or heel/ankle areas during application. 7. Using a 4-inch roll of plaster, briefly wet the material. Wrap the foot and leg from distal to proximal. All “tucks” or folds of excess plaster should be made over the padded areas only. 8. Wet a 3-inch roll of fiberglass and apply in the same fashion. Wrap the foot and leg from distal to proximal. All tucks or folds of excess plaster should be made over the padded areas only. 9. Fabricate a posterior splint from 4-inch fiberglass without wetting, extending from the toes to the most proximal part of casting material. Place the splint so any excess material hangs over the width of the foot medially and can be rolled inward to fill any void in the arch area. 10. Place 1/4-inch plywood on the bottom of the foot with a walking heel. 11. Fashion another posterior splint with 3-inch fiberglass without wetting and cut in the appropriate place for the walking heel to show through. 12. Apply a final layer of wet 4-inch roll of fiberglass as in step 8 to finish the cast. 13. Do not allow weightbearing for 15 minutes or until the cast has cooled and hardened. 14. Provide the patient with an instruction sheet and an emergency removal instruction card. Instruct the patient to carry the card with him or her in case of an emergency. Be Aware Of Potential Complications After applying a TCC, you may encounter complications, including new ulcers or abrasions caused by the cast. These complications may occur if the cast becomes loose, rubs in any area or pistons on the leg with walking. One should be well-trained in applying these casts in order to minimize these complications. Other complications include pain from the cast or the development of any systemic signs of infection such as fever, chills, nausea or vomiting. At the first sign of any of the above complications, one should remove the cast and reassess the patient prior to reapplying the TCC. Removal of the TCC requires familiarity with the cast and its unique areas of padding. (See “How To Remove The TCC” below.) How To Remove The TCC Since there is no posterior or lateral padding in a total contact cast (TCC), using a cast saw to remove the cast without cutting, abrading or burning the patient requires significant caution and great care. The procedure to remove a TCC is as follows: • Note the lines in the photo that indicate approximate cuts for removing the cast. • Make two parallel cuts down the anterior crest of the tibia approximately 1 inch apart on the padded area. • Cut medially and laterally over the padded area to the malleoli. • Cut distally across the toes medial to lateral. • Open the cast with small spreaders. • Remove the padding along the tibia and dorsum of the foot. • Use blunt scissors to cut the stockinette from top to bottom. • Remove the foot and leg from the cast. Essential Post-TCC Care In order to facilitate the patient’s smooth transition into shoes after he or she has achieve wound healing with the TCC, it is our practice to cast patients for extra-depth shoes with custom insoles prior to complete wound healing. This allows time for the shoes to be made and delivered so the patient does not return to inappropriate shoes after graduating from the cast. Frequent follow-up in the first several weeks after wound healing is also important to ensure proper shoe fit and accommodation for high-pressure areas. Without appropriate shoe gear, recurrence rates can be as high as 83 percent within 26 months of wound healing.14 Case Study: How A TCC Resolved A Four-Month-Old Ulcer One 58-year-old female came into the office. She had a 24-year history of diabetes and Charcot neuroarthropathy. Her foot ulcer had been present for four months. Past treatments included various topical medications, foot soaks and antibiotics. We evaluated and treated the patient at our wound center with weekly debridements and TCC. Her wound healed in 55 days. The patient has maintained her healed status in accommodative shoes and custom inserts. In Conclusion The TCC benefits patients, payers and practitioners alike. The benefit to the patient is the ability to ambulate and continue daily activities while achieving the unsurpassed healing benefits of the TCC. Payers benefit because successful healing of wounds eliminates the potential risk and added cost of lengthy hospitalizations, amputations, long-term antibiotics and rehabilitation. For example, PacifiCare of Colorado estimated in 1996 that a below the knee amputation costs approximately $75,000 from wound inception to prosthetic fitting. For practitioners, the TCC heals wounds more rapidly than any other treatment modality tested to date and allows for the incorporation of a gold standard therapy into practice. Fortunately, Medicare recognizes the TCC as the gold standard for plantar wound healing and currently reimburses for both application and materials. Perhaps the TCC has a place for treating patients with wounds in your clinical practice. Dr. Jensen is an Associate Professor at the University of Colorado Health Sciences Center. He is also a Diplomate of the American Board of Podiatric Surgery. Dr. Jaakola is a third-year resident within the Podiatric Surgical Program at the North Colorado Medical Center in Greeley, Co. Dr. Weber is a second-year resident at the aforementioned institution. Dr. Dairman is in private practice in Suffolk, Va.
 

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