OFF-LOADING

Off-loading is the most frequently used treatment for diabetic foot ulcers, especially for plantar ulcers. It physically alleviates pressure from the wound and surrounding tissues and allows for redistribution of pressure across a greater area of the foot. Off-loading also eliminates shear, protects the bony structure of the foot, and facilitates increased circulation to the wound (WOCN, 2021).

The International Working Group on Diabetic Foot Ulcers has made the following recommendations on the role of off-loading in the treatment of uncomplicated diabetic foot ulcers:

• Pressure relief needs to be a part of the treatment plan for all diabetic foot ulcers.
• Total contact casting (TCC) and nonremovable walker casts are the preferred forms of off-loading.
• Normal footwear and standard therapeutic shoes should not be used in an attempt to provide off-loading.
• Patients should be advised to limit standing and walking and to rest with the affected extremity elevated as much as possible.
  (IWGDF, 2019)

Total Contact Casting for Offloading

TCC is regarded as the gold standard for healing diabetic plantar ulcers, with reported healing rates of between 72% and 100% over a period of five to seven weeks. These healing rates are achieved by consistently distributing pressure over the complete plantar surface of the foot and by ensuring patient compliance since the cast cannot be removed. However, not all patients are candidates for total contact casting. The most important consideration is adequate circulation to the extremity (IWGDF, 2019; Baranoski & Ayello, 2020).

TCC APPLICATION

A total contact cast has minimal padding and is gently molded to the shape of the patient’s foot. A rocker bottom walking plate or sole is attached to assist with walking while at the same time eliminating pressure during ambulation. TCC is closed at the toes to prevent possible injury (WOCN, 2022).

DISADVANTAGES TO TCC

There are drawbacks to using TCC as an intervention for an existing diabetic foot ulcer. One of the most critical is that it prevents frequent wound assessment since the cast is normally only replaced once a week. However, a skilled clinician can apply a TCC with cut-out windows around the wound(s), which allows for dressing changes and wound inspection in the interval between TCC changes (Bryant & Nix, 2016).

Other disadvantages of TCC include:

• It must be applied by fully trained and experienced clinicians.
• It is time consuming to apply and remove.
• Improper application can lead to skin irritation and further ulcer development.
• In most cases it makes it impossible for the patient to continue working.
• It can make it difficult for the patient to sleep.
• The cast must be kept dry, so showering and bathing becomes a problem.
• It can be uncomfortable to wear, especially during warm and hot weather.

Removable Cast Walkers

Other options for off-loading diabetic foot ulcers are removable devices, although none of them has demonstrated the same healing rates as TCC. However, such devices do allow for frequent wound inspection and are often a better match for the patient’s lifestyle. They permit patients to bathe and sleep more comfortably.

The biggest drawback with removable devices is a common lack of patient compliance, and this may account for their decreased effectiveness compared to TCC. The findings from one study indicated that patients wore their removable off-loading device less than 30% of the time on a daily basis.

Another alternative to TCC is a prefabricated pneumatic walking brace (PPWB) fitted with a custom insole. PPWBs have the advantage that they are easy to remove, have a high satisfaction rating with patients, and have not been associated with any major complications. They are made from a lightweight, partially rigid casing with an inner lining that supports the patient’s lower leg on the affected side to a few inches below the knee. They are usually secured in place with buckles and Velcro straps. However, they have limited use in patients with severe foot deformity. A further drawback is patient compliance, since this is a device that can be removed at home.

Since most patients do not consistently wear removable cast walkers, patient education on this topic is vital. Walking even short distances without a cast walker is contraindicated and puts the patient at risk for a nonhealing ulcer and possible amputation (IWGDF, 2019).

Felt Foam Dressing

Felt foam dressing (FFD) is sometimes referred to as the “football” dressing due to its final shape. It is constructed of inexpensive gauze dressings and foam. It provides the off-loading advantages of TCC and is used along with special footwear such as a surgical shoe or a walking splint. The FFD is constructed using adhesive felt cut to accommodate the shape of the patient’s foot, with a window cut out over the wound site.

The clinician applies skin-prep to the patient’s foot then places the adhesive side of the felt to the patient’s skin, ensuring that the window is directly over the wound site. The pad is then wrapped in place with a gauze bandage, secured with tape, and covered with a sock or stockinette. Finally, a surgical shoe is applied (WOCN, 2022).

How often FFD is changed is often dependent on the patient’s ability to return to the clinic. Notably, one study indicated that felted foam reduces peak plantar pressure at the wound site by approximately 70% for the first three days of wear but by the fourth day has lost the ability to provide pressure relief (Armstrong & Lavery, 2016).

Healing Shoes

Inexpensive, off-the-shelf shoes are available that provide off-loading and enhance wound healing. These shoes also have the advantage of being reusable. Darco boots are one example of this type of footwear; they provide room for bulky wound dressings and closed-toe protection. They can also be fitted with cushioning insoles (Abbas & Bal, 2019; Wound Source, 2021).

An important feature of pressure-relieving shoes is a specialized insole that allows for customized pressure relief using a removable peg system. The first step is for the clinician to place a transparent film over the wound and outline the wound site with a marker. The clinician then asks the patient to step on the insole, which transfers the shape and area of the wound onto the insole. The clinician then removes the pegs from the insole in the area of the wound, effectively off-loading the wound site when the patient ambulates.

Other variations of these shoes include the Ortho-wedge forefront off-loading shoe and the heel wedge off-loading shoe. The Ortho-wedge forefront off-loading shoe provides pressure relief for the toes and metatarsal head using what is known as a rocker bottom wedge. The construction of this shoe, which includes 10 degrees of built-in dorsiflexion, redistributes weight from the forefoot to the hindfoot, while the presence of a semirigid heel adds stability. The heel wedge off-loading shoe removes pressure from the posterior end of the patient’s foot, with pressure being transferred to the midfoot and forefoot areas (Baranoski & Ayello, 2020).

Healing shoes have the same disadvantages as other removable pressure-relief devices, particularly patient compliance. Another concern is safe ambulation, and the wound care clinician (nurse, physical therapist, or occupational therapist) must ensure that the patient receives instruction on walking safely when wearing healing shoes. The clinician should also caution the patient that driving while wearing healing shoes is not advisable; family members and friends should be enlisted to assist with transportation.

Other Off-Loading Devices

Crutches, knee scooters, walkers, and wheelchairs can also be used to assist with off-loading.

Safe ambulation and stability are crucial for patients using these off-loading devices. The physical therapist determines the most appropriate mobility aid for the patient based on the patient’s current mobility status (i.e., wheelchair, walker, or crutches).

Physical therapy interventions also include exercises for balance and coordination and gait training. Therapists instruct the patient on the type of gait that will allow for safe ambulation, usually three-point gait for patients with off-loading. Other team members also observe that the patient is performing the gait correctly and reinforce teaching.

It may also be necessary for an occupational therapist to assess the patient’s home environment, with the patient’s permission, to determine what hazards and risks are present for safe mobility. For example, for a patient on crutches who has stairs at home, negotiating stairs with crutches must be included in the patient education (Inverarity, 2021).

CRUTCH WALKING

Crutch walking is a special technique and ideally includes instruction from a physical therapist, who also ensures that the crutches are a correct fit for the patient. The therapist may recommend either axillary or forearm crutches depending on the patient’s overall condition and level of trunk stability. The therapist also ensures correct sizing and positioning of the crutches. It is recommended that axillary crutches reach to 1 to 1-1/2 inches below the patient’s armpits when standing erect. Younger patients often do better with crutches than older patients, who may not have the upper body strength and endurance to safely use crutches. Crutches should not be prescribed for a patient with postural hypotension due to the increased risk of falling.

There are several different gait patterns that can be used with crutches. For individuals who are non-weight-bearing on one leg, the recommended gait pattern is three-point crutch gait. The physical therapist instructs the patient in the following step sequence:

• Move both crutches and the non-weight-bearing leg forward in one movement.
• Bear weight down on the crutches and move the unaffected leg forward.
• Repeat this pattern of movement.

While this gait pattern eliminates weight from the affected leg, it also requires that the patient has good balance to be able to perform it safely (Warees et al., 2021).

KNEE SCOOTER USE

Knee scooters provide a good alternative to crutches for many patients. With the patient placing their body weight on the knee-pad, the unaffected leg is in contact with the ground and provides for propulsion. The clinician will adjust the height of the knee rest so that the patient’s knee is at 90 degrees. Although scooters are safer to use for patients than crutches, they do have limitations. Scooters cannot be used on stairs, and they can be bulky and difficult to load into a vehicle compared to crutches.

Knee scooters come in a two-, three-, or four-wheeled version. Smaller units are suitable for indoor use only, while the larger, stronger versions can be used outdoors. Before recommending a knee scooter for a patient, the clinician ensures that the patient does not exceed the weight limitations for the scooter and that the patient has the cognitive ability to safely use it.

Safety instructions provided prior to using a knee scooter are:

• Do not use the scooter to pull up from a sitting position.
• Before placing body weight on the scooter, make sure the brakes are locked.
• Wear comfortable, nonskid footwear on the nonaffected extremity.
• Use extra caution when changing from one surface gradient to another (i.e., from the sidewalk to the street).
• Use extra care and slow down when going around corners.
• When moving from the scooter to a chair or other surface, back the scooter up to the seat and lock the brakes prior to sitting down.
  (Martin, 2018)

The clinician will also look at payment sources for renting or purchasing a scooter: Is it covered by the patient’s insurance, or will the patient have to pay part or all of the cost out of pocket?

WALKER USE

Many patients may find that a walker provides more stability and comfort than either crutches or a knee scooter. There are several types of walkers, including standard, two-wheeled, three-wheeled, or four-wheeled (rollator). The clinician selects the type of walker most appropriate for the individual patient’s abilities and needs. A physical therapist may need to work with the patient to ensure safe and appropriate gait technique when using a walker.

The following instructions provide a general guideline for safe use of a standard walker:

• Begin by standing centrally behind the walker.
• Look straight ahead, not down at your feet.
• Grasp the walker grips with both hands.
• Move the walker forward to a distance that feels comfortable.
• Do not over-reach; the back legs of the walker should be even with the patient’s toes.
• Step forward into the center of the walker with the affected leg.
• Step forward with the nonaffected leg while simultaneously bearing some weight through the arms.
• Maintain a firm hold on the walker with both hands.
• Do not attempt to move until all walker legs (or wheels) are securely on the walking surface.
• Do not use the walker to pull up from a sitting position.
• Maintain upright posture while walking; avoid leaning over the walker.
• Take extra care and time when using a walker on a carpeted surface or when using an elevator.
• Never use a walker on stairs or an escalator.
• Stay away from areas covered in ice or snow, and take extra care in bad weather.
  (UPMC, 2021)

WHEELCHAIR USE

Wheelchairs provide for total off-loading. Safe technique is important when training a patient to use a wheelchair and is individualized to a patient’s needs and abilities. A few general safety recommendations include:

• Ensure that the wheelchair is locked before transferring in or out of it.
• Do not place heavy items on the back of the wheelchair; this could cause the wheelchair to tip backwards.
• Adjust the arm- and footrests to maintain good posture and comfort.
• When getting in or out of the wheelchair, first move the footrests (if swing-away style) to one side to prevent tripping over them.
  (TOUSDA, 2021)

Assessing Off-Loading Effectiveness

Regardless of the choice of off-loading, it is essential for the clinician to continually assess its effectiveness in providing pressure relief to the area of the ulcer. Indicators of effective off-loading include:

• Progress in wound healing, demonstrated by the presence of healthy granulation tissue and a decrease in wound dimensions
• No or very little reoccurrence of callus formation around the wound
• Absence or resolution of local inflammation (decreased redness, swelling, and skin temperature)

The clinician also monitors the nonaffected extremity closely, since mechanisms used for off-loading can often cause undue pressure to the unaffected limb, increasing the risk for new ulceration (IWGDF, 2019; WOCN, 2022).