Historical perspectives

With the increasing use of gunpowder in warfare, surgeons treating battlefield casualties encountered large numbers of patients suffering from burns to the extremities and hands.⁵ Early pioneers in the treatment of these wounds, such as Ambrose Pare, William Clowes, Fabricius Hildanus, and Richard Wiseman, developed approaches to the treatment of burned hands.⁵ This early work demonstrated the importance of the use of splints to prevent contractures. Contemporary approaches to splinting the burned hand have evolved from these concepts to emphasis on correct positioning of the hand and wrist and establishing the use of not only static but also dynamic splints to optimize early and late rehabilitation of these injuries.

Pathophysiology

The typical deformities seen in the burned hand are hyperextension deformity of the metacarpophalangeal joints, flexion deformity of the interphalangeal (IP) joints, loss of the transverse metacarpal arch, adduction contracture of the thumb, volar flexion contracture of the wrist, and shrinkage of the dorsal skin. The metacarpophalangeal joint assumes the hyperextended position because of with joint edema. The metacarpophalangeal joint collateral ligaments are relaxed when this joint is extended because of the cam effect of the metacarpal head, which is longer in the dorsal–volar plane. This allows increased volume within the joint to accommodate edema. In contrast, edema in the IP joints results in a flexed posture and tightening of the volar plate. Persistent edema, infection, poor compliance with hand therapy, ineffective splinting, long immobilization, and loss of skin coverage all contribute to the development of the burned hand deformity. Success is best assessed by restoration of function, which often correlates with an improvement in appearance.

Current issues

Ideally, rehabilitation of the burned hand should be instituted immediately after the thermal injury.⁷ A hand therapist should be involved in the care of the patient at presentation. The treatment plan is directly influenced by the depth of the burn and the requirement for surgery. Superficial burns do not require skin grafting and are treated with wound care and early active range of motion exercises. These patients usually do not develop contractures and do not require splints. Currently, deep partial thickness and full thickness burn wounds are treated with early excision and grafting. This goal of early excision of damaged tissue and skin grafting is to minimize the secondary problems of scar formation and contracture. Early excision is important for reducing the inflammatory phase, expediting wound coverage and healing to allow for earlier active motion rehabilitation.⁷ At the time of excision and skin grafting, the patient is placed in a dorsal or volar splint made of plaster. The splint immobilizes the hand and wrist, to decrease shearing of the skin graft from the wound bed and increase graft survival. This requires immobilization for 5 days to optimize revascularization of the skin graft. This intraoperatively placed splint maintains the IP joints at 0 degrees of extension, the metacarpophalangeal joints in 70 degrees of flexion, the thumb in maximal abduction, and the wrist in neutral.

Treatment considerations and recommendations

Treatment of burns that involve the hand are complicated by the potential for exposure or injury to numerous important structures, including tendons, bones, and joints. Therefore, splinting and therapy protocols can be distinctly different for burns of the dorsal and palmar surfaces. The skin over the dorsum of the hand is thin, supple, and highly mobile, which allows for gliding of the underlying extensor tendons. When the dorsal surface is involved in burn injuries, significant functional disturbances may result. The close proximity of the underlying extensor tendons, especially on the dorsal surfaces of the fingers, makes these areas prone to tendon injuries and may result in deformities such as mallet fingers, boutonnière, and swan neck deformities. In performing excisions of dorsal burns, it is critical to preserve the extensor tendon apparatus, including the terminal extension, lateral bands, and central slip when possible. Palmar hand burns also result in significant deformities that can be very difficult to correct. Serious burns to the palmar surface of the hand frequently cause devastating and sometimes uncorrectable flexion contractures. These burns can result in loss of the first web space, thus compromising use of the thumb. Fortunately, palmar burns frequently are only partial thickness and do not require excision and grafting owing to thickness of the glabellar skin. Sensory nerves of the hand are frequently injured both by the burn and possibly by required excision and debridement. Sensory involvement of both the dorsal and palmar surfaces poses an even more complex challenge. Circumferential third-degree burns and electrical burns of the hand can result in compartment syndrome and subsequent muscle loss. Loss of function and fibrosis of the intrinsic muscles are the most complex challenges to rehabilitation. It is critical to perform early escharotomies and compartment releases when indicated to prevent this muscle loss. Therefore, many factors must be considered as part of the evaluation of the acutely burned hand.

Edema is a major deterrent to successful outcome and should be addressed immediately following injury. Edema that is not controlled will be detrimental to the overall function of the hand because it compromises circulation and limits joint mobility. Protein-laden edema fluid accumulates in the joint capsules, collateral ligaments, and other soft tissues of the hand. Eventually this fluid becomes gelatinous and ultimately is replaced by dense fibrous tissue. The soft tissue structures of the hand thicken and shorten, resulting in a stiff hand and fixed contractures. If edema is controlled early, scar formation and stiffness can be lessened.

Generally, significant edema formation occurs within the first 48 to 72 hours after burn injury. Compression should not be used during this time because venous return may be impaired. Initially, emphasis should be placed on active range of motion (AROM) and elevation to control edema and keep the joints mobile. Elevation promotes venous return and prevents gravitational pooling of fluid in the dependent extremity. AROM provides a pumping action by means of active muscle contraction. This in turn assists with venous and lymphatic return to the central circulation. In patients with deep circumferential burns or burns accompanied by severe edema, overly aggressive range of motion should be avoided because it may aggravate swelling. These patients may benefit more from brief and frequent periods of AROM throughout the day. Active assisted range of motion (AAROM) may be initiated if necessary. Passive range of motion (PROM) is not recommended in the acute phase because forceful joint manipulations may disrupt the healing wounds. This in turn can cause additional inflammation and swelling, which will result in pain and loss of motion and increase scar formation and stiffness.

Wound healing is a complex process of collagen synthesis, with an end result of scar formation. If not managed properly, scar formation can result in deformities such as scar hypertrophy and soft tissue contractures. Wound contraction is a normal component of the healing process and is characterized by a shortening of collagen fibers. Unchecked, it may result in scar contractures. Hypertrophic scars are thick raised scars caused by deposition of disorganized layers of collagen fibers. Early application of pressure and sustained stretch to healing burn wounds may minimize the incidence of soft tissue contractures and scar hypertrophy, respectively.² Skin and soft tissue will adjust to the tension that is placed on it. Tissues can lose length (as in contracture) by losing cells, or they can increase in length by adding new cells. Remodeling occurs as a result of low-grade, gentle, sustained tension. By increasing tissue force over normal resting levels, cell proliferation is stimulated. Therefore, stretch over the scarred hand can initiate remodeling of collagen as well as increase the extensibility of collagen. Collagen fibers will tend to align along the lines of stress. Constant pressure on the healing wound will induce close approximation of collagen bundles by stimulating collagen cross-linking and reorganization of collagen into parallel fibers.² Remodeling of collagen fibers not only will inhibit scar contracture and hypertrophy but also will diminish vascular and lymphatic pooling and help reduce hypersensitivity of the skin.² Pressure therapy can be applied as early as 72 hours postinjury or after maximal edema has subsided. These early methods of pressure treatment may include compressive dressings or a figure-of-eight ace wrap over the burn dressing to provide light pressure. Fine mesh gauze can be draped between the web spaces of the digits to prevent scar syndactyly. Patients can be measured for custom-fit garments, such as Jobst garments, if they have no open areas larger than the size of a quarter. Temporary pressure garments may be used until custom garments are ready and a proper fit is assured. Temporary pressure may be provided with Isotoner gloves, elasticized stockings such as Tubigrip, coban ace wraps, and digital compression sleeves. Patients whose wounds heal within a 2-week period may not require customized pressure therapy because scarring may be minimal. Due to the expense of custom garments, theses patients can be managed with elastic stockinettes and Isotoner gloves. If development of heavy scarring later is determined, custom garments should be provided. Although a patient is fitted with a pressure glove, continuation of ROM exercises is necessary. Intermetacarpal glides and palmar stretches may help to counteract the transverse force of the glove and assist in maintaining the transverse palmar arch of the hand. Also, because the dorsum of the hand is convex and the palm is concave, the pressure will be greatest on the dorsum of the hand. The glove may bridge across the palm, providing little or no pressure to palmar scars. Custom insets on the palmar surface may be necessary to achieve even distribution of pressure. This can be accomplished with elastomer, Otoform, silicon gel sheeting, or foam inserts to the palm.

The burned hand must be carefully evaluated before motion exercises are initiated. Exposed tendons or deep dorsal burns over the fingers may result in tendon rupture and increased morbidity and deformity if not managed properly. If no tendons are exposed and the depth of the burn does not place underlying tendons at risk, AROM can be initiated immediately postinjury. In general, it is best to begin exercises with isolated joint motion and blocking to achieve differential tendon gliding. After each joint is exercised individually, composite joint motion or composite fist making can be instituted to provide stretching of all joint motion, or composite fist making can be instituted to provide stretching of all joint surfaces. Other necessary exercises include isolated extensor mechanism blocking to encourage IP extension (only if the central slip is intact), isolated MP joint motion, intrinsic stretches, web space stretches, thumb abduction and opposition, wrist flexion and extension, radial deviation, and ulnar deviation.⁹ All are important components of a complete burned hand exercise regimen.

Ideally, the burn patient should be able to cooperate with an active assisted exercise program. The amount of exercise required frequently is greater than the amount of time the therapist can spend with the patient. For this reason, provision of clear instructions to the patient, the patients’ family, and the nursing staff are of great importance. Such communication will allow the patient to perform an effective exercise program even when the therapist is unable to supervise. The patient should be instructed to exercise six to eight times daily. Exercising in warm water is beneficial and should be encouraged whenever possible. The warm water may help reduce pain and provide a soothing relaxing effect that may increase patient cooperation. The buoyancy may increase the ease of exercise. Exercising in water also allows the therapist to observe and monitor the wound. If the patient is unable to actively participate in an exercise program, then passive range of motion (PROM) exercises may be required. Such an approach may be dictated by patient disorientation or unconsciousness, or it may be used because of patient fear. In certain cases, use of a continuous passive motion device may be beneficial. PROM may be necessary as wound healing progresses and the antagonistic scar forces begin to exceed the patient’s active abilities.