Musculoskeletal Issues in Pediatric Burn Patients

Abstract

A burn injury affects virtually every organ system. The purpose of this article is to review musculoskeletal issues in children with burn injuries. Both acute and long-term problems will be discussed. A low threshold to consult a pediatric orthopaedist is recommended.

A burn injury affects virtually every organ system. The purpose of this article is to review musculoskeletal issues in children with burn injuries. Both acute and long-term problems will be discussed. A low threshold to consult a pediatric orthopaedist is recommended.

Acute Issues

Acute musculoskeletal issues include compartment syndrome, exposed bone and open joints, and fractures. Long-term issues include progressive limb deformities, amputation complications, heterotopic ossification (HO), and bone health.

Deeply burned skin loses its elasticity, and when a burn injury is circumferential, the risk of compartment syndrome development during the large fluid load of acute resuscitation is high. ¹ The usual clinical signs of compartment syndrome may be difficult to discern in acutely burn children. The burn itself may lead to diminished or absent sensation as well as severe pain. Just as in other traumatic scenarios, the presence of distal pulses does not rule out the possibility of compartment syndrome. ² Escharotomies have long been recommended for circumferential burns to extremities and are frequently performed. ³ Compartment pressures can be measured by a variety of devices to help determine the need for a formal fasciotomy. ⁴ Compartment syndrome has been reported to occur in the absence of significant burn injuries to extremities and is presumed due to the fluid shifts associated with resuscitation. ⁵ Children with compartment syndrome seem to have a better prognosis than adults. ⁶

Most of the children sustaining burn injuries do not have fractures as well. Burned children with additional trauma have an increased length of stay. ⁷ Young children (under 24 months) who sustained burns thought to be nonaccidental should have a skeletal survey as part of their evaluation. ⁸ Children thought to have inflicted burns are more likely to have fractures as well. ⁹ A fracture under burned skin can be challenging to manage. Immobilization with a cast or splint, while normally appropriate for many children's fractures, may compromise local wound care. Operative management can include placement of an external fixator or internal fixation, including pins, plates, and screws or intramedullary devices. ¹⁰ Several studies recommend operative fracture fixation within 48 hours of the burn injury before the burned skin is extensively colonized. ^{11 12} Others have questioned this recommendation and reported high complication rates with operative fracture management. ¹³ The incidence of complications of operative fracture fixation seems to be higher in burn patients, but the benefit of skeletal stabilization allowing early mobilization is substantial as well.

Debridement of a burned limb can result in open joints. Closing such wounds can be difficult. An external fixation device spanning the joint has been reported in a small series to be successful in limiting the number of grafting procedures needed. ¹⁴

Severely burned limbs, particularly those from electrical injuries, may require amputation. ^{15 16} Amputation coverage plans should consider the need for a residual limb segment long enough to allow functional prosthetic wear. ¹⁷ Skin grafts in an amputation residual limb do not increase prosthetic complications in children. ¹⁸ In children, disarticulation should be considered when possible. ¹⁹ The flare of the distal metaphysis makes the suspension of the prosthesis simpler. Retention of the distal physis of the bone segment, particularly in the femur, allows more segmental growth. Finally, disarticulation eliminates the risk of stump overgrowth that frequently occurs in transdiaphyseal amputations in children. ²⁰ Phantom limb pain is more common in amputations following electrical burn injury. ²¹ Targeted muscle reinnervation (TMR) is a promising new technique to prevent and manage residual limb and phantom limb pain. ²² While well described as beneficial for adult amputees, appropriate use of TMR in the pediatric population has yet to be determined. ²³

Transdiaphyseal amputations in children are frequently complicated by stump overgrowth. In extreme cases, the bone may grow out through the skin. The exact cause of this phenomenon is still unknown. A variety of capping procedures have been reported with mixed results. ²⁴ Families should be warned of this at the time of primary and revision surgeries.

Long-Term Issues

Joint contractures are frequent long-term complications of burn injuries in children. Contractures are commonly a consequence of continued skeletal growth with inelastic scar tissue crossing a joint. In a large database study, 25% of children developed at least one contracture by the time of hospital discharge. ²⁵ The most common contractures were reported to be at the shoulder, elbow, and wrist. Extensive burn scars on the trunk can be associated with spinal deformities. ²⁶ Attempts at correcting ankle equinus contractures in burned children with circular external fixators were reported to have a high recurrence rate. ²⁷ Contractures in burned children can also result from an imbalance of muscle forces crossing a joint. A common contracture is equinus at the ankle from a lack of ankle dorsiflexion power which is primarily the tibialis anterior muscle. The function of the tibialis anterior can be compromised from peripheral neuropathy, ^{28 29} from damage, from an unrecognized compartment syndrome, or from extensive debridement. Correction of such contractures may require muscle balancing procedures in addition to scar revision. Muscle balancing procedures to correct ankle contractures can include Achilles tendon lengthening. The lack of dorsiflexion power can be corrected in selected cases with the anterior transfer of the tibialis posterior through the interosseous membrane. ³⁰

HO can be another cause of limited joint motion. The cause of this complication remains unclear. ^{31 32 33} In adults with burn injuries, risk factors for HO include increased percent total body surface area burn and grafting procedures to the arm, trunk, head, and neck. ³⁴ No such data have been reported for children. In burned children, it most commonly involves the elbow. ³⁵ In patients with severely limited elbow motion, surgical excision can substantially improve function. ^{36 37 38} Nonsteroidal anti-inflammatory drugs and radiation therapy have been used as adjuncts in the management of HO, particularly after surgery in other clinical scenarios. ^{32 33 39 40} There are sparse data about their use in burn-injury-related HO. ⁴¹

A severe burn injury results in a child losing both bone and muscle mass for a variety of reasons, including the catabolic stress response to injury, nutritional challenges, as well as immobilization for their burn management. ^{42 43} This may increase a child's risk of long bone fractures, particularly in children under 3 years of age. ⁴⁴ A variety of pharmacologic interventions have been proposed to ameliorate these effects, including growth hormone, anabolic steroids, and bisphosphonates. While they have been shown to have some positive effects in small studies, ^{42 45} they are not routinely used in most burn centers.