Porth's Essentials of Pathophysiology, 4e

Disorders of the Skeletal System: Trauma, Infections, Neoplasms, and Childhood Disorders 1089

C h a p t e r 4 3

TABLE 43-1 Complications of Fracture Healing Complication Manifestations

Contributing Factors

Delayed union

Failure of fracture to heal within predicted time as determined by x-ray

Large displaced fracture Inadequate immobilization Large hematoma Infection at fracture site Excessive loss of bone Inadequate circulation

Malunion

Deformity at fracture site Deformity or angulation on x-ray Failure of bone to heal before the process of bone repair stops Evidence on x-ray

Inadequate reduction Malalignment of fracture at time of immobilization

Nonunion

Inadequate reduction Mobility at fracture site Severe trauma Bone fragment separation Soft tissue between bone fragments Infection Extensive loss of bone Inadequate circulation Malignancy Bone necrosis Noncompliance with restrictions

Motion at fracture site Pain on weight bearing

Fracture Blisters. Fracture blisters are skin bullae and blisters representing areas of epidermal necrosis with separation of the epidermis from the underlying dermis by edema fluid. They are seen with more severe, twist- ing types of injuries (e.g., motor vehicle accidents and falls from heights) but can also occur after excessive joint manipulation, dependent positioning, and heat applica- tion, or from peripheral vascular disease. They can be solitary, multiple, or massive, depending on the extent of injury. Most fracture blisters occur in the ankle, elbow, foot, knee, or areas where there is little soft tissue between the bone and the skin. The development of fracture blis- ters reportedly is reduced by early surgical intervention in persons requiring operative repair. 23,24 This probably reflects the early operative release of the fracture hema- toma, reapproximation of the disrupted soft tissues, liga- tion of bleeding vessels, and fixation of bleeding fracture surfaces. Prevention of fracture blisters is important because they pose an additional risk of infection. Compartment Syndrome. The compartment syn- drome has been described as a condition of increased pressure within a limited space (e.g., abdominal and limb compartments) that compromises the circulation and function of the tissues within the space. 25,26 The abdominal compartment syndrome alters cardiovas- cular hemodynamics, respiratory mechanics, and renal function. The discussion in this chapter is limited to the limb compartment syndromes. The muscles and nerves of an extremity are enclosed in a tough, inelastic fascial envelope called a muscle compartment (Fig. 43-7). If the pressure in the compartment is sufficiently high, tissue circula- tion is compromised, causing death of nerve and muscle cells. Permanent loss of function may occur. Intracompartmental pressures greater than 30 mm Hg (normal is approximately 6 mm Hg) are considered

sufficient to impair capillary blood flow; however, the amount of pressure required to produce a compart- ment syndrome depends on many factors. 5 Compartment syndrome can result from a decrease in compartment size, an increase in the volume of its con- tents, or a combination of the two factors. Among the causes of decreased compartment size are constrictive dressings and casts, closure of fascial defects, and burns. In persons with circumferential third-degree burns, the inelastic and constricting eschar (thick coagulated crust or slough) decreases the size of the underlying compartments. An increase in compartment volume can be caused by trauma, including contusions and soft tissue injury,

Biceps muscle

Median nerve

Brachioradialis muscle

Brachial artery Brachialis muscle

Radial nerve

Humerus

Extensor carpi radialis

longus muscle

Triceps muscle

Ulnar nerve

FIGURE 43-7. The proximal muscle compartment of the arm, showing the location of fascia, muscles, nerves, and blood vessels.