Introduction
The incidence of fractures of the distal radius, proximal humerus, proximal tibia, hip, pubic ramus, and vertebrae is low until the 6th and 7th decades of life, when it increases dramatically.
Most fractures in the elderly result from low-energy trauma, often occurring indoors. The elderly are predisposed to fractures because their bones are weakened by osteoporosis (ie, reduced bone mass) and thus require less mechanical force to break, because they tend to fall more frequently, and because they have less effective protective reflexes to cushion the impact of a fall. These factors act together to cause fractures in characteristic patterns and anatomic sites.
Pathologic fractures result from underlying disorders that weaken bone, including malignancy, benign bone tumors (eg, endochondroma of the phalanges or metatarsals), metabolic disorders (eg, Paget's disease, hyperparathyroidism), infection, and osteoporosis. The most common malignancies causing pathologic fractures are metastatic lesions originating in the breast, lung, prostate, gastrointestinal tract, kidney, or thyroid gland. Primary bone malignancies occur much less frequently. Multiple myeloma and lymphoma are the most common; osteosarcoma, fibrosarcoma, and chondrosarcoma are rare. However, osteosarcoma is more common in persons with Paget's disease.
Anatomy and Pathophysiology
A typical long bone is divided into the diaphysis (shaft), the epiphysis (the articular region at each end), and the metaphysis (the flared region joining the diaphysis and epiphysis). The diaphysis is composed of cortical bone, whereas the epiphyses and metaphyses are composed primarily of trabecular bone. Cortical bone is histologically dense and thus very strong. Trabecular bone is porous and varies widely in density and strength, depending on age, anatomic site, and associated disorders (eg, osteoporosis).
The tensile strength of cortical bone decreases only slightly with age. With age, the diameter of the diaphysis increases as bone is resorbed from the inner (endosteal) surface and is added to the outer (periosteal) surface. This change makes the diaphysis more resistant to bending forces and compensates for the decreased strength of cortical bone in the elderly. Thus, diaphyseal fractures do not occur more frequently with age.
The compressive strength of trabecular bone is proportional to its density. Density decreases with age; trabecular bone is not remodeled, so there is no compensation for the decrease in density. Age-related fractures (of the distal radius, proximal humerus, proximal tibia, proximal femur, pubic ramus, or vertebra) involve predominantly trabecular bone, often in the metaphyses. The fracture threshold (ie, the bone density at which the risk of fracture becomes likely) is estimated to be 0.77 g/cm3 for the proximal femur; bone density < 0.77 g/cm3 increases the risk of fracture. In a 70-year-old woman, the average bone density of the proximal femur is 0.70 g/cm3, usually because of osteoporosis.
Normal healing: Normally, fractures heal in three overlapping phases: inflammation, repair, and remodeling.
The inflammatory phase begins as an immediate response to injury and lasts several days. The trauma that fractures the bone also injures the surrounding blood vessels, muscles, and other soft tissues. Hemorrhage at the fracture site results in a hematoma. Traumatic devascularization of the fracture ends and bony fragments may result in nonviable or necrotic bone, causing immediate acute inflammation. The fracture site becomes swollen and tender.
The reparative phase begins <= 24 hours after the fracture and peaks after 1 to 2 weeks. Diaphyseal fractures that are not rigidly stabilized heal by rapid formation of new bone around the fracture site. This new bone, called the external callus, is not visible on x-ray until about 3 to 6 weeks after the fracture. Until the external callus provides sufficient stability (which may take several months for long-bone fractures), the fractured bone can collapse and become displaced.
The remodeling phase may last many months. In diaphyseal fractures, the callus is slowly resorbed and replaced by mechanically stronger bone that is distributed to best resist load-bearing stresses. During remodeling, patients usually feel some activity-related discomfort. Thus, although a fractured wrist may be strong enough for unrestricted use in 2 months, the patient may report pain when gripping forcefully for up to 1 year.
Symptoms and Signs
Most fractures cause swelling, deformity, and pain when movement is attempted. For example, patients with occult subcapital fractures feel pain when the hip is rotated internally, tightening the joint capsule. For patients who cannot speak, refusal to move an extremity may be the only sign of a fracture.
Occasionally, patients present with an impending pathologic fracture (one in which the bone has not broken entirely). The affected area is tender when palpated and painful when the affected limb is used. For example, a patient with an impending femoral fracture may feel pain in the thigh when rising from a chair.
Complications
Compartment syndrome: Compartment syndrome is the most common limb-threatening complication associated with trauma to the extremities. Swelling of injured muscle within a confining envelope (eg, a splint, a dressing, a cast, fascia) increases tissue pressure and blocks normal perfusion. The resulting ischemia leads to further muscle injury and swelling, higher tissue pressures, and, after only a few hours, irreversible injury and necrosis.
The most reliable clinical signs of impending compartment syndrome are progressively increasing pain in an immobilized extremity, pain with passive flexion or extension of the toes or fingers, and numbness in a specific peripheral nerve distribution. The presence of distal pulses in a limb does not exclude compartment syndrome.
Compartment syndrome can be definitively diagnosed using a device that percutaneously measures intramuscular pressure. Treatment consists of removal of all confining envelopes around the swollen muscle. Thus, a splint, dressing, or cast must be thoroughly loosened immediately, or if increased muscle swelling causes the surrounding fascia to become constricting, an emergency fasciotomy must be performed.
Pulmonary embolism: Pulmonary embolism (thromboembolism) is the most common fatal complication due to major hip and pelvic trauma. Of patients with a hip fracture who die, 38% die of pulmonary embolism. Of patients with a hip fracture who are not given anticoagulants, about 50% develop deep vein thrombosis; about 10%, pulmonary emboli; and about 2%, fatal pulmonary emboli. Patients with hip fractures are at high risk because of the combination of trauma to the lower extremity, forced immobilization for several hours or even days, and surgery. The associated clinical findings--pain, swelling, tenderness, Homans' sign (pain on forced dorsiflexion of the foot), fever, leukocytosis--are unreliable criteria for diagnosis. Venography remains the standard diagnostic test; ultrasonography is the most effective noninvasive test for diagnosing deep vein thrombosis.
Warfarin is generally regarded as the most effective prophylaxis against pulmonary embolism for patients with a hip fracture. Warfarin 5 mg may be given up to 24 hours preoperatively because onset of action is delayed. Maintenance doses must be determined by monitoring the prothrombin time; the goal is an international normalized ratio (INR) of 1.5 to 2.0. Advantages of warfarin include once-daily oral administration and low cost; disadvantages include the need for regular monitoring of the prothrombin time, significant bleeding (in 1 to 5% of users), and interaction with many drugs. For example, the combination of warfarin and nonsteroidal anti-inflammatory drugs increases the incidence of hemorrhagic peptic ulcer almost 13-fold in the elderly.
Newer low-molecular-weight heparins have been found to be safe and effective compared with warfarin for patients with a hip fracture. They offer the advantages of subcutaneous fixed dosing (once or twice daily) without the need for laboratory monitoring except for periodic CBC and platelet counts. Preoperative use may increase intraoperative bleeding.
Antiplatelet drugs (eg, aspirin) are easy to administer and provide some prophylaxis against pulmonary embolism but are less effective than warfarin. They are appropriate for patients at lower risk of pulmonary embolism (eg, those with tibial or pubic ramus fractures). Aspirin can be given to patients with a hip fracture if warfarin is contraindicated.
Diagnosis
A pathologic fracture should be suspected when a fracture occurs after minimal trauma or during activities of daily living (eg, walking, getting out of a chair). Usually, a patient with such a fracture has a history of progressively increasing pain in the affected extremity, particularly at night and with weight bearing. Diagnosing a pathologic fracture is important because prognosis and treatment may differ depending on the underlying disorder.
Physical examination may be inadequate for patients who are uncooperative because of pain. For example, a hip fracture makes examination of the contralateral side difficult.
X-rays are the most important tool for diagnosing fractures. Standard x-ray evaluation of suspected fractures should include anteroposterior and lateral views, because on a single view, the characteristic displacement, discontinuity, or altered alignment of a fracture may be hidden by overlap or projection of the broken bone. When a diagnosis cannot be made based on standard views (eg, in minimally displaced spiral fractures), oblique views can help.
Fractures may be missed if only a small area is evaluated. For example, pain in the thigh or knee may be caused by a hip fracture, which may be missed unless x-rays of the entire femur are obtained. A physician should obtain x-rays of both hips and the pelvis for patients with a femoral or pubic ramus fracture because coexisting injuries and preexisting disorders may be present.
Typically, x-rays of pathologic fractures caused by underlying malignancy show multiple lytic lesions, seen as lucencies. X-rays cannot differentiate the disorders that cause abnormally decreased bone density (osteopenia); such disorders include osteoporosis, osteomalacia, hyperparathyroidism, and myeloma. Thus, if a pathologic fracture is caused by osteopenia, laboratory evaluation is required to correctly identify the underlying disorder.
CT, although not routinely needed, can be a useful adjunct to plain x-rays. CT can show occult fractures in areas difficult to image with x-rays because of overlying bony structures (eg, the cervical spine). CT helps determine the extent of articular surface disruption in joint fractures. If a pathologic fracture is suspected, CT may be used to check for bone destruction and soft tissue masses.
MRI readily shows soft tissues and differentiates fat- and water-dense tissues. Within 24 hours, MRI can detect the edema that rapidly accumulates at the fracture site during the initial inflammatory phase, enabling early diagnosis of occult fractures. MRI also helps in the evaluation of pathologic fractures and in the diagnosis of osteonecrosis and osteomyelitis, both of which can mimic fractures. However, MRI cannot directly show calcification or bone mineralization and thus does not image bone structure as well as x-ray or CT does.
Bone scanning, using technetium-99m-labeled pyrophosphate or similar radioactive analogs, can detect focal injury to bone regardless of cause. Uptake occurs wherever new bone forms (eg, in response to infection, arthritis, tumor, or fracture). Occult fractures not visible on x-rays can often be detected on bone scans 3 to 5 days after injury. If a pathologic fracture is suspected, bone scans must be performed to check for metastatic and metabolic bone disease at sites other than the fracture site.
Measurement of the Hct level is the most widely used laboratory test for evaluating blood loss from fractures. Fractures, especially those of the hip, can result in substantial bleeding into soft tissues, which may warrant transfusion.
Measurement of the serum alkaline phosphatase level is the only routinely available laboratory blood test that corresponds directly with fracture healing. The serum alkaline phosphatase level increases when bone turnover (remodeling) increases, which occurs during normal fracture healing, during skeletal growth (in childhood), or when certain malignancies or metabolic disorders (eg, Paget's disease) affect the skeleton. In contrast, the serum calcium level does not change with normal fracture healing. The serum calcium level can increase when one of several endocrine disorders (eg, hyperparathyroidism) or metastatic disease, especially breast cancer, is present and when bone is resorbed very rapidly in bedridden patients with Paget's disease.
Prognosis
The elderly are more adversely affected by the secondary effects of fractures than are younger persons. Immobilization from cast treatment causes joint stiffness. Enforced bed rest predisposes to pulmonary complications, thromboembolism, disorientation, and musculoskeletal weakness. Even minor fractures of the wrist or shoulder may disable formerly independent elderly persons, who may require personal assistance in activities of daily living (eg, eating, dressing, bathing) for many months. More severe injuries have greater impact on the elderly. In the year after a hip fracture, the mortality rate increases by 15%. Of functionally independent patients who lived at home before the fracture, 20% require institutional care for > 1 year, and 30% depend on mechanical aids or assistive personnel.
Treatment
The goal of treatment is rapid return to the activities necessary for independent living rather than restoration of perfect limb alignment and length. The urgency of treatment is frequently mandated by secondary effects of the fracture (eg, pain, loss of function, swelling, uncertainty of outcome) rather than by the fracture itself. For most closed fractures, the application of casts or surgical treatment can be delayed up to 1 week without adversely affecting outcome. Until seen by a physician, the patient should be instructed to immobilize and support the injured limb with a makeshift splint, sling, or pillow; elevate the limb to limit swelling; apply ice to control pain and swelling; and take only acetaminophen to relieve pain. If surgery is a possibility, the patient should drink only small amounts of clear liquids and avoid eating.
When a fracture is suspected, the patient's primary care physician should determine the appropriate facility for treatment. Choice of facility depends on the fracture's severity. For example, patients with displaced hip fractures, who are often immobile and in pain, usually must be transported by ambulance staffed with trained personnel to a hospital with appropriate surgical facilities. Patients with minor wrist and shoulder fractures can be treated in medical offices with x-ray facilities.
Initial immobilization: A fracture is initially immobilized (before definitive stabilization, eg, with casts or surgical stabilization) to prevent further damage. Usually, injuries distal to or at the knee or elbow can be initially immobilized with splints. Splints may be made of preformed aluminum or plastic or inflatable clear plastic, have easily adjustable Velcro closures, or be individually molded of plaster of paris (calcium sulfate hemihydrate), which provides excellent support. Ideally, all splints are applied by one health care practitioner while another holds the injured extremity with gentle longitudinal traction.
Most fractures of the shoulder, upper arm, and elbow can be immobilized with a sling. The arm can be kept close to the body, if necessary, by an elastic wrap or swath. Hip fractures can be immobilized by carefully positioned pillows or by light skin traction.
Casts: Casts keep the fracture aligned while it heals. Because plaster of paris molds and conforms well, it is often used for the initial cast. Subsequent casts may be made of polymeric resins and fiberglass, which are stronger, stiffer, and lighter than plaster of paris. For complete immobilization, the cast must extend one joint above and one joint below the fracture site. For example, the cast for a distal radial fracture should extend from above the elbow to just proximal to the metacarpal joint; however, because joint stiffness is a major problem for the elderly, the cast often ends below the elbow to allow joint motion.
Patients must be taught how to care for the cast (see Table 22-1). The extremity should be elevated for 24 to 48 hours after the cast is applied to prevent swelling. Rhythmic flexion and extension of the fingers or wiggling of the toes facilitates venous return. The patient should immediately report progressive or unrelenting pain, pressure, or numbness because muscle swelling under the cast can lead to the compartment syndrome.
Surgical stabilization: In the elderly, most fractures, except those of the hip, are treated nonsurgically. However, surgical stabilization can restore function and relieve pain more rapidly. For example, patients with hip fractures can usually begin walking within days after surgery. The risks of immobility or prolonged traction outweigh those of surgery, especially for leg fractures. However, severe osteoporosis, in which bone is very porous and unstable, may make securing the hardware used in surgical stabilization difficult; the hardware becomes displaced if it does not have a secure hold in the bone.
Surgical stabilization of most fractures should be postponed if the patient has a correctable acute medical problem (eg, fluid and electrolyte imbalance, acute infection, cardiac arrhythmia). Fractures require immediate treatment only if the limb is threatened (eg, if compartment syndrome is impending or if there is neurovascular compromise or an open wound). Some conditions are relative contraindications to surgery; eg, active sepsis can lead to infection of the surgical site and contraindicates the use of metallic implants.
Traction: For the elderly, traction should be used only when application of a cast and surgical stabilization are contraindicated because the fracture is too fragmented or the patient's medical condition is unstable.
Skin traction is applied using foam boots and carefully wrapped moleskin strips, a sash cord, and a pulley with a 2.3-kg (5-lb) weight. Weights > 2.3 kg should never be used. This procedure is particularly hazardous for the elderly because of its complications, including pressure sores, deep vein thrombosis, pulmonary embolism, depression, disorientation, loss of appetite, deconditioning, atelectasis, and pulmonary infection. Meticulous, aggressive nursing care with vigilant monitoring is required. Skin traction is used only to provide comfort by temporarily and gently restraining the extremity. If strong, prolonged traction is needed to maintain bone alignment, skeletal traction with pins must be used. The proximal tibia is the most common pin site for femoral and acetabular fractures.
Internal fixation of impending pathologic fractures with metal plates, rods, or prostheses often prevents displacement, relieves pain, and preserves function. If an impending pathologic fracture breaks through completely and becomes displaced, treatment can be more difficult, decreasing function and increasing morbidity.
Joint replacement: Joint (prosthetic) replacement, especially of the hip, may be necessary if a fracture damages the joint or the femoral head. Implants made of metal and polyethylene are used to replace the damaged bone fragments. This method restores skeletal strength immediately, unlike alternative treatments that rely on bone fragment healing or bone graft incorporation. Joint replacements, although inappropriate for younger patients, are appropriate for elderly patients because such procedures place fewer demands on the musculoskeletal system and offer other advantages (eg, more rapid return of function and full weight-bearing gait). Other treatments may require patients to use crutches, which the elderly usually cannot use because of diminished muscular strength and coordination.
Rehabilitation
Rehabilitation is often prolonged, and recovery is often incomplete. Usually, patients require several months to 1 year to regain their preinjury capabilities. Orthotic and self-help devices may help.
Nursing and Caregiver Issues
Elderly persons with fractures are especially vulnerable to certain complications, including stiffness, swelling, pressure sores, and functional impairment. Important nursing and caregiver issues include preventive management of these complications.
Stiffness is managed by daily active and/or passive range-of-motion exercises of joints adjacent to the fracture (eg, the fingers, shoulder, and elbow for patients in a short arm cast). Periodic changes of position can prevent hip and knee flexion contractures caused by unrelieved sitting. Periodic sessions of standing and walking and, in nonambulatory patients, sessions of recumbency promote hip and knee flexibility.
Swelling is managed by elevating the injured extremity to the level of the heart. For upper extremity fractures, elevation uses pillows. For lower extremity fractures, effective elevation requires sessions of recumbency. Daytime use of elastic stockings also helps to control swelling.
Elderly fracture patients with impaired sensation and peripheral circulation are vulnerable to pressure sores when an injured limb rests on a hard surface. Diligent inspection and padding of contact points (especially heels) are mandatory.
Fractures often result in functional impairment in activities of daily living. Diminished muscular strength, flexibility, and balance in elderly fracture patients can impair independence in eating, dressing, bathing, and even walking (if dependent on a walker). Disuse can lead to stiffness, weakness, and further impairment. Nurses and caregivers must help and encourage elderly fracture patients to regain the ability to perform activities of daily living.
|
