HIP FRACTURE

Hip fractures, particularly in frail elderly persons, have a profound effect on morbidity, mortality, and length of hospitalization, and they are a significant risk factor for institutionalization. With the age of the world's population ever increasing, hip fractures will constitute an increasingly large health, social and economic burden. A coordinated multidisciplinary approach, including orthopaedic surgeons, geriatricians, nurses, physiotherapists, occupational therapists, and social workers will be required to provide optimal management of persons who suffer hip fractures.

Etiology

The majority of hip fractures are caused by a simple fall inside the home. Frail, elderly people are particularly susceptible to falls, given their many coexisting medical conditions that influence gait, balance, and coordination. Fracture incidence is directly related to age, doubling with each decade beyond age fifty. Women are much more commonly affected than men, by a ratio of 2.5 or 3 to 1. The white population in the United States is much more commonly affected than the African-American, Hispanic, or Asian populations. Other factors associated with injury include osteoporosis and osteomalacia, a history of smoking, excessive use of alcohol and caffeine, physical inactivity, and previous hip fracture.

Diagnosis

The clinical diagnosis of a displaced hip fracture is often readily apparent due to the so-called down and out posture, with the affected limb being shortened and externally rotated. In nondisplaced fractures there may not be an obvious deformity. The diagnosis in such cases is made based on the history of fall (a single fall) and subsequent inability to bear weight, as well as pain when the hip is moved either actively by the patient or passively by the examining clinician.

Routine radiographs of the hip, usually taken in two views (front and side) are sufficient to confirm the diagnosis. Occasionally a fracture may not be apparent radiographically, so if the clinical suspicion is strong, further investigations should be carried out. Radionuclide imaging with technicum bone scanning is most commonly used, but even with this tool diagnosis can be difficult. Particularly in an elderly person, a fracture may not become apparent on bone scan for two to five days after an injury. More recently, MRI has been shown to be more accurate and, if hospitalization of the patient is required, more cost effective. These techniques would only be used in the exceptional case where the diagnosis is not clear. For example, metastatic cancer frequently affects the proximal femur. Specific attention to bone quality on the radiograph is required to detect an occult lesion indicating a pathologic fracture. (A fracture through abnormal quality bone, generally a metastatic diseased bone. Certain cancers commonly metastasize to the proximal femur, especially lung, breast, prostate, thyroid and renal cancers.) The likely primary cancer sites are breast, lung, prostate, thyroid, and kidney.

Principles of management

The primary goal of management is to return patients to their prefracture ambulatory status and level of function. Initial treatment is directed toward pain control, and small, frequent doses of analgesics can be utilized. In displaced hip fractures, splinting of the limb is helpful. Simple splinting, such as bunny-boot traction with five pounds, or skin traction can be utilized. In the undisplaced fracture traction is unnecessary, but care must be used when moving the patient. Skin breakdown can occur within hours, and it is therefore important that the patient position is changed frequently. Only in rare instances is nonsurgical management appropriate. Nonsurgical management may be considered for the stable impacted hip fracture when the patient has already walked following the fall and has minimal or no pain with passive range of motion of the hip; minimal pain with active range of motion of the hip; or nearly full range of motion. Radiographs should demonstrate a stable fracture pattern. Nonoperative management can also be considered in the severely debilitated, cognitively impaired, and previously nonambulatory patient who does not appear to be having any significant discomfort.

Preparation for surgery

A complete history and physical examination with specific concern for any anaesthetic risk is required prior to surgery. Previous infections about the hip or history of venous thromboembolism (blood clots) should be specifically applicable to hip surgery. A careful review of current medication is also necessary. Specific emphasis on the history of malignancies to help rule out occult pathologic fractures is required. In addition, careful note should be made of the patient's cognitive and functional status prior to surgery. This information is helpful in making prognosis for recovery after surgery and for assessing the need for postoperative rehabilitation. Cross matching of blood is necessary, as transfusion frequently will be required perioperatively.

Unnecessary delay of a patient's operative intervention appears to worsen the outcome. Ideally, elderly patients should undergo surgery within the first forty-eight hours of injury, as delay beyond this appears to decrease their overall recovery. As these patients often have significant medical problems, the focus should be on correcting any reversible medical condition within twenty-four to forty-eight hours. Similarly, because of the periods of fasting (once admitted into hospital, patients are not permitted to eat or drink prior to surgery. If there are delays prior to surgery this might prolong the period of fast or there may be multiple fasts depending on delays), care must be taken to optimize the patient's nutrition and hydration prior to surgery.

Hip fractures are often clinically obvious, but other causes of groin pain and leg deformity need to be considered, including fractures of the pubic rami, lumbar spine disease, trochanteric bursitis, osteoarthritis or inflammatory arthritis of the hip, or, rarely, a septic hip joint.

Classification of fractures

A simple classification of hip fractures can direct surgical management and indicate prognosis. In general, hip fractures can be divided into two types: intracapsular fractures and extracapsular fractures (see Diagram 1). The reason for this dichotomy concerns the blood supply to the femoral head. Blood flow arises chiefly from branches of the medial circumflex femoral artery that runs along the posterior superior aspect of the femoral neck with the capsule (fibrous covering of the joint that maintains the joint's synovial fluid and with the hip joint maintains it's blood supply) to form a ring of blood vessels around the femoral head. Therefore, if the fracture is intracapsular and the femoral head is displaced it can tear or disrupt the blood supply. This gives rise to a condition known as avascular necrosis. In addition, a displaced fracture gets bathed in the synovial fluid capsule of the hip joint. This does not lead to an optimal healing environment. The fracture, therefore, is at a greater risk for nonunion.

Displaced intracapsular fractures have, at least, a one in three risk of avascular necrosis and an additional one in three risk of nonunion. Therefore, in an elderly person, management usually consists of prosthetic replacement of the hip joint. By contrast, undisplaced hip fractures have much lower rates of avascular necrosis and nonunion and are usually treated with multiple screw fixations.

Extracapsular fractures consist of intertrochanteric fractures and subtrochanteric fractures. These can be further classified as stable or unstable. Unstable fractures have loss of bone continuity posteromedially along the proximal femur, which is where most weight bearing occurs. If there is significant disruption of bone here these fractures are inherently unstable. In general these require anatomic reduction and fixation.

Subtrochanteric fractures comprise approximately 15 percent of hip fractures. In the elderly population there are two groups of patients who sustain this injury. The first includes those whose femurs are quite osteoporotic and break from a minor fall. The second group may have pathologic lesions in the proximal femur, and a fracture may occur to the weakened pathologic bone. Special care needs to be taken in evaluating these patients clinically and radiographically. These fractures, because of the high biomechanical stresses in this region of the femur, tend to be unstable and often require intramedullary fixation. Displaced pathologic fractures may require prosthetic replacement.

Specific surgical management

Patients who sustain an undisplaced subcapital hip fracture (a fracture occurring beneath the femoral head at the head neck junction; it is an intracapsular fracture of the hip) have a lower risk of avascular necrosis and nonunion, and the fracture is therefore best managed by in situ fixation of the fracture. This consists primarily of partially threaded screws that can grip the cancellous bone of the femoral head and are placed in a parallel position along the axis of the femoral neck to allow compression of the fracture site. This compression will enhance stability and progression to union. Three or four pins are generally utilized (see Figure 1).

The displaced subcapital hip fracture continues to be somewhat of an enigma and challenge, and there is no specific ideal treatment program. In general, in elderly people, high rates of avascular necrosis and nonunion mean that no attempt is made to salvage the hip. Agreement exists that a prosthetic replacement will be utilized, but the specific type of prosthesis has been controversial. The traditional method uses an uncemented unipolar prosthesis. This consists of a single-size femoral stem that is placed into the femoral canal with the diameter of the head size of the ball varying according to patient size (see Figure 2). This is a cost-effective, straightforward management of these fractures. However, questions about this device concern its ability to achieve fixation and its potential for long-term acetabular erosion. Both conditions may lead to pain and require revision surgery. More recent evidence suggests that a cemented unipolar replacement maybe superior in outcome to the uncemented type, although acetabular erosion remains a potential problem.

Bipolar hip replacement consists of a femoral stem, similar to that used in total hip replacement, which allows matching of size to the femoral canal (usually with cement techniques) to fix it to the proximal femur. The bipolar component allows a floating acetabulum or second head to fit on top of the standard total hip head, and this allows, in theory, for motion to occur at the smaller head to the larger head (the standard total hip femoral head articulates with the longer acetabular head), as well as the larger head to the acetabulum. One theoretical advantage of the bipolar design has been that it can be converted relatively easily to a total hip replacement—the bipolar larger head can be removed and a cup placed into the acetabulum without replacing the femoral component. The significant disadvantage, compared to unipolar replacement, has been that it is substantially more expensive.

Total hip arthroplasty has also been utilized in the management of displaced subcapital hip fractures. However, long-term outcomes are poor compared to total hip arthroplasty for osteoarthritis of the hip. There are numerous variables for this, including that patients tend to be more frail, the bone stock is less, and patients tend to have a higher dislocation rate. Overall, it has higher morbidity and mortality rates than the same procedure for osteoarthritis.

Extracapsular intertrochanteric fractures

Surgical management of the intertrochanteric fracture requires a sliding hip screw. This consists of a plate and barrel firmly fixed to the proximal femur with a large lag screw that enters into the femoral head and is connected to the plate through the barrel. The fracture site is compressed, as the screw is able to collapse inside the barrel, and compression of osteoporotic bone at the fracture site affords increased stability and enhances bone union. If there is comminution (multiple bone fragments) at the posteromedial aspect of the proximal femur, the fixation can be unstable and may reduce the patient's ability to walk after surgery until bone union occurs (see Figure 3).

Extracapsular subtrochanteric fractures

These fractures are associated with increased blood loss and increased risk of pathologic origin. They are generally treated with intramedullary devices or sliding hip screws with long side plates. Intramedullary devices are rods that insert through the canal of the bone and have interlocking screws that pass through both sides of the bone and the rod to stabilize the fracture. In the case of pathologic fracture, the surgeon may choose to utilize methyl methacrylate (bone cement) and/or prosthetic replacement to enhance stabilization.

As bone becomes more osteoporotic, fracture patterns can become more complex and extracapsular fractures can consist of intertrochanteric fractures with subtrochanteric extension. These fractures can be very unstable and technically challenging to fix. The specific choice of implant will vary from surgeon to surgeon and center to center. Since their introduction, cephalomedullary interlocking femoral nails have been utilized as an intramedullary nail, with screws that lock into the femoral head through the nail. The hardware is also locked with screws distally in the nail through the bone. These devices have been successful in treating such complex fracture patterns.

Postoperative rehabilitation

Postoperative management (of hip fracture patients) requires multidisciplinary coordination, with the combined goal of returning the patient to prefracture status and back to independent living. A large number of patients lose independence and end up being institutionalized after hip fracture because of general disability and loss of ambulation.

Functional recovery after hip fracture can be variable. Only 40 to 60 percent of patients recover their full prefracture ambulatory function, and only 25 to 35 percent regain their full independence in activities of daily living prior to fracture. Factors contributing to these low rates include older age, cognitive impairment, and few outside social contacts.

Early discussion with patients and their families is needed so that everyone is well versed in the intended rehabilitation goals. This is especially important for patients returning home, as structural adjustments may be needed to the house, such as the installation of handrails and grab rails or moving the patient to a single level accommodation. Other home support systems may also need to be implemented. Occupational therapy services and social services can be very valuable. With respect to physiotherapy, the goal is to mobilize patients quickly, and the surgeon needs to make the decision on their weight-bearing status. Medications to prevent thromboembolic disease (blood clots) are required.

Morbidity and mortality

The one-year mortality after hip fracture ranges from 12 to 36 percent. The highest risk of mortality appears to be in the first four to six months, and there is also significant intrahospital mortality. These rates are significantly higher than age-matched controls. Following one-year postfracture, the mortality rate appears to drop back to age-matched control rates. Factors associated with increased mortality include advanced-stage impaired cognition, institutionalization, cardiovascular disease, and male gender.

Morbidity rates are also quite significant. In the early hospital course, patients are at risk for fracture disease. This includes pneumonia, urinary tract infections, decubitus ulcers, and thromboembolic disease. Additionally, cognitive impairment can be exacerbated. This is often multifactorial in nature, with analgesic medication and other polypharmacy effects, complications of the fracture disease, and even the sudden change in environment all implicated.

Peter Rockwood, M.D.

See also Arthritis; Balance and Mobility; Multidisciplinary Team; Osteoporosis; Pressure Ulcers; Rehabilitation; Surgery in Elderly People.

BIBLIOGRAPHY

Beaty, J. H. Orthopedic Knowledge Update 3-Home Study Syllabus. American Academy of Orthopaedic Surgeons, 1999.

Crenshaw, A. H. Campbell's Operative Orthopedics, vol. 2, 8th ed. St. Louis, Mo.: Mosby Year Book, 1992.

Rockwood, Charles A., and Green, David P. Rockwood and Greene's Fractures in Adults, 5th ed. Philadelphia: Lippincott-Williams & Wilkins, 2001.

Rockwood, Peter R.; Rockwood, Kenneth J.; and Eaton, William H. "Elderly Long-Stay Surgical Patients." Canadian Journal of Surgery 31, no. 1 (1988): 62–64.

Rockwood, Peter R., and Horne, J. Geoffrey. "Hip Fractures: A Future Epidemic?" Journal of Orthopedic Traumatology 4 (1990): 388–393.

Wiesel, Sam. W., and Delahay, John N. Essentials of Orthopedic Surgery, 2d ed. Philadelphia: W.B. Saunders Company, 1997.

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