David Cifu, M.D.
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Ninety-five percent of hip fractures occur in people 50 years and older and
it is estimated that 250,000 hip fractures occur each year in persons over 65
years.28 The incidence of hip fractures in the United States is approximately
80 per 100,00010 and it increases with increasing age, doubling with every five
to seven years over age
to seven years over age 60.32 The number of Americans age 65 and older
increased from 3 million in 1900 to more than 12 million in 1985 and is
projected to increase to 28 million by the year 2000. The fastest
growing segment of the population are people aged 85 and older and it
is anticipated they will number 5.6 million individuals by the year 2000.13 Not
only is there a greater proportion of people aged 65 and older, but
they are also tending to stay increasingly active and thus may be more prone
to accidents and falls. This increase in the "vigorous" older adult
population, along with advances in medical science which allows the
"frail" elderly to live longer and increased survivability after motor
vehicle trauma and falls, have resulted in a greater number of older adults
with hip fractures.5,9,24 Risk factors for hip fracture include;
increased age,22 increased incidence of falls (falls account for nearly
90% of hip fractures in the older adult),22 increased osteoporosis,8,28
female gender,8,10 Caucasian race,8 prior hip fracture,10 Alzheimer's
dementia,4 and low calcium diet.15
Hip fractures account for about 50% of all inpatient days for fracture care and when all medical and rehabilitation costs are considered, the annual costs exceed 7 billion dollars.14 Morbidity and mortality after hip fracture contribute significantly to this total.1 The highest risk of mortality after hip fractures occurs in the first 4 to 6 months and the current overall mortality rate at 1 year ranges from 14 to 36%.6,17,31 Factors which contribute to increased morbidity and mortality after hip fracture include; increasing age (although often confounded by concomitant morbidity),3,18,31 male gender,6,31 concomitant morbidity,18,31 cognitive deficits,25 premorbid institutionalization,26 and limited premorbid function.3,16 Reducing the incidence of hip fractures and post- fracture morbidity and mortality by utilizing preventative strategies in the face of known risk factors is an important means of reducing health care costs. Additionally, optimizing acute and long term treatment methods to achieve maximal functional outcome while minimizing morbidity and mortality will assist in limiting expenses.
The hip joint is a "ball and socket" joint composed of the acetabulum of the pelvis and the femoral head portion of the proximal femur. The meshwork of trabecular bone of the femoral head allows for the initial absorption and subsequent distribution of stresses to the dense cortical bone of the femoral neck and proximal femur. The head of the femur and the majority of the femoral neck lie within the hip joint capsule; thus femoral neck fractures are intracapsular. The intertrochanteric region distal to the femoral neck is extracapsular and includes the greater and lesser trochanters and the calcar femorale. The trochanters provide bony insertions for the gluteal musculature and the calcar femorale, which extends from the posterior portion of the neck to the posteromedial aspect of the shaft, provides a strong conduit for the transfer of stresses through this region. The sub trochanteric region extends from the lesser trochanter to 5 centimeters distally.12,32
The musculature of the hip may be divided into the adductors (adductor longus, brevis and magnus and gracilis), abductors (gluteus medius and minimus), flexors (rectus femoris, pectineus, sartorius and iliopsoas), extensors (gluteus maximus, adductor magnus, semimembranosus, semitendinosus, and long head of the biceps femoris), internal rotators (gluteus minimus and medius and tensor fascia lata) and external rotators (gluteus maximus, piriformis, obturator internus and externus, inferior and superior gemelli and quadratus femoris). Nervous innervation of the musculature of the hip includes the obturator nerve (adductors), superior gluteal nerve (abductors and internal rotators), femoral nerve (flexors), tibial branch of the sciatic nerve (extensors), inferior gluteal nerve (external rotators and extensors) and small branches directly off the lumbosacral plexus (external rotators). Sensory innervation to the hip joint is provided by the femoral, obturator, superior gluteal nerves and the nerve to the quadratus femoris.12 Hip fractures rarely result in neurologic injury, however posterior hip dislocations and surgical implantation of femoral endoprostheses may result in contusion or traction injuries to the sciatic nerve.30 Anterior dislocations may cause similar injuries to the femoral nerve.
The pubofemoral, iliofemoral and ischiofemoral ligaments are thickenings of the joint capsule, which provide stability to the hip. The capsule provides greater anterior than posterior stability, and thus posterior dislocations are more common. Additionally, the capsule is taut with full extension of the hip and slack with full hip flexion. This allows for hip stability in full extension without hip musculature activity, as in quiet standing, and accounts for the majority of dislocation occurring when the hip is in flexion.12
The blood supply to the hip is particularly important with regard to the femoral head, because there is a greater than 20% incidence of osteonecrosis of the head in displaced femoral neck fractures.21 A branch of the femoral artery, the profunda femoris, divides into the medial and lateral circumflex arteries. The ascending branches of these arteries comprise an extracapsular arterial ring at the base of the femoral neck. Ascending cervical arteries from this ring then join with the intramedullary nutrient artery of the femur to form an intracapsular arterial ring. Branches from this ring then provide the primary blood supply to the head, with an insignificant secondary supply coming through an artery within the ligamentum teres. In short, the blood supply to the head traverses the neck in a distal to proximal direction and disruption of the neck may cause disruption of the blood flow, and with it osteonecrosis of the head.12
Hip dislocations occur most commonly in 30-40 year olds as a result of
high speed trauma (motor vehicle accidents) and may occur in conjunction
with acetabular, femoral head and femoral neck fractures. They are
typically divided into anterior (10 to 15%) and posterior
(85-90%) dislocations. Further classification includes presence or
absence of fracture and stable or unstable.
Fractures of the femoral neck are most commonly caused by falls or near-falls in the older adult. They occur in this population at approximately the same incidence as intertrochanteric fractures10,22,23, but may be more likely to affect women and the frail elderly.22 The most common classification of femoral neck fractures was introduced by Garden in 1961.11 A Type I fracture is an incomplete or impacted fracture in which the bony trabeculae of the inferior portion of the femoral neck remain intact. A Type II fracture is a complete fracture without displacement of the fracture fragments. A Type III fracture is a complete fracture with partial displacement of the fracture fragments. A Type IV fracture is a complete fracture with total displacement of the fracture fragments allowing the femoral head to rotate back to an anatomical position. A simpler classification system, which correlates with treatment options, grouping fractures into either non-displaced (Types I and II) or displaced (Types II and IV) is also utilized.
Fractures of the intertrochanteric region of the femur are commonly caused by significant trauma (falls, motor vehicle accidents) and occur more often in males and the vigorous elderly.22,23 A common classification utilized was refined by Kyle in 1979.19 Type I fractures are two-part fractures that are non-displaced. Type II fractures are displaced into varus with a smaller lesser trochanteric fragment, but an intact postermedial cortex. Type III fractures are displaced into varus with postermedial cortical comminution and a greater trochanteric fracture (four-part fracture). Type IV fractures are similar to Type III fractures with extension into the subtrochanteric region. A simpler classification, which correlates with treatment options, grouping fractures into either stable (Type I and II) or unstable (Type II and IV) is also utilized. Isolated injuries to the greater or lesser trochanters are uncommon.
Fractures of the subtrochanteric region of the femur are caused by
falls (older adults) and motor vehicle accidents (younger adults). The
subtrochanteric region is also a common site of pathologic fractures
from neoplastic disease. Fractures may be classified as having either a
stable or unstable posteromedial cortical buttress.
Acute non-operative or operative management should be instituted as soon as necessary medical evaluation and treatment has been completed. The majority of patients can and should have surgery performed within 24 hours of the fracture. Rehabilitative efforts are begun as soon as possible, either the first post- operative day or when medically feasible in non-operative cases.
Dislocations and fracture-dislocation injuries of the hip are typically caused by high-energy trauma, therefore a comprehensive trauma evaluation must be performed in these patients. Neurologic, vascular, visceral and additional skeletal injuries are not uncommon.
Anterior dislocations without associated fractures, which can be successfully closed reduced, are treated with 5 to 7 days of bed rest. Mild skin traction or pillows are utilized to maintain hip flexion. Range of motion can be initiated when tolerated and ambulation with full weight-bearing is begun by day 5. If hip stability or patient compliance are issues, then an orthosis which limits extension and abduction may be used for 6 to 8 weeks. Anterior dislocations without associated fractures which need to be open reduced are treated similarly, however greater care is taken with range of motion restrictions (i.e., orthoses are always used). Associated fractures of the femoral head or neck may be excised if small and then mobilized similarly. Larger fractures may require open reduction and internal fixation (e.g., in younger patients), primary prosthetic replacement (e.g., in older patients), or total hip arthroplasty (e.g., when stability is lost due to acetabular, labral or capsular injuries). Post-operative management will be determined primarily by the fracture type and fixation. Posttraumatic arthritis (30-50%) and femoral head osteonecrosis (8%) are the most common late complications.32
Posterior dislocations which are stable and without fracture are closed reduced, managed with 5 to 7 days of bed rest and positioned with an abduction pillow. Range of motion is initiated to pain tolerance and full weight-bearing ambulation initiated by day 5. In poorly compliant patients, an orthosis which limits hip flexion, adduction and internal rotation is used for 6 to 8 weeks. Posterior dislocations with fractures require open reduction and internal fixation, primary prosthetic replacement, or total hip arthroplasty. Post-operative management will be determined primarily by the fracture type and fixation. Unstable posterior dislocations which cannot be stabilized surgically, are treated with traction for a period of 6 to 8 weeks. A continuous passive motion (CPM) machine for hip flexion, initiated on post-operative day 1, is utilized throughout the day and night to maintain some degree of movement in these patients. Isometric and active assisted exercises are utilized in bed to maximize range of motion, muscle bulk and strength and cardiopulmonary endurance. Touch down or foot flat weight-bearing (i.e., less than 10% weight-bearing) may be initiated once stability is achieved, and is liberalized over 4 to 6 weeks. An orthosis is utilized to limit adduction, flexion and internal rotation when out of traction. Post-traumatic arthritis (30-100%) and femoral head osteonecrosis (10-50%) are the most common late complications.32
Fractures of the femoral neck can be difficult to diagnosis initially if nondisplaced, with groin pain and reluctance to full weight bear being the only symptoms. A thorough evaluation is crucial to ascertain diagnosis. All femoral neck fractures are treated initially with bed rest, positioning the leg with slight hip flexion and external rotation. Early aspiration or surgical decompression of hemarthrosis is controversial and not commonly employed. Surgical intervention is indicated for all patients, except; when severe medical conditions precluding surgery are present or in the nonambulatory, demented patients. Non-operative treatment can either involve 6-8 weeks of traction for the displaced fracture followed by gradual weight-bearing and ambulation, or mobilization from bed to chair when tolerating pain for the non-displaced fracture.32
Impacted, non-displaced femoral neck fractures (Garden I) are often treated with in-situ internal fixation using multiple screws or pins. Patients should then mobilized rapidly; out of bed the first post-operative day and ambulating with weight-bearing as tolerated by the second day.32
Displaced fractures may be managed either with reduction (closed or open) and internal fixation (screws and pins) or with primary prosthetic replacement. The tenuous blood supply to the femoral head may be compromised by the fracture or by the treatment utilized. Reduction and fixation is primarily utilized, if possible, for the active, healthy patient under age 70. Post-operative management encourages mobilization out of bed by the day after surgery. There remains a controversy about the limits of weightbearing for reduced, fixated femoral neck fractures. Some have advocated restricted weightbearing (toe touch to foot flat) for 6 to 8 weeks, others have indicated that with adequate fixation there should be no limits except to tolerance, while a third faction believes in a compromise between the two (foot flat for 1 to 2 weeks, then partial weightbearing for 2 weeks).32 Range of motion restrictions may be dictated by the surgical approach used, however orthoses or long term precautions are rarely indicated.
Older patients are at higher risk for failure of fixation or femoral head osteonecrosis and therefore prosthetic replacement is often used. The first unipolar endoprostheses used in the 1950's through 1970's (e.g., Austin-Moore, Thompson), which articulated directly with the anatomic acetabulum, provided good fixation but often caused acetabular erosion and pain within 5 years. The newer bipolar endoprostheses (Bateman, Gilberty) consist of a smaller femoral head that articulates by a snap-fit with a polyethylene liner of a metal acetabular shell that, in turn articulates with the anatomic acetabulum. This feature reduces the incidence of acetabular erosion and also allows simple conversion for total hip arthroplasty, if necessary. The surgical approach to the hip will vary by clinical preference, however each (anterior, lateral or posterior) results in some degree of joint capsule instability. The lateral approach is used most commonly. The majority of endoprostheses today are cemented with methyl methacrylate, which offers the advantage of immediate stabilization of the prosthesis in the femoral canal. It also allows for almost immediate full weightbearing. Disadvantages of a cemented endoprosthesis include; difficulty with revision to total hip arthroplasty, greater difficulty eradicating hip joint infections, potential restrictions on use of deep heating modalities (e.g., ultrasound) and difficulty revising for fractures below the prosthesis. Patients are mobilized out of bed by the first post- operative day, and then ambulated without weightbearing restrictions. An abduction pillow is utilized while in bed. Range of motion restrictions may be dictated by the surgical approach used, however orthoses or long term precautions are rarely indicated. Uncemented prostheses, which allow a more physiologic fixation by encouraging growth of bone into the porous prosthesis, may be utilized in younger hip fracture patients. A longer prosthesis lifespan and more secure fit are advantages, while non- weightbearing status for 4-6 weeks is a major disadvantage.32
Primary total hip arthroplasty following a femoral neck fracture should be reserved for the patient with preexisting acetabular disease (Rheumatoid Arthritis, osteoarthritis, Paget's Disease). Patients are mobilized out of bed by the first post-operative day, and then in the majority of cases ambulated without weightbearing restrictions. An abduction pillow is utilized while in bed and with sitting. Range of motion restrictions are strictly enforced for at least the first three months and they include no hip flexion greater than 900, no internal rotation passed neutral, and no adduction passed neutral (the "90-90-90 rule"). Uncemented total hip arthroplasties, which allow a more physiologic fixation by encouraging growth of bone into the porous prosthesis, may be utilized in younger hip fracture patients. A longer prosthesis lifespan and more secure fit are advantages, while non-weightbearing status for 4-6 weeks is a major disadvantage.32
Intertrochanteric fractures occur extracapsularly and therefore the complications of nonunion or osteonecrosis are avoided and the stability of the joint capsule is not affected. Surgical intervention is indicated for all patients, except; when severe medical conditions precluding surgery are present or in the nonambulatory, demented patients. Non-operative treatment can either involve 6-8 weeks of traction followed by gradual weight-bearing and ambulation, or mobilization from bed to chair when tolerating pain.32
The first implants used to fixate intertrochanteric fractures were fixed-angle, nail-plate devices (Jewett nail, Holt nail). These devices allowed for a static fixation of the fracture, however they did not allow for the impaction of the fracture fragments. This often resulted in breakage of the devices or migration of nail into the hip joint. An improved on these early devices was the sliding hip screw which provided good static fixation (like the nail-plate devices) in combination with the physiologic healing brought about by the dynamic impaction of the proximal and distal bone fragments. Patients are mobilized out of bed by the first post-operative day. Weight-bearing restrictions vary from toe touch for 6 to 8 weeks, to immediate weightbearing as tolerated.32 There are no range of motion restrictions imposed.
Intertrochanteric fractures may also be fixated using flexible intramedullary nails or rods (e.g., Ender nails). These devices are inserted distal to the fracture site (at the distal femur) and passed across the fracture site. The major advantage offered would be for the patient with skin problems in the area of the fracture. Patients are mobilized out of bed by the first post-operative day. Weightbearing restrictions vary from toe touch for 6 to 8 weeks, to immediate weightbearing as tolerated.32 There are no range of motion restrictions imposed.
The use of a bipolar endoprosthesis following an intertrochanteric fracture is extremely limited. Anchoring the prosthesis becomes difficult due to fracture location. It may be used to allow full weightbearing for a frail or demented older adult.
Similar to femoral neck and intertrochanteric fractures, subtrochanteric fractures should be surgically fixed if at all possible. The same fixation techniques utilized for intertrochanteric fractures are utilized for subtochhanteric fractures, however intramedullary devices are used with greater frequency. Prosthetic replacement is not an option. Complications of fixation (nonunion, malunion, and implant failure) are more common following subtrochanteric fractures than for intertrochanteric or femoral neck fractures. Pathologic fractures are typically fixated if the patient has a life span of greater than 30 days and is in significant pain. Patients are mobilized out of bed by the first post-operative day. Weightbearing restrictions vary from toe touch for 6 to 8 weeks, to immediate weightbearing as tolerated.32 There are no range of motion restrictions imposed.
All patients who survive a hip fracture will benefit from some type of rehabilitative services. The primary goal of a rehabilitation program after hip fracture is to reduce disability and maximize function to allow the person to return to their prior activity level. The intensity of services and the setting of care are on a continuum, depending on the type and duration of disability. The goal of any rehabilitation program is to develop a home or community-based program which can be performed by the disabled person and his/her caregivers and family. It is imperative that services; begin early (typically by post-operative day 1), be interdisciplinary in nature, continue until the person reaches their maximal functional level, and be focused on the goals of the patient and their family. Functional skills and potential for improvement with rehabilitation can only be assessed if a person's premorbid and present social supports, physical status and functional level are known. The majority of patients after hip fracture will return to their premorbid level of basic functions within 4-6 weeks of the fracture.5 More advanced skills (e.g., driving, vocation, avocations) may take a longer period of recovery or may need to be modified to permit performance. Driving skills are best delayed until at least 8 weeks post-fracture.5,20
Evaluations focus on the patient's social structure and supports prior to the change in ability or illness and present status of these supports. Input from family and caregivers is vital, and allows them to be involved with the rehabilitation process. The specific areas to be investigated include the physical environment, social supports and economic factors. The physical environment includes the type of abode, steps to entry and ramps, steps and obstacles within the home, type of flooring, wheelchair and walker accessibility, and location of bedroom, kitchen and bathroom. The social supports system includes the role of patient, roles of other persons living in home, roles of persons living in proximity, roles of other significant persons, and the health and functioning of these supports. Economic factors include type and coverage of health insurance, sources and amounts of income and assets, and financial capabilities of significant others.5
Physical status may be reflected by history of hospitalizations and medical visits, past medical history, types and amounts of medications and other physical parameters (e.g., pulmonary function tests, cardiac stress tests). Physical status should focus on physical findings and parameters which directly impact function and ability to participate in a program to improve function. These include blood pressure and pulse (dynamic), respiration and need for supplemental oxygen, cardiac limitations (post-MI, angina, claudication), nutritional status, skin integrity, chest wall or abdominal pain, limb edema and pain, mentation (ability to follow commands, ability to retain learned information, ability to tolerate mental activity), vision, hearing, sensation, strength, joint ROM and pain, balance (sitting and standing), visual-perceptual skills (e.g., verticality), skeletal weight-bearing limitations, medications which may limit abilities (anticoagulants, beta-blockers), and conditions which may limit participation (virulent infections, psychiatric disorders). In the hip fracture patient, joint pain and limitation and bony weight bearing considerations are very important and are determined by the type of fracture sustained, type of fixation utilized, ability of the patient to follow prescribed limitations and the clinical judgement of the orthopedic surgeon.5
Functional status is best quantified by the Functional Independence Measure (FIM), looking at self-care, mobility, communication, psychosocial and cognitive skills.29 Particularly important information to obtain is what skills could not be done premorbidly and who was assisting in performing them. The assessment should be dynamic in nature, and is best accomplished over 2 to 3 days, at different times during the day. It is also best when supplemented by input from other health professionals (nurses, therapists, + family) This allows one to assess consistency, improvement, and diurnal variability. While a static (one time) assessment is less desirable, it may be also somewhat dynamic if you can note changes over the course of the exam, changes with different examiners or examination style and the role of the family.5
Acute Rehabilitation Services. All patients should have Physical and Occupational Therapy initiated immediately post-operatively or after the initiation of traction, to institute a program of bed level range of motion, strengthening and conditioning exercises. This program is taught to the patient, caregivers and nursing staff, so that it may be performed throughout the day. Patients in traction are continued with bed level activities until released for out of bed activity. Patients who are not limited by traction are mobilized out of bed to chair by the first post-operative day. Chair level exercises (e.g., active quadriceps exercises, ankle pumps) are implemented. On post-operative days 2-5 the program consists of; bed to chair mobility using a standing pivot transfer, wheelchair skills, pregait (e.g., sit to stand, standing balance and tolerance) and gait (parallel bars to walker to crutches) activities, bathroom skills, activities of daily living (ADL) training and continued performance of range of motion, strengthening and conditioning exercises. Advanced skills in transfers (tub, car), mobility (stairs) and ADL's are instituted by days 6-10 and equipment is procured (e.g., raised toilet seat, bathtub bench with hand-held shower, bathroom grab bars, long handled dressing and ADL devices, walker and/or rental wheelchair) in preparation for discharge. Outpatient or home health therapy (usually only physical therapy) is typically utilized for 2 to 8 weeks after discharge, to assist with the transition to home and advance mobility skills (eg., use of crutches or cane) and endurance. These rehabilitative services are typically reimbursed by Medicare, Medicaid and private insurances.
Patients who are unable to rapidly (i.e., 6-10 days) progress to a level of functional independence which will allow them to safely return to and remain in the community and are willing and able to tolerate a 2-4 week comprehensive rehabilitation program should be admitted to a rehabilitation unit. Factors which often predispose patients to require such a program include; concomitant morbidity which limits rapid mobilization (e.g., arthritis, cardiac disease), complicated acute care stay, limited social supports, and premorbid disability. The program will focus on similar aspects of function as addressed in acute care rehabilitation, but will do so at a slower pace and with greater repetition. Day rehabilitation which allows for 6-7 hours of intensive and interdisciplinary rehabilitation while still allowing the patient to return to home at night, may be a good alternative for patients unwilling or unable to remain in the hospital. Outpatient or home-based rehabilitation services are available to help transition the patient back to the community, but are not used as often when inpatient or day rehabilitation programs are implemented. Medicare reimburses for inpatient and day rehabilitation, Medicaid does also in most states, and private insurances will usually reimburse for these services but specifics will vary by policy.
Patients who are unable to return to the community in the acute phase of care and who do not qualify or wish to undertake comprehensive rehabilitation, can also be managed with a more slowly paced rehabilitation program in a nursing home or other skilled facility. These programs are not typically interdisciplinary in focus and often are primarily physical therapy based. Medicare will reimburse for limited skilled nursing facility stays if extensive rehabilitation services are necessary, Medicaid will reimburse for skilled nursing facility rehabilitation, but private insurance rarely reimburses for this service.**[Insert TABLE 3 here}**
Complications After Hip Fracture
Hip fractures have a 20% mortality at one year and a 33% mortality at 2 years post-injury.7 Orthopedic complications may include; fracture non-union, joint or prosthesis infection, leg length discrepancy (often unavoidable), heterotopic ossification, and prosthetic or internal fixation device loosing. Non- orthopedic complications may include; exacerbation of premorbid medical conditions, sciatic (more often the lateral or peroneal division), obturator and femoral nerve injuries secondary to stretch injury at the time of injury or surgery, peroneal nerve injury at the fibula head due to excess pressure, poor wound healing in the debilitated patient, skin breakdown secondary to prolonged pressure (e.g., heels, sacrum), atelectasis and pneumonia, constipation secondary to immobilization and narcotic pain medication usage, and deep venous thrombosis.
Heterotopic ossification, the production of bone in aberrant locations around the hip with resultant loss of motion, following hip fracture occurs most frequently after total hip replacement (up to 70% of patients), followed by endoprosthesis use, then open reduction and internal fixation. While the etiology is unclear, risk factors include a history of; hypertrophic osteoarthritis (in males), prior heterotopic arthritis, or Paget's Disease. The diagnosis can be made early (within one week) by utilizing a three-phase radionuclide bone imaging and correlated later (in 3-4 weeks) with plain film radiography. Prevention of HO may include NSAID's, calcium chelating agents, radiation therapy ( 600-2000 RADs) and controlled range of motion and activity. Treatment is similar to preventative measures, with a goal of maintaining functional mobility. Surgical removal of HO is rarely indicated.2
Deep venous thrombosis may occur in up to 70% of patients after hip fracture and concomitant pulmonary embolus in up to 16%. The vast majority will occur in the first week and may occur intraoperatively. Risk factors for DVT following hip fracture include; prior thromboembolic disease, prior hip fracture, presence of congestive heart failure, use of estrogen supplements, obesity, immobilization and increased age. Physical exam is only accurate about 50% of the time, however duplex doppler scanning and venography are accurate greater than 90% of the time. All patients who sustain hip fractures should be prophylaxed with either adjusted dose heparin or warfarin for 1 to 3 months post- fracture. Intermittent pneumatic compression devices and early mobilization are acceptable alternatives in patients who cannot tolerate anticoagulation. TED hose, subcutaneous heparin, aspirin or mobilization alone are not sufficient prophylaxis.27 Treatment of DVT's involves either 3-6 months of anticoagulation or placement of an inferior vena cava filter.