HIP FRACTURES

The clinical significance of hip fractures is reflected in the annual rate of fractures and the financial burden to the economy that hip fractures produce.10,16 Goldstein¹⁰ states that more than 300,000 fractures occur annually with an associated cost of $10 billion. Other authorities^4,16 report that 267,000 fractures occur annually, with a price tag of $33.8 billion.⁴ Although fractures in general occur to all age groups, hip fractures are most common among elderly women.^4,16,17 Hip fractures in women can be attributed in part to the higher incidence of osteoporosis in this group¹⁷; with regard to age, hip fractures represent the most common acute orthopedic injury in the geriatric population.¹⁶

The classification of hip fractures is clinically significant for the PTA because the severity and location of the fracture profoundly affect surgical management and physical therapy interventions. The vascular supply to the femoral head and neck may be significantly compromised with certain fracture patterns and levels of severity (Fig. 19-1).¹⁷ LeVeau¹⁷ states, “The extent of the supply of blood to the head of the femur determines remodeling and healing after femoral neck fracture or hip dislocation.”

Generally, hip fractures can be classified by location and described by severity (simple or comminuted).⁹ Fractures of the hip can be located in the following areas:

 Extracapsular or intertrochanteric9,10,21 (Fig. 19-2, A)

 Femoral neck or subcapital areas¹¹ (intracapsular) (Fig. 19-2, B)

 Proximal femoral shaft or subtrochanteric areas (Fig. 19-2, C)¹¹

Secondary to the location and severity of hip fracture, the most significant complication is related to osteonecrosis and the loss of blood supply to the femoral head leading to avascular necrosis (AVN). Gross and associates¹¹ affirm, “any fracture of the neck (femoral) can disrupt this tenuous blood supply. As a result, there is an exceedingly high incidence of avascular necrosis of the femoral head after hip fractures.” LeVeau¹⁷ states, “avascular necrosis may occur after hip fracture in about 65% to 85% of the patients.”

Three main clinical complications are noted with subtrochanteric fractures: malunion, delayed union, and nonunion avascular necrosis.¹⁸ Two factors associated with malunion and nonunion of subtrochanteric hip fractures are:

Many options are available in treating hip fractures: The choice depends on the patient’s age, location of the fracture, quality of bone, severity of the fracture (simple, displaced, or comminuted), activity level of the patient, associated soft-tissue injuries, and specific goals for the patient’s return to activity. Generally, hip fractures are managed surgically with an open reduction with internal fixation (ORIF) procedure that secures the fracture fragments with various rods, nails, pins, screws, and plates.9,10,16 Some hip fractures can be managed conservatively with bed rest, traction, and protected weight bearing.¹⁸ For example, in a fractured greater trochanter where the displaced fracture fragment is less than 1 cm (as evaluated by the physician radiographically), the treatment could be bed rest for several days, range of motion (ROM) exercises, and limited weight bearing for 4 weeks.¹⁸

With an isolated lesser trochanteric fracture (most common in adolescents), the physician bases treatment on the amount of fragment displacement. If the fracture is displaced more than 2 cm, the physician could perform an ORIF procedure; if the fragments are in closer apposition, the physician may elect rest, protected weight bearing, and limited exercise for 3 to 4 weeks.¹⁸ Figure 19-3 depicts common fixation devices used to secure fracture fragments using an ORIF procedure.

While treating patients with hip fractures, the PTA must be aware that venous thrombosis is a potentially critical complication after hip surgery. Without prophylactic medications to minimize thrombosis, statistics show that 40% to 90% of patients develop this condition after hip surgery.¹⁸ Venous thrombosis is the most common complication after hip fracture in the elderly population of patients.¹⁸

Hip fractures and dislocations can occur in combination, as well as isolated events. Usually hip dislocations are either anterior or posterior (Fig. 19-4). Isolated hip dislocations generally are treated conservatively with bed rest, traction, and protected limited weight bearing for up to 12 weeks.¹⁸ For example, with an anterior hip dislocation, bed rest with traction is prescribed, with specific precautions to strictly avoid extreme hip abduction and external rotation to prevent redislocation. Usually protected weight bearing is allowed when the patient can achieve painless hip ROM around 3 to 4 weeks after the incident.¹⁸ Conversely an isolated posterior hip dislocation is treated with bed rest and traction in abduction with precautions to prevent hip abduction, flexion, and internal rotation to protect the joint from dislocation.¹⁸

Rehabilitation after Hip Fractures

The patient’s overall preoperative physical and mental condition is a predictor of postoperative success. Patients with major cardiovascular or pulmonary disease processes, obesity, osteoporosis, dementia or poor upper body strength are at increased risk for postoperative complications. Overall mortality rates of 20% after 1 year, 50% at 3 years, 60% at 6 years, and 77% after 10 years have been reported.⁷

Although the overall goal of rehabilitation is to restore patients to preinjury level, this may not be realistic. Only 20% to 35% of patients regain their preinjury level of independence. As many as 15% to 40% require institutionalized care for more than 1 year after surgery. Many (50% to 83%) require devices to assist with ambulation.¹⁴

Any rehabilitation program used to treat hip fractures is highly individualized. The nature of the fracture type, classification, location, and method of internal fixation (if any) are considered, and the treatment program is adjusted to the patient’s ability to cope with specific identified criteria. These criteria are established by the physical therapist (PT) and carried out by the PTA.

The progression from maximum to minimum protection closely follows the rate of bone healing. However, other factors are considered in safely and effectively providing an environment for the return to functional activities. In the maximum-protection phase of recovery (phase 1 to 21 days postoperatively, as described by Goldstein⁹), the fracture site is protected; pain and swelling are reduced; and isometric exercises, gentle protected ROM, and limited weight bearing begin.^9,17

The general goals of recovery are to increase muscular strength specific to the surgery, improve overall conditioning, increase ROM of the affected hip, enhance aerobic fitness, increase local muscular endurance, reduce pain and swelling, reestablish normalized gait mechanics, and protect the healing structures from internal and external forces that can impede healing.9,17

During the maximum-protection phase the exercises used include active ankle pumps for both lower extremities, isometric quadriceps sets, gluteal sets, heel slides, hip abduction and adduction, and supine internal and external hip rotation. These exercises must be done at submaximal levels at first, and then progressively made more difficult according to the patient’s tolerance.

Goldstein⁹ identified a few major complications that occur, particularly during the maximum-protection phase of recovery. Generally, no combined diagonal or rotary forces are used in exercises during this phase. Hardware loosening and delayed healing may occur if increased torque is placed through the healing fracture site by excessive unwanted forces.⁹ No active straight-leg raises or supine hip bridges should be performed during the first 6 to 8 weeks after surgery. Goldstein states, “The power generated by the massive hip muscles is so great during those exercises that there is a danger of displacing the fractured segments.”⁹

In addition to rudimentary isometric quadriceps sets, gluteal sets, ankle pumps, and gentle hip-motion exercises, authorities advocate adding the exercises described in Figure 19-5 progressively during the first 3 weeks after surgery,⁹ although exercises number 3 (forward bending of trunk) and 12 (hip extension in prone) are not advocated by the author of this chapter.

Early protected weight bearing is encouraged soon after surgery. Generally, touch down weight bearing (TDWB) or partial weight bearing (PWB) is allowed by the second day postoperatively. Weight-bearing status increases as dictated by the rate of bone healing (more than 8 to 12 weeks), which should be verified radiographically by the physician. Avoiding torque through the affected limb during standing minimizes loosening of the fixation device.

More demanding exercises are added as the bone and associated soft tissues heal. Closed-chain functional exercises are added as full weight bearing (FWB) is achieved. Partial wall squats and step-ups are usually initiated to regain concentric and eccentric muscle control of the quadriceps and hip extensors. A restorator or bike ergometer can be used during the early recovery phase if the patient can tolerate sitting, and depending on restrictions about hip flexion, ROM, and precautions.

The moderate-protection phase, defined as 3 to 6 weeks after surgery,⁹ provides for more challenging exercises directed at regaining hip and knee motion, improving quadriceps and hamstring strength, and increasing strength to the hip extensors, abductors, and adductors. Standing four-position hip strengthening can be achieved initially without any resistance until a proper pattern of movement is achieved. Advancing this exercise can be accomplished using a cable system (Fig. 19-6), lower levels of Thera-Band, or ankle weights. The initiation of limited ROM leg presses can commence during this phase as well.

The late healing phase (after 6 to 8 weeks) is characterized by normalized gait mechanics and reduced use of assistive devices for ambulation. A treadmill can be used, with step cadence and stride length adjusted, to enhance gait and provide a stimulus for greater hip and quadriceps strength.

More advanced hip strengthening exercises can be added cautiously for more active patients. The stair-stepper stimulates hip extension strength and local muscular endurance, but extreme caution must be used when initiating various open- and closed-chain exercises after surgery for hip fractures. A fine line must be applied to avoid excessive forces (e.g., straight-leg raises or hip bridges), torque, and weight bearing while stimulating hip and knee motion and improving strength and function.

PROXIMAL FEMORAL OSTEOTOMY

Intertrochanteric osteotomy may be performed when degenerative joint disease (DJD) is extensive and results in hip pain associated with subchondral bone erosion, articular cartilage fibrillation and fissuring, and hip joint incongruity.¹⁵ The goal of this surgical procedure is to reduce pain and improve function related to advanced osteoarthritis by surgically changing the femoral neck-shaft angle so that healthy cartilage is exposed, thus “improving joint surface congruity.”¹⁵ Figure 19-7 illustrates this procedure and shows the changed neck-shaft angle relationship, reduced ligamentous and muscular tension, and improved joint articulation occurring after surgery.¹⁵

HEMIARTHROPLASTY OF THE HIP

For femoral head osteonecrosis or severe femoral head fractures, hemiarthroplasty is used to eliminate pain and improve function. This procedure replaces the damaged femoral head with a bipolar prosthesis. Because hemiarthroplasty requires a normal acetabular surface,15,22 it is rarely used for arthritis.²² This is considered a conservative procedure¹⁵ when compared with a total hip replacement. Hemiarthroplasty can be converted at a later date to total hip replacement if symptoms persist and the joint degenerates.²² The term bipolar refers to two separate snap-fit components of one femoral prosthetic unit. A bipolar prosthesis is usually a large-diameter femoral head component that snap-fits snugly onto a smaller diameter femoral head, which is part of the total prosthetic unit.^9,15 A unipolar femoral prosthesis is a self-contained femoral head and shaft without additional components. The bipolar prosthesis usually produces less wear caused by friction and reduced impact loading of the acetabulum.²⁰

FIXATION OF PROSTHETIC HIP COMPONENTS

As discussed in Chapter 9, the method of fixation of various prosthetic components directly affects the short- and long-term course of rehabilitation after hip arthroplasty. Both femoral and acetabular components usually can be secured to the bone with a cement, polymethylmethacrylate (PMMA), which is not actually an adhesive, but rather provides a strong interference fit between the prosthesis and the bone.²⁰ Or the components can be secured with a noncemented biologic tissue ingrowth prosthesis. Miller²² recommends that cemented femoral stems be used only for patients older than 65 years of age, and that noncemented prostheses be used for younger patients. Weight-bearing precautions are related to the specific type of fixation procedure used to secure the prosthesis. Weight bearing generally is deferred for longer periods of time with a noncemented biologic tissue fit prosthesis so that the bone can grow into the porous coated femoral stem. Weight bearing with cemented devices can progress at a slightly faster rate. However, in either case, rotational forces (torque) must be strictly avoided to minimize the loosening of components.

TOTAL HIP REPLACEMENT

Total hip arthroplasty (total hip replacement, [THR]) involves replacing both the femoral head and the acetabulum, as contrasted with a hemiarthroplasty, which replaces only the femoral head. Indications for the use of THR include the following:

Before discussing rehabilitation procedures, this chapter reviews pertinent complications and component designs related to THR because these issues influence specific physical therapy interventions and precautions.

Surgeons must select a proper femoral head size for each patient. In theory, a large-diameter femoral head may provide for greater ROM and inherent stability.20,22 This makes sense because greater forces are necessary to dislocate a large-diameter head from the acetabulum. In practice, large-diameter femoral head components do not reduce the incidence of dislocation after surgery. Therefore the most commonly used head size is moderate (26 to 28 mm) rather than overly large (32 mm).^20,22

One of the most common complications related to THR, using a noncemented femoral stem component, is persistent thigh pain with an antalgic gait (painful limp-gait) pattern. This thigh pain may last for 1 or 2 years after surgery and is reported in approximately 20% of all patients with this fixation type.20,22

The most significant complication after THR, with the highest mortality, is thromboembolic disease.²⁰ The entire rehabilitation team (PT, PTA, physician, etc.) must be concerned with this complication and monitor for this continually. While many of the signs of thromboembolitic disease after THR are the same as with any other lower extremity injury or surgery, some specific signs post THR would be localized tenderness and swelling along the distribution of the deep venous system of the hip, specifically the femoral vein along the anterior thigh.

Because the method of fixation is directly related to the initiation and progression of weight bearing after surgery with uncemented components, some authorities recommend TDWB on the second day postoperatively, gradually progressing to FWB by 8 weeks postoperatively.⁹ With a cemented (PMMA) prosthesis, Goldstein⁹ suggests TDWB 2 days after surgery, progressing to FWB by the third week postoperatively. These timetables for weight bearing are directed by the biologic rate of bone healing and the wishes of the physician and are applied under the direction of the PT. A cemented component generally allows earlier motion and weight bearing than an uncemented prosthesis.

Loosening of the components has been estimated at 10% to 40% by 10 years postoperatively.²² Loosening is more common among younger, more active patients, obese patients, patients with rheumatoid arthritis, and patients with previous hip surgery.²² The PTA must be acutely aware of these factors when treating THR patients and recognize the increased potential for component loosening.

Postoperative dislocation of the hip after THR is another clinically significant complication occurring at rates between 1% and 4%.²² These dislocations are multifactorial, requiring an awareness of the basic concepts of hardware design, fixation procedures, and surgical approaches and patient compliance with specific total hip precautions to avoid dislocation. The most immediate concern during the recovery from THR is teaching and reinforcing precautions to the patient, nursing staff, family, and other caregivers.

The PTA also should be familiar with the surgical approach used to gain exposure to the hip. Universal total hip precautions are intended to avoid the exact position the surgeon used to expose and dislocate the hip to carry out the procedure. Usually these precautions are as follows:

The preceding precautions apply when a posterior (Fig. 19-8), posterolateral, or lateral approach is used. If an anterior surgical approach is used, combined hip extension and external rotation should be avoided.⁹ Again, this variation is needed because the surgeon had to extend and externally rotate the limb to dislocate the hip and gain exposure for replacement.