Operative Techniques in Orthopaedic Surgery (4 Volume Set) 1st Edition

82. Hemiarthroplasty of the Hip

Hari P. Bezwada, Robert H. Cho, and David G. Nazarian

DEFINITION

images Femoral neck fractures are classified according to the Garden classification11 (Table 1).

images Further simplification of this classification divides these fractures into displaced versus nondisplaced fractures. Guidelines for treatment of nondisplaced femoral neck fractures are beyond the scope of this chapter.

images The indications for a hemiarthroplasty of the hip include displaced femoral neck fractures and salvage for massive acetabular osteolytic defects in revision hip replacement.

images Published reports suggest that bipolar hemiarthroplasty has poor outcomes when used as a primary prosthesis for failures with degenerative joint disease, and this technique currently is not recommended.

images The two types of hemiarthroplasty implants are the unipolar type (eg, Austin-Moore; FIG 1A), and the bipolar type (FIG 1B).

images The bipolar prosthesis has been favored because of its theoretical reduction of wear on the acetabular side, because motion between the inner and outer heads of the prosthesis leads to less motion at the acetabulum–implant interface.15

ANATOMY

images The neck–shaft angle is about 130 ± 7 degrees in adults and does not vary significantly between genders.

images The femoral neck is anteverted 10.4 ± 6.7 degrees with respect to the femoral shaft in Caucasians.

images Some ethnic groups (eg, Asians) have a propensity for higher degrees of anteversion, up to 30%.

images Femoral head diameters range from 40 to 60 mm.

images Femoral neck length and shape vary considerably.

images In cross section, the femoral neck is cam-shaped, with a shorter anteroposterior than mediolateral diameter.

images The calcar femorale is a condensed, vertically oriented area of bone that originates superiorly toward the greater trochanter and fuses with the cortex at the posterior aspect of the femoral neck.

images The major vascular supply of the femoral head comes from the lateral epiphyseal branch of the medial femoral circumflex artery.

images

images Other contributing vessels include the inferior metaphyseal artery, arising from the lateral femoral circumflex artery, and the medial epiphyseal artery through the ligamentum teres, arising from the obturator artery.

PATHOGENESIS

images In elderly persons, a femoral neck fracture usually is the result of a fall.

images Several mechanisms have been proposed:

images A direct blow to the lateral aspect of the greater trochanter from a fall

images A sudden increase in load with the head fixed in the acetabulum along with a lateral, rotatory force. This causes impaction of the posterior neck on the acetabulum.

images Completion of a fatigue fracture that precedes and causes a fall

images The incidence of femoral neck fractures increases as bone density falls to osteoporotic levels.

images Femoral neck fractures in young patients typically are the result of high-energy mechanisms.

images The mechanical explanation is axial loading of the distal femur or the foot if the knee is extended.

images The amount of bony displacement and associated soft tissue injury can be much higher.

images Displacement of a femoral neck fracture can lead to disruption of the vascular supply of the femoral neck.

images This vascular compromise may contribute to the high incidence of avascular necrosis (AVN) with this injury.

images If femoral neck fracture occurs, the intraosseous cervical vessels are disrupted.

images The risk of AVN generally corresponds to the degree of displacement of the fracture of the femoral neck on initial radiographs.

images

FIG 1  A. Austin Moore prosthesis. B. Cemented bipolar prosthesis.

images

FIG 2  Geography of proximal femoral fractures.

images In displaced fractures, most of the retinacular vessels are disrupted. Femoral head blood supply is then dependent on remaining retinacular vessels and those functioning vessels in the ligamentum teres.

images The role of early fixation and joint capsulotomy in prevention of AVN remains controversial.

images The incidence of nonunion following a displaced fracture is as high as 60% with nonoperative treatment in some reports.

images Femoral neck fractures can be divided into subcapital, transcervical, and basicervical types, based on the location of the injury.

images Basicervical fractures often can be treated in a manner similar to intertrochanteric fractures with regard to fracture fixation (FIG 2).

NATURAL HISTORY

images Femoral neck fractures are most commonly seen in patients over the age of 50 years.17

images Patients with a single femoral neck fracture have an increased risk of sustaining a second hip fracture.

images Bateman3 and Gilberty12 reported the use of a bipolar prosthesis.

images The rationale was that less erosion and protrusion of the acetabulum would occur because motion is present between the metal head and polyethylene socket, inner bearing.

images Acetabular wear is diminished by reduction of the total amount of motion that occurs between the acetabular cartilage and metallic outer shell with interposition of the second low-friction inner bearing within the implant.

images Overall hip motion also may be greater, because of the compound bearing surface.

images Barnes et al1 showed that mortality in the first month postoperatively was substantial: as high as 13.3% in men and 7.4% in women.

images More importantly, delaying surgery beyond 72 hours led to a substantial increase in mortality rate.

images Factors influencing mortality in cemented bipolar hemiarthroplasty include cardiac history, residence in a nursing home, chronic pulmonary disease, elevated serum creatinine, pneumonia, history of myocardial infarction, duration of surgery, and gender.10

images Associated injuries may include subdural or epidural hematoma and ipsilateral upper extremity injury for lowenergy fractures.

images High-energy fracture patterns have a higher incidence of associated injury, including closed head injury, pneumoor hemothorax, spinal fracture, visceral injury, and ipsilateral lower extremity bony injury.7

PATIENT HISTORY AND PHYSICAL FINDINGS

images A complaint of groin, proximal thigh, or, rarely, lateral hip pain following a fall in an elderly patient should raise suspicion for a low-energy femoral neck fracture.

images Finding a demented patient down on the floor and unable to ambulate also should raise suspicion for a femoral neck fracture.

images The patient's preinjury ambulatory status must be ascertained when the history is taken. His or her preoperative activity level can help determine the most appropriate type of surgical management.

images Care must be taken to evaluate other possible sources of injury about the hip as well as associated ipsilateral injury.

images Pelvic fracture: Associated injury to the pelvic rami is common. Radiographs are useful in diagnosing these associated injuries.

images Acetabular fracture: In a low-energy injury, acetabular fracture is an uncommon association with a femoral neck fracture. This, however, is not the case in high-energy injury patterns. Thin-slice CT may be useful for diagnosing this injury.

images Interand subtrochanteric fracture: Injury to the intertrochanteric area is commonly seen about the hip in elderly patients. Subtrochanteric fractures are less common. Usually, the limb is held in extension, not in a flexed, externally rotated position. Radiographs again are useful for establishing the diagnosis.

images A thorough physical examination should include:

images Observation of the lower extremity. If it is shortened, externally rotated, and painful to move, a joint effusion secondary to fracture hematoma is most likely responsible, which increases the available space in the joint capsule.

images Logroll maneuver, which is the most sensitive physical finding. A positive result elicits pain at the groin due to the side-to-side movement of the lower extremity, which creates shear forces across a femoral neck fracture, leading to exquisite pain.

images Axial load test, which is positive if the maneuver elicits pain at the groin. This test is less specific than the logroll test.

images Range-of-motion tests. Pain at endpoints of the range of motion may be the only clue to a nondisplaced occult fracture.

IMAGING AND OTHER DIAGNOSTIC STUDIES

images Plain radiographs of the AP pelvis and injured hip should be obtained.

images If possible, the legs should be immobilized in internal rotation for the film.

images A shoot-through lateral radiograph is useful for determining the degree of displacement of the fracture fragment, especially for fractures that appear minimally displaced on an AP view.

images A radiograph taken while applying axial traction is helpful to determine location of the fracture along the femoral neck if displacement of the fracture fragments obscures view of the fracture pattern.

images CT scanning is useful for identifying nondisplaced fractures when clinically suspected as well as associated injuries. It usually is not employed for an isolated, low-energy femoral neck fracture, however.

images Radionucleotide uptake bone scans are helpful in identifying occult femoral neck fractures, but may take up to 72 hours to be apparent on film.

images MRI is more sensitive to identifying occult femoral neck fractures than CT scan or bone scan within the first 72 hours.

images It also is highly sensitive to identifying occult fractures at the ipsilateral intertrochanteric area.

DIFFERENTIAL DIAGNOSIS

images Intertrochanteric fracture

images Subtrochanteric fracture

images Pelvic fracture

images Acetabular fracture

images Hip contusion or traumatic trochanteric bursitis

NONOPERATIVE MANAGEMENT

images Femoral neck fractures rarely are managed nonoperatively. Both nondisplaced and displaced fracture patterns have better functional and overall outcomes when treated surgically.

images Nonoperative management may be relatively indicated in the patient with severe medical comorbidities who would be unable to tolerate anesthesia for surgery intervention.

images Because nondisplaced fractures can be internally fixed with percutaneous techniques under local anesthetic and monitored sedation, nonoperative treatment usually is not indicated for this fracture type.

images In most cases nonoperative treatment should be limited to initial management of the injury before surgical stabilization.

images A soft pillow should be placed under the patient's knee and leg to keep him or her in a comfortable position.

images All patients with femoral neck fractures should be placed on strict bed rest, with a Foley catheter, and intravenous fluids on admission.

images Axial traction of the injured lower extremity is contraindicated for femoral neck fractures, because it can increase displacement of the fracture fragments.

SURGICAL MANAGEMENT

images The best method of surgical fixation of femoral neck fractures is controversial. The debate between internal fixation versus hemiarthroplasty versus total hip arthroplasty continues and is beyond the scope of this chapter.

images General indications for surgical management using hemiarthroplasty include the older patient with low functional demands, or poor bone quality not amenable to internal fixation.

images Hemiarthroplasty is indicated for patients with displaced femoral neck fractures who meet the following criteria.

images Reasonable general health

images Pathologic hip fractures

images Neurologic diseases including Parkinson disease, previous stroke or hemiplegia, or other neurologic diseases

images Physiologic age greater than 70 years

images Severe osteoporosis with loss of primary trabeculae in the femoral head

images Inadequate closed reduction

images Displaced fracture

images Preexisting hip disease on the femoral side, namely osteonecrosis, without any acetabular disease.

images Contraindications include the following:

images Preexisting sepsis

images Young age

images Failure of internal fixation devices, mainly because of acetabular damage that often occurs in that situation

images Preexisting acetabular disease. Even patients with normal preoperative cartilaginous space may become symptomatic after about 5 years due to degradation caused by friction between the metal and the acetabular cartilage.

images Indications for cementing a femoral stem vary from surgeon to surgeon and institution to institution.

images Primary candidates for this approach are patients with poor bone quality, such as those with a “stovepipe” femur or Dorr type C femur.8 These patients can be difficult to manage with uncemented implants, because they require either massive, canal-filling, uncemented implants that often produce significant stress shielding of the femur or have proximally filled implants that can make accurate adjustment of limb lengths very difficult.

images Antibiotic-impregnated cement may be advisable for certain high-risk groups of patients. Some patients, such as those on dialysis, may be more prone to sepsis, so use of antibiotic-impregnated cement should be considered for them.

images Appropriate antibiotics include tobramycin, vancomycin, cefazolin, and erythromycin.

images Cemented stems also should be considered for patients with pathologic fractures. For these patients, the use of cement with a bone-replacing prosthesis may be the preferred treatment, regardless of age or bone quality.

images The first-generation cementing technique involved fingerpacking without the use of pressurization and a reduction of porosity. Modern cementing techniques use a medullary brush, a cement restrictor, medullary pulsatile lavage, the insertion of epinephrine-soaked sponges, a reduction of cement porosity (ie, vacuum mixing), cement centralizers, and a cement gun for retrograde cement insertion, after which pressurization can be performed with a surgeon's gloved finger or, alternatively, with a wedge-shaped pressurization device.

images Because of the embolic load secondary to pressurization, many surgeons avoid cemented components in patients with a history of cardiopulmonary disease.

Preoperative Planning

images It is important for preoperative planning that the preoperative x-rays are reviewed and templated for appropriate size and for fixation.

images Pending those findings, appropriate implant selection should be undertaken as well, whether to proceed with a tapered stem, a fully coated medullary-locking stem, or include a cemented stem.

images The patient should undergo an appropriate preoperative workup including medical, cardiac, and anesthesia evaluations.

images Banked blood should also be available.

images Important preoperative laboratory studies include complete blood counts, electrolytes, and coagulation studies.

images Additional blood tests could include total protein, albumin, and appropriate liver studies to evaluate overall the patient's nutritional status.

images Electrocardiogram, chest radiograph, and, possibly, further cardiac studies, including echocardiogram, may be appropriate preoperatively.

images The femoral head size must be evaluated to establish the correct component size.

images If the component is too large, equatorial contact occurs, which can result in a tight joint with decreased motion and pain.

images If the component is too small, polar contact occurs, leading to increased contact stresses and, therefore, to greater erosion and possible superomedial migration.

images It is also important to template neck length and offset.

images If the neck length is too long, reduction can be difficult, and the increased soft tissue tension also could lead to increased pressure on the acetabular cartilage.

images The offset should be reproduced postoperatively. It is important to create that by evaluating the distance between the center of the femoral head and the greater trochanter, thereby restoring the length of the abductor mechanism and decreasing postoperative limp.

images These procedures can be performed under spinal or combined spinal and epidural anesthesia, because hypotensive anesthesia can have the benefit of reducing blood loss.

images Prophylactic antibiotics are administered before the surgery.

images The procedure must be performed in a clean operating room with laminar flow. Vertical laminar airflow in conjunction with operating suite and body exhaust systems is helpful.

images Associated injuries should be addressed concurrently if possible.

Positioning

images Patient positioning is important and should be done very carefully.

images General positioning principles include padding all bony prominences, positioning in a stable position for implant placement, and providing a range-of-motion arc so that implant position and stability can be tested intraoperatively.

Supine Position

images Once the patient is adequately anesthetized, he or she is placed in a supine position, which allows for direct measurement of leg length.

images The operating table is placed in a flat position. A bump is placed beneath the sacrum.

images The patient is brought to the edge of the table, so that the operative hip slightly overhangs the edge of the table.

images A sacral pad is constructed of folded sheets and placed directly beneath the sacrum.

images The modest elevation of the sacrum allows the fat and soft tissues from above the trochanter to fall posteriorly away from the incision, thereby minimizing the amount of tissue that must be dissected in a lateral approach.

images It also allows hip stability to be evaluated in extension.

images A footrest is fixed to the operating table, so that the surgical hip is flexed 40 degrees.

images Both arms are placed on armboards secured at 90 degrees of abduction.

images The operating room table is then inclined 5 degrees away from the operating surgeon to improve visualization of the acetabulum.

Lateral Position

images The lateral position is used for a posterolateral approach to the hip and also can be used for an anterolateral approach.

images Once the patient is adequately anesthetized and a Foley catheter is inserted, he or she is placed in the desired position in a gentle, organized fashion.

images The anesthesiologist controls the patient's head and neck, holding the endotracheal tube securely.

images One surgical team member controls the patient's hands and shoulders, and another controls the patient's hips.

images The ipsilateral arm is positioned in no more than 90 degrees of forward flexion and slight adduction.

images An axillary pad is placed by lifting the patient's chest and positioning the pad distal to the contralateral axilla.

images The contralateral arm must be kept in no greater than 90 degrees of forward flexion.

images Extremities are padded over all bony protuberances.

images The operating room table must be kept in an absolute horizontal position, parallel to the floor.

images A number of holders can be used to hold the patient in a lateral decubitus position.

images A beanbag can be used, although it is not as rigid as a variety of other holders. The pubis and sacrum must be secured in the holder.

images Placement of the pubic clamp must be done cautiously, with the pad directly against the pubic symphysis.

images Placement of the pad more inferiorly causes occlusion or compromise of the femoral vessels in the opposite limb, which may go unrecognized.

images Placement of the pad superiorly may compromise ipsilateral femoral vessels, and may prevent adequate flexion and adduction of the operated hip.

images A sacral pad is placed over the mid-sacrum. It should be at least 3 to 5 inches away from the most posterior end of the skin incision (FIG 3A).

images When the patient is securely positioned in lateral decubitus, the position of the pelvis is checked, to make sure that it is not tilted in the anteroposterior direction (FIG 3B).

images

FIG 3  A. Palpation of anterior superior iliac spine for lateral positioner. B. Adequate range of motion must be ensured after positioning.

images A chest positioner and pillows between the arms are helpful in preventing anterior displacement of the torso.

images The perineum is isolated using an adhesive U-shaped plastic drape.

Approach

images Hemiarthroplasty can be performed through a number of different approaches.

images There are four commonly employed approaches to the hip joint

images Anterior (Smith-Petersen)

images This approach uses the interval between the sartorius and the tensor fascia lata.

images Risks include injury to the lateral femoral cutaneous nerve.

images This approach delivers the surgeon directly onto the anterior hip capsule.

images Femoral preparation is difficult and may require traction, hip extension, and the use of a hook to deliver the femur anteriorly for preparation.

images Anterolateral (Watson-Jones)

images Lateral (modified Hardinge)

images Posterior (Southern)

images Choice of approach is highly dependent on surgeon preference.

images We use a modification of the lateral muscle-splitting approach to the hip, as originally described by Hardinge, and the use of a cementless tapered stem.4

images A cemented stem can be implanted through a number of surgical exposures.

LATERAL APPROACH (MODIFIED HARDINGE)

Preparation of the Surgical Site

images Plastic adhesive drapes are used to isolate the operative field from the perineum and adjacent skin.

images A large U-drape is placed isolating the perineum and abdomen from the hip.

images A second drape is placed transversely above the level of the iliac crest, completing the isolation of the wound area from the abdomen and thorax.

images The foot also is sealed, with a plastic 10 × 10 drape isolating the foot above the level of the ankle.

images The operative field is scrubbed with a Betadine soap, followed by a preparation with Betadine solution and alcohol (TECH FIG 1A).

images The incision area is dried to allow better adherence of Ioban drapes (3M, St. Paul, MN).

images The limb is removed from the leg holder, and the surgeon grasps the foot with a double-thickness stockinette.

images Impermeable drape is placed across of the bottom of the operating table up to the level of the patient's buttock.

images

TECH FIG 1  A. Skin preparation for lateral (Hardinge) approach to the hip. B. Lateral skin incision.

images The stockinette is unrolled to the level of the midthigh and secured with a Coban dressing (3M).

images The limb is draped sterilely using two full-sized sheets brought beneath the leg and buttock and held above the level of the iliac crest.

images A double sheet is placed transversely across the abdomen above the level of the iliac crest.

images A clean air room is then sealed at the head of the operating table with sterile adhesive drape.

images The hip area is marked using a sterile pen.

images The greater trochanter is outlined.

images The iliac crest and femoral shaft are palpated, and the skin incision, centered over the trochanter and slightly anterior, is drawn with large cross-hatchings (TECH FIG 1B).

images The hip is flexed to 40 degrees and slightly adducted. The foot is placed on the footrest.

Incision

images The skin incision is approximately 5 inches in length.

images The incision is slightly anterior to the apex of the vastus ridge.

images The length of the incision also depends on the patient's degree of obesity.

images The skin incision is taken sharply through subcutaneous tissues down to the tensor fascia lata (TECH FIG 2A).

images The fascia is exposed to a small degree, just to allow the incision and subsequent closure.

images Hemostasis is achieved in the subcutaneous tissue with electrocautery and bayonet forceps.

images The incision through the fascia lata is in line with the skin incision.

images A scalpel is used to penetrate the fascia lata and allow a safe entrance to the compartments.

images The incision is continued with the use of heavy MayoNoble scissors. It is not undermined beyond the skin incision or distal or proximal to the skin incision (TECH FIG 2B).

Proximal Dissection

images More proximally, the fibers of the gluteus maximus muscle are split using firm thumb dissection.

images

TECH FIG 2  A. The tensor fascia lata exposed. B. An incision is made into the tensor fascia.

images A Hibbs retractor is used to retract the anterior flap of the fascia lata.

images Once that is done, the gluteus medius, greater trochanter, and vastus lateralis are clearly visualized.

images The abductor mass is split.

images The basic premise of the modified Hardinge approach is to develop an anterior flap, composed of the anterior portion of the vastus lateralis, anterior capsule, anterior third of the gluteus medius muscle, and most of the gluteus minimus muscle to allow exposure of the hip joint.

images The muscle split usually is located in the anterior third of the gluteus medius.

images The muscle split is made using electrocautery through the gluteus medius (TECH FIG 3A,B).

images Once the gluteus medius is penetrated, the surgeon encounters a fatty layer, beneath which is found the gluteus minimus.

images The gluteus minimus is isolated, and a more posterior incision is made with the electrocautery through the gluteus minimus and the capsule onto the acetabulum. (TECH FIG 3C).

images A blunt Hohmann retractor is placed posteriorly to expose the gluteus minimus and capsule. The blunt end of the Hibbs retractor is used to retract the anterior aspect of the gluteus medius.

images The capsule then is visualized in the depths of the wound.

images The capsule is incised parallel to the superior aspect of the femoral neck, and the incision is extended to the bony rim of the acetabulum with care not to damage the labrum.

images This area is then packed with an E-tape sponge (TECH FIG 3D).

Distal Dissection

images Attention is next turned to the more distal aspect of the wound and the vastus lateralis.

images The anterior third of the vastus lateralis is incised longitudinally using electrocautery, beginning at the trochanteric ridge and extending 2 to 3 cm beyond.

images Once this is dissected subperiosteally in the anterior direction, a blunt Hohmann retractor is placed around the femur medially to reflect the vastus lateralis anteriorly.

images An anterior bridge of soft tissue remains along the greater trochanter between the incision in the vastus lateralis and the incision in the gluteus medius and superior capsule. This bridge consists of the anterior fibers of the gluteus medius, minimus, and capsule.

images

TECH FIG 3  A. Diagram of the splitting of the abductor mass. B. The abductor mass exposed. C. Detachment of the abductor mass. D. Exposure of the femoral neck.

images

TECH FIG 4  More proximal femoral exposure.

images This bridge is incised through the tendon in a gentle arc along the anterior aspect of the greater trochanter, connecting the incisions.

images Healthy soft tissue must be present on both sides of this arc to allow effective repair during closure.

images The bridge is dissected using electrocautery, in the anterior aspect of the greater trochanter, to develop a flap in continuity consisting of the anterior portion of the gluteus minimus and going around the gluteus medius, anterior hip capsule, and gluteus minimus. This exposes the femoral neck and head.

images The dissection is carried medially until the medial aspect of the neck is exposed (TECH FIG 4).

images Exposure usually is adequate to allow for dislocation of the hip, femoral neck, or proximal femur.

images A bone hook is placed around the neck of the femur anteriorly, and the leg is externally rotated to allow for dislocation of the hip, ie, the hip is placed in the figure-4 position.

images At this point, with a femoral neck fracture, the proximal femur often will dissociate from the femoral neck.

images An initial rough cut of the femoral neck can be performed in line with appropriate preoperative templating.

images Two blunt-tip retractors are placed around the femoral neck to protect the soft tissues.

images Electrocautery is used to mark the femoral neck, and an initial cut of the femoral neck is made with an oscillating saw.

Placement of Acetabular Retractors

images Attention is turned to the acetabulum.

images The first retractor is placed in the anterior acetabulum.

images A small plane is created between the anterior wall of the acetabulum and the anterior capsule using a Cobb elevator.

images A blunt-tip Hohmann retractor is placed in the 12 o'clock position anterior to the acetabulum beneath the capsule.

images An assistant can then easily retract the anterior soft tissues.

images The second spiked Mueller acetabular retractor is placed in the superior aspect of the acetabulum, retracting the superior capsule in the cranial direction.

images The retractor is placed at 10 o'clock for the right hip and 2 o'clock for the left hip.

images The exact placement of the retractor is outside the labrum and inside the capsule.

images Using the impactor mallet, the surgeon drives this retractor into the ilium in a slightly cranial direction.

images The tip is not driven perpendicular to the axis of the body, because it may perforate the dome of the acetabulum.

images To facilitate appropriate exposure prior to placement of the third retractor and to allow posterior mobilization of the proximal femur, a medial capsular release must be performed.

images A curved hemostat is placed between the iliopsoas and capsule, anterior and in line with the pubofemoral ligament.

images The capsule is incised medial to lateral, thereby increasing the mobilization of the femur in a posterior direction.

images A third, double-angled acetabular retractor is placed inferiorly.

images It is placed in the ischium inferiorly, with the blade of the retractor resting on the neck of the femur rather than on the cut surface.

Femoral Head Removal and Implant Sizing

images At this point, the femoral head and neck are clearly visualized in the acetabulum.

images The femoral head and neck fracture can be removed using a corkscrew in combination with a Cobb elevator or a tenaculum.

images This should be done carefully so as not to damage the acetabular cartilage or the labrum (TECH FIG 5A,B).

images Once the femoral head is removed, it should be measured to enable the surgeon to estimate the size of the acetabulum.

images The acetabulum should be sized with a trial bipolar or unipolar component to ensure that there will be good fit without overfilling the acetabulum.

images This can be achieved with a good suction-tight feel with placement of the trial component.

images It should move freely without resistance.

images If it floats freely in the acetabulum, the trial component is undersized (TECH FIG 5C).

Femoral Reaming

images The femur is exposed with the use of two double-footed retractors, one beneath the greater trochanter and a second retractor medially in the area of the calcar.

images The leg is placed in a figure-4 position, crossed over the opposite thigh.

images The femur should be easily exposed.

images If there is difficulty in this exposure, the leg should be placed in a greater degree of figure-4 and rotation.

images Excess soft tissue is removed from the tip of the greater trochanter to allow for reaming and broaching. This will prevent varus positioning of the component.

images A large rongeur is used to open the femoral canal slightly.

images A small, straight curette is introduced into the femoral canal in neutral orientation.

images The second assistant should use his or her hand to create a target at the distal femur in line with the femur.

images As the surgeon is placing the small curette, he or she can use the opposite hand on the patient's knee to help direct the small metal curette in the appropriate orientation (TECH FIG 6A).

images

TECH FIG 5  A. Placement of point-to-point clamp around the femoral head. B. Removal of femoral head from acetabulum. C. Insertion of prosthesis head sizer.

Femoral Broaching

images An entry reamer is then introduced into the femoral canal, pushed into valgus, and worked into the trochanter to ensure appropriate component positioning (TECH FIG 6B).

images The bone within the area of the greater trochanter in the lateral aspect of the femoral canal is removed using a lateral rasp or a curette (TECH FIG 6C).

images

TECH FIG 6  A. Use of a curette for femoral orientation. B. Reaming of the femoral canal. C. Lateralization of the femoral canal with a lateral rasp.

Femoral Broaching

images The femoral broach is introduced in neutral position, and neutral version of the rotation is judged in relation to the position of the knee.

images Broaching is begun with the smallest broach and then increased until appropriate fit and fill is achieved. This can be gauged by preoperative templating and tactile feedback.

images The broach is then introduced each time to its full depth.

images If significant resistance is met, broaching should continue with a series of small inward and then outward taps.

images Broaching is continued until full cortical seating has been accomplished. This is indicated by an upward change in pitch as the broach is being seated.

images Final seating and sizing is determined by pitch, tactile feedback, and lack of progression (TECH FIG 7A).

images Once the final seating of the femoral broach is accomplished, an initial reduction with the appropriate-sized hemiarthroplasty bipolar or unipolar trial component is performed (TECH FIG 7B).

images

TECH FIG 7  A. Broaching of the femoral canal. B. Placement of trial head onto trial femoral prosthesis.

images

TECH FIG 8  Intraoperative evaluation of trial prosthesis leg length.

Evaluation of Trial Prosthesis

images The hip is reduced for evaluation.

images Hip stability is evaluated in full flexion and in internal and external rotation.

images One finger is kept in the joint to evaluate for anterior impingement.

images Anterior stability is evaluated with external rotation, adduction, and extension.

images Leg lengths are measured directly.

images The position of the pelvis, shoulders, and the knees must be evaluated as the assistants help with orientation (TECH FIG 8).

images Stability also is evaluated with a longitudinal shuck test, with a goal of 1 or 2 mm of shuck.

images Excessively tight soft tissues about the hip cause difficult or incomplete extension of the hip; excessive laxity leads to increased shuck.

images For inadequate soft tissue tension and appropriate leglength restoration, a lateral offset also can be used.

images It is important to achieve stability, which takes precedence over leg length.

Placement of the Femoral Stem

images Once stability is satisfactory, the trial components are removed.

images The wound and the femur are irrigated with pulsatile lavage.

images Excessive debris is removed.

images The femur is prepared again, with the curette only, to clear any soft tissue debris from the lateral aspect of the femur.

images The femoral canal must be copiously irrigated.

images The surgeon and assistant change outer gloves.

images The appropriately sized femoral component is placed in the femoral canal with the use of an impactor.

images Varus positioning must be avoided. It can be prevented with appropriate valgus positioning of the stem on insertion, with attention also paid to maintaining the appropriate version.

images The femoral component is seated into position using firm taps with a mallet.

images A pause between taps may allow some plastic deformation of the femur.

images Final seating is determined in relation to the last broach, tactile feedback, pitch change, and lack of progression (TECH FIG 9).

Completion of Implant Placement

images Once the stem is placed, a second trial reduction can be performed with the trial next segment and trial bipolar shell, or a final component can be placed if the broach and stem achieve the same position.

images If the trial bipolar shell is desired, trial reduction is performed again.

images The reduction is performed with the patient held in position by the second assistant and the first assistant.

images The surgeon reduces the hip with distraction, internal rotation, and adduction.

images The surgical technician can assist the reduction with longitudinal traction.

images The bipolar is assembled on the back table with the outer acetabular bipolar shell impacted on the appropriate size head.

images This can be a 22-, 28-, or 32-mm head, depending on the implant system, with a polyethylene insert and bipolar shell that sits over that (TECH FIG 10A).

images Once that is assembled on the back table, the trunion is cleaned and dried, and the bipolar shell is then impacted on to the trunion of the neck of femoral prosthesis.

images

TECH FIG 9  A. Placement of final femoral stem. B. Impaction of femoral stem.

images

TECH FIG 10  A. Assembly of bipolar head. B. Placement of bipolar head onto femoral stem. C. Relocation of the prosthetic hip into the native acetabulum.

images The acetabulum is checked one last time before final reduction for any debris or any soft tissue (TECH FIG 10B).

images Once it is checked and cleared, the hip is reduced, and the bipolar shell is reduced and checked for appropriate position, after which the wound is thoroughly irrigated and copiously irrigated with pulsatile lavage (TECH FIG 10C).

images At this point, drains can be used according to the preference of the surgeon. We prefer not to use drains.

Wound Repair and Closure

images The abductor mass is then repaired.

images The vastus lateralis is repaired to the remaining tissue sleeve with interrupted absorbable sutures in figure-8 fashion with no. 1 Vicryl.

images The gluteus medius tendon and capsule are repaired to the tissue sleeve on the bridge of the trochanter.

images This is done with heavy absorbable sutures in figure8 fashion.

images The repair is done at the corner of the gluteus medius tendon and then extended into the proximal split with simple sutures (TECH FIG 11A).

images Once the hip abductor is adequately repaired, the tensor fascia lata is approximated with absorbable sutures in figure-8 fashion.

images This must be done to both the proximal and distal extents of the fascia lata.

images The potential dead space is then obliterated with heavy absorbable sutures, and then smaller, absorbable 2-0 sutures are placed in subcutaneous tissue (TECH FIG 11B).

images Skin staples are applied.

images Sterile dressing is applied with Microfoam surgical tape (3M, St. Paul, MN).

images An abduction pillow is placed between the legs and loosely secured.

images The patient is awakened from anesthesia and brought to the recovery room if, or as soon as, his or her condition is stable.

images Postoperative radiographs are taken in the recovery room (TECH FIG 11C).

images

TECH FIG 11  A. Repair of the abductor mass. B. Repair of the tensor fascia lata. C. AP radiograph of an implanted bipolar prosthesis.

POSTERIOR APPROACH (SOUTHERN)

Incision and Dissection

images Exposure of the hip begins with appropriate identification of the bony landmarks.

images The posterolateral corner of the greater trochanter and the anterior and posterior borders of the proximal femoral shaft are marked 10 cm below the greater trochanter (TECH FIG 12A,B).

images The incision begins at this point and extends obliquely over the posterolateral corner of the greater trochanter, continuing proximally, so that the acetabulum is centered in the incision.

images The incision usually is 15 to 20 cm, although this will vary, depending on the patient's body habitus (TECH FIG 12C).

images Once the subcutaneous tissue is divided, the fascia lata is identified and incised in line with the incision.

images The fibers of the gluteus maximus belly are bluntly separated with firm finger pressure (TECH FIG 12D,E).

images A Charnley self-retaining retractor is placed to retract the gluteus maximus and tensor fascia. The gluteus maximus tendon may be released from the femur.

images The hip is internally rotated to offer exposure to the posterior structures.

images The piriformis tendon is identified by palpation, and a curved retractor is placed deep to the abductors just superior to the piriformis (TECH FIG 12F).

images A cobra retractor is then placed inferiorly, inferior to the femoral neck.

images The short external rotators and piriformis may be released separately from the capsule and tagged.

images The piriformis and conjoint tendons should be divided as close to their insertions as possible.

images Alternatively, the external rotators and capsule can be taken down as one continuous sleeve off the trochanter and femoral neck (TECH FIG 12G).

images

TECH FIG 12  A. Palpation of bony landmarks for posterior approach. This is created by the midpoint of the anterior superior iliac spine and the ischial tuberosity. B. Incisional line. Note its placement with respect to the axis of the femur, the proximal extent of the greater trochanter, and the previous line created by bony palpation. C. Skin incision. D. Identification and incision of the tensor fascia lata. E.Exposure of the deep posterior structures of the hip after blunt separation of the gluteus maximus. F. Deep posterior structures of the hip. G. Reflection of the short external rotators. (A–E, Courtesy of Norman A. Johanson, MD.) Sciatic nerve External rotators and capsule (reflected)

images Following the reflection of the short external rotators, the capsule is isolated by repositioning the superior and inferior retractors.

images The curved superior retractor is placed deep to the gluteus minimus just over the superior femoral neck and capsule.

Site Preparation

images A capsulotomy is performed from this posterosuperior acetabulum and continued to the tip of the trochanter in line with the posterior border of the abductors.

images It is continued inferiorly along the femoral neck instead of making oblique posterior limit of the capsulotomy in favor of reflecting this capsule as continuous sleeve to the level of the lesser trochanter (TECH FIG 13).

images The quadratus femoris can be released along with the capsule leaving a small muscular cuff with later reattachment. The capsule can be tagged with a suture.

images The hip is gently dislocated using a combination of flexion, internal rotation, and adduction.

images The leg is held at 90 degrees of internal rotation so that the femoral neck is parallel to the ground.

images At this point, the proximal femur usually dissociates from the femoral neck and head, which often remain in the acetabulum.

images Two retractors can be placed around the proximal femur, and a fresh cut of the femoral neck can be performed with an oscillating saw.

images Alternatively, if this is a low femoral neck fracture, this area can be smoothed with a rongeur and attention turned to the acetabulum.

images At this point, the retractors are placed around the acetabulum. Initially a curved retractor is placed anteriorly, retracting the proximal femur out of the view of the acetabulum.

images The operated extremity is placed in slight flexion, which aids in exposure.

images Occasionally, the reflected head of the rectus femoris must be released.

images A Steinmann pin can be placed in the ilium to reflect the abductors, and a small capsulotomy can be made inferiorly to allow for placement of a cobra retractor deep to the transverse acetabular ligament.

images

TECH FIG 13  Exposure of the hip capsule. (Courtesy of Norman A. Johanson, MD.)

images A bent Hohmann retractor can be placed posteriorly, taking care to first palpate the sciatic nerve to ensure that it is out of harm's way.

images At this point, the acetabulum is exposed, and the femoral head can be removed again with a corkscrew and a Cobb elevator.

images This step should be done very carefully, to avoid damaging the acetabular cartilage.

Component Placement

images The femoral head is measured. A trial shell can be placed in the acetabulum for appropriate sizing, which is performed as described for the modified Hardinge approach.

images Once an appropriate size has been determined, the leg is flexed and internally rotated to expose the proximal femur.

images The leg is held at approximately 90 degrees of internal rotation and 70 degrees of flexion, bringing the osteotomized neck into the surgeon's view.

images A trochanteric elevator is placed with the teeth under the anterior aspect of the femoral neck, lifting it out of the wound. This allows for unencumbered preparation of the femoral neck (TECH FIG 14A).

images The femur is then prepared in a fashion similar to that described for the modified Hardinge approach (TECH FIG 14BF).

images In cases where cemented femurs are preferred, a trial of reduction for leg lengths can be performed, and then a final component can be cemented into place.

images The component must be cemented in the appropriate version, and the neck of the prosthesis must sit on the femoral neck, which can be additionally prepared with a calcar planer.

Completion of the Procedure

images Once the final components are placed and the hip is reduced, two drill holes can be made in the posterior aspect of the greater trochanter for repair of the capsular and short external rotators.

images Once the hip is reduced, two nonabsorbable sutures are placed in the capsular flap.

images The capsular and external rotator tagging sutures are then brought through the drill holes and the greater trochanter tied in layers.

images The quadratus femoris and gluteus maximus tendon also can be repaired if that is the surgeon's preference (TECH FIG 15).

images Subsequently, the Charnley retractor is removed, and the tensor fascia lata and gluteus maximus fascia are reapproximated.

images Dead space is closed with absorbable sutures in the subcutaneous fat, and then absorbable sutures are placed in the subcutaneous tissue.

images Skin staples are applied at the skin level, and a sterile compressive dressing is applied.

images The hip must be held in abducted position. An abduction pillow is placed, and the patient is taken from the lateral position and placed in the supine position at the end of the operation.

images

TECH FIG 14  A. Presentation of the proximal femur. B. Pilot hole for femoral preparation. C. Reaming of the femoral shaft. D. Lateralization of the femoral shaft using a reamer. E. Reamed femoral shaft. Note the lateralization of the canal. F. Broaching of the femoral shaft. (Courtesy of Norman A. Johanson, MD.)

images

TECH FIG 15  Approximation and repair of the short external rotators.

CEMENTED TECHNIQUE

images The trochanteric fossa is cleared of soft tissue, and a pilot hole is made in it with a small metal curette.

images An entry reamer is inserted along this pilot hole to seek the long access of the femoral canal.

images The residual femoral neck is cleared with a rongeur or box osteotome. Sometimes a lateralizing reamer is used to ensure direct access to the femoral canal and minimize the possibility of varus implantation.

images Broaches often are oversized relative to the final implant size, thereby ensuring a minimum cement mantle all around the implant.

images The final broach is determined when it adequately fills the proximal femur; it also serves as a trial component for reduction.

images Once the stability, limb length, and offset are satisfactory, cementation can be performed. The canal is gently curetted to remove any loose cancellous bone.

images The canal is irrigated with a long pulsating irrigating tip.

images High-quality cancellous bone remains in the femoral canal following this preparation.

images It is important to centralize the prosthesis to ensure an uninterrupted cement mantle around the implant.

images A plug is placed after the canal is irrigated.

images We prefer to allow 1 to 2 cm of cement below the tip of the implant so that the plug may be placed at that level.

images It must be secure enough to withstand pressurization.

images Three 40 gram packs of cement are typically mixed with a vacuum system.

images The canal is then packed with sponges to keep it dry during the cementation. Alternatively, continuous suction may be used.

images The viscosity of the cement is an important consideration. The cement should be somewhat doughy and delivered through a cement gun.

images Appropriate cement viscosity has been reached when the cement no longer sticks to the surgical gloves.

images Once the cement reaches the appropriate viscosity, the packing sponges are removed and the canal is suctioned. Cement is delivered in a retrograde fashion into the canal.

images Once the canal is filled with cement, a pressurizing unit can be placed over the proximal femur, or pressurization can be achieved with a gloved finger.

images The prosthesis is then inserted into the doughy mass of cement with the centralizer attached to the tip.

images The leg is placed in a secure position, and the prosthesis is inserted.

images The prosthesis must be inserted with the appropriate anteversion from insertion all the way down.

images It is preferred not to rotate the femoral component within the canal, because this will create undesirable cement voids.

images The prosthesis must be inserted with great care to avoid varus malposition.

images All the excess cement is then removed, and the stem is held in place until the cement has fully hardened. The femoral trunion should be cleaned at this point, and the hemiarthroplasty component should be inserted onto the stem.

images The hip is then reduced and the appropriate closure is performed.

ANTEROLATERAL (WATSON-JONES) TECHNIQUE

images One major difficulty with the Watson-Jones technique is dealing with the gluteus medius and minimus.

images The hip abductors lie over anterior hip capsule and could be damaged in an effort to obtain adequate exposure.

images The original approach used by Charnley placed the patient in a supine position and required a trochanteric osteotomy. This approach is used less commonly now because of problems associated with trochanteric reattachment.

images The skin incision is made 2.5 cm behind the anterior superior iliac spine to the tip of the greater trochanter, then extended vertically along the anterior margin of the trochanter.

images The intraneural interval is between the tensor fascia lata and gluteus medius. An incision is made in the underlying iliotibial band, after which the tensor fascia lata is retracted medially and the gluteus medius is retracted laterally.

images Deep dissection may require release of the anterior parts of the gluteus medius and minimus, which are raised from the femur and retracted posteriorly.

images The upper part of the capsule at hip joint will be seen with reflected head of the rectus femoris attached to the upper part of the acetabular rim.

images It can then be detached with greater exposure of the capsule, which may be incised.

images The ascending branch of the lateral femoral circumflex artery and the accompanying veins run deep to the muscles and must be ligated.

images A longitudinal incision is made in the joint capsule, along the femoral neck and transversely from the proximal femur.

images A bone hook can be used to apply a direct lateral force to disimpact the femoral neck fracture. The femoral head can then be carefully removed from the acetabulum.

images The acetabulum is then sized as previously described.

images After the femur is externally rotated, adducted, and extended, it can be prepared.

images Femoral preparation in this approach may require specialized instruments.

images Consider detaching or splitting along the anterior third of the gluteus medius to eliminate the risk of damage to the superior gluteal nerve, which passes 4.5 cm above and 2 cm behind the tip of the greater trochanter.

images

images

POSTOPERATIVE CARE

images All patients are placed into a soft hip abduction pillow, and bilateral thromboembolic stockings are put on with sequential venous compression devices.

images Antiembolic prophylaxis is started according to the surgeon's preference.

images Extended prophylaxis may be considered for these patients.

OUTCOMES

images Bipolar hemiarthroplasty was introduced in the 1970s in an effort to prevent or retard acetabular wear.

images These femoral prostheses have a 22-to 32-mm head that articulates with a polyethylene liner.

images The liner is covered with a polished metal outer shell that articulates with the acetabular cartilage.

images Depending on implant design, about 45 degrees of angular motion is available before the prosthetic neck impinges on the liner and axial rotation is restricted.

images Theoretically, hip motion occurs primarily at the prosthetic joint and only secondarily at the metal-cartilage interface.

images The polyethylene liner may help to protect the native acetabular cartilage by cushioning the high-contact pressures that occur across the bearing.

images LaBelle et al14 reported no acetabular protrusio or articular cartilage wear greater than 2 mm in 49 femoral neck fractures treated with cemented bipolar hemiarthroplasties at 5-to 10year follow-up.

images Wetherell and Hinves19 reported a 50% reduction in acetabular erosion for patients treated with a cemented bipolar prosthesis when compared to those treated with a unipolar prosthesis.

images Research attempting to demonstrate that motion occurs within a bipolar prosthesis has yielded conflicting results.

images Drinker and Murray9 fluoroscopically evaluated 13 hips in 10 young patients following bipolar reconstruction for AVN and noted that only a minor amount of motion occurred at the inner bearing and that motion tended to decrease over time.

images They further demonstrated that in this group most implants functioned as a unipolar prosthesis and concluded that motion will occur at the interface where there is the least frictional resistance. They found that this location is not the same in arthritic hips as in fractured hips.

images These patients with acute hip fracture proved that with normal articular cartilage, primary intraoperative or intraprosthetic motion occurred in only 25%, and most implants again functioned as unipolar.

images Brueton et al,6 whose radiographic analysis of 75 bipolar prostheses, were equally divided between 32-mm and 22-mm heads, showed that the smaller head was associated with more motion.

COMPLICATIONS

images Thromboembolism (eg, deep vein thrombosis, pulmonary embolism)

images Kenzora et al13 reported a mortality rate of 14% during the first year following hip fracture.

images When compared to 9% mortality in population of similar age, the mortality after hemiarthroplasty is 10% to 40%.

images The incidence of intraoperative femur fracture is 4.5%. Most are nondisplaced and involve either the trochanter or calcar.

images When an intraoperative femur fracture occurs, treatment options include methylmethacrylate combined with longstem prosthesis or, alternatively, with a fully coated cementless stem and cables.

images The rate of dislocation is less than 10%. Dislocation is more common with incorrect version, posterior capsulectomy, and excessive postoperative flexion or rotation with the hip adducted.

images Postoperative sepsis has been reported to range from 2% to 20% and may be more common with the posterior surgical approach. Infections may be superficial or deep.

images Loosening or migration may be suspected with the presence of a radiolucent line around the prosthesis.

images If clinical signs and symptoms are present, or loosening or migration is present, a revision arthroplasty may be considered.

images Cementation does present some hazards, and in some cases the application of pressurized cement is associated with an embolization phenomenon with cement elements (ie, monomer, polymethylmethacrylate elements, or fat). Embolization of these materials may result in hypoxia, cardiac arrest, or death.

images The risk factors include older age or patent foramen ovale.

images The use of pulsatile lavage can reduce that risk by removing fat and marrow from the femoral canal.

images In older patients with substantial medical comorbidity, it may be wise to avoid pressurization of the cement within the canal, because the risk of acute embolization may be high.

REFERENCES

1.     Barnes JT, Brown JT, Garden RS, Nicoll EA. Subcapital fractures of the femur: a prospective review. J Bone Joint Surg Br 1976;58B:2–24.

2.     Barnes R. The diagnosis of ischaemia of the capital fragment in femoral neck fractures. J Bone Joint Surg Br 44B:760–761.

3.     Bateman JE. Single assembly total hip prosthesis preliminary report. Orthop Dig 1974;2:15.

4.     Bezwada HP, Shah AR, Harding SH, et al. Cementless bipolar hemiarthoplasty for displaced femoral neck fractures in the elderly. J Arthroplasty 2004;19(7 Suppl 2):73–77.

5.     Browner BD, Jupiter JB, Levine AM, et al, eds. Skeletal Trauma: Basic Science, Management, and Reconstruction, ed 3. Philadelphia: WB Saunders, 2003:1714–1766.

6.     Brueton RN. Effect of femoral component head size on movement of the two-component hemi-arthroplasty. Injury 1993;24:231–235.

7.     Dedrick DK, Mackenzie JR, Burney RE. Complications of femoral neck fractures in young adults. J Trauma 1986;26:932–937.

8.     Dorr LD, Faugere MC, Mackel AM, et al. Structural and cellular assessment of bone quality of proximal femur. Bone 1993;3:231–242.

9.     Drinker H, Murray WR. The universal proximal femoral endoprosthesis: a short-term comparison with conventional hemiarthroplasty. J Bone Joint Surg Am 1979;61A:1167.

10. Eiskjaer S, Ostgard SE. Risk factors influencing mortality after bipolar hemiarthroplasty in the treatment of fracture of the femoral neck. Clin Orthop Relat Res 1991;270:295–300.

11. Garden RS. Stability and union in subcapital fractures of the femur. J Bone Joint Surg Br 1964;46B:630–647.

12. Gilberty RP. Bipolar endoprosthesis minimizes protrusio acetabuli, loose stems. Orthop Rev 1985;14:27.

13. Kenzora JE, McCarthy RE, Lowell JD, et al. Hip fracture mortality. Relation to age, treatment, preoperative illness, time of surgery, and complications. Clin Orthop Relat Res 1984;186:45–56.

14. LaBelle LW, Colwill JC, Swanson AB. Bateman bipolar arthroplasty for femoral neck fractures. A fiveto ten-year follow-up study. Clin Orthop Relat Res 1990;251:20–25.

15. Phillips TW. Thompson hemiarthroplasty and acetabula erosion. J Bone Joint Surg Am 1989;71A:913–917.

16. Reikeras O, Bjerkreim I, Kolbenstvedt A. Anterversion of the acetabulum and femoral neck in normals and in patients with osteoarthritis of the hip. Acta Orthop Scand 1983;54:18–23.

17. Robinson CM, Court-Brown CM, McQueen MM, et al. Hip fracture in adults younger than 50 years of age—epidemiology and results. Clin Orthop Relat Res 1995;312:238–246.

18. Schroder HM, Erlandsen M. Age and sex as determinants of mortality after hip fracture: 3895 patients followed for 2.5–18.5 years. J Orthop Trauma 1993;7:525–531.

19. Wetherell RG, Hinves BL. The Hastings bipolar hemiarthroplasty for subcapital fractures of the femoral neck. J Bone Joint Surg Br 1990; 72B:788–793.



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