Principles, Planning, and Decision Making

 

 

 

Revision total hip arthroplasty is complex and demanding. The stakes are high. The risks of intraoperative and postoperative complications are increased compared to primary total joint arthroplasty. To maximize the chances of success on the day of surgery, one must be prepared and must try to anticipate all possible surgical scenarios. A smooth operation depends on identifying the problem to be addressed and carefully crafting a surgical plan (Plan A) and contingencies (Plans B, C, D, etc.) that will be executed to solve the identified problem. This chapter discusses an approach to evaluating a patient who presents with a failed total hip arthroplasty for a revision and how one may go about planning and making decisions in preparation for the day of surgery.

PATIENT EVALUATION

Patients often have complex histories of problems relating to their total hip arthroplasty, multiple prior surgeries, and multiple prior providers. Success in revision surgery begins with the initial encounter. A careful and thorough history is critical.

Some baseline information is essential in the initial evaluation. In addition to the general aspects of the patient history, one can ask questions relating to the Harris hip score (1), as these give a uniform baseline to compare the severity of symptoms across patients. The orthopedic surgeon should also elicit details of all prior hip surgeries and information on the specific implants and bearing surfaces

 

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used. Past medical history specifically relating to diseases that may relate to bone quality or immune status is important. A history of metal allergy or venous thromboembolism should also be elicited. One should ask specifically about the original postoperative course and complications, particularly relating to wound drainage and postoperative antibiotic administration. Finally, one should note any recent trauma, hospitalizations, or infections that were temporally related to the onset of symptoms.

What Is the Chief Complaint?

To treat the patient, one must understand what has brought the patient in for evaluation. In failed total hip arthroplasty, the most common presenting complaints are pain, instability, infection, periprosthetic fracture, and metal-related adverse local tissue reaction, with or without pain.

Pain

For the painful total hip arthroplasty, it is important to obtain a history of the pain as this may suggest a diagnosis. In particular, it is important to understand the temporal onset, severity, site, character, and location of the pain. There have been a number of excellent articles describing the evaluation of a painful total hip arthroplasty (2,3). It is helpful to review these articles when faced with a diagnostic challenge. Pain can be either intrinsic to the hip or extrinsic. A list of intrinsic and extrinsic causes of hip pain is listed in Table 21-1. It is obviously important to avoid revising a total hip arthroplasty for pain that is extrinsic to the hip.

It is important to understand the temporal onset of pain. Persistent pain since surgery, new onset of pain following a pain-free interval, severe activity-related pain relieved by rest, or constant pain, including pain at rest and pain at night, all suggest different possible diagnoses (Table 21-2).

 

 

 

Intrinsic Causes	Extrinsic Causes
Infection	Trochanteric bursitis
Mechanical loosening	Lumbar spine disease
Tip of stem pain	Peripheral vascular disease
Periprosthetic fracture	Peripheral nerve injury or irritation
Occult instability	Complex regional pain syndrome
Adverse local tissue reaction	Bone metabolic disease
Iliopsoas tendonitis	Malignancy or metastases
	Hernia
	Referred pain
	Psychiatric disease

 

 

TABLE 21-2 Temporal Onset of Hip Pain and Possible Diagnoses

Persistent pain since surgery Wrong initial diagnosis Infection

Failure to obtain initial implant stability Impingement or instability

 

New onset of pain following pain-free interval Aseptic loosening/osteolysis-related loosening Periprosthetic fracture

Late infection Metal reaction

 

Severe activity-related pain relieved by rest

Loosening Fracture

Iliopsoas tendonitis

Neurogenic or vascular claudication

 

Constant pain, pain at rest, pain at night

Infection Malignancy Loosening

Lumbar spine disease

 

 

 

TABLE 21-1 Intrinsic and Extrinsic Causes of Hip Pain

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

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TABLE 21-3 Location of Pain

Groin or deep buttock Acetabular loosening Iliopsoas tendonitis Adverse metal reaction Hernia

Inguinal lymphadenopathy Psoas abscess

Gynecologic or genitourinary etiology

 

Thigh pain

Femoral component loosening

Stiffness mismatch between femoral component and bone

 

Pain over greater trochanter Trochanteric bursitis Trochanteric nonunion

Buttock pain radiating to the knee or below Lumbar disc disease or spinal stenosis

 

The location of pain is also helpful in suggesting a diagnosis. It is important to identify whether the pain is primarily in the groin or deep buttock, in the thigh, or over the greater trochanter. It is also important to distinguish hip pain from other sorts of pain such as low back pain and radiating pain from the buttock to the knee and below. Table 21-3 summarizes some of the possible diagnoses that are associated with various locations of pain about the hip.

Dislocation

Instability and dislocation are also common reasons for patients to present for revision total hip arthroplasty. A careful history of the dislocations, how many, when they occurred, what the patient was doing at the time of dislocation, and how they were treated is important to understand. Generally speaking, if a patient has dislocated three times or more and has failed reasonable attempts at maintaining stability such as education, home evaluation, and bracing, many surgeons will be inclined to reoperate. If the implants are grossly malpositioned, most will reoperate sooner.

Infection

Deep infection is unfortunately also a common presenting complaint. It is important to understand the history of the symptoms, particularly the temporal onset in relation to the index surgery and any prior history of infection, either in the hip or elsewhere in the body. Fitzgerald (4) originally described three different types of periprosthetic infection, the acute fulminating infection that occurs shortly after surgery, the delayed infection that is likely related to the initial surgery but presents late due to a less virulent organism, and the late hematogenous infection that is an acute infection occurring in a previously uninfected total joint arthroplasty. Diagnosis of deep infection, particularly the delayed infection, can be challenging. The AAOS published a very helpful clinical practice guideline in 2010 on the diagnosis of periprosthetic infection (5). More recent work on synovial fluid biomarkers for infection holds the promise of very highly sensitive and specific tests for deep periprosthetic infection (6).

Periprosthetic Fracture

Periprosthetic fracture can occur in the setting of acute trauma or can happen subacutely, usually in the setting of osteolysis. Obviously in the trauma setting, the patient presents to the emergency department with a history of trauma. A patient may present to clinic, however, with a history of a sudden increase in pain, but no history of significant trauma. This may represent an osteolysis-related periprosthetic insufficiency fracture. In either case, plain radiographs are usually sufficient to confirm the diagnosis, though CT may be needed in more subtle cases, particularly those relating to osteolysis.

Metal-related Adverse Local Tissue Reaction

Though corrosion and metal reaction can happen in any total hip arthroplasty, metal-related adverse local tissue reaction should be on the differential diagnosis of anyone with a metal on metal bearing, a total hip arthroplasty with a cobalt-chrome head, or a total hip arthroplasty with a modular femoral neck. Metal-related adverse local tissue reaction, however, must be treated as a diagnosis of exclusion. Other intrinsic and extrinsic causes of hip pain must be ruled out before metal reaction is diagnosed as the cause of the patient's problems.

 

 

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Metal-related adverse local tissue reactions may or may not be painful. Even without pain, substantially elevated metal ion levels or progressive local tissue reaction as seen in metal artifact suppression MRI can be an indication for surgery. The American Academy of Orthopaedic Surgeons has recently published an information statement on current concerns with metal on metal hip arthroplasty, which includes guidelines on the evaluation and management of patients with metal on metal total hip arthroplasty (7).

 

Physical Examination The physical examination of a new patient with a problematic hip replacement is also of importance. The physical examination starts with an evaluation of the patient's gait. As the patient gets up from a seated position, look for signs of startup pain. Have the patient walk across the examination room. A Trendelenburg limp is indicative of abductor muscle weakness—a critical finding. A vaulting gait may be a sign of a leg length inequality, though spine alignment must also be evaluated to ensure that a perceived leg length inequality is not due to spinal deformity. Note whether the patient requires the use of walking aids to move about the examination room. Inability to bear weight at all suggests a periprosthetic fracture. While walking, ask the patient to point with one finger where he or she is experiencing the most pain. Then get the patient onto the examination table. Evaluate the prior surgical incision for clues on the prior surgical approach and for signs of prior wound healing problems or infection. Note the patient's range of motion, and evaluate the patient for patterns of pain or early impingement at this stage. Painful active range of motion, painful passive range of motion, pain with passive straight leg raising, pain or apprehension at certain extremes of range of motion, or pain with resisted hip flexion or passive hip flexion may all suggest different diagnoses (Table 21-4). Palpate around the hip and compare the side-to-side appearance of the hip with the other hip. In patients in whom metal-associated adverse tissue reaction is suspected, one can sometimes palpate a pseudotumor or fluid collection. Perform a neurologic exam of the leg evaluating strength and sensation, and palpate pedal pulses. Note any other important signs such as leg swelling, skin problems, and signs of venous stasis. Have the patient turn to the lateral decubitus position and palpate the area around the greater trochanter to rule out trochanteric bursitis as a cause of pain.

 

	TABLE 21-4 Patterns of Pain with Hip Range of Motion and Possible Diagnoses   Painful active ROM or at extremes of motion Loosening   Painful passive ROM Occult infection   Painful passive straight leg raising Sciatica   Pain or apprehension at certain extremes of motion Impingement or instability   Pain with resisted hip flexion or passive extension Iliopsoas tendonitis

 

 

 

Imaging

Plain radiographs are critical to evaluating a problematic total hip arthroplasty. If possible, try to obtain old x-rays of the hip in question for comparison to current films. Standard radiographs should include the low AP pelvis, which provides a view of the entire femoral component, the frog lateral of the hip, and the cross-table lateral of the hip. Each view provides important information.

On the AP pelvis, look at the acetabular component first. Note the type of fixation used for the acetabular component and try to identify the model of the acetabular component based on its radiographic appearance. Evaluate the acetabular component abduction angle and get a sense of the acetabular anteversion (to be confirmed later on the cross-table lateral). Figure 21-1 shows the presenting radiograph of a patient who had undergone a metal on metal total hip arthroplasty and developed metal-related soft adverse local tissue reaction and hip instability due to an overabducted acetabular component. Look at the location of the hip center and note whether it is proximal or distal and medial or lateral compared to normal hip anatomy. Look at the quality of the bone supporting the acetabulum and look for osteolytic defects. If there is substantial osteolysis and the implant has migrated, the patient may have had a periprosthetic insufficiency fracture of the bone supporting the acetabular component. If concerned about pelvic discontinuity,

 

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order Judet views of the pelvis and a lateral view of the pelvis or a false-profile view of the hip, as these last views often provide a view of the posterior column without interference from the hip hardware (8,9). The lateral view of the pelvis done in the standing position can also give a sense of the natural pelvic tilt for that particular patient. Look for radiographic signs of loosening, including migration and radiolucent lines, and look for signs of fixation such as spot welds on an uncemented component. Figures 21-2 and 21-3 show dramatic examples of cemented and

 

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uncemented acetabular component migration. Figure 21-4 shows a more subtle case of acetabular component loosening associated with osteolysis and bead shedding.

 

 

 

FIGURE 21-1 A large head metal on metal total hip arthroplasty is shown. This radiograph demonstrates an acetabular component that was placed in excessive abduction. This patient had a large metal-related adverse local soft tissue reaction and hip instability.

 

 

 

 

 

FIGURE 21-2 An example of a grossly loose and migrated cemented acetabular component is shown. Note the broken cement fragments and the loss of superior bone stock. Reconstruction in this case would have been complicated by the acetabular bone loss, by the general osteopenia, and by the existing well-fixed cemented

monoblock femoral component. The patient, however, was over 90 years old, had significant comorbidities, and had a reasonable quality of life. He elected not to have revision surgery.

 

Look at the femoral component on the low AP pelvis. Note the type of fixation used and try to identify the model of the femoral component. Evaluate the position of the femoral component in relation to the femur. This involves evaluating the center of the femoral head in relation to the tip of

 

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the trochanter. Locate the collar, or the proximal extent of the porous coating in a collarless implant, and note its relation to the calcar and lesser trochanter of the femur. Look at the quality of the bone supporting the femoral component, and look for osteolysis or a periprosthetic fracture—particularly in the area of the greater trochanter. Then, look for radiographic signs of loosening (Tables 21-5 and 21-6). Figures 21-5 and 21-6 provide examples with classic findings of loose cemented femoral components in total hip arthroplasty including subsidence, cement mantle fracture, and complete

 

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radiolucent line between the cement and bone. Figure 21-7 provides a nice example of a loose uncemented femoral component with complete radiolucency around the implant, lack of spot welds, and a large pedestal. In both the cemented and uncemented cases, note the varus remodeling of the femur.

 

 

 

 

FIGURE 21-3 An example of a grossly loose and migrated uncemented acetabular component is shown. Note the loss of superior bone stock and dramatic osteolysis about the entire acetabulum. There is also osteolysis in the greater trochanter and a well-fixed femoral component with notable spot welds.

 

 

 

FIGURE 21-4 A: A more subtle case of acetabular component loosening is shown. In this case, there is dramatic asymmetric wear of the acetabular component with associated osteolysis of the supporting bone. The acetabular component has loosened due to insufficient supporting bone, and bead shedding is visible around the implant.

This case was complicated because the well-fixed uncemented femoral component, which was monoblock, had a damaged femoral head, and needed to be extracted. B: The well-fixed and extensively ingrown femoral component was removed by using an extended trochanteric osteotomy and multiple Gigli saws. The patient required removal of this stem because of this unusual and occult fatigue failure of the monoblock metal head.

 

 

 

TABLE 21-5 Radiographic Signs of Loosening—Cemented Components

Definite loosening Component migration Fracture of the stem Cement fracture

 

Probable loosening

Continuous 2-mm radiolucent line around the entire cement-bone interface

 

Possible loosening

Incomplete radiolucent line at the cement-bone interface

 

 

 

TABLE 21-6 Radiographic Signs of Loosening—Uncemented Components

 

Extensive reactive lines around the porous coating of the implant Absence of spot welds

Migration Pedestal formation

 

 

 

 

 

FIGURE 21-5 An example of a loose cemented femoral component is shown. Note the subsidence at the shoulder of the implant revealing loosening at the prosthesis-cement interface and the cement mantle fracture.

 

Then, with the low AP pelvis x-ray, determine if there is leg length inequality, and compare the offset of the hip with the contralateral side.

The frog lateral x-ray of the hip is useful because it commonly gives me a better lateral view of the proximal femur than the cross-table lateral. Assess the x-ray for femoral component fit and position

 

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in the femoral canal and look for radiographic signs of loosening and osteolysis. Periprosthetic fracture in the femur may be visible on this view but not on the AP. If a better look at the bow of the femur is needed for potential templating purposes, order a true lateral (Lowenstein) view of the femur. Figure 21-8 shows a loose long stem revision cemented total hip arthroplasty component with anterior osteolysis at the tip of the stem, fracture of the cement mantle, and radiolucent lines. Trying to remove this cement mantle from the top would be very difficult and would risk anterior cortical perforation. Figure 21-9 shows another interesting case where the frog lateral of the hip

 

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proved very helpful for diagnosis. This was a case of recurrent dislocation following a revision total hip arthroplasty with a malunited extended trochanteric osteotomy. The etiology for the recurrent dislocation is

actually best seen proximally on the femur in the frog lateral. The greater trochanter had migrated anteriorly prior to healing. This led to early bone-bone impingement with flexion and minimal internal rotation.

 

 

 

FIGURE 21-6 An example of a loose cemented femoral component is shown. Note the complete radiolucency around the implant, cement mantle fracture, subsided position of the implant (with the collar nearly resting on the lesser trochanter), and the varus remodeling of the femur.

 

 

 

 

 

FIGURE 21-7 An example of a loose uncemented femoral component is shown. Note the complete radiolucency and sclerotic line around the femoral component with a complete absence of spot welds. Also, note the large pedestal at the base of the implant and the varus remodeling of the femur. This femur required an extended trochanteric osteotomy for removal of the stem due to the geometry of the tip of the femoral component. The

osteotomy also allowed safe drilling of the thick pedestal, correction of the femoral bow, and placement of a long, straight stem for reconstruction.

 

 

 

 

 

FIGURE 21-8 A frog lateral of a hip with a loose cemented long stem revision total hip arthroplasty is shown. This view was particularly important as it revealed osteolysis and thinning of the anterior cortical bone at the tip of the stem and showed that it would be difficult to remove the distal cement with straight instruments from the proximal end of the femur without penetrating the anterior cortex due to the femoral bow.

 

 

 

 

 

FIGURE 21-9 AP (left) and frog lateral (right) of a patient who had undergone revision total hip arthroplasty with an extended trochanteric osteotomy in the distant past. He presented with a history of recurrent hip dislocations. The contour of the greater trochanter looks unusual in the AP view, but the frog lateral shows that the greater trochanter had malunited in an anterior position. This patient had impingement of the greater trochanter on the pelvis with hip flexion and minimal internal rotation. Rather than reosteotomizing his entire greater trochanter and risking a nonunion, the author resected the portion of the greater trochanter that was impinging.

The cross-table lateral x-ray of the hip is useful for evaluation of acetabular anteversion. If the image is done well, one can also see the posterior column of the pelvis and can look for pelvic discontinuity. The cross-table also gives a good look at the relationship between the anterior lip of the acetabular component and the anterior wall of the acetabulum. If the prosthesis is prominent here, this could be a cause for iliopsoas tendonitis. An example of this is shown in Figure 21-10. If the image is taken properly, one can also get a sense of the patient's femoral anteversion, though this is subject to error if the x-ray was taken with the hip internally or externally rotated.

A metal suppression CT scan of the pelvis and hip can be helpful if there is concern about significant osteolysis and if a detailed three-dimensional assessment of remaining bone stock is needed. A CT scan can also be helpful if one is looking for an occult periprosthetic pelvic fracture or a pelvic discontinuity. Figure 21-11 shows an example of a patient who had dramatic osteolysis and pseudotumor formation from a worn metal on polyethylene total hip arthroplasty. The CT scan and 3-D reconstruction aided in defining the area of lysis. The CT can also give a much more accurate assessment of femoral component anteversion as long as the knee is included in the images.

A metal artifact reduction sequence (MARS) MRI scan of the hip should be ordered if there is concern about metal-related adverse tissue reaction. Figure 21-12 shows a MARS MRI scan of a left resurfacing hip arthroplasty with a pseudotumor. Another option in this setting is an ultrasound of the hip to look for soft tissue mass or fluid collection.

Most surgeons now are using nuclear medicine tests sparingly. A white blood cell scan can provide information regarding a periprosthetic hip joint infection if other studies outlined above are equivocal. A three-phase bone scan can provide some information regarding increased bone metabolic activity around the prosthesis. Though a positive study can be suggestive for mechanical loosening, it is not diagnostic. A positive bone scan at the tip of the femoral component suggests tip of stem pain from modulus mismatch as a diagnosis.

 

 

 

 

FIGURE 21-10 Cross-table radiographs of the hip are presented for a patient with deep groin pain following total hip arthroplasty. As can be seen in the presentation films (top), the patient has a minimally anteverted acetabular component with significant anterior prosthetic overhang. The iliopsoas tendon runs over the prominent lip of the acetabular component resulting in pain from tendonitis. In the bottom x-ray, the acetabular component has been

revised to a better position, resulting in resolution of symptoms. (Images courtesy of Dr. James I. Huddleston.)

 

 

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FIGURE 21-11 A: This radiograph shows the pelvis of a patient who had a right total hip arthroplasty long ago who has developed symmetric wear of the polyethylene, and massive osteolysis of the pelvis extending from close to the level of the SI joint to halfway down the pubis and beyond the ischial tuberosity. Careful examination of this radiograph also shows a large cyst within the pelvis that displaces all of his normal pelvic contents to the left. This patient developed sudden onset of pain and inability to bear weight. He had a subtle insufficiency fracture of the bone supporting his socket. B: A representative coronal slice of the patient's CT scan is shown. Superior and inferior osteolysis is seen, as well as a massive intrapelvic cyst, which is displacing his normal pelvic contents toward the left. C: The three-dimensional CT reconstruction of this case is presented here with the image as viewed from posterior to show the lytic destruction of the posterior column of the pelvis and ischium. Note the patient's dramatic bone loss and pelvic discontinuity. The author did not feel that a cage reconstruction or jumbo cup with or without augments would work here due to the severe osteolysis of the ischium and chose to reconstruct this with a custom triflange acetabular component. D: The postoperative x-ray of the patient with the custom triflange component is shown.

 

 

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FIGURE 21-12 A metal artifact reduction sequence (MARS) MRI scan reveals a large pseudotumor about the greater trochanter of the left hip in a patient with a painful left hip resurfacing arthroplasty. (Image courtesy of Dr. James I. Huddleston.)

 

Laboratory Tests

Laboratory tests are particularly important in the workup of patients in whom periprosthetic infection is being considered as a diagnosis. The American Academy of Orthopaedic Surgeons has published guidelines for the diagnosis of periprosthetic infections of the hip and knee in 2010 (5), and the author follows those recommendations. ESR and CRP should be ordered on everyone being considered for revision hip replacement and anyone being worked up for infection. If either test is positive, have the hip aspirated under fluoroscopic guidance. Most consider a cell count over about 3,000 to 4,000 cells per microliter to be positive for infection and a neutrophil percent over about 80% to be positive (10). These numbers hold even for patients who have inflammatory arthritis (11). If the aspirate is being done on a patient who is within 6 weeks of hip replacement surgery, one can still use the cell count, but the cutoff value must be adjusted to about 30,000 cells per microliter

(12). More recent work has focused on synovial fluid biomarkers for infection (6). Tests for these biomarkers appear to have very high sensitivity and specificity for diagnosing periprosthetic infection. Assays for these biomarkers are presently just becoming available.

Send the synovial fluid aspirate for aerobic and anaerobic culture and susceptibility. If there is reason to be concerned for other less common or less virulent organisms, fungal cultures may be sent, or the cultures can be held and observed for an extended period of time.

If one is concerned about metal-related adverse tissue reaction about a total hip arthroplasty, serum cobalt and chromium levels should be sent. The value of these tests is still debatable, but they do provide some additional information regarding the extent of the patient's metal ion exposure. Generally speaking, metal ion levels less than 3 parts per billion (ppb) are considered low, 3 to 10 ppb are considered moderate, and greater than 10 ppb are considered high. The sensitivity and specificity of these tests in diagnosing adverse local tissue reaction are not very good, however, and thus, a decision to proceed with revision surgery should not be based solely on serum metal ion levels. If a synovial fluid aspirate is sent to the lab for analysis, it is important to ask for a manual cell count rather than an automated cell count. The automated cell count will count necrotic cells and debris as

white blood cells and will give a falsely elevated reading.

 

PUTTING IT ALL TOGETHER—DECIDING WHETHER TO OPERATE

Having completed the history, physical examination, and radiographic analysis and obtained all relevant laboratory tests, one must synthesize all of the information to come up with a diagnosis that explains the patient's symptoms and chief complaint. This is a critical step as the preoperative planning depends on making an accurate diagnosis. If the problem is intrinsic to the hip replacement, then the process of planning for a revision moves forward.

 

 

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The next consideration is the severity of the symptoms. To begin to determine severity, routinely ask patients, “Are your symptoms bad enough that you would want to go through a big operation to fix them?” The answers to this question are particularly revealing regarding the patient's perception of severity and psychiatric state. Also, ask the patient about his or her expectations to make sure that they are realistic. Answers from the Harris hip score questions in the history also factor in heavily here as they give a baseline standard to compare across patients. If the symptoms and functional deficits are mild and there are no negative consequences to observing and treating conservatively, one may advise the patient not to have surgical treatment. One needs to be alert, however, for patients with mild or absent symptoms who have progressive osteolysis or enlarging metal-associated adverse tissue reaction on imaging studies. Despite their minimal symptoms, these patients should be counseled to have surgery sooner, rather than later, to avoid progressive bone loss, periprosthetic fracture, or progressive soft tissue necrosis. If the symptoms are severe and are significantly altering the patient's quality of life, or if the consequences of observation are substantial, proceed to the next step of decision making.

Based on the diagnosis and the symptoms, make a preliminary plan regarding what would be involved to surgically treat this patient's symptoms. Most importantly, is this problem solvable? If so, do you anticipate a small procedure like a head and liner exchange or a larger procedure? Will you need to revise the acetabular component? Will the femoral component need to come out? Will your need to employ extensile exposures or surgical measures such as an extended trochanteric osteotomy to extract implants? At this stage, you are trying to gauge how big of an operation will be needed to treat the problem. What will the operative time be? How much blood do you anticipate losing? How difficult will the recovery be from such an operation? The answers at this stage do not need to be detailed. The idea here is to get a sense of how big a “hit” to the patient's physiology this operation is going to deliver. This will be important as you then consider the patient's medical comorbidities and ability to withstand the operation and its consequences.

Consider the patient's medical comorbidities. Revision total hip arthroplasty can involve substantial risk to any patient, but a patient with multiple complex medical comorbidities may simply not have the reserve to withstand a big operation. A multidisciplinary approach is critical at this stage. One may contact the patient's primary care doctor because he or she knows the patient best and may be able to coordinate an extended preoperative workup if one is needed. Also, you may consult specialists in other fields depending on the comorbidities identified. Some comorbidities such as congestive heart failure or poorly controlled diabetes can be “optimized” or modified prior to the operation, and you may ask the consultants to proceed with this if the orthopedic consequences for delay are not significant. Consider consulting the anesthesia service as they are experts in the intraoperative and immediate perioperative management of complex patients. Any additional studies requested from any of the expert consulting services are ordered and followed up on. Establishing strong relationships with expert consultants and having clear communication channels are critical at this stage. The consultants provide an objective and expert opinion regarding the risks of proceeding with the operation and become familiar with the patient should a postoperative complication arise. Only if the medical risks of proceeding are deemed acceptable to all of the parties involved should one proceed with surgical planning.

Consider social and behavioral issues at this point. Smoking, drug use, and excessive alcohol consumption are all risk factors for postoperative complications that are potentially modifiable. In addition, the patient will ultimately need to be discharged to a stable and clean living environment with adequate social support. Do not proceed with surgical planning until these important social and behavioral issues are addressed.

If the patient has made it this far in the decision-making process, he or she has a problem that is intrinsic to the total hip replacement and is solvable with surgery. This problem is severe enough that it is substantially altering the patient's quality of life and the patient is willing to consider surgery. All of the medical and social comorbitities have been addressed, and all the consultants have agreed that the risks of surgery, given the magnitude of surgery that is anticipated, have been minimized to the extent possible. At this point, the author has a frank and thorough discussion of the risks and benefits of proceeding with surgery with the patient. Using a shared decision-making process, the patient and surgeon must both agree that proceeding with surgery is in his or her best interest. The next step is to move forward with planning for the operation itself.

FORMULATING A SURGICAL PLAN

Revision hip replacement can be a long and difficult operation. As you think about and plan for the operation, take a sequential approach and think about the operation from start to finish.

The first item to consider is positioning and the surgical approach. Think about the extent of exposure needed and consider the need for trochanteric osteotomy or trochanteric slide if you anticipate

 

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difficulty with a wide acetabular exposure. Heterotopic bone may make exposure difficult, and you should make plans for dealing with it as needed.

In many patients, particularly patients who had a nonarticulating spacer for treatment of infected hip replacement, think about how to mobilize the scar tissue surrounding the hip to restore leg length. This will commonly involve a 360-degree removal of scar tissue around the hip.

On the other hand, if operating for instability or metal-related adverse local tissue reaction, plan to evaluate the quality of the soft tissues about the hip including the capsule or pseudocapsule and the hip abductor musculature and attachments. In the case of adverse tissue reaction, carefully evaluate the preoperative MRI and anticipate where you will need to remove necrotic tissue and try to anticipate whether you will face a stability problem following the reconstruction.

Then, think about how you will intraoperatively evaluate the joint and the components. If you are concerned about infection, think about which cultures to send and from where to obtain the cultures. If operating for instability, take the hip through a range of motion and look for prosthetic, bony, and soft tissue impingement that may be causing the problem. Think about how to assess the position, stability, and integrity of the components in the hip replacement. At this point, make decisions regarding what components to retain and what components to revise.

As you think about the operation at this stage, first anticipate the most likely findings based on the preoperative history, physical, radiographic, and laboratory workup. Then, step through the remainder of the operation assuming the expected findings. This is “Plan A.” As you progress thinking through this plan, make a list of implants, special tools, and special techniques that you will need to successfully complete the operation.

If you are planning to keep the femoral component and revise the acetabular component, plan how to expose the acetabular component while retaining the femoral component. This will involve mobilizing the scar and soft tissues sufficiently and, with a posterior approach, creating a pocket in the soft tissues anterior to the acetabulum to place the proximal portion of the femoral component. Plan how to remove the acetabular component. Newer explantation tools that use the center of the acetabular component as a guide for the cutting blades conserve

bone and are particularly useful to extract a well-fixed uncemented acetabular component. Clear 360-degree access to the acetabular component is needed to take out a well-fixed component. Consider the bone loss on the acetabular side and make a plan for the eventual reconstruction. If you anticipate needing bone graft, make sure that sufficient graft is available for the day of surgery. Make sure you are familiar with all reconstruction options and make sure that everything you need will be available on the day of surgery.

On the femoral side, deformity is commonly a problem. If you are planning to remove the femoral component, first consider the shape of the femur and pay particular attention to the contour of the greater trochanter. Commonly, the greater trochanter overhangs the femoral canal, blocking the extraction of the femoral component from above. If you do not intend to do a trochanteric osteotomy, then plan to use a burr or osteotome to remove the medial aspect of the trochanter and gain access to the entire proximal femur. If you intend to do a trochanteric osteotomy, plan out the length of the osteotomy and measure on the x-rays how distal the end of the osteotomy will be from a fixed and surgically recognizable landmark on the femur.

Consider the tools that you will need to extract the femoral component. If not planning to do a trochanteric osteotomy, you will need to have full 360-degree exposure of the femoral component from above. You will need flexible osteotomes and a pencil-tip burr. If the component is well fixed, uncemented, and with a proximal porous coating, note how far down the porous coating extends and where the spot welds are and make a plan for disrupting the bone implant interface down to that level. You will then need a slap hammer extraction tool that will attach to the proximal end of the implant. If the implant is cemented, also ask for the specialized cement removal tools and consider wearing a headlamp to visualize down the canal for cement removal. Note the location of the distal cement plug, note whether it appears to be well fixed or loose, and then plan on having a drill that is long enough to drill through the cement plug to remove it.

If planning to do all of the work from above, take particular note of the shape of the proximal femur. Commonly with a loose femoral component, the bone will remodel into varus. Furthermore, osteolysis may be evident down the shaft on both the AP and frog lateral views of the femur. Note where the bone is thin and what direction cement removal tools and drill will be aimed as you work further and further down the shaft of the femur. Avoid fracturing the femur or penetrating the cortex with straight tools that do not contour with the femur. If there is too much deformity or cement removal will be too deep within the canal, you may plan on doing an extended trochanteric osteotomy.

More commonly for a cemented implant, or if there is a more extensively coated well-fixed uncemented implant that needs to be removed, you may opt to do an extended trochanteric osteotomy,

 

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from the beginning. Preoperatively plan on the length of the osteotomy measured from an easily recognizable landmark on the femur. After performing an osteotomy for a cemented implant, plan on removing the cement with osteotomes and burrs as needed. For the well-fixed and extensively porous-coated implant, choose between two possible techniques for component extraction. If you can make the osteotomy long enough to expose all of the porous coating and still have enough intact femur distally to securely hold a new uncemented stem, you may take the osteotomy to the end of the porous coating, remove the lateral part of the femur with the osteotomy, and then wrap a Gigli saw around the medial aspect of the prosthesis from above and work the saw all the way down to the end of the porous coating. It is common in this scenario to need five or six Gigli saws as they will break during the extraction. If, instead, the existing implant is so long that extending the osteotomy would make placement of a new implant difficult, plan to take the osteotomy down to a point where the distal portion of the implant is straight and cylindrical. One can then carry out that osteotomy, use Gigli saws down to the level of the osteotomy, transect the proximal portion of the implant with a metal cutting wheel, and use trephines to remove the distal portion of the stem.

In the case of periprosthetic fracture of the femur, classify the fracture according to the Vancouver classification

(13) and treat accordingly. Important considerations are where the fracture is in relation to the stem, whether the existing implant is loose or stable in the proximal fragment, and the quality of the remaining bone. An example of a challenging periprosthetic femur fracture is shown in Figure 21-13.

Templating is important at this point to determine which specific implants to use on both the acetabular and femoral sides of the joint (14). Options for acetabular reconstruction based on bone quality have recently been reviewed (15). Try to get the hip center down to its anatomic location. Most commonly, there is sufficient supportive bone that a hemispherical cup will have enough native bony support that additional reconstructive measures are not needed. However, if there is deficient bone superiorly, consider whether to accept a slightly high hip center or if you will need to place porous metal augments or bone grafts to restore a more normal hip center. You may fill most cavitary defects with morselized cancellous graft. If there is ischial osteolysis, you may consider augmenting inferiorly as well as superiorly. Anticipate the anterior and posterior support to the socket as well and consider buttressing with a porous metal augment posteriorly and superiorly if the wall is deficient there. Generally speaking, if the posterior column is intact and robust enough to accept multiple screw fixation, additional measures are generally not needed. As bone loss becomes more substantial, however, cage or cup-cage reconstruction may be indicated. Massive impaction grafting approaches to acetabular reconstruction have also been reported to be successful. As the defect progresses to pelvic discontinuity, options include open reduction and plating of the pelvic discontinuity if there is adequate healthy bone for healing and acetabular reconstruction. Unfortunately, pelvic discontinuity is commonly associated with osteolysis in which there is minimal good bone for healing. In this situation, very large sockets in combination with pelvic distraction can be used to obtain stability and bridge the discontinuity (16). Other options include cage or cup-cage reconstruction

(17) or, for very large defects, a custom triflange component (18). Mark on the x-ray where you expect to have the center of the acetabular component after reconstruction and then plan the femoral component.

On the femoral side consider the shape of the femur including the anterior bow, the bone quality, the location of planned osteotomy, and the location of the distal bone that will primarily fix the implant and choose an implant that will fix the patient's anatomy and maximize chances of successful fixation. Plan the stem design and size for fixation and stem position for length and offset to match the patient's normal anatomy as closely as possible.

More straightforward cases may simply require a fully porous-coated stem with cylindrical cross-section. For more difficult cases, modular tapered fluted stems provide intraoperative flexibility in restoring femoral length, offset, and anteversion and provide adequate stability and fixation in poor quality bone (19). Plan on having an allograft cortical strut graft available if one side of the femur has poor quality bone and needs augmentation. If there is very poor-quality circumferential bone proximally, consider a proximal femoral replacing prosthesis or an allograft-prosthetic composite reconstruction.

If there are any concerning aspects to the case, plan to order an intraoperative radiograph. It is also helpful to see how the reconstruction looks radiographically with trial implants in or prior to closure. In this way, the chance of surprises on the recovery room films is minimized, and you can address any issues that are visible on the x-rays prior to closing the wound.

Once you have run through the entire procedure for “Plan A,” think about the most likely variant to the surgical plan and run it all the way through the process noted above. This will be “Plan B.” If there are more contingencies, make additional plans as necessary. Each plan has a list of tools, implants, and specialized techniques associated with it.

 

 

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FIGURE 21-13 A: A periprosthetic femur fracture in an elderly and frail man is shown. The cemented femoral component exhibits disruption of the bonecement interface and is loose. There is marked osteoporosis and additional osteolysis of the pelvis and the femur. The author treated this as a Vancouver B2 fracture, though it is arguable as to whether the poor bone quality of the proximal fragment merits a B3 classification. B: It is important for all revision total hip arthroplasty cases to obtain images of the entire femur. In this case, the patient had hardware in the distal femur from a prior supracondylar femur fracture. Measuring the distance from the cement plug visible at the top of the image to the hardware aided in anticipating the need to remove screws for placement of the eventual revision femoral component. C: The eventual reconstruction is shown at 1-year followup. The liner of the socket was changed, and lytic defects in the pelvis were grafted through the screw holes.

The long cylindrical stem was press fit into the intact distal femur. Two screws needed to be removed from the plate to place the stem at the appropriate height. Cerclage cables were used to wrap the fractured bone fragments around the distally potted stem, and a femoral cortical strut was placed with the hope that it would incorporate and augment the patient's bone stock. The patient lost quite a bit of blood during surgery and required 1 week of postoperative care in the intensive care unit. He was eventually discharged and healed the fracture with a stable reconstruction. Fortunately, he has not broken his femur between the implant and the plate.

 

 

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INVOLVING THE ENTIRE SURGICAL TEAM ON THE DAY OF THE OPERATION

Success in revision total hip arthroplasty depends on clear communication with the entire operative team. Contact company representatives soon after the plan is developed to ensure that all the implants and instrument trays will be delivered and available on the day of surgery. As you list the case for surgery, alert the anesthesia service if you anticipate a long surgery or significant blood loss. If needed, reserve an ICU bed for postoperative care. Make sure that blood products are available if needed.

On the day of surgery, discuss the case with the scrub nurse and the circulating nurse before they open instrument trays and prepare the room for the operation. Step through the anticipated plans with them to ensure that you will have all the tools needed for the operation. Similarly, review the x-rays and surgical plan with your assistant so that he or she can anticipate any special maneuvers or critical steps that you will need particular help. During the surgery, communicate intermittently with the anesthesiologist about blood loss and learn how the patient is tolerating the operation. Coordinating the entire surgical team before and during the operation is critical to the smooth and safe progression of a complex case.

 

 

SUMMARY

The surgeon who is evaluating a patient for possible revision hip replacement is first faced with diagnosing the problem. Once the problem is identified, the surgeon must evaluate whether an operation is indicated based on the severity of symptoms, the magnitude of the surgery needed to address the problem, and the patient's comorbidities and risk profile. The patient and the surgeon must then both agree that the potential benefits of surgery outweigh the risks. Careful preoperative planning is then done in a systematic fashion considering each step of the operation. Plans for evaluation and removal of the existing implants and stable implantation of the new implants are made based on the diagnosis and the pelvic and femoral anatomy. A list of tools, implants, and specialized techniques is made for each of the possible contingencies in the operation, and arrangements are made to ensure that everything is available for surgery. On the day of surgery, the surgical plan is clearly communicated with all members of the surgical team including the scrub nurse, the circulating nurse, the assistant, and the anesthesiologist. Revision total hip arthroplasty is complex and demanding, and proper decision making and planning are key to surgical success. A careful and systematic approach such as outlined in this chapter will maximize the chances that the procedure will be executed smoothly, safely, and effectively.

 

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