ELECTIVE JOINT RECONSTRUCTION HAS BECOME increasingly common for those with painful, advanced joint disease. Over a million total knee arthroplasty (TKA) and total hip arthroplasty (THA) surgeries were performed in 2010 alone, and this number continues to increase exponentially.1 It is predicted that by the year 2030, there will be approximately 3.5 million primary total knee arthroplasties (TKA) and almost 600,000 primary total hip arthroplasties (THA) performed each year in the United States.2 Improvements in implant design and manufacturing, surgeon experience, and changes in surgical, anesthetic, and rehabilitative protocols have allowed these procedures to be successfully performed on a much wider range of patients—including old and young, healthy and frail.
In the United States, the most common reason for arthroplasty surgery is primary generalized osteoarthritis.3,4 “Secondary” osteoarthritis is defined as that which stems from other conditions, such as instability or malalignment, trauma, inflammation (e.g., pigmented vilonodular synovitis), bone disorders, and remote infection of the joint or iatrogenic interruptions of the articular cartilage (e.g., multiple arthroscopies).
The radiographic hallmarks of osteoarthritis are joint space narrowing, osteophyte formation, subchondral cysts, and sclerosis; in advanced cases, there may also be large erosions and/or bony fusion (Fig. 91–1A and B).
Worldwide, avascular necrosis is one of the leading indicators for hip replacement, stemming most commonly from femoral neck fracture, steroids, excessive alcohol use, sickle cell disease, systemic lupus erythematosus, amyloidosis, developmental hip dysplasia, Legg-Calve-Perthes disease, and HIV disease. Additionally, inflammatory joint disease commonly leads to arthroplasty; underlying causes include autoimmune diseases (e.g., rheumatoid arthritis, spondyloarthropathies), crystalline arthropathies (e.g., gout, chondrocalcinosis), metabolic conditions (e.g., hemochromatosis), and hemophilic arthropathy.
Careful patient selection improves the odds of a successful surgery and a favorable patient outcome. Some patients are ineligible because of medical comorbidities—hip and knee replacements are considered high risk, major surgeries. Contraindications to hip or knee replacement surgery include the patient’s inability to provide consent and/or follow through with instructions and recommendations (e.g., significant dementia), the presence of an active infection or a history of recurrent bone or joint infections, profound osteoporosis, marked joint or soft tissue laxity (e.g., Ehlers–Danlos Syndrome), insufficient cardiovascular capacity (functionally unable to withstand 4 METs of activity), or other medical comorbid condition that is deemed to heighten the risk of surgical complications to an extent that it overshadows the benefit.
End-stage joint disease can result from a variety of inflammatory, pathologic, or metabolic conditions that lead to deterioration of the articular surfaces, with consequent pain, stiffness, deformities, and impaired physical and psychological function. Both clinicians and patients should understand that radiographic joint disease does not directly correlate with pain or disability. Elective joint replacement is indicated only when there is functional decline, at least moderate radiographic disease and pain which is not responsive to nonsurgical management. Despite the advances in “minimally invasive surgery” and “rapid recovery programs,” joint replacement remains a major surgery that rarely can lead to catastrophic, life-changing consequences. Wise surgeons understand that careful patient selection, frank discussion of realistic expectations, and appropriate surgical timing are critical to satisfied patients. Several studies have shown, unfortunately, that this is not always the case—there is wide heterogeneity in surgical indications and timing.5
The spectrum of arthritis pain reducing interventions that can be used before surgery is reviewed in Chapter 80. A variety of treatments (e.g., medications, bracing, physical therapy (PT), and topical agents) are used to reduce pain and help patients maintain function. A variety of treatments (e.g., medications, bracing, physical therapy (PT), and topical agents) are used to reduce pain and help patients maintain function. More recent management options include the use of injected corticosteroids, hyaluronates, growth factor, platelet rich plasma, and stem cells. A note of caution is necessary: intra-articular hip steroid injections have been linked to postoperative hip arthroplasty infections. Most surgeons now prohibit hip intraarticular steroid injections a minimum of 3 months (and perhaps as much as a year) before that hip is replaced.6
Many patients can delay or avoid surgery by dedication to weight loss, strength, flexibility, joint alignment and posture, and improved gait mechanics. In those whom ultimately undergo surgery, the focus on aggressive nonsurgical care helps patients be less disabled prior to surgery and facilitates easier recoveries. The myriad of confounding patient-specific and treatment variables makes it difficult to perform traditional research into the effectiveness of rehabilitation prior to joint replacement surgery.7,8 Rehabilitation prior to hip and knee replacement can be justified, however, as medically necessary through understanding the impairments and disabilities associated with arthritis and how these impact recovery:
In knee osteoarthritis, quadriceps weakness is a better predictor of pain and function than radiographs.9,10
Pain and obesity are better predictors of disability than structural deformity. The extent of osteoarthritis on knee radiographs is not predictive of disability.11
Patients have worse outcomes if they are more disabled going in to surgery.12
Patients with more preoperative OA knee pain have more postoperative pain and use more resources in the first year after knee replacement.13
Patients with heightened preoperative pain, depression, anxiety, and low self-efficacy or high “catastrophization” scores are at risk for poor outcome; this may be mitigated through individualized physical therapy focusing on self-efficacy training.14
Preoperative knee flexion is the most significant predictor of postoperative flexion.15
Preoperative quadriceps strength is associated with better outcome 12 weeks after THA.16
There are gait abnormalities in the short and long term after THA and TKA; preoperative gait abnormalities predict long-term gait pathology.17,18
In Medicare patients, physical therapy before TKA is associated with less postoperative skilled nursing and home health care services.19
There is an economic argument for the prescription of physical therapy before surgery. Snow and colleagues compared preoperative physical therapy and postoperative care usage patterns for 4,733 THR and TKR patients. Nearly 77% of patients utilized postacute care services following surgery. Patients receiving preoperative physical therapy showed a 29% reduction in postoperative postacute care, resulting in an adjusted cost reduction of $1,215 per patient (primarily as a result of lower skilled nursing facility and home health agency costs).19
Thus, both experience and evidence suggest the importance of preoperative physical therapy. Treatment should focus on the impairments seen in patients with end-stage joint disease, highlighting the factors understood as important for functional recovery.
Many THA patients complain of limitations long after surgery—for example, 22% of 5,707 THA patients from the Mayo Clinic Total Joint Registry surveyed 2 years after surgery reported persistent moderate or severe walking limitations.20 Preoperative gait abnormalities are strong predictors of postoperative gait patterns; it is hypothesized that abnormal gait may be associated with accelerated implant wear.18 Hip flexion contractures have been shown to be present or reoccur a year after surgery, from a number of factors including persistent muscle weakness, capsular or other soft tissue scarring, leg length discrepancies, pelvic malalignment, learned gait patterns, and other joint pathology (such as from the lumbar flexion posturing of spinal stenosis). Additionally, patients with hip stiffness may be more at risk to fall.21 Postoperative range of hip motion is associated with better clinical outcome scores.
Total knee replacement patients also may have many long-term physical and functional deficits. The impact of bundled payments for THA on postoperative physical therapy prescriptions has not been fully investigated, but intuitively seems to be at risk. However, even the most skeptical clinicians believe that PT for TKA (before and/or after surgery) is necessary. There is clear evidence that TKA patients have worse outcomes if they are more disabled going in to surgery.12 Patients with more preoperative OA knee pain have more postoperative pain and use more resources in the first year after knee replacement.13 Patients with limited knee range of motion prior to surgery are more likely to have similar findings after TKA.15
Abnormalities of gait remain long after TKA, with knee flexion in standing most predictive of poor result. Even at a year after surgery, walking speed cadence remains diminished; TKA patients maintain the characteristics of their preoperative antalgic, arthritic gait long after their surgeries, even when pain has been reduced or eliminated.17 This “quadriceps avoidance” gait pattern seems to include prolonged co-contractions of rectus femoris, hamstrings, and tibialis anterior during stance phase.17 It is widely accepted that TKA patients exhibit an ineffective hyperactivity of the rectus femoris, weakened hip flexors, weakened quadriceps (especially vastus medialis), weakness in the hip abductors, and stiffness of the iliotibial band for a long time after surgery.
The prescription of physical therapy before THA surgery should focus on eliminating hip flexion contractures, strengthening the “core” muscles (transversus abdominis, multifidus, obliques, rectus abdominis, erector spinae, pelvic floor), hip abductors, gait training, and normalizing motor sequencing (e.g., eliminating the painful and ineffective co-contraction of the hip abductors and hip flexors). Before TKA, the prescription should also focus on aggressive knee range of motion (ideally via closed kinetic chain, active/active-assistive techniques, and using body weight for force, such as with lunges), achieving full knee extension, improving flexibility of the iliotibial band, and strengthening of the vastus medialis, gluteal, and “core” musculature. Gait training is critical, with a focus on eliminating the stiff knee pattern of gait. Specifically, TKA gait pattern can be improved by focusing on hip flexion during swing, heel strike, knee extension in stance, minimizing weight shifts, and eliminating the painful co-contractions of rectus femoris, hamstrings, and tibialis anterior.
Because full muscle contraction can be so painful prior to joint replacement, customized pain control and exercises techniques can help patients through their preoperative rehabilitation. For example, preoperative genicular nerve ablations several weeks before TKA may help reduce the preoperative (and postoperative) pain of exercise, allowing patients to do more in therapy. Blood flow restriction strength training can be incorporated into the preoperative routine in order to facilitate greater and faster strength gains with less joint force.22 Preoperative utilization of aquatic-based therapy or a weightless treadmill (such as the Alter-G ©) are optional strategies allowing patients to improve function with less pain.
Physical therapists should review with patients and their caregivers important postoperative instructions (such as THA range of motion precautions) and teach a home exercise program. Improving patient “self-efficacy” is probably the most important goal of preoperative physical therapy sessions. Lastly, the physical therapist should be instructed to contact the surgeon’s office to express any pathology they discover—as they are often are the first to identify patient red flag signs.
Most experienced joint replacement surgeons and hospitals require elective hip and knee replacement patients to participate in an educational class before surgery. The topics of the classes include an explanation of surgery, various preparation instructions (e.g., when to stop specific medications, the chlorhexidine wash, removing hair at the surgical site, how to set up the home discharge planning, aligning post-hospital services, the ways to avoid complications, strategies on setting up their home, etc.), pain medication self-management, and a realistic timeline for achieving various outcomes. Patient satisfaction with the outcome of surgery is dictated mostly by whether their recovery correlates with what they expected; aligning expectations with reality is, therefore, critical.23 Attendance in a preoperative educational session may be associated with shorter length of stay, in the hospital or in rehabilitation facility.24 Preoperative education does appear to be effective at reducing anxiety before surgery.25 Patient education (“verbal persuasion”) is one of the main ways to teach self-efficacy, critical to success after surgery, as described later in this chapter. When this education is done in a group setting, patients also benefit from comparing themselves to and learning from others (“vicariously”), another fundamental technique to improving self-efficacy. Therefore, evidence and experience suggest requiring patients to attend a preoperative educational class is an effective intervention and should become standard of care.
Preoperatively identifying patients at risk for poor or difficult outcomes is important to achieve successful surgical outcomes. Preventing and/or identifying “outliers” early is the cornerstone of “episode of care” management. In 2016, the Centers for Medicare and Medicaid (CMS) began a bundled payment program that attempts to hold hospitals and surgical practices accountable for patient care costs that exceed a certain level and incentivizes providers if costs are less than expected. This risk-sharing model targeted covering 50% of all Medicare beneficiaries with hip or knee replacement by 2021.26 The most successful organizations use this incentive to focus on identifying patient risk factors for complications or difficult recovery and intervening before surgery to mitigate that risk.
Risk factors for complications after hip or knee replacement surgery are varied. Patients with these risks should be carefully evaluated before surgery and treatments should be initiated to mitigate the risk. Reviewing preoperative medical risk factors and interventions in detail is beyond the scope of this chapter. An overview is demonstrated, outlining risk factors for surgical complications (Table 91–1), preoperative medical screening and management protocol to mitigate postoperative risk of complications (Table 91–2), the use of functional metabolic equivalents to assess risk (Table 91–3), acute care treatment protocols (Table 91–4), perisurgical pain management (Table 91–5), and DVT/PE prevention using risk stratification (Table 91–6).
History of cardiovascular (CV) disease, other CV risk factor History of cerebrovascular disease Pulmonary disease (e.g., COPD), hypoxemia History of DVT, bleeding disorder, blood disease Diabetes Mellitus Inflammatory arthritis Renal Insufficiency (Cr >2.0 mg/dL) Anemia – Hct <28% Poorly controlled HTN (BP >150/95) Low physical functioning <4 METS | Body weight: (BMI >35 or <20) Dementia Smoker History of daily (>2) alcohol intake Edema, varicosities (more than mild) Multiple prescription medications Bilateral simultaneous joint replacement History of infection in operative or other joint Prior surgery in operative joint Age >80 Depression, anxiety, excessive fear |
| Test/Intervention | Rationale/Indication |
Electrocardiogram | All patients undergoing TJA (“intermediate risk surgery”) |
Chest X-Ray | Age >60 or symptoms |
Urinalysis; Antibiotics | All patients undergoing TJA |
Basic Metabolic Panel (BUN, Cr, & Electrolytes), Albumin | All patients undergoing TJA |
Glucose, HgbA1c | Any possible diabetic |
Tightly manage blood sugars | |
HgbA1C >8, initiate insulin preop and continue through postop | |
Complete blood count (CBC, Platelets) Preoperative iron, consider erythropoietin | All patients undergoing TJA Anemia is associated with infection, length of stay, need for transfusion. Preop consider treating HCT <28 |
Stress Test | Cardiac Risk Factors: History of ischemic heart disease, angina History of heart failure History of cerebrovascular disease Untreated hypertension Chronic Obstructive Pulmonary Disease Smoker Diabetes Mellitus Renal Insufficiency (Cr >2.0) Poorly controlled HTN Poor function (<4.0 MET) or unknown function capacity Abnormal ECG Bilateral simultaneous knee replacement Age >70 |
Echocardiogram | Murmur, history of valvular heart disease |
Cardiology Consult | If there is:
|
Nutritional Assessment and supplementation; delay surgery for at least 8 weeks | Malnourishment: BMI <18.5 kg/m2 Albumin <3.0 g/d Unplanned weight loss >5%–10% within last 6 months, or other |
Smoking cessation at least 6 weeks | Smokers have increased risk of complications including infection |
Obstructive Sleep Apnea Screening checklist; Sleep study | Undiagnosed OSA associated with increased postop complications |
Stress dose steroids (e.g., Hydrocortisone 100 mg IV preop and then 50 mg × 3 doses) | Risk for acute adrenal insufficiency Use if prior 3+ weeks treatment/year or >20 mg a day for more than 3 weeks. |
Instructions regarding rheumatologic drugs Instructions regarding anticoagulants | Methotrexate, sulfasalazine etc.—may continue through surgery TNF inhibitors (Enbrel, Remicade, Humira)—hold for 1 dose cycle & restart after staples/sutures removed NSAIDs should be held depending on half-lives Anti-platelet and anticoagulants should be held depending on half-lives |
Perioperative Beta Blocker | High cardiac risk, prior beta-blocker use |
Blood donation/transfusion: offer patient opportunity for autologous blood donation | Unilateral TKA or THA no blood is needed; transfusions restricted to Hgb <8 or symptomatic/high risk patients Bilateral TKA or hip revision likely need blood available |
Prophylaxis against thromboembolic event | See Table 91–6 Prophylaxis Stratification |
Screening for depression, referral to psychologist, social worker or to internist preoperatively to address; PT/class preop | Suspicious for depression, significant anxiety or fear |
| 1 MET | ≥4 METs | >10 METs |
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| On Day of Surgery: Meloxicam 400 mg + paracetamol 1,000 mg + Famotodine 20 mg + gabapentin 100 mg at bedtime. |
| Intraoperative: Combined Spinal Epidural (e.g., 1% bupivacaine 3–6 mL/hr) and peripheral blocks (e.g., adductor canal TKA; fascia iliaca block THA). |
| Peri-articular Knee injection: 400 mg ropivacaine + 30 mg ketorolac +. 6 mg epinephrine morphine PF 5 mg +/− methylprednisolone + add. 9% NS until 100 mL Inject 1/3 posterior capsule and 2/3 into soft tissues. |
| After Surgery: paracetamol 1,000 mg TID + Meloxicam 7.5 mg daily + tramadol or hydrocodone as needed for rescue pain (before PT and at bedtime) + gabapentin 100–300 mg QHS. It is common for TKA patients to use narcotics (hydrocodone or tramadol) for up to 8 weeks after surgery, in declining amounts. THA patients may use narcotics for up to a month, also in declining amounts. |
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Malnutrition is an example of a modifiable risk factor: it is considered a significant risk factor for infection after elective joint replacement. Malnutrition is deemed present when serum albumin level is <3.5 g/dL, serum transferrin levels <200 mg/dL, serum prealbumin <15 gm/dL and total lymphocyte count (TLC) < 1,500 cells/mm3. Body mass index (BMI) can be used as a proxy for nutrition: when BMI is less than 18.5 kg/m2 or if patients report unintentional weight loss of 5% to 10% of body weight in last 3 to 6 months, they are considered malnourished. Interestingly, not only very thin patients are at risk. Obese patients, who often consume diets high in calories but low in nutrition, can have significant micronutrient deficiencies, such as in vitamin D, biotin, and thiamine. Several authors have demonstrated the impact of poor nutrition on wound healing and infection. There is a fivefold greater risk of postoperative joint infection seen in patients with preoperative total lymphocyte counts <1,500 cells/mm3 and a seven-times greater risk of infection in patients with albumin levels <3.5 g/dL.27 Thus, if a patient with advanced hip or knee disease considering elective joint replacement has a BMI <20, serum albumin <3.0 g/dL or reports unplanned weight loss >5% within last 6 months, surgery should be delayed until nutritional status can be evaluated and improved. That patient should be referred back to their primary care physician for assessment and management to exclude underlying causes of unexplained weight loss and to begin nutritional supplementation.
The influence of psychological state on knee replacement (unlike hip replacement) has been well-studied, and is important for rehabilitation professionals to understand in order to guide and motivate patients through their recovery.28,29 Total knee replacement is often described as one of the most painful orthopedic recoveries, requiring patients to actively participate in an aggressive and regular exercise regime (for some the first time in their life). Patients bring to their surgeries complicated emotions and psychosocial issues. The postoperative recovery period seems to unmask negative psychology. With little knowledge of the exact issues and limited expertise in psychology, orthopedic teams must somehow motivate patients so that these issues do not sabotage recovery.
With the advent of minimally invasive joint replacement surgery, aggressive physician and hospital marketing strategies, and media accounts highlighting the dramatic recoveries of selected high-performance patients, it is not surprising that many patients and their families have high expectations of surgery. Add to that mix the impatience of many “baby boomers” to pain or to compromise of their lifestyles and the result is a patient population whose anticipated recovery may fall short of expectations. In general, patients underestimate their time to full recovery, overestimate the likelihood of being pain free, and overestimate their ability to participate in usual activities without limits. Unmet expectations after joint replacement are key drivers of poor patient satisfaction, no matter how unrealistic the expectations may be. High expectation of outcome in the face of less severe osteoarthritis at the time of surgery is a factor associated with “unexplained pain” after knee replacement.30 On the other hand, the expectation of a poor surgical recovery, a situation more common among African Americans, appears to interfere with or delay the choice to have surgery.31 These patients ultimately come to surgery more disabled than their peers, making recovery more challenging.
Many clinicians have managed the postsurgical patient who calls weekly, requires prolonged narcotics, schedules multiple follow-up visits for pain, and utilizes additional diagnostic studies (e.g., radiographs, venous blood flows, erythrocyte sedimentation rates) which are all invariably all normal. This patient might simply be “catastrophizing.” Catastrophizing is characterized by the tendency to focus on being unable to control pain symptoms (helplessness and is a robust predictor of the pain experience.32,33 Catastrophizing has been associated with a longer hospital length of stay, excessive pain medication use, impaired activities of daily living, heightened pain following surgery, and has been proposed to be a risk factor for chronic, long-term pain after knee arthroplasty.13,28,33–36 Thus, patients who catastrophize appear to be at risk for a difficult early surgical recovery, with significant pain complaints, as well as unhappiness with their outcome in the long run. Simply prescribing higher doses of narcotic analgesics is unlikely to adequately manage these patients’ pain. In this situation, interventions that help control behavior, anxiety, and negative thoughts may be much more likely to be effective.
There is strong evidence that poor mental health is associated with disability. Depression may be both a consequence of living with chronic joint pain as well as contributing to the disability that occurs from osteoarthritis. It has been reported that as many as 10% of people with osteoarthritis are depressed, exacerbating pain and disability.37 Anxiety in OA is also associated with poorer physical functioning.38 In a systematic review of the studies that looked at psychological factors influencing the outcome of total knee and hip arthroplasty, worse preoperative mental health and pain catastrophizing were associated with lower scores on function and pain at 1 year after TKA. For THA, only limited, conflicting, or no evidence was found.33 In two prospective, observational studies, the relationship between pain, depressive symptoms, and anxiety on short (1 year) and long (5 year) outcome of TKA were defined. Patients with greater preoperative pain had more postoperative pain, used more home therapy, and underwent more postoperative manipulations. Preoperative depressive symptoms and anxiety were associated with heightened pain at 1 year. We concluded that pain after knee replacement resolves quickly, declining by half in 3 months. However, one in eight patients continued to report moderate to severe pain at 1 year.13 At 5-year follow-up, pain and depressive symptoms predicted lower outcomes, but anxiety did not.13 Others have confirmed and expanded upon these findings, reporting that depressive symptoms, somatization, and psychological distress were all significant predictors of poorer clinical outcome.34
Self-efficacy is the measure of a person’s belief in their competence in succeeding at a task. This trait appears to be a critical factor in success, including after joint replacement. Self-efficacy is believed to derive from mastery experiences, vicarious experiences, veal persuasion, and physiological states.14 Mastery experiences are the most compelling—as they reinforce the individual’s ability to perform the task at hand. Vicarious experiences are those in which one compares their activities to others—less compelling but still useful. Verbal persuasion describes learning states. Physiological states, although usually described as a negative (such as increased fatigue), can be positive—for example, increasing quadriceps strength during exercise reinforces the individual’s perception that they have the capacity to achieve certain goals.
The following are practical office-based interventions that might help reduce the impact of negative psychological factors on outcome after joint replacement. This approach only requires that considering negative psychology as one of many risk factors, and proactively managing it through the surgical experience. The keys are to acknowledge pain, indicate to the patient that their pain and disability are normal, and reassure them that certain activities will be painful but not damaging to their joint.
Identify depression or excessive anxiety prior to surgery, and refer those patients preoperatively for treatment.
Improve patients’ self-efficacy before surgery using the following techniques:
Mastery experiences.
Enroll the patient in individualized preoperative physical therapy with a skilled therapist. This will allow them to master various physical tasks, and translate into a reduced fear of movement.
Vicarious experiences.
Connect the patient with former patients who have successfully negotiated surgery. Allowing former patients to mentor current patients is a profoundly effective intervention.
Verbal persuasion.
Preoperative educational classes and knowledgeable clinicians who focus on education are essential.
Maximize physiology.
Couple aggressive preoperative pain management with an exercise program, injections and analgesics to reduce pain while insisting all patients perform exercise before surgery.
Manage postoperative pain with more than just narcotics. It is tempting to overmedicate postoperative patients who catastrophize; however, interventions that focus on giving patients better self-control and reducing anxiety are more effective. Help patients restore their sleep and encourage their early return to activities they enjoy, and keep them in PT or exercise classes as long as possible.
A basic understanding of arthroplasty surgery (implants, materials, approach, and biomechanical principles) is necessary for physiatrists. Many physiatrists work in acute or subacute facilities where postoperative patients recover. When these patients have problems, knowledge of surgical issues better prepares physiatrists to properly handle complications. A very basic example: hip replacement precautions vary depending upon surgical approach. A patient who has had a THA through the anterior approach is more likely to dislocate anteriorly, in contrast to the more common posterolateral dislocation seen with posterior surgical exposure. Anterior THA patients should avoid hip extension (such as “bridging” exercises) early after surgery to reduce the possibility of anterior dislocation. If an acute dislocation is suspected, radiographic evaluation must include a “shoot-through lateral” image, as the standard AP view may miss the anteriorly dislocated hip.
Knowledge of surgical factors is also relevant for physiatrists specializing in outpatient musculoskeletal pain. Arthroplasty patients often come to see physiatrists for “pain management,” sometimes without an evaluation or referral from their surgeon. Properly diagnosing the patient’s pain requires knowledge of the underlying structures and the possible pathologies (see Clinical Example 91-1).
Clinical Example 91-1
A patient with an 18-month history of limping and recurrent “trochanteric bursitis” presents to you for pain management. The patient had an ipsilateral THA 3 years earlier, has longstanding lumbar spine disease, and prior to seeing you, underwent two trochanteric bursa injections, each marginally and transiently reducing pain. On examination, you identify disproportionate weakness in hip abduction, with a Trendelenburg lurch. Radiographs, ESR, and CRP were unremarkable. Your differential diagnosis includes: lumbar spine disease (especially L4–S1 facet arthropathy/stenosis) with atrophy of the abductors causing an “overuse” syndrome of recurrent lateral hip pain; tendonosis/tear of the abductors/external rotator muscle or tendons (e.g., gluteus medius); a biomechanical/prosthesis problem (such as reduced prosthetic head-neck offset resulting in weakness from imperfect length-tension curve; metal fretting at the modular head neck junction, causing an abnormal local tissue reaction, with possible pseudotumor and necrosis of the gluteus medius), or indolent hip arthroplasty infection. Your choices (MRI hip using MARS technique, MRI lumbar spine, physical therapy, epidural injection, referral for revision hip surgery, hip aspiration, or other diagnostic test or intervention) depend on your accurate diagnosis.
Hip replacements are one of three types. The classic total hip replacement involves excision of the femoral head and neck and replacing it with a prosthetic implant, preparing the acetabulum, and fitting a prosthetic acetabular component. The prostheses are fixed to bone via cement or “press-fit.” There is a polyethylene liner between the femoral head and acetabulum, unless the implant is metal-on-metal or metal-on-ceramic (Fig. 91–2).
Figure 91–2
Postsurgical portable radiograph demonstrating good positioning of an artificial hip. (Used with permission from John E. Delzell, Jr., MD)
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