Osteoarthritis is a progressive degenerative joint disease caused by primary or secondary factors ( Table 90-1 ). Whereas primary osteoarthritis is believed to be caused by an interplay of genetic and environmental factors that eventually lead to late joint degeneration in older persons (i.e., persons generally older than 60 years), secondary osteoarthritis is frequently found in a much younger patient population. Although some pathophysiologic overlap occurs between primary and secondary osteoarthritis, the latter is commonly observed as a consequence of a structural abnormality of the hip joint that causes indirect cartilage damage or a known deficiency in normal cellular function that directly affects hyaline cartilage. Conditions that lead to indirect cartilage damage occur as a result of the development of morphologic abnormalities in the femur or acetabulum that cause labral damage and mechanical overload of the articular cartilage and ultimately induce a chronic degenerative process involving the cartilage, subchondral bone, and synovium, which leads to the characteristic findings seen in osteoarthritis.
|Environmental factors (e.g., weight and activity level)|
|Direct causes||Rheumatoid arthritis|
|Rapidly progressive osteoarthritis|
|Indirect causes||Developmental dysplasia of the hip|
|Slipped capital femoral epiphysis|
Epidemiologic studies have estimated that the incidence of osteoarthritis in the United States for patients younger than 50 years is 21 per 100,000 population. The etiology is multifactorial, but anatomic abnormalities, metabolic diseases, and environmental factors have all been implicated. Several of these mechanisms represent modifiable risk factors; in several studies and joint registry reports it has been observed that young patients who are overweight or who participate in high-impact athletic activities, particularly professional athletes, have an increased risk for the development of osteoarthritis.
Treating patients with osteoarthritis who are younger than 50 years may be challenging. Although implant survivorship has markedly increased with the advent of modern cementless stem and cup designs, large-diameter femoral heads, and newer generations of highly cross-linked polyethylene that have improved wear properties, many young patients may still require revisions at some point in their lifetime. Although alternative bearing surfaces such as ceramic-on-ceramic or metal-on-metal bearings have been evaluated as a potential replacement for traditional metal-on-polyethylene bearings because of their better wear properties, they have been found to have drawbacks. Concerns regarding implant fracture or chipping with ceramic bearings and early failure from adverse tissue reactions to metallic wear debris have restricted their use.
With an increased understanding of the etiology and pathologic processes that occur in persons with primary and secondary osteoarthritis, there has been a trend toward increased emphasis on activity modification and joint-preserving procedures that attempt to delay the need for total hip arthroplasty (THA). However, despite efforts to save the patient’s native joint, many of these patients will still require a THA at some point in their lives. Consequently, it is important to properly educate this younger subset of patients on the limitations of hip arthroplasty because they are likely to demand greater motion and partake in more physical activity than the traditional THA population.
Various treatment options for young patients with hip arthritis are discussed in this chapter, with a focus on surgical treatment options such as hip arthroscopy, osteotomy, and THA. The complications observed in these patients and their postoperative management are also discussed, with particular attention to a return to previous athletic activities.
Hip arthritis in the young patient may present a diagnostic challenge, but the correct diagnosis of the specific condition is imperative to achieve a successful clinical outcome. The surgeon should first elicit a complete history, including family information, and exclude other conditions that may lead to referred hip pain. These conditions may include lumbar spinal involvement, sacroiliac joint involvement, greater trochanteric bursitis, tendinitis, athletic pubalgia, or an inguinal hernia ( Box 90-1 ). The surgeon should also carefully consider potential nonarthritic causes of hip pain that may include labral tears, loose bodies due to synovial chondromatosis, synovitis, and, rarely, sepsis.
Greater trochanteric bursitis
Iliotibial band tendonitis
Athletic pubalgia (sportsman’s hernia)
Sacroiliac joint arthritis
Pelvic arterial pseudoaneurysm
Patients with arthritis commonly report a history of vague, dull pain that localizes to the groin and has a gradual onset. The pain is exacerbated by activity and is usually associated with stiffness and, less commonly, buckling. Usually patients relate an antecedent event such as a minor trauma or a misstep while playing sports to which they attribute their pain. Unlike conditions that may mimic hip arthritis, patients with true osteoarthritis classically present with pain after activity and stiffness after a period of rest such as prolonged sitting or sleeping. When asked to localize their pain, they may demonstrate the classic C sign, which helps distinguish arthritis from other more common causes of pain such as bursitis. The patient may also report a family history of “early arthritis” that may be indicative of an underlying anatomic abnormality or rheumatologic disease.
Symptoms of catching, locking, or clicking are more indicative of labral pathology or loose bodies than arthritis, although both of these conditions can be considered secondary risk factors for arthritis. A history of pain along the lateral aspect of the hip is likely due to greater trochanteric bursitis, whereas lumbar or gluteal pain may be indicative of a peripheral neuropathy. Although rare, the presence of vascular pathology such as a delayed presentation of a pseudoaneurysm may also be a cause of hip pain. This condition is more commonly seen in patients after a major trauma or prior pelvic surgical procedures, and it can be distinguished from arthritis by the acute onset of groin pain that is usually associated with a pulsatile mass and, in extreme cases, hemodynamic compromise.
The surgeon should be careful to rule out the possibility of athletic pubalgia (sportsman’s hernia), which is a condition caused by dilation of the superficial inguinal ring. In a recent study by Hammoud et al., 32% of patients treated for femoroacetabular impingement (FAI) had previously undergone surgery for athletic pubalgia and had not experienced symptom resolution. These patients frequently present with reports of hip pain with physical activity and stiffness after prolonged rest, and their condition can be difficult to distinguish from the early presentation of arthritis. The presence of classic findings seen on magnetic resonance imaging (MRI) helps distinguish this condition from other causes of hip pain.
Many patients who present with hip pain will have a benign, self-limited course in which the symptoms disappear with time. Thus examining the temporal relationships between the onset of pain or stiffness, the location of the pain, and any response to a prior course of nonoperative therapy is often the best way to differentiate arthritis from other potential causes of hip pain.
Through physical examination of a young patient with hip pain, the clinician should aim to arrive at a definitive diagnosis while ruling out other potential sources for hip pain that require different treatment approaches (see Box 90-1 ). The examination should always begin with a complete visual inspection of the involved extremity, with particular attention given to any marked anatomic abnormalities, abnormal gait, and the presence of any discoloration, masses, or scars on the skin.
True joint pain should be distinguished from referred back pain by having the patient perform a passive straight leg raising test to provoke radicular symptoms and comparing the results with pain elicited with active hip flexion against resistance. Patients who have true hip pain will note pain or yield to resisted active hip flexion but will have no radicular symptoms with passive hip flexion.
Assessment of the patient’s range of motion includes hip flexion, extension, and internal and external rotation. Patients with FAI will present with loss of internal rotation, whereas patients with arthritis due to other causes lose external rotation. Pain is frequently observed at the extremes of range of motion, although in some patients stiffness compared with the contralateral limb may be the only physical finding. In advanced stages of osteoarthritis, range of motion is restricted globally.
FAI can be diagnosed by the presence of a positive impingement sign that reproduces the patient’s pain. Two different tests may be used, the anterior and posterior impingement tests, both of which are performed with the patient supine ( Fig. 90-1, A and B ). In the anterior impingement test, the hip is passively flexed to 90 degrees and internally rotated, which causes anterior impingement between the femoral neck and labrum, eliciting the pain. Similarly, the posterior impingement test is the reverse, where the hip is passively extended and externally rotated. However, the presence of an impingement sign is a nonspecific finding. Other conditions that can elicit a positive impingement sign may include iliopsoas bursitis, displaced labral tears, and a tight anterior capsule.
In equivocal cases, fluoroscopically guided intraarticular injections may help distinguish hip pain from other sources of referred pain. When combined with corticosteroid injections, they can be both diagnostic and therapeutic. Patients should be instructed to record their pain with physical activity. Injections are an attractive option that allow patients to continue with physical therapy while helping to diagnose the source of the hip pain before obtaining advanced imaging studies.
Even when a thorough history and physical examination have been performed, a definitive diagnosis often is reached only after evaluation of radiographic studies. Standard radiographs include an anteroposterior view of the pelvis and a frog-leg lateral view of the affected hip ( Fig. 90-2, A and B ). Both the affected hip and the contralateral hip should be evaluated. In patients with early evidence of arthritis, subtle indications of early degeneration can lead to a diagnosis without the need for advanced imaging studies.
Classic radiographic findings include joint space narrowing, osteophytes, cysts, and subchondral sclerosis. In a subset of patients who have a condition known as rapidly progressive osteoarthritis, rapid joint space narrowing occurs, which is defined as more than 2 mm per year of joint space loss. In severe forms of this disease, massive femoral head osteolysis may occur within 1 year of symptom onset.
For patients with signs of impingement, the surgeon should evaluate the sphericity of the femoral head and the morphology of the acetabulum for signs of a cam or pincer lesion ( Table 90-2 ). However, it should be noted that many patients with aspherical heads are completely asymptomatic throughout their lifetimes. The acetabulum should be evaluated for pincer lesions, retroversion, or a shallow acetabular index, which may help guide future surgical treatment options. The crossover sign is a clear indication of acetabular retroversion and posterior impingement. The surgeon should note the presence of inferior and notch osteophytes, which, although often more subtle than other indications, are signs of an early presentation of osteoarthritis. Notch osteophytes in particular place increased sheer pressures on the femoral head and may contribute to early degeneration. In severe cases, labral calcification (os acetabuli) can also be observed on plain radiographs late in the disease course.
|Type of Lesion||Plain Radiographic Findings|
|Pistol grip deformity (lateral contour deformity)|
|Prior slipped capitol femoral epiphysis|
Determination of the α angle on either a lateral plain radiograph or oblique MRI section can help stratify patients and determine the risk of progression of cam lesion disease. The α angle is defined as the angle between a line from the center of the femoral head through the femoral neck and a line from the center of the femoral head to the head-neck junction ( Fig. 90-3 ). Notzli et al. noted that patients who have an α angle greater than 55 degrees are considered to have radiographic evidence of impingement. The sensitivity and specificity of plain radiographic measurement of the α angle has been reported as 91% and 88%, respectively.
Furthermore, normal plain radiographs do not exclude the early presentation of arthritis. In equivocal cases, an MRI of the hip can be obtained to determine the cause of hip pain and rule out other causes such as labral tears, osteonecrosis, or tumors. An early sign of arthritis on MRI is articular cartilage delamination, although it may be difficult to visualize. In patients with labral pathology, an MRI scan is the most sensitive and specific study available; however, noncontrast studies may be limited in their ability to visualize chondral lesions. Gadolinium arthrogram MRI scans have been demonstrated to have 92% sensitivity for identifying labral tears. Coronal, sagittal, and axial (oblique) scans should be obtained to completely visualize the entire labrum, particularly the anterior labrum, where most pathology is observed.
The goal of treating young patients with hip arthritis is to preserve the native joint and delay the need for THA as long as possible. This process begins with the correct diagnosis of the patient’s underlying pathology and timely treatment with the appropriate techniques. Surgeons should be comfortable performing the necessary intervention and should not hesitate to refer the patient to a specialist center if they are not familiar with the appropriate treatment options.
Patients with normal plain radiographs and an equivocal physical examination that is suggestive of an early presentation of arthritis should first undergo a course of nonoperative therapy with analgesics, activity modification, and injections. However, in the setting of clear abnormalities, early surgical intervention is likely to have greater long-term benefits than continued nonoperative treatments. Particularly in patients with FAI or acetabular abnormalities, no amount of nonoperative therapy will reverse the underlying mechanical causes that are the source of the patient’s disability. In this situation, the surgeon should attempt early joint salvage rather than waiting and increasing the likelihood that earlier THA will be required.
In late-stage disease with evidence of osteoarthritis on plain radiographs and clear patient symptomatology, it is best to proceed immediately to THA. Worse postoperative clinical outcomes have been observed when surgery is delayed. A recent study by Vergara et al. demonstrated significantly lower postoperative clinical scores in patients who waited 6 months rather than only 3 months for THA.
Any concomitant conditions that may have a negative effect on postoperative rehabilitation or outcomes also should be assessed prior to any surgical intervention. Several studies have demonstrated poor outcomes for patients who are depressed or have other sources of pain, such as lumbar stenosis. If necessary, the patient should be referred to a psychiatrist or specialist to resolve, to the extent possible, any outstanding comorbidities prior to surgery.
Economic considerations are also important when caring for young patients with arthritis because these patients are still in the productive part of their lives. Because of employment demands, young patients may not be able to engage in physical therapy, and a prolonged time away from work may represent a substantial economic burden. It has been estimated that for young patients with severe osteoarthritis, the annual cost of lost productivity may be as high as $17,000, and continued nonoperative therapy may be twice as expensive as THA when all costs are considered.
Patient education regarding expected outcomes with surgical intervention is paramount in the mature athlete with osteoarthritis, particularly when managing expectations after hip arthroscopy. Recent literature has suggested a role for arthroscopy in the face of mild to moderate osteoarthritis in the mature adult (younger than 55 years). However, preoperative education and postoperative management are necessary to optimize patient satisfaction.
Arthroscopy of the hip is a minimally invasive procedure that can be performed for patients with varying degrees of osteoarthritis who have not responded to conservative measures and may not yet be a candidate for a THA. In patients with osteoarthritis, hip arthroplasty may be used to remove loose bodies and perform joint lavage, labral repairs or debridement, synovectomy, femoral osteoplasty, or acetabuloplasty.
Cartilage lesions often are dormant on plain radiographs or poorly visualized on magnetic resonance arthrography. The Outerbridge grading classification of chondral lesions is not specific for osteoarthritis. Conversely, the Tönnis classification represents radiographic changes. Arthroscopic evaluation of these lesions can better lend itself to both current and future expectations, which is particularly true in lesions that may not have declared themselves radiographically. Although uniformity of hip osteoarthritis may not be present, a universal theme across the literature is that the outcomes are poorer in patients with more advanced osteoarthritis. Sampson attempted to classify osteochondral lesions of the femoral head and acetabulum to better predict outcomes ( Boxes 90-2 and 90-3 ). In this classification, poorer outcomes were noted with higher grade lesions. More aggressive intervention is recommended as well in these higher grade lesions in an effort to maximize outcomes and stave off further surgical intervention. Furthermore, the nature of the osteochondral defect must be understood. Most lesions may be classified as either substance loss of the articular cartilage (partial or full thickness) or delamination. Sampson again noted that with an intact labrocartilage junction, the cartilage may be repaired with the labrum back to bone as a flap. When the junction is torn the labrum may be repaired, although the cartilage may need to be excised.
Intact Head Substrate Bone with Chondral Damage (No Avascular Necrosis)
HC 0 5 No damage
HC 0T 5 Uniform thinning
HC 1 5 Softening
HC 2 5 Fibrillation
HC 3 5 Exposed bone
HC 4 5 Any delamination
HTD 5 Traumatic defect (size in mm)
HDZ 5 Demarcation zone from femoroacetabular impingement
HC, Femoral head cartilage; HDZ, demarcation zone for femoroacetabular impingement; HTD, femoral head traumatic defect; T, thinning.
AC 0 5 No damage
AC 1 5 Softening no wave sign
AC 1w 5 Softening with wave sign intact labrocartilage junction
AC 1wTj 5 Softening with wave sign and torn labrocartilage junction
AC 1wD 5 Softening with wave sign and intact labrocartilage junction with delamination
AC 1wTjD 5 Softening with wave sign and torn labrocartilage junction with delamination
AC 2 5 Fibrillation
AC 2Tj 5 Fibrillation with torn labrocartilage junction
AC 3 5 Exposed bone small area <1 cm 2
AC 4 5 Exposed bone large area >1 cm 2
A, Acetabulum; C, cartilage defects; D, with delamination; Tj, torn labrocartilage junction; w, with wave sign.
Recent literature has suggested a role for arthroscopy in the face of mild to moderate osteoarthritis in mature adults who are younger than 55 years. Haviv and O’Donnell retrospectively reported on 564 patients who underwent hip arthroscopy. They noted that over a 7-year period, 16% of all participants eventually required THA. These investigators concluded that the time from the first arthroscopy to a hip replacement was found to be longer in patients younger than 55 years and in those who were diagnosed as being in a milder osteoarthritic stage. The patients who underwent osteoplasties also had a lower incidence of needing a THA.
McCarthy et al. performed a 10-year retrospective study in which 106 hip arthroscopies were analyzed. On the basis of their findings, lower Harris hip scores and older age were predictive of poorer outcomes. No difference in outcome was observed with regard to gender; however, it was found that older age had a 3.6 times higher likelihood of leading to subsequent THA. In addition, chondral defects of either the femoral head or acetabulum were 20 to 60 times more likely to lead to a THA; however, it was noted that patients with Outerbridge scores of 0 to 2 were less likely to need a replacement. These findings, which corroborated those of the multivariate 10-year analysis by Byrd and Jones, suggested that patients older than 40 years with any grade 3 or 4 chondral lesions had a 90% chance of progressing to a THA.
Appropriate patient counseling of the risks and benefits and expected outcomes after hip arthroscopy will almost certainly lead to higher patient satisfaction. Appropriate postsurgical rehabilitation must be emphasized to offload pressures across the hip joint. Additionally, activity modifications based on intraoperative findings may lead to longevity of the procedure and pain relief. An example of this modification includes switching from running to swimming or elliptical training. Although hip arthroscopy may be an effective treatment for mechanical symptoms or for symptomatic osteoarthritis, it must be emphasized to the patient that it is unlikely to significantly halt the progression of the condition in patients with higher grades of disease. Hip arthroscopy in this setting should be viewed as a palliative and delaying intervention rather than a curative measure. During the decision-making process, appropriate patient selection and expectation management should guide the surgeon through the treatment algorithm.
Nonoperative treatment options include use of medication and physical therapy. Patients should always be instructed to attempt lifestyle modifications such as weight loss, light aerobic physical activity, and avoidance of activities that exacerbate their symptoms. In the case of nonprofessional athletes, it may be reasonable to recommend that they switch from high-level sports to recreational activities. Patients who wish to remain active should be encouraged to partake in low-impact sports such as swimming, cycling, or walking that do not result in repetitive demands for hip movement at the extremes of range of motion seen in high-impact sports such as football, soccer, or gymnastics.
Symptomatic treatment can be achieved through the use of nonnarcotic analgesics and nonsteroidal antiinflammatory drugs (NSAIDs). Because of the risks involved with chronic NSAID administration, it is recommended that acetaminophen be prescribed as a first-line analgesic. In a metaanalysis, Wegman et al. observed that acetaminophen is just as effective as NSAIDs while having fewer adverse effects. If this regimen does not alleviate symptoms, the physician may consider prescribing antiinflammatory agents, but low doses should be used along with a gastroprotective agent, especially in patients with a history of gastric ulcers or upper gastrointestinal bleeding. In patients who do not tolerate nonselective NSAIDs, selective cyclooxygenase-2 inhibitors may be used. Narcotic pain medications should be avoided when possible and if necessary should only be used as a bridge until definitive surgical treatment has been provided. Worse postoperative clinical outcomes for total joint arthroplasty are seen in patients who take opioid medications on a long-term basis before surgery.
Corticosteroid injections can also be used as an adjunct and were demonstrated to be efficacious for up to 3 months in a recent study by Robinson et al. The authors noted that a prednisone dose-equivalent of 80 mg was necessary to demonstrate efficacy at 3 months and that lower doses have variable efficacy and duration. Hip injections are technically more demanding than knee injections and present a potential risk for damage to neurovascular structures in the anterior compartment. Intraarticular injections should not be attempted without fluoroscopic guidance.
As a consequence of our increased understanding of lesions that are a potential precursor to osteoarthritis, along with the refinement of arthroscopic instrumentation and surgical technique, hip arthroscopy has become a mainstay of early joint-preservation efforts. Hip arthroscopy is ideal for the removal of loose or foreign bodies, the repair of labral damage, and the treatment of small chondral lesions, FAI, and synovial chondromatosis.
In the setting of FAI, arthroscopy is an ideal option to resolve any size mismatch between the femoral head and acetabulum that is causing mechanical overload of the articular cartilage, while enabling concurrent labral repair. Although this procedure can be performed with use of an open or mini open technique, arthroscopy requires less tissue dissection, which leads to shorter hospital stays, fewer complications, and faster recovery periods when compared with open debridement.
Arthroscopy requires distraction of the hip to reach the central compartment, whereas the peripheral compartment can be examined without distraction. Most of the resistance to distraction is caused by negative hydrostatic pressure within the hip joint, and the remainder is caused by the ligamentous structures and dynamic resistance from the surrounding musculature. To reduce the required distraction force, patients should be anesthetized and the muscles completely relaxed. Negative hydrostatic pressure can be reduced via injection of sterile saline solution prior to distraction. Although the necessary distraction force is highly variable, in most patients, adequate visualization of the central compartment can be obtained with 50 lb of distraction force.
The patient may be positioned in a supine or lateral decubitus position according to the preference of the surgeon. Benefits of the lateral decubitus position include ease of instrument insertion as a result of less overlying soft tissue laterally, having the greater trochanter as a readily palpable fixed landmark, and being able to access both anterior and posterior structures via the paratrochanteric portals.
The choice of entry portal depends on the location of hip pathology, but the anterolateral portals (supine) or anterior paratrochanteric portals (lateral decubitus) are most commonly used because most hip pathology is present anteriorly. Other portals that can be used are the proximal and posterior paratrochanteric portals and the posterior portal. The surgeon should be familiar with the surrounding anatomy and the neurovascular structures that are at risk. The lateral femoral cutaneous nerve is at risk with use of the anterior portal and the sciatic nerve is at risk with use of the posterior portal. If the posterior portal is to be used, it is recommended that a small incision be used initially to identify the posterior capsule and sciatic nerve, thus preventing injury. Insertion of the trocar too deeply through the anterior portals, although less common, risks damage to the femoral neurovascular bundle.
Pelvic and femoral osteotomies are other joint-preserving treatment options that are ideal in the setting of symptomatic developmental dysplasia of the hip or other structural abnormalities that lead to a decreased joint contact area or impingement. The majority of the pathology is observed on the acetabular side, although a small subset of patients may have a femoral deformity that is amenable to osteotomy. It is imperative to ensure that potential osteotomy candidates have viable articular cartilage. Otherwise, the resultant procedure may improve the mechanical properties within the joint but will have no effect on the patient’s symptoms or long-term survival of the joint.
A pelvic osteotomy is necessary to reorient the acetabulum in cases of a shallow acetabular index to obtain increased femoral head coverage (thereby decreasing the load per unit area and contact stress) or to correct a pincer lesion. Several different procedures have been described in the literature during the past 50 years, including innominate (single, double, or triple) and periacetabular osteotomies. Single innominate osteotomies may lead to lateralization of the hip joint, which was addressed by the development of the triple innominate osteotomy. Although triple osteotomies lead to improved acetabular coverage with less joint lateralization, they may result in nonunions, particularly in the anterior pelvic ring, which may require a second procedure. The risk for nonunions in the superior public ramus is of particular concern with external rotation of the osteotomy fragment to achieve better head coverage. This complication can be avoided by medialization of the fragment or by bone grafting.
The periacetabular osteotomy was developed as an alternative to innominate osteotomies. It offers the advantage of maintaining the continuity of the pelvic ring and obviates the need for postoperative traction or immobilization. However, necrosis of the acetabular fragment is a risk because of disruption of the normal blood supply, which in the immediate postoperative period is provided primarily by the hip capsule.
Femoral osteotomies are less commonly used and are limited to patients with a deformity localized to the proximal femur. A varus osteotomy may lead to inequality of leg length and in rare cases can lead to instability and decreased strength because of laxity of the secondary stabilizers of the hip joint. This problem can be corrected by advancement of the greater trochanter. Similarly, a valgus osteotomy may lead to the opposite complication with increased leg length, hip tightness, and, in rare cases, sciatic neuropathy. Rotational osteotomies have also been described that may be used to treat small osteonecrotic lesions in the weight-bearing portion of the femoral head. As with all osteotomies, femoral nonunion is a risk.
The osteotomy is a challenging joint-preserving treatment option that should only be attempted by experienced surgeons who have received training in the procedure.
Total Hip Arthroplasty
THA is often the only option for patients who have not responded to nonoperative therapy or joint-preserving procedures. Although arthroplasty provides excellent pain relief and return to function, concerns exist regarding implant durability and survivorship in younger, more active patients. Furthermore, the presence of abnormal anatomy as a consequence of the patient’s underlying disease or as a result of prior surgical procedures adds a further layer of complexity regarding implant choice, positioning, and the surgical approach.
As mentioned previously, joint salvage is the goal; however, in the presence of worsening symptoms, the patient and surgeon should not delay THA. Unnecessary waiting or prolonged nonoperative treatment courses place an increased economic burden on the patient and decrease the likelihood that they will be able to achieve a similar level of postoperative function had surgery not been delayed.
Cementless fixation of the femoral and acetabular component has become the standard procedure in the United States. Cementless fixation offers the benefit of biologic fixation at the bone-implant interface, which has the potential to remodel over time. The use of proximally porous coated stems offers the advantage of proximally loading the femur, which may lead to less thigh pain and proximal stress shielding. Excellent long-term survivorship has been observed with these stem designs. Another option is resurfacing arthroplasty or use of short neck-preserving stems. These bone-preserving options may facilitate future revisions by maintaining proximal bone stock and allowing use of a metaphyseal rather than a diaphyseal engaging stem during a future revision, if necessary.
The choice of surgical approach is based on the surgeon’s preference and experience, as well as the presence of prior surgical scars. The anterior or anterolateral approach both provide excellent exposure while avoiding disruption of the posterior soft tissues. Dislocation rates of less than 1% have been reported with these approaches even in the absence of any hip precautions. Dislocation or instability can be further avoided with the use of large-diameter femoral heads or dual-mobility bearings.
The choice of bearing selection is an important consideration. Factors that need to be assessed include durability and wear, the maximal femoral head size that can be used with the system, and the risk for complications. The complications that have been reported in the literature with metal-on-metal and ceramic-on-ceramic bearings have led to decreased usage of these bearing surfaces in the United States.
Although ceramic bearings display excellent wear properties (5 µm/year linear wear), problems with chipping and squeaking of ceramic bearings have been well reported in the literature. However, these problems appear to have been largely solved with newer generation ceramics. The incidence of squeaking is less than 2.5% in recent studies, and a chipping rate of less than 0.005% has been observed in hip simulators. One potential drawback of ceramic bearings is that they may require the use of small femoral heads. This factor is particularly relevant in women who have small dysplastic acetabuli, which necessitates the use of small cups that cannot accept femoral heads measuring 36 mm or larger.
Adverse tissue reactions and higher levels of failure of stemmed metal-on-metal total hip arthroplasties compared with metal-on-polyethylene bearings have been well documented in national joint registry data. Although these alternative bearing surfaces were originally developed to address dislocation rates seen with polyethylene bearings that used small-diameter femoral heads, recent advances in component and polyethylene design have obviated the need for metal-on-metal articulations to gain the benefits of a large-diameter femoral head.
Modern metal-on-polyethylene bearings utilizing highly cross-linked polyethylene have excellent wear that has been reported to be 58% to 74% lower than that of conventional polyethylene. Use of this material has allowed the use of thinner polyethylene liners (3.9 mm) and 36-mm femoral heads even in patients with small acetabular cups. A recent study by Sayeed et al. demonstrated very low wear and no acetabular rim fractures, wear through, or early failures of a 3.9-mm polyethylene liner at 2-year follow-up. Another option is to use a dual mobility bearing that has demonstrated excellent clinical results and low dislocation rates in Europe and has recently been introduced in the United States. Dislocation rates with this bearing system have been reported to be less than 1% in a recent systematic review.