Total Hip Replacement: What Will You Tell Your Patient?

Is my patient a candidate for total hip replacement? How safe is the surgery? What is the long-term outlook?

These are just a few of questions you will need to address if your patient suffers from hip joint failure. Each year, more than 285,000 total hip replacements are performed in the United States, according to the Agency for Healthcare Research and Quality.¹ For many of the markedly disabled persons who undergo replacement, the procedure offers enhanced mobility and relief from pain.

The indications for and expected outcomes from total hip replacement were just two of the issues addressed at a consensus conference convened by the National Institutes of Health.² Recommendations from the conference were recently updated.³

What are the current indications for total hip replacement?

Primary total hip replacement is indicated to relieve chronic pain and improve function in persons with hip joint failure. Most often, such failure results from osteoarthritis. An array of other conditions can also cause hip joint failure, however; these include rheumatoid arthritis, avascular necrosis, traumatic arthritis, certain hip fractures, bone tumors (both benign and malignant), arthritis associated with Paget’s disease, ankylosing spondylitis, and rheumatoid arthritis.

Who are the best candidates?

Total hip replacement is considered appropriate for persons with radiographic evidence of joint damage, as well as moderate to severe pain or disability (or both) that does not respond to long-term conservative measures, such as analgesics, physical therapy, walking aids, and lifestyle modifications.

How old is too old for a total hip replacement?

Age alone is not a contraindication. Poor surgical outcomes seem to be related to comorbity, not age.

Persons between ages 60 and 75 were once considered the best candidates for total hip replacement. That age range has expanded over the past decade and now includes persons beyond both end points of this age spectrum.

Are there any specific contraindications?

A few: the most important are local or systemic infection and coexisting medical conditions that markedly increase the risk of perioperative complications or death.

Obesity has been a relative contraindication, primarily because of the higher associated rate of mechanical failure. Nevertheless, the prospect for substantial long-term reduction in pain and disability for heavier persons is no worse than that for the rest of the population.

What developments in device design and surgery should I be aware of?

Cementing techniques are more successful now than they were in the past, and non-cemented components that rely on bone growth into porous or onto roughened surfaces for fixation are now widely used, particularly in younger, more active patients. Cemented and non-cemented prostheses have comparable rates of success. The primary disadvantage of a non-cemented prosthesis is the extended recovery period: patients with non-cemented replacements must limit activities for up to 3 months.

Also, the implants themselves have been substantially modified. New alloys and designs have markedly reduced the incidence of femoral fracture and made the outcome of surgery more predictable.

Minimally invasive, or mini-incision, hip replacement, requires smaller incisions and a shorter recovery time than traditional hip replacement. Candidates for this type of surgery are usually age 50 or younger, of normal weight, and healthier than patients who undergo traditional surgery. A recent meta-analysis found no strong evidence either for or against mini-incision compared with standard-incision total hip replacement. The evidence regarding the longer-term performance of mini-incision
replacement—especially the risk of revision arthroplasty—is limited.⁴

What are the chief areas of concern regarding implant design?

The main problems include the following:

•Long-term fixation of the acetabular component.

•Osteolysis caused by particulate materials.

•Biologic response to particles of implant materials.

•Results of revision surgery that are inferior to those of primary
procedures.

Has the incidence of surgical complications dropped?

Strides have been made over the past 2 decades. Specifically:

•Routine use of antibiotic prophylaxis has helped prevent infection.

•Anticoagulant therapy and early mobilization during the perioperative period have cut down on the incidence of deep venous thrombosis and pulmonary emboli.

•The rate of mechanical loosening has decreased with the advent of improved fixation methods.

•The great majority (over 90%) of all artificial hip joints do not require subsequent surgical revision, in
part because of improved surgical techniques.

How great is the risk that an implant will become infected?

Currently, the infection rate at 1 year is less than 1%. Nevertheless, infection remains a devastating complication of total hip replacement, and treatment options are controversial.

Antibiotic therapy must be tailored after the infecting organism is recovered. If the pathogen is highly susceptible to multiple anti-biotics, one-stage surgical approaches with extensive debridement and exchange of implants result in a 77% to 94% chance of success. Two-stage revisions that include at least 4 weeks of antibiotic therapy and subsequent implant removal, wound debridement, and reinsertion have yielded a success rate of about 80%.

What is the chief cause of long-term prosthetic failure?

The predominant mode appears to be the generation of particulate matter. This triggers an inflammatory reaction and subsequent bone
resorption around the prosthesis.

What can my patient expect after the surgery?

It is reasonable to anticipate immediate and substantial pain relief, as well as improved functional status and overall quality of life. It is also reasonable to hope that these immediate benefits will persist over the long term. However, hip weakness can linger for up to 2 years after the operation, even in persons with a normal gait.

Are women more likely than men to undergo total hip replacement?

Women are the recipients of about 60% of all total hip replacements in the United States. These women’s preoperative functional status is significantly worse than that of male recipients, and they are 35% more likely to need a walking aid at the time of surgery. These facts suggest that women are undergoing surgery at a more advanced stage of disease than men.

What is the outlook for patients who must undergo revision of a primary total hip replacement?

Revision surgery, which is indicated when mechanical failure occurs, is technically more difficult, and the long-term prognosis is not as favorable as for primary hip replacement. The risk of revision surgery is highest (approximately 2% per year) during the first 18 months after the primary total hip replacement.⁵ The NIH recommends that you monitor patients periodically to identify early evidence of impending hip joint failure.