When discussing total joint replacement (TJR) with patients, I and most other surgeons who perform TJRs are invariably asked, “How long will my new hip last?’” or “Will I need to replace this new knee with another one if I live to be 90?” Although these important questions have essentially been studied since the implants and procedures were first developed, precise answers are still hard to come by. That’s largely because many factors can affect the longevity of an implant, including the implant material and design and the patient’s size/weight, activity level, and comorbidities. Also, many patients die before their joints wear out, and their data is often not captured accurately by researchers and registries. It is therefore difficult to give patients anything better than rough-estimate answers.
That is why I was interested to read two recently published systematic reviews in The Lancet. The reviews—one focused on knee replacement and the other on hip replacement—evaluated studies from six different non-US countries with robust joint registries in an effort to answer these “how long” questions. Based on the authors’ pooled analysis of registry data, the reviews found that:
- Nearly 60% of >215,000 hip replacements lasted 25 years, 70% lasted 20 years, and almost 90% lasted 15 years.
- The nearly 300,000 total knee replacements evaluated lasted even longer: 82% lasted 25 years, 90% lasted 20 years, and 93% lasted 15 years.
While these data are helpful, they do still not provide specific answers for the many individuals who may not be “standard” patients, and they do not take into account advances in implant designs and materials that have occurred over 25 years. However, as registry data becomes more ubiquitous and robust, especially in the United States with the growth of the American Joint Replacement Registry, I believe these questions will be answered with increased specificity for individual patients.
Chad A. Krueger, MD
JBJS Deputy Editor for Social Media
Over the past 15 to 20 years, the use of arthroscopic procedures for hip pathologies has rapidly increased. Leaders in sports medicine have standardized many arthroscopic techniques, including methods of joint distraction, portal location, approaches to labral repair or debridement, and management of cartilage lesions.
Many in the orthopaedic community have wondered whether this expansive use of hip arthroscopy is justified by significant improvement in patient function or is simply a first (and perhaps overused) step toward inevitable hip arthroplasty. To help answer that question, in the June 21, 2017 issue of The Journal, Menge et al. document the 10-year outcomes of arthroscopic labral repair or debridement in 145 patients who originally presented with femoroacetabular impingement (FAI).
Whether these patients were treated with debridement or repair, their functional outcomes and improvement in symptoms were excellent over the 10-year time frame, and the median satisfaction score (10) indicates that these patients were very satisfied overall. However, as seen in other similar studies in the peer-reviewed literature, the results in older patients with significant cartilage injury or radiographic joint space narrowing were inferior, and most of the patients with these characteristics ended up with a hip replacement.
The Menge et al. study helps confirm that arthroscopic repair or debridement in well-selected FAI patients yields excellent longer-term outcomes, and it provides concrete criteria for patient selection.
Marc Swiontkowski, MD
Ceramic hip components are often chosen for younger patients to minimize long-term wear. Ceramic femoral head fractures arise mainly from trauma; non-compatible, damaged, or contaminated femoral head/stem taper connections; or material or manufacturing defects.
Because ceramic head fractures are more likely to occur from insults during or after implantation than from manufacturing defects, the Watch includes four “golden rules” surgeons can follow to reduce the risk of these events, including making sure that the tapers on both the head and stem are compatible in all dimensions. The Watch also emphasizes the importance of patient education, during which patients should be encouraged to promptly report any and all postsurgical irregularities.
A late-August headline on MedPage Today ominously read, “MI Risk Soars After Joint Replacement.” The article cited a recent Arthritis & Rheumatology study that found a more than 8-fold increase in risk of myocardial infarction (MI) for one month after knee replacement and a more than 4-fold increased risk during the month after hip replacement, all compared with equal numbers of matched controls who did not have joint replacement surgery.
A look at the absolute risk instead of the relative risk, however, reveals a different and less scary story. For example, among the 13,849 patients who underwent knee replacement, 306 (2.2%) had a heart attack within the first month after surgery. The rate of heart attacks among the equal number of people who did not have a knee replaced was 2.0%. Also, the increased MI risk seen during the first month after surgery steadily declined with increasing length of follow-up to the point where it became statistically insignificant at 6 months after surgery.
There’s little doubt that major orthopaedic surgery can stress the heart, but the many long-term cardiovascular benefits of joint arthroplasty, including advantages from increased physical activity and decreased use of NSAIDs, seem to outweigh the short-term risk of a heart attack.
We know that more than 1 million total hip and total knee replacements are performed each year in the US. But how many people are actually walking around right now with such prostheses?
That’s the question Kremers et al. answer in the September 2, 2015 edition of The Journal of Bone & Joint Surgery. Using the so-called “counting method” to combine historical incidence data, these Mayo Clinic authors concluded that about 7 million US residents (slightly more than 2% ) were living with a hip or knee replacement in 2010.
Prevalence of hip replacement was 0.83%, while that of knee replacement was 1.52%. Not surprisingly, prevalence increased with age (5.26% for total hip and 10.38% for total knee at 80 years of age), but the authors also found a shift toward younger people having the procedure.
These prevalence stats for hip and knee replacement are similar to those for stroke (6.8 million) and myocardial infarction (7.6 million), underscoring just how common these orthopaedic procedures are. Even in the unlikely event that the annual incidence of these joint replacements remains steady rather than rises, the authors estimate that 11 million people will be living with artificial hips or knees in 2030.
According to Kremers et al., among the many implications of these findings is “a need for the medical profession and the policy makers to recognize and address the lifelong needs of this population,” including the development of evidence-based protocols for follow-up care and radiographic assessments.
Along with the sharply rising number of total hip and knee arthroplasties performed in the US comes an increasingly compelling need to prevent periprosthetic joint infections (PJIs). If a PJI occurs, guidelines recommend a two- to six-week post-revision course of pathogen-specific intravenous antibiotic therapy. However, the benefit of chronic suppression with oral antibiotics beyond that is unproven.
In the August 5 edition of The Journal of Bone & Joint Surgery, Siqueira et al. compared the infection-free prosthetic survivorship in 92 patients who underwent chronic oral antibiotic suppression for a minimum of six months with prosthetic survivorship in a matched cohort who did not receive extended antibiotic treatment. In so doing, they also attempted to determine factors associated with failure of chronic suppression with oral antibiotics.
The five-year infection-free prosthetic survival rate in the suppression group was 68.5% compared with 41.1% in the non-suppression group. Patients who benefited the most from chronic suppressive antibiotic therapy were:
- Those who underwent irrigation and debridement with polyethylene exchange. (Antibiotic suppression following two-stage procedures did not affect prosthetic survival.)
- Those with Staphylococcus aureus (Chronic antibiotic therapy did not influence infection-free survival after revisions for non-S. aureus infections.)
Suppression-group patients in whom antibiotic treatment failed had had more prior joint revisions and were more likely to have had a knee PJI than a hip infection.
Noting the benefit of suppressive therapy in patients who underwent irrigation and debridement with polyethylene exchange, the authors concluded that “persistence of a latent infection is common in patients with retained implants, and thus antibiotic suppression seems to be a reasonable alternative that avoids the need for a more invasive two-stage revision.”