Doc, Will My New Joint Outlive Me?
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
Guest Post: New AUC for Surgical Management of Knee OA
OrthoBuzz occasionally receives posts from guest bloggers. This guest post comes from Richard Yoon, MD and Grigory Gershkovich, MD.
The AAOS recently reviewed the evidence for surgical management of osteoarthritis of the knee (SMOAK) and issued a set of appropriate use criteria (AUC) that help determine the appropriateness of clinical practice guidelines (CPGs). These AUC can be accessed on the OrthoGuidelines website: www.orthoguidelines.org/auc.
The AUC were developed after a panel of specialists reviewed the 2015 CPGs on SMOAK and made appropriateness assessments for a multitude of clinical scenarios and treatments. The panel found 21% of the voted-on items “appropriate”; 25% were designated “maybe appropriate,” and 54% were ranked as “rarely appropriate.”
Importantly, these AUC do not provide a substitute for surgical decision making. The physician should always determine treatment on an individual basis, ideally with the patient fully engaged in the decision.
This OrthoBuzz post summarizes some of the updated conclusions according to three clinical time points—pre-operative, peri-operative, and postoperative—specifying the strength of supporting evidence. This post is not intended to review appropriateness for every clinical scenario. We encourage physicians to explore the OrthoGuidelines website for complete AUC information.
Pre-operative
Strong evidence: Obese patients exhibit minimal improvement after total knee arthroplasty
(TKA), and such patients should be counseled accordingly.
Moderate evidence: Diabetic patients have a higher risk of complications after TKA.
Moderate evidence: An 8-month delay to TKA does not worsen outcomes.
Peri-operative
Strong evidence: Both peri-articular local anesthetics and peripheral nerve blocks decrease postoperative pain and opioid requirements.
Moderate evidence: Neuraxial anesthesia may decrease complication rates and improve select peri-operative outcomes.
Moderate evidence: Judicious use of tourniquets decreases blood loss, but tourniquets may also increase short-term post-operative pain.
Strong evidence: The use of tranexamic acid (TXA) reduces post-operative blood loss and the need for transfusions.
Strong evidence: Drains do not help reduce complications or improve outcomes.
Strong evidence: There is no difference in outcomes between cruciate-retaining and posterior stabilized implants.
Strong evidence: All-polyethylene and modular components yield similar outcomes.
Strong, moderate, and limited evidence to support either cemented or cementless techniques, as similar outcomes and complication rates were found.
Strong evidence: There is no difference in pain/function with patellar resurfacing.
Moderate evidence: Patellar resurfacing decreases 5-year re-operation rates.
Moderate evidence shows no difference between unicompartmental knee arthroplasty (UKA) and high tibial osteotomy (HTO).
Moderate evidence favors TKA over UKA to avoid future revisions.
Strong evidence against the use of intraoperative navigation and patient-specific instrumentation, as no difference in outcomes has been observed.
Postoperative
Strong evidence: Rehab/PT started on day of surgery reduces length of stay.
Moderate evidence: Rehab/PT started on day of surgery reduces pain and improves function.
Strong evidence: The use of continuous passive motion machines does not improve outcomes after TKA.
Richard Yoon, MD is a fellow in orthopaedic traumatology and complex adult reconstruction at Orlando Regional Medical Center.
Grigory Gershkovich, MD is chief resident at Albert Einstein Medical Center in Philadelphia. He will be completing a hand fellowship at the University of Chicago in 2017-2018.
No Surprise: Infection Biggest Culprit in Amputation for Failed TKA
Of the hundreds of thousands of total knee arthroplasties (TKAs) performed annually around the world, very few result in failure so irreparable that transfemoral amputation is the last resort. But what does “very few” really mean? In the December 7, 2016 issue of The Journal of Bone & Joint Surgery, Gottfriedsen et al. determine the cumulative incidence of amputation for failed TKAs among nearly 93,000 registered knee replacements performed in Denmark from 1997 to 2013.
The authors used a competing-risk model (which took into account the competing risk of death) to avoid overestimating incidence. From a total of 115 amputations performed for causes related to failed TKA, they calculated a cumulative 15-year incidence of amputation of 0.32%. They noted a tendency toward decreasing incidence during the 2008-2013 period, relative to the 1997-2002 period.
The three most common causes of post-TKA amputation were periprosthetic infection (83%), soft-tissue deficiency (23%), and severe bone loss (18%). The authors add, however, that the latter two causes are “most likely the result of long-term infection together with several revision procedures, in which soft tissue and bone stock are gradually damaged.”
The authors encourage orthopaedists to consider newer treatment options to avoid amputation (such as skin grafts and muscle flaps for soft-tissue loss), but they also assert that, in each individual case, those contemporary approaches should be balanced against the “psychological and physical strains related to repeated surgery performed in an attempt to salvage the knee.”
Read Key Knee Content from JBJS
The recently launched JBJS Knee Spotlight offers highly relevant and potentially practice-changing knee content from the most trusted source of orthopaedic information.
Here are the five JBJS articles to which you will have full-text access through the Knee Spotlight during the month of October 2016.
- What’s New in Adult Reconstructive Knee Surgery
- The Effect of Timing of Manipulation Under Anesthesia to Improve Range of Motion and Functional Outcomes Following Total Knee Arthroplasty
- Nonsurgical or Surgical Treatment of ACL Injuries: Knee Function, Sports Participation, and Knee Reinjury
- Topical Intra-Articular Compared with Intravenous Tranexamic Acid to Reduce Blood Loss in Primary Total Knee Replacement
- Total Knee Replacement in Young, Active Patients: Long-Term Follow-up and Functional Outcome
Knee studies offered on the JBJS Knee Spotlight will be updated monthly, so check the site often.
Patient Pain Perception: Two New Studies
The connection between patient pain and clinical orthopaedic outcomes has received much attention lately. Here are relevant findings from two recent studies:
–An in-press study of 48 patients (average age of 72 years) who underwent TKA found that those with low pain thresholds prior to surgery (as measured with VAS scores while a blood-pressure cuff was inflated over the proximal forearm) were more likely to have lower Knee Society pain and function scores two years after surgery than those with moderate or high pain thresholds. The authors use this test in preoperative workups, and they advise patients who grade the cuff stimulus as severe that “their clinical outcomes are expected to be inferior to [those of] other patients,” encouraging such patients to take that into account before consenting to surgery.
–Among more than 1,100 patients (average age of 67 years) who participated in the Multicenter Osteoarthritis Study (MOST), inflammation, as evidenced by synovitis and effusion, was associated with reduced pain thresholds. However, resolution of established inflammation did not deliver a significant change in pain thresholds over two years, leading the authors to conclude that “early targeting of inflammation is a reasonable strategy to test for prevention of sensitization and…reduction of pain severity.”
Time-to-Drive after TKA?
There are currently no standards or regulations governing when it’s safe to drive after a knee replacement. But researchers reporting in the American Journal of Physical Medicine & Rehabilitation found that patients with right-knee replacements using an automatic-transmission driving simulator had 30% slower braking times eight days after surgery compared with presurgery measurements.
Braking times were significantly reduced in the right-knee group for six weeks and reached preoperative levels at 12 weeks postsurgery. Braking time was only 2% slower after left-knee replacements, but braking force, a crucial factor in emergency stopping, decreased by 25% to 35% in both groups during the week after surgery.
The authors conclude that, while “categorical statements cannot be provided,” these automatic-transmission findings suggest that “right TKA patients may resume driving six weeks postoperatively.” However, even the presurgery measures of braking time and force that these researchers used may not represent “normal” values because severe osteoarthritis can impair driving skills. And the findings have no bearing on TKA patients who drive manual-transmission cars with clutch pedals.
Un-Hyping Recent Joint Replacement–MI Findings
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.
7 Million People in US Walking on Artificial Knees or Hips
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.
Chronic Oral Antibiotics Boost 5-Year Infection-Free Implant Survival after Certain PJIs
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.”
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