Tag Archive | TKA

Bundled Payments for Hip and Knee Replacement: Working as Planned?

When Medicare’s Comprehensive Care for Joint Replacement (CJR) program was implemented in 2016, the health care community—especially orthopaedic surgeons— had 2 major concerns. First, would the program actually demonstrate the ability to decrease the costs of total joint replacements while maintaining the same, or improved, outcomes? Second, would CJR promote the unintended consequence of participating hospitals and surgeons ”cherry picking” lower-risk patients and steering clear of higher-risk (and presumably higher cost) patients?  Both of these questions were at the heart of the study by Barnett et al. in a recent issue of the New England Journal of Medicine.

The authors evaluated hip and knee replacements at 75 metropolitan centers that were mandated to participate in the CJR program and compared the costs, complication rates, and patient demographics to similar procedures at 121 control centers that did not participate in CJR. The authors found significantly greater decreases in institutional spending per joint-replacement episode in institutions participating in the CJR compared to those that did not. Most of these savings appeared to come from CJR-participating institutions sending fewer patients to post-acute care facilities after surgery. Furthermore, the authors did not find differences between centers participating in the CJR and control centers in terms of composite complication rate or the percentage of procedures that were performed on high-risk patients.

While this 2-year evaluation does not provide the level of detail necessary to make far-reaching conclusions, it does address two of the biggest concerns related to CJR implementation from a health-systems perspective. There may be individual CJR-participating centers that are not saving Medicare money or that are cherry picking lower-risk patients, but overall the program appears to be doing what it set out to do—successfully motivating participating hospitals and healthcare facilities to look critically at what they can do to decrease the costs of a joint-replacement episode while simultaneously maintaining a high level of patient care. The Trump administration shifted CJR to a partly voluntary model in March 2018, and I hope policymakers consider these findings if further changes to the CJR model are planned.

Chad A. Krueger, MD
JBJS Deputy Editor for Social Media

Full-Thickness Cartilage Defects More Predictive of Future TKA than Joint-Space Narrowing

Many older patients present to orthopaedic surgeons with clinical knee pain suggestive of osteoarthritis (OA) but with little or no radiographic evidence of disease. And a substantial proportion of those patients do not respond adequately to the recommended, first-line nonsurgical treatment approaches to knee OA. A prognostic study by Everhart et al. in the January 2, 2019 issue of The Journal of Bone & Joint Surgery helps explain why that might be.

The authors evaluated baseline knee radiographs and MRIs from >1,300 older adults (mean age of 61 years) who were enrolled in the Osteoarthritis Initiative, a multicenter observational cohort study with a median of 9 years of follow-up data. They sought to determine independent risk factors for progression to total knee arthroplasty (TKA) among this cohort, all of whom showed Kellgren-Lawrence grade 0 to 3 OA on knee radiographs. MRIs taken at baseline revealed that 38% of those patients had a full-thickness knee-cartilage defect. After the authors adjusted for various confounders (including age, weight, and symptom severity), they found that regardless of radiographic grade, the presence of a full-thickness cartilage defect was a strong independent risk factor for subsequent TKA. Moreover, patients with a defect ≥2 cm2 had twice the risk of arthroplasty compared with patients with defects <2 cm2.

According to the authors, the findings highlight the “greater importance of full-thickness cartilage loss over radiographic OA grade as a determinant of OA severity, specifically regarding the risk of future knee arthroplasty in older adults.” In his commentary on this study, Drew A. Lansdown, MD emphasizes that Everhart et al. “do not advocate for the routine use of MRI in the diagnosis of knee osteoarthritis,” but he says the findings “do suggest that early MRI may have a diagnostic role for patients who are not responding as expected to nonoperative measures.” Noting that the patients in this cohort would probably not be ideal candidates for current cartilage-restoration procedures, Dr. Lansdown encourages further research focused on identifying “patient-specific factors that can match patients with the treatment…that will provide the greatest likelihood of symptom relief and functional improvement.”

Unexplained Pain After TKA? Duloxetine Might Help

Somewhere between 10% and 15% of patients are unsatisfied with their outcome after primary total knee arthroplasty (TKA). In some cases, dissatisfaction is related to poor range of motion, but more often it is related to residual—or even intensified—pain in the knee several weeks after surgery.

In the January 2, 2019 issue of The Journal, Koh et al. report the results of a prospective randomized trial assessing the effects of duloxetine (Cymbalta) in TKA patients who were screened preoperatively for “central sensitization.” In central sensitization, a hyperexcitable central nervous system becomes hypersensitive to stimuli, noxious and otherwise.

Koh et al. randomized 80 centrally sensitized patients (mean age of 69 years), 40 of whom received a multimodal perioperative pain management protocol plus duloxetine, and 40 of whom received the multimodal protocol without duloxetine. During postoperative weeks 2 through 12, patients taking duloxetine reported better results in terms of pain and functional and emotional outcome measures than those not receiving the drug. Patients in the duloxetine group expressed greater satisfaction with pain control (77% vs 29%) and daily activity (83% vs 52%) at postoperative week 12, compared with those in the control group.

This research represents an important advance in identifying and treating patients who are prone to poor outcomes after TKA. The concept of central sensitization is relatively new to the orthopaedic community, and this pharmacologic intervention is likely to be just the first among many that will help these patients. I think it is probable that other, nonpharmacological interventions will eventually be as or even more successful in helping TKA patients with central sensitization. Koh et al. make a valuable  contribution in this article by educating us as to the neurophysiologic basis of this condition, and their work should pave the way for more important research in this area.

Marc Swiontkowski, MD
JBJS Editor-in-Chief

Physical Parameters Beyond BMI Affect TKA Outcomes

It is well established that obese patients who undergo total joint arthroplasty have increased risks of complications and infections. But what about folks who are not obese, but are just generally large? Do they also have increased post-arthroplasty complications, compared to their smaller counterparts? That is the question Christensen et al. explored in a registry-based study in the November 7, 2018 edition of JBJS.

In addition to BMI, the authors examined 3 other physical parameters—body surface area, body mass, and height—to determine whether these less-studied characteristics (all contributing to “bigness”) were associated with an increased rate of various adverse outcomes, including mechanical failure and infection, after primary total knee arthroplasty (TKA).  They evaluated data from more than 22,000 TKAs performed at a single institution and found that the risk of any revision procedure or revision for a mechanical failure was directly associated with every 1 standard deviation increase in BMI (Hazard Ratio [HR], 1.19 and 1.15, respectively), body surface area (HR, 1.37 and 1.35, respectively), body mass (HR, 1.30 and 1.27, respectively), and height (HR, 1.22 and 1.23, respectively). In this study, 1 standard deviation was equivalent to 6.3 kg/m2 for BMI, 0.3 m2 for body surface area, 20 kg for body mass, and 10.5 cm for height.

These findings, while not all that surprising, are enlightening nonetheless. The study shows that increasing height has a greater negative impact on TKA outcomes than previously thought. While I spend a lot of time counseling patients with high BMIs about the increased risks of undergoing a TKA (and while such patients can take certain actions to lower their BMI prior to surgery), I do not spend nearly as much time counseling patients who are much taller than normal about their increased risks (and height is not a modifiable risk factor). Nor do I spend much time thinking about a patient’s overall body mass or body surface area in addition to their BMI. This study will remind me not to overlook these less commonly examined  physical parameters when discussing TKA with patients in the future.

Chad A. Krueger, MD
JBJS Deputy Editor for Social Media

Cost Analysis of Treatments for Unicompartmental Knee Arthritis: UKA Wins

UKA for OBuzzSurgical treatment for knee osteoarthritis (OA) has become increasingly common. The many people who have damage to only one part of their joint (unicompartmental knee OA) are faced with three options—total knee arthroplasty (TKA), unicompartmental knee arthroplasty (UKA), or nonsurgical treatment.  A study by Kazarian et al. in the October 3, 2018 issue of The Journal estimates the lifetime cost-effectiveness for those three options in patients from 40 to 90 years of age.

The authors used sophisticated computer modeling to estimate both direct costs (those related to medical/surgical care) and indirect costs (such as missed workdays) of the three options as a function of patient age at the time of treatment initiation. Here are the key findings:

  • The surgical treatments were less expensive and provided patients from 40 to 69 years of age with a greater number of quality-adjusted life years (QALYs) than nonsurgical treatment.
  • In patients 70 to 90 years of age, surgical treatments were still cost-effective compared with nonsurgical treatment, albeit less so than in younger patients. In this older age group, “cost-effectiveness ratios” of surgical treatment remained below a “willingness to-pay” threshold of $50,000 per QALY.
  • When the two surgical treatments were compared to one another, UKA beat TKA decisively in cost-effectiveness among patients of any age.

After crunching more numbers, Kazarian et al. estimated that, by 2020, if all of the patients with unicompartmental knee OA who were candidates for UKA or TKA (a projected total of 120,000 to 210,000 people) received UKA, “it would lead to a lifetime cost savings of $987 million to $1.5 billion.

From these findings, the authors conclude that patients with unicompartmental knee OA should receive surgical treatment, preferably UKA, instead of nonsurgical treatment until the age of 70 years. After that age, all three options are reasonable from a cost-effectiveness perspective.

But perhaps the most important thing to remember about these findings is that they add information to—but should not replace—clinical decision-making based on complete and open communication between doctor and patient.

Primary TJA Volume Growth from 2014 to 2030: Not So Fast?

TJA Volume for OBuzzAnnual volume projections for total joint arthroplasty (TJA) have been cited frequently and applied broadly, often to estimate future costs. But with a slowdown in the growth of the annual incidence of total knee arthroplasty (TKA), updated projections are needed, and that’s what Sloan et al. provide in the September 5, 2018 issue of JBJS.

Using the National Inpatient Sample to obtain TJA incidence data, the authors first analyzed the volume of primary TJA procedures performed from 2000 to 2014. They then performed regression analyses to project future volumes of TJA procedures. Here are the numbers based on the 2000-to-2014 data:

  • Primary total hip arthroplasty (THA) is projected to grow 71%, to 635,000 annual procedures by 2030.
  • Primary TKA is projected to grow 85%, to 1.26 million annual procedures by 2030.

However, the TKA procedure growth rate has slowed in recent years, and models based on 2008-to-2014 data project growth to only 935,000 annual TKAs by 2030—325,000 fewer procedures relative to the 2000-to-2014 models.

Earlier studies, notably one by Kurtz et al. in 2007, obviously could not account for the reduced growth rate in TKA after 2008. A 2008 analysis by Wilson et al., based on the Kurtz et al. data, estimated that annual Medicare expenditures on TJA procedures would climb  from $5 billion in 2006 to $50 billion in 2030. “Using our projections,” say Sloan et al., “we predict that Medicare expenditures on these procedures in 2030 will be less than half of that predicted by Wilson et al.”

These findings lend credence to the authors’ observation that “it is imperative that projections of orthopaedic procedures be regularly evaluated and updated to reflect current rates.”

New Patient-Outcomes Data Hint at Benefits from Computer-Navigated TKA

computer navigation knee for OBuzzLike the vast majority of orthopaedic surgeons, I do not use computer navigation for total knee arthroplasties (TKAs). My hospital does not own the equipment, I have not asked for it, and I feel confident in the outcomes for my patients using current conventional techniques. Moreover, we have not had published data suggesting that using computerized navigation actually improves the one thing we care most about: patient outcomes.  However, the two-year data presented by Petursson et al. in the August 1, 2018 issue of JBJS may represent a tipping point.

The authors report on 2-year results from a double-blind, prospective randomized trial evaluating outcomes in 167 patients following TKAs performed using conventional techniques or computer-guided navigation. Both patients and observing radiologists/physical therapists were blinded to the technique used.

Among the many patient-reported measures used to compare 2-year outcomes, the authors found that scores for 3 subscales favored the computer-navigation group. Specifically, the symptom and sports-and-recreation subscales of the KOOS and the stiffness subscale of the WOMAC showed significantly greater improvements in the group that underwent computer-navigated TKA. These results led Petursson et al. to conclude that TKAs completed with the assistance of computer navigation provided better pain relief and function at two years postoperatively.

These are important findings, as this is one of the largest randomized, double-blind analyses comparing computer navigation versus conventional TKA. While previous studies had found computer navigation to be useful in terms of obtaining neutral mechanical alignment, data showing improved patient outcomes was either lacking or revealed no clinically important between-group differences.  These 2-year data suggest that this is no longer the case.  However, it is important to note that the study does not explicitly state whether patients were still blinded to their treatment at the time when the 2-year follow-up data was collected.  If they were no longer blinded at that point of follow-up, the results would need to be viewed from a more tempered perspective.

Either way, it is important to note that in this study—as in previous research investigating similar questions—TKAs completed using conventional techniques also yielded large improvements in patient-reported outcomes. Still, because patients and surgeons alike continue to be intrigued by the possibilities that technological advances in arthroplasty may offer, studies like this are vital.

Chad A. Krueger, MD
JBJS Deputy Editor for Social Media

Using Tranexamic Acid: Not If, But How

TXAMost surgeons agree that tranexamic acid (TXA) is effective at reducing blood loss associated with a variety of surgical procedures, including total joint arthroplasty. The question is no longer whether it works but, more specifically, how is TXA most safely and effectively used. That was the main question Abdel et al. set out to answer in their study in the June 20, 2018 edition of The Journal. The authors completed a two-center randomized trial that compared blood loss, drain output, and transfusion rates among 320 total knee arthroplasty (TKA) patients who received intravenous (IV) TXA and 320 TKA patients who received topical TXA.

Statistically, the results of the study are clear: Patients who received intravenous TXA had significantly less blood loss (271 mL vs 324 mL; p=0.005) than those who received topical TXA. Furthermore, after authors controlled for several patient characteristics, they found that those who received topical TXA were 2.2 times more likely to receive a transfusion than those who received intravenous TXA. Still, both modalities resulted in very low transfusion and complication rates of <2% each.

Although IV TXA seems to be more effective at decreasing blood loss than topical TXA in the setting of TKA, Abdel et al. question whether the 53 mL difference is “clinically important,” considering the very low transfusion rates in both groups. What might be more clinically meaningful is the fact that the topical TXA group experienced a 5-minute delay during the procedure so the TXA could stay in contact with the tissues prior to suction and wound closure. Such a delay (which could account for about 5% of total surgical time) could put some patients at risk for other complications and is questionable without an appreciable benefit.

So, will every knee-replacement surgeon now use IV TXA instead of topical TXA? Of course not. Although the authors emphasize that there does not appear to be an increased risk of blood-clot-related complications when using IV TXA, some surgeons will still shy away from using that route of administration in certain patients.  Also, some surgeons may question this study’s generalizability because of the number of perioperative variables described in the methods.

Still, I commend the authors on performing such a large, well-designed study.  It is easy to pick apart data from the viewpoint of external validity, but these results are statistically steadfast. While we probably do not need more studies looking at the efficacy of TXA in total joint arthroplasty, further studies looking at the optimal manner in which the medication can be administered are welcomed.

Chad A. Krueger, MD
JBJS Deputy Editor for Social Media

Horseshoes and Total Knee Arthroplasty

TKA Alignment for OBuzzOrthoBuzz occasionally receives posts from guest bloggers. This guest post comes from Matthew Herring, MD, in response to a recent JBJS article.

The old adage that “close only counts in horseshoes” may also apply to total knee arthroplasty (TKA). Much attention has been paid to coronal alignment during TKA based on conventional wisdom that prosthetic durability and patient function are strongly dependent on that parameter. To re-check that hypothesis, in the March 21, 2018 issue of JBJS, Abdel et al. evaluated the influence of coronal plane alignment on implant survival by analyzing results from a large cohort of patients who underwent primary TKA 20 years ago.

In 2010, Abdel’s group reviewed a consecutive series of 398 primary cemented TKAs done between 1985 and 1990. Knees were divided into 2 groups based on their mechanical alignment as measured using a full-length hip-knee-ankle radiograph. Knees in the “aligned group” (n = 292) were defined as having alignment within 0° ± 3° of the mechanical axis, and knees in the “outlier group” (n = 106)  were defined as having alignment >3° in varus or valgus. Implant survival was evaluated based on the need for revision, and the specific indications for revisions were recorded.

In the current study, at 20 years of follow-up, the authors found revision rates that were not significantly different between the same 2 groups—19.5% in the mechanically aligned group and 15.1% in the outliers. Multivariate analysis controlling for patient age and BMI did not demonstrate any implant survivorship benefit for the mechanically well aligned group as compared to the outliers.

This study seems to call into question the dogma that a neutral mechanical axis protects against mechanical failure. The effort, time, and money spent on techniques and devices to improve coronal plane alignment by a few degrees (i.e., computer navigation, custom jigs, and robotics) may not translate into meaningful improvements in patient outcomes.

It is important to note that in this group’s 2010 study evaluating the same cohort, 66% of knees in the outlier group were only 4° shy of neutral and only 12% (13 knees) were >6° off. So, while we should still strive for neutral mechanical alignment, it seems that we may miss the neutral mark by a few degrees without harming our patients.

Matthew Herring, MD is a senior orthopaedic resident at the University of Minnesota and a member of the JBJS Social Media Advisory Board.

JBJS 100: Pavlik Harness and the Infected TKA

jbjs_pl_journal_4c_5Under one name or another, The Journal of Bone & Joint Surgery has published quality orthopaedic content spanning three centuries. In 1919, our publication was called the Journal of Orthopaedic Surgery, and the first volume of that journal constituted Volume 1 of what we know today as JBJS.

Thus, the 24 issues we turn out in 2018 will constitute our 100th volume. To help celebrate this milestone, throughout the year we will be spotlighting 100 of the most influential JBJS articles on OrthoBuzz, making the original content openly accessible for a limited time.

Unlike the scientific rigor of Journal content, the selection of this list was not entirely scientific. About half we picked from “JBJS Classics,” which were chosen previously by current and past JBJS Editors-in-Chief and Deputy Editors. We also selected JBJS articles that have been cited more than 1,000 times in other publications, according to Google Scholar search results. Finally, we considered activity on the Web of Science and The Journal’s websites.

We hope you enjoy and benefit from reading these groundbreaking articles from JBJS, as we mark our 100th volume. Here are the first two:

  • Congenital Dislocation of the Hip
    PL Ramsey, S Lasser, GD MacEwen: JBJS, 1976 Oct; 58 (7): 1000
    The introduction of the Pavlik harness revolutionized the treatment of congenital dislocation of the hip in infants. The concept of the “safe zone” was introduced in this article.
  • Two-Stage Reimplantation for the Salvage of Infected Total Knee Arthroplasty
    J N Insall, F M Thompson, B D Brause: JBJS, 1983 Jan; 65 (8): 1087
    This was the first paper to show that a specific reimplantion protocol (debridement of the soft tissues and removal of the prosthesis and all cement, six weeks of parenteral antibiotics, and implantation of a new total knee) could provide predictable results in managing this difficult problem.