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RCT: “Mini-Navigation” Improves TKA Component Alignment

Alignment is one of the most important factors affecting the longevity of total knee arthroplasty (TKA) prostheses. Among the many available tools for attaining good alignment are new palm-sized, accelerometer-based navigation systems. In the November 18, 2020 issue of The Journal of Bone & Joint Surgery, Minoda et al. deliver robust evidence from a multicenter randomized controlled trial comparing post-TKA coronal alignment with such a “mini-navigation” system versus results using conventional navigation.

The 90 TKAs analyzed (45 in each group) were performed by 8 different surgeons across 5 hospitals in Japan. The primary outcome was the number of tibial-prosthesis alignment outliers, defined as alignment error of >2° relative to neutral, based on weight-bearing radiographs 6 months after surgery. Researchers also compared absolute differences from neutral alignment for both tibial and femoral components, operative time, and complications.

Relative to conventional navigation, the mini-navigation system reduced the number of outliers in tibial alignment and hip-knee-ankle (HKA) angle. In addition, the absolute differences in the coronal alignment of the femoral and tibial prostheses were less in the mini-navigation group. Researchers found no increase in operative time with the portable navigation system, nor was there any observed increase in perioperative complications compared with conventional navigation.

Conversely, there were no significant between-group differences in postoperative Knee Society scores, but the authors note that “another study design with a longer follow-up period” is needed to evaluate the patient-centered clinical effects of prosthetic alignment using portable navigation. Both the authors and Andrew P. Kurmis, FRACS(Ortho), who commented on the study, assert that the true value of navigation systems (mini and full-sized alike) probably lies in higher reproducibility of tibial-component alignment relative to conventional navigation, regardless of the skill and experience of the surgeon.

Antibiotic-Laden Cement Lowers TKA-Revision Rates in US Veterans

We recently celebrated Veteran’s Day with the annual tradition of rightfully honoring the men and women who have served in the Armed Forces. After their active duty ends, servicemembers are eligible for care in Veterans Health Administration (VHA) hospitals around the nation. The VHA is a “closed” medical system that affords ample opportunity for population-based research.

In the November 18, 2020 issue of The Journal, Bendich et al. utilized VHA data to compare revision rates after primary total knee arthroplasty (TKA) among veterans treated with antibiotic-laden bone cement (ALBC) or plain cement. Although results of similarly designed studies focused on this question have been equivocal, antibiotic-laden cement seems to be especially effective at preventing infection in higher-risk populations, which is what the US veteran population is considered to be.

The researchers identified 15,972 primary TKAs that were implanted using Palacos bone cement between 2007 and 2015. Approximately 70% (11,231) of those cases used cement mixed with gentamicin, while 30% (4,741) utilized plain bone cement. The authors found similar patient demographics among patients treated with ALBC and those treated with plain cement, but ALBC was used more frequently in patients with higher comorbidity scores.

Overall, utilization of ALBC increased from 50.6% of the cases in 2007 to 69.4% in 2015. At a follow-up of 5 years, ALBC TKAs had a lower all-cause revision rate (5.3%) than plain-cement TKAs (6.7%) and a lower rate of revision for infection (1.9% compared to 2.6%). Even after multivariable adjustments to account for patient, surgical, and hospital factors, these revision-rate differences remained.

Bendich et al. also found that 71 TKAs needed to be implanted with ALBC to avoid 1 revision TKA. With a cost differential of $240 per case for ALBC, I think spending $17,040 ($240 × 71) is more cost-effective than 1 revision TKA, although a formal cost analysis is warranted.

In the interest of full disclosure, as an active-duty US Air Force officer, I am inherently biased, but I feel that no cost is too great to improve the health of our veterans. The authors review arguments against using ALBC, such as a theoretical risk of poor cement mechanical properties and systemic toxicity, but the findings of this study suggest that cement with antibiotics enhances treatment outcomes among these US heroes.

Click here to view the “Author Insight” interview about this study with co-author Alfred Kuo, MD, PhD.

Matthew R. Schmitz, MD
JBJS Deputy Editor for Social Media

Dashboard Depicts Surgeon-Level Value of TKA/THA

Remember when a “dashboard” referred to the display just behind a car’s steering wheel? In today’s digital universe, the word has come to mean any number of visual information displays. At the same time, the meaning of the word “value” has narrowed somewhat. In relation to health care, “value” is defined quite precisely as the quality of patient outcomes per dollar spent on healthcare services.

In the November 4, 2020 issue of The Journal of Bone & Joint Surgery, Reilly et al. explain how they created a “value dashboard” for total hip and knee arthroplasty (THA and TKA) at a tertiary-care medical center in New England. The goal: track and display the surgeon-level cost and quality of these procedures against institutional benchmarks to identify opportunities for improving value.

The 7 quality metrics that Reilly et al. used included both clinical and patient-reported outcomes, weighted by surgeons using a modified Delphi process. Average direct costs per surgeon were calculated from the medical center’s billing system, and data were collected over a 15-month period from 2017 to 2018 to ensure at least 1 year of outcomes. Six surgeons were included in the TKA value dashboard, and 5 were included in the THA dashboard.

Relative to the institutional benchmarks:

  • Value for TKA by surgeon ranged from 7% below benchmark to 12% above.
  • Value for THA by surgeon ranged from 12% below benchmark to 7% above.

The dashboard itself (see Figure above) displays quality, cost, and overall value so viewers can see at a glance which metrics are driving the value score for each surgeon, whose procedural volume is also depicted. The authors cite as one limitation of this study the fact that the quality metrics were weighted by local surgeons only, and they say that “ideally the weighting would be informed by a panel of national experts and several stakeholder groups,… including patients.”

PROMs Analyzed after Aseptic Revision TKA

The current literature about revision total knee arthroplasty (rTKA) for aseptic causes is focused mainly on “doctorly” data such as complication rates and implant survivorship. Taking a different tack in the October 21, 2020 issue of JBJS, Siddiqi et al. report findings from a comprehensive evaluation of patient-reported outcome measures (PROMs) at baseline and 1 year following rTKA. The PROMs evaluated included KOOS-Pain, KOOS-Physical Function, KOOS-QOL, and Veterans Rand-12.

Here is a general summary of the findings:

  • Patients undergoing aseptic rTKA had overall improvements in pain and function scores at 1 year postoperatively.
  • Knee-related QOL improved nearly 30 points, but >50% of patients did not report improvement in their overall global health at 1 year.
  • Predictors of improved 1-year pain scores were older age, baseline arthrofibrosis, lower baseline pain, and non-Medicare/Medicaid insurance.
  • Predictors of improved 1-year function scores were baseline arthrofibrosis and female sex.
  • Larger mean pain-score improvements occurred in patients undergoing rTKA for implant failure and aseptic loosening; pain-score improvements were lower in patients undergoing rTKA for instability.

Although 31% of the 246 eligible patients were lost to follow-up and excluded from the final analysis, the authors say their findings “corroborate the overall quality and, most importantly, the value that aseptic rTKA provides to patients.” Perhaps the findings’ greatest value is their potential application in the shared decision-making process between surgeons and patients pondering an aseptic rTKA, and in helping set realistic patient expectations if the surgery is undertaken.

Time Waits For No One—Aging Increases Costs

The cost of medical care in the United States has been shown to rise with advancing patient age, and total joint arthroplasty (TJA) is a prime example of this unsurprising phenomenon. In attempts to curtail costs and reduce variability, Medicare and other payers have introduced alternative payment models (APMs), such as the Bundled Payments for Care Improvement (BPCI) initiative. In this model’s application to TJA, when participating institutions keep the cost of the “episode” below a risk-adjusted target price, they accrue the savings as a profit, but they sustain a financial penalty if the episode costs more than the target price.

Multiple studies have suggested that APMs can negatively affect the fiscal health of institutions that care for many high-risk patients. Although increasing age has been associated with higher-cost episodes of care, age is not one of the factors that the BPCI model accounts for. Consequently, concerns have been raised that providers may practice “cost discrimination” against very old patients.

In the October 7, 2020 issue of The Journal, Petersen et al. examine how an aging population has affected a New York City orthopaedic center in terms of the BPCI model applied to TJA. The authors analyzed the relationship between patient age and cost of care among 1,662 patients who underwent primary total hip and knee arthroplasty over a 3-year period under BPCI. They then used a modeling tool to predict shifting age demographics for their local area out to the year 2040.

Petersen et al. found that under BPCI, their institution sustained a nearly $2,000-per-case loss for TJA care episodes among patients 85 to 99 years of age. Currently this loss is offset by profits realized by performing TJAs in younger patients. However, predictive modeling identified an inflection point of 2030, after which a relative increase in older patients and a decrease in younger patients will yield an overall net decrease in profits for primary TJA.

Because no one, including orthopaedic surgeons, can turn back the clock on aging, health care stakeholders must find ways either to adjust downward the cost of care for the elderly (seemingly difficult without adversely affecting outcomes) or adjust reimbursement models to account for the increased costs associated with aging. I agree with the conclusion of Petersen et al.: “The BPCI initiative and [other] novel APMs should consider age as a modifier for reimbursement to incentivize care for the more vulnerable and costly age groups in the future.”

Matthew R. Schmitz, MD
JBJS Deputy Editor for Social Media

Cost-Effectiveness of PRP for Knee OA Questioned

The cost-effectiveness analysis of platelet-rich plasma (PRP) for knee osteoarthritis by Rajan et al. in the September 16, 2020 issue of JBJS is accompanied by 105 references. That’s just one indication of the level of interest in this anti-inflammatory and pro-angiogenic orthobiologic. Current literature suggests that PRP is safe, but its clinical efficacy in musculoskeletal conditions has been hotly debated in the orthopaedic community.

Rajan et al. applied Markov decision analysis to a clinical scenario in which a 55-year-old patient with Kellgren-Lawrence grade-II or III knee osteoarthritis (OA) undergoes either a series of 3 PRP injections and a 1-year delay to total knee arthroplasty (TKA), or TKA from the outset. Their primary outcome measures were total costs and quality-adjusted life years (QALYs), organized into incremental cost-effectiveness ratios (ICERs). In Markov analyses, if one treatment costs less and produces more QALYs than a comparative treatment, it is considered to be the “dominant” approach.

The authors found that, from a health-care payer perspective, PRP (at an estimated cost of $728 per injection in 2018 US dollars) was not cost-effective if it yielded only a 1-year delay of TKA. However, from a societal perspective (which considered both lost productivity and the need for unpaid caregiving associated with TKA surgery), PRP was cheaper over a lifetime because it delayed direct and indirect costs associated with TKA. The ICER for TKA at the outset was $4,175 per QALY, which is well below the predetermined willingness-to-pay threshold of $50,000. The authors emphasize that this favorable ICER reflects the improved quality of life after TKA compared with published results of PRP injections for knee OA.

Rajan et al. do specify a clinical scenario in which PRP may have a cost-effectiveness advantage over TKA: “…in a higher-risk patient population in whom the perioperative complication rates, TKA revision rate, or postoperative functional outcomes are projected to be worse.”

Preop X-Rays Don’t Predict TKA Patient-Reported Outcomes

OrthoBuzz occasionally receives posts from guest bloggers. This guest post comes from David Vizurraga, MD in response to a recent study in JBJS Open Access.

Whoever coined the phrase, “a picture is worth a thousand words” never treated a patient with knee osteoarthritis (OA). While knee OA is one of the most common conditions encountered in orthopaedic practice and its diagnosis and treatment are fairly straightforward, predicting the outcomes of total knee arthroplasty (TKA)—the definitive treatment for most cases of end-stage knee OA—can be challenging. The severity of OA on radiographs has long been debated as a tool to aid surgeons in predicting post-TKA outcomes and framing expectations for patients. In general, we tend to say, “The worse the x-ray, the better the patient-reported outcome,” and conversely, “The better the x-ray, the worse the patient-reported outcome.”

Lange et al. investigated this assumption in a study published in JBJS Open Access on July 9, 2020. The authors leveraged data from a 2-arm, randomized controlled trial that evaluated the role of “motivational interviewing” in enhancing rehabilitation following TKA. In their cohort analysis, Lange et al. compared pre- and postoperative WOMAC pain scores and KOOS activities-of-daily-living (ADL) scores with preoperative radiographic severity of knee OA, as measured by the Osteoarthritis Research Society International (OARSI) Atlas score. Among the 240 patients who had 2-year outcome measures and imaging available, the median preoperative OARSI score was 10 (on a scale of 0 to 18), and the authors defined “milder OA”  as an OARSI score of <10 and “more severe OA”  as a score of ≥10.

The researchers found a cohort-wide postoperative improvement in WOMAC pain and KOOS ADL scores of ~30 points, but they did not find any significant or clinically important differences in pain and function scores between patients with “milder OA” and “more severe OA.” The authors were also unable to demonstrate any correlation between radiographic severity and pain and function scores preoperatively.

Additionally, Lange et al. looked for associations between the WOMAC and KOOS improvements and 4 four other radiographic assessments of knee OA severity (Kellgren-Lawrence grade, compartment-specific OARSI score, compartment-specific joint-space-narrowing score, and 4-level OARSI score). Again, they failed to observe any clinically important postoperative differences in pain or function between the subjects with radiographically milder or more severe OA.

These findings provide further evidence that radiographs should represent only one piece in the puzzle of diagnosis and treatment planning for our patients with knee OA. To me, it’s worth noting that the study capitalized on data from a trial investigating motivational interviewing, which aims to improve outcomes by empowering patients—yet in the multivariable analysis that adjusted for several confounders, use of motivational interviewing was not among them. Still, the many aspects of outcome prediction following knee replacement are most definitely worthy and in need of continued investigation.

David Vizurraga, MD is a San Antonio-based orthopaedic surgeon specializing in adult hip and knee reconstruction and a member of the JBJS Social Media Advisory Board.

September 2020 Article Exchange with JOSPT

For the last 6 years, JBJS has participated in an “article exchange” collaboration with the Journal of Orthopaedic & Sports Physical Therapy (JOSPT) to support multidisciplinary integration, continuity of care, and excellent patient outcomes in orthopaedics and sports medicine.

During the month of September 2020, JBJS and OrthoBuzz readers will have open access to the JOSPT systematic review titled “Meniscus or Cartilage Injury at the Time of Anterior Cruciate Ligament Tear Is Associated with Worse Prognosis for Patient-Reported Outcome 2 to 10 Years after Injury.”

The authors of this systematic review conclude that “patients, physical therapists, orthopaedic surgeons, and athletic trainers [should] be aware that concomitant meniscus or cartilage injuries may lead to worse knee function 2 to 10 years after ACL reconstruction.”

Validity of Non-English PROMs to Assess TKA

Patient-reported outcome measures (PROMs) have become increasingly important tools in the 30 years since the orthopaedic community began embracing the movement toward the “patient perspective.” Clinical findings such as range of motion and imaging results remain important, but we have come to understand that pain and function–as reported by the patient–are the most crucial data points. And we are not alone. Insurance companies, registries, scholarly publications, and research review panels now often require PROMs as part of their core evaluations.

But not all PROMs are created equal. For clinicians to trust the output from these instruments, validation of the measures is required. This entails reliability testing and assessment of face, construct, and criterion validity. Furthermore, translating PROMs validated in English into other languages involves not only linguistic translation, but also cultural components in order to capture the full patient perspective.

In the August 5, 2020 issue of The Journal, Bin Sheeha et al. report their work in evaluating the responsiveness, reliability, and validity of the Arabic-language version of the Oxford Knee Score (OKS-Ar). After painstaking statistical analysis of OKS-Ar questionnaires completed by 100 Arabic-speaking patients (80 of whom were female) before and after total knee arthroplasty (TKA), the authors concluded that the OKS-Ar is a valid, sensitive, and easy-to-use instrument to assess pain and function in TKA-treated individuals whose main language is Arabic.

To be truthful, this is not very glamorous research to conduct or very exciting to read about. However, it is absolutely fundamental to ensuring the validity of multicenter, international trials and registry studies. In essence, Bin Sheeha et al. have dug a conduit that facilitates the flow of reliable data and that will help improve future patient care worldwide. As such, it deserves our attention, understanding, and appreciation.

Marc Swiontkowski, MD
JBJS Editor-in-Chief

What’s New in Musculoskeletal Infection 2020

Every month, JBJS publishes a review of the most pertinent and impactful studies published in the orthopaedic literature during the previous year in 13 subspecialties. Click here for a collection of all OrthoBuzz specialty-update summaries.

This month, Thomas K. Fehring, MD, co-author of the July 15, 2020 What’s New in Musculoskeletal Infection,” selected the five most clinically compelling findings—all focused on periprosthetic joint infection (PJI)—from among the more than 80 noteworthy studies summarized in the article.

PJI Prevention
–A retrospective case-control study1 found that patients who received an allogeneic blood transfusion during or after knee or hip replacement had a higher risk of PJI than those who were not transfused.

PJI Diagnosis
–A retrospective review2 found that using inflammatory markers to diagnose PJI in immunosuppressed joint-replacement patients is not suitable and that newly described thresholds for synovial cell count and differential have better operative characteristics.

Treating PJI
–A retrospective review3 of a 2-stage debridement protocol with component retention in 83 joint-replacement patients showed an 86.7% success rate of infection control at an average follow-up of 41 months.

–A single-center study4 of perioperative antibiotic selection for patients undergoing total joint arthroplasty found that the risk of PJI was 32% lower among those who received cefazolin compared with those who received other antimicrobial agents. The findings emphasize the importance of preoperative allergy testing in patients with stated beta-lactam allergies.

–A review of regional and state antibiograms5 showed that 75% of methicillin-sensitive S. aureus (MSSA) isolates and 60% of both methicillin-resistant S. aureus (MRSA) and coagulase-negative Staphylococcus isolates were susceptible to clindamycin, whereas 99% of all isolates were susceptible to vancomycin.

References

  1. Taneja A, El-Bakoury A, Khong H, Railton P, Sharma R, Johnston KD, Puloski S, Smith C, Powell J. Association between allogeneic blood transfusion and wound infection after total hip or knee arthroplasty: a retrospective case-control study. J Bone Jt Infect. 2019 Apr 20;4(2):99-105.
  2. Lazarides AL, Vovos TJ, Reddy GB, Kildow BJ, Wellman SS, Jiranek WA, Seyler TM. Traditional laboratory markers hold low diagnostic utility for immunosuppressed patients with periprosthetic joint infections. J Arthroplasty.2019 Jul;34(7):1441-5. Epub 2019 Mar 12.
  3. Chung AS, Niesen MC, Graber TJ, Schwartz AJ, Beauchamp CP, Clarke HD, Spangehl MJ. Two-stage debridement with prosthesis retention for acute periprosthetic joint infections. J Arthroplasty.2019 Jun;34(6):1207-13. Epub 2019 Feb 16.
  4. Wyles CC, Hevesi M, Osmon DR, Park MA, Habermann EB, Lewallen DG, Berry DJ, Sierra RJ. 2019 John Charnley Award: Increased risk of prosthetic joint infection following primary total knee and hip arthroplasty with the use of alternative antibiotics to cefazolin: the value of allergy testing for antibiotic prophylaxis. Bone Joint J.2019 Jun;101-B(6_Supple_B):9-15.
  5. Nodzo SR, Boyle KK, Frisch NB. Nationwide organism susceptibility patterns to common preoperative prophylactic antibiotics: what are we covering? J Arthroplasty.2019 Jul;34(7S):S302-6. Epub 2019 Jan 17.