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Reimbursement for Revision TKA Has Not Kept Pace with Inflation

I was once told that if you don’t have any cases with complications, you either aren’t operating enough or aren’t following your patients. Although we in the orthopaedic community make every effort to minimize the occurrence of patient complications, one that remains difficult to eradicate is periprosthetic joint infection (PJI), which is a leading cause of revision total knee arthroplasty (TKA). The welfare of our patients requires successfully addressing this potentially devastating outcome, but reimbursement for these complex cases has decreased over the past decade.

In the upcoming issue of JBJS, Jella et al. offer insight on temporal trends in Medicare physician reimbursement for revision TKA. They queried the Medicare Physician Fee Schedule Look-Up Tool for pricing information corresponding to 1 and 2-stage revision TKAs and used monetary data from Medicare Administrative Contractors to calculate nationally representative means. The authors evaluated aseptic revision of 1 component, 1-stage revision (aseptic or septic), and both the first and second stages of a 2-stage septic revision.

They found that, from 2002 to 2019, there was a mild increase in the physician fee for each CPT code, with the exception of that for second-stage implantation. However, after adjusting for inflation, total Medicare reimbursements declined for both septic and aseptic revision TKAs (between 23% and 33%), with a significantly greater decline observed for septic revision.

The authors also found that Medicare spending on aseptic revision TKA nearly doubled from 2004 to 2017, while spending on septic revision TKA increased only slightly. They note that a main driver of the discrepancy between septic and aseptic revision may be the reimbursement for the second stage of the former procedure using CPT 27447 instead of a revision procedure code (27487).

We know that an increase in revision TKAs (both septic and aseptic) is expected as the number of primary TKA procedures continues to rise. If reimbursement doesn’t keep pace, it is likely to drive certain surgeons away from tackling the sometimes difficult cases, in turn, leaving our patients with fewer available resources when faced with PJI.

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

Low Adherence to Open-Fracture Antibiotic Guidelines

The prompt administration of prophylactic antibiotics is considered a critical component of open-fracture management. In 2011, the Eastern Association for the Surgery of Trauma (EAST) recommended updates to traditional antibiotic administration, including gram-positive coverage for Gustilo Type-I and Type-II fractures, the addition of gram-negative coverage for Type-III, and additional penicillin for the presence of fecal or clostridial contamination. Concerns regarding the side effects of antibiotics, along with changing patterns in bacteria resistance, have led many treating physicians to consider alternative antibiotic choices.

In a recent JBJS article, Lin et al. report on the level of adherence to open-fracture antibiotic guidelines (both traditional and EAST recommendations), analyzing data collected as part of 2 large, ongoing, multicenter trials. They also evaluated the association of Gustilo type, wound contamination, and multifracture injuries with antibiotic choice and duration.

Included were 1,234 patients from 24 medical centers in the US and Canada, all of whom received antibiotics on the day of admission. While cefazolin monotherapy was the most commonly prescribed regimen (53.6%), 54 different combinations of prophylactic antibiotics were prescribed. Lin et al. found moderate adherence to traditional antibiotic treatment guidelines for Gustilo Types-I and II fractures and low adherence for Type-III, and less-than-optimal compliance with the EAST recommendations: 31% of Gustilo Type-I and Type-II fractures received gram-negative coverage, and 54.9% of Type-III fractures did not.

The authors offer many plausible reasons for low compliance, including increased incidence of methicillin-resistant S. aureus infections, concerns regarding the nephrotoxicity of aminoglycosides, and the more frequent use of intraoperative topical antibiotics.

The median duration of antibiotic use following wound closure in this study was 2 days. The authors note that the most widely recommended duration in the literature is 3 days after wound closure, which they add, contradicts the <24 hours recommended by the EAST guidelines (for Type-III fractures, discontinuation within 72 hours post-injury or 24 hours after soft-tissue coverage).

The study provides helpful insight into the sometimes contradictory and confusing guidelines for open-fracture antibiotic prophylaxis and the variations that exist in current practice patterns. It also begs the question: is it time for a stringent new look at the guidelines and more high-quality research into which practices help ensure the best patient outcomes and the most sensible antibiotic stewardship?

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

 

Machine Learning Algorithm May Predict Postfracture Infection

Infection after surgery to treat a tibial shaft fracture can have devastating consequences, with significant associated costs and burdens. Although research has identified general risk factors that increase the likelihood of infection (including complexity of injury and fracture patterns and patient-related factors such as smoking and diabetes), predicting risks for individual patients remains difficult.

In a recent study in The Journal, investigators from the Machine Learning Consortium reported on an algorithm they developed to predict the risk of  infection in specific patients who receive operative treatment for a tibial shaft fracture. To develop their model, the researchers used high-quality data from the SPRINT (Study to Prospectively Evaluate Reamed Intramedullary Nails in Patients with Tibial Fractures) and FLOW (Fluid Lavage of Open Wounds) randomized controlled trials.

The Australian researchers “trained” 5 machine learning algorithms and tested them against various performance measures to evaluate 1,822 fractures, including 170 (9%) that developed an infection. Based on predictive performance in that derivation portion of the study, 3 algorithms were validated and 1 prediction model was found to be superior. In that model, Gustilo-Anderson Type IIIA and IIIB fractures, age, AO/OTA type 42C3 fractures, crush injuries, and falls were the strongest predictors of infection.

Researchers have made their model available in an online, open-access prediction tool. Although the authors emphasize that this preliminary tool is intended for research and not for widespread clinical use, I think it has profoundly positive potential. Being able to risk-stratify a patient with a tibial shaft fracture at or near the time of admission could allow surgeons to closely monitor—and intervene sooner—in fracture cases at risk for infection, thereby possibly preventing devastating complications. This prediction tool certainly needs external validation prior to “prime-time” adoption, but when it comes to exploring artificial intelligence and machine learning in orthopaedics, the future is now.

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

Accuracy of Rapid Alpha Defensin Test Confirmed

In June 2019, OrthoBuzz reported on the FDA approval of a rapid, lateral-flow alpha defensin test that helps detect periprosthetic joint infections (PJIs) from synovial fluid. In the January 20, 2021 issue of The Journal of Bone & Joint Surgery, Deirmengian et al. report findings from the Level II diagnostic-accuracy study that led to this FDA approval.

The authors compared diagnostic sensitivity and specificity of the lateral-flow alpha defensin test with the “gold-standard” PJI diagnostic criteria endorsed by the Musculoskeletal Infection Society (MSIS) in 2013. They made the comparison with 2 groups: a prospective patient cohort of 305 patients with a failed hip or knee arthroplasty (57 of whom were determined by MSIS criteria to have a PJI) and among a “control” cohort of 462 synovial fluid samples (65 of which met MSIS criteria for PJI).

After excluding 17 patients from the prospective cohort who had grossly bloody aspirates, the authors found a sensitivity of 94.3% and a specificity of 94.5% for the lateral-flow test in that group. Among the control cohort, the lateral-flow test’s sensitivity was 98.5% and its specificity was 98.2%. Furthermore, after combining data from the 2 cohorts, Deirmengian et al. found no performance difference between the lateral-flow test (which yields results in 10 to 15 minutes) and the lab-based alpha defensin ELISA test (which typically yields results in 24 hours). Finally, in a nonstatistical descriptive comparison between the 2 alpha defensin tests and 4 other individual lab tests used in the MISI criteria to diagnose PJI (such as synovial fluid white blood cell count and erythrocyte sedimentation rate), the authors concluded that “alpha defensin tests led to the highest raw number of correct diagnoses (accuracy).”

The 2018 International Consensus Meeting on Orthopaedic Infections included alpha defensin as a minor criterion. That decision, along with these findings and the FDA approval of the lateral-flow test, should lead to increased adoption of the rapid test—and to more data being published on its clinical utility.

What’s New in Adult Reconstructive Knee Surgery 2021

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 such OrthoBuzz specialty-update summaries.

This month, author Michael J. Taunton, MD summarizes the 5 most compelling findings from the 130 studies highlighted in the January 20, 2021 “What’s New in Adult Reconstructive Knee Surgery.”

Waiting for a Knee Replacement
–Patient wait times for joint arthroplasty, exacerbated in many places by the COVID-19 pandemic, continue to increase. As measured by the EQ-5D, the health among 12% of 2,168 patients awaiting total knee arthroplasty (TKA) in a recent cross-sectional analysis was rated as “worse than death.”1 Joint-specific function and various comorbidities were associated with these findings.

UKA vs TKA
–The multicenter randomized TOPKAT trial2 compared unicompartmental knee arthroplasty (UKA) with TKA for treating medial compartment osteoarthritis. At the 5-year follow-up, there was no between-group difference in Oxford knee scores, but UKA was more cost-effective and provided an additional 0.24 quality-adjusted life year.

Perioperative Patient Optimization
–An observational study analyzing >1,000 total joint arthroplasties3 found that implementing a “perioperative orthopaedic surgical home”—a surgeon-led screening and optimization initiative targeting 8 common modifiable comorbidities—resulted in a 1.6% 30-day readmission rate (versus 5.3% among patients not involved in the initiative).

Pain Management and Opioids
–A randomized controlled trial of >300 patients undergoing primary total knee or hip arthroplasty4 demonstrated that reducing the number of 5-mg oxycodone pills prescribed at discharge from 90 to 30 resulted in the following findings 30 days postoperatively:

  • Similar between-group pain scores
  • No between-group differences in patient-reported outcomes
  • Significant reductions in unused opioid pills and in pain pills taken in the 30-pill group

Periprosthetic Joint Infection
–Patients undergoing primary TKA who had a history of periprosthetic joint infection (PJI) in another joint had a significantly higher risk of PJI after the primary TKA, compared with the risk among a matched cohort with no history of PJI.5

References

  1. Scott CEH, MacDonald DJ, Howie CR. ‘Worse than death’ and waiting for a joint arthroplasty. Bone Joint J.2019 Aug;101-B(8):941-50.
  2. Beard DJ, Davies LJ, Cook JA, MacLennan G, Price A, Kent S, Hudson J, Carr A, Leal J, Campbell H, Fitzpatrick R, Arden N, Murray D, Campbell MK; TOPKAT Study Group. The clinical and cost-effectiveness of total versus partial knee replacement in patients with medial compartment osteoarthritis (TOPKAT): 5-year outcomes of a randomised controlled trial. 2019 Aug 31;394(10200):746-56. Epub 2019 Jul 17.
  3. Kim KY, Anoushiravani AA, Chen KK, Li R, Bosco JA, Slover JD, Iorio R. Perioperative orthopedic surgical home: optimizing total joint arthroplasty candidates and preventing readmission. J Arthroplasty.2019 Jul;34(7S):S91-6. Epub 2019 Jan 18.
  4. Hannon CP, Calkins TE, Li J, Culvern C, Darrith B, Nam D, Gerlinger TL, Buvanendran A, Della Valle CJ. The James A. Rand Young Investigator’s Award: large opioid prescriptions are unnecessary after total joint arthroplasty: a randomized controlled trial. J Arthroplasty.2019 Jul;34(7S):S4-10. Epub 2019 Feb 4.
  5. Chalmers BP, Weston JT, Osmon DR, Hanssen AD, Berry DJ, Abdel MP. Prior hip or knee prosthetic joint infection in another joint increases risk three-fold of prosthetic joint infection after primary total knee arthroplasty: a matched control study. Bone Joint J.2019 Jul;101-B(7_Supple_C):91-7.

When Does I&D Beat 2-Stage Exchange in Second rTKA?

It’s hard to contemplate “conservative treatment” in the case of a revised total knee arthroplasty (rTKA) with extensive instrumentation that needs a reoperation due to periprosthetic joint infection (PJI), because all the treatment options in that scenario are pretty complex. In the January 6, 2021 issue of JBJS, Barry et al. report on a retrospective review of 87 revisions of extensively instrumented rTKAs that found that irrigation and debridement (I&D) with chronic antibiotic suppression was as effective as 2-stage exchange in preventing another reoperation for infection—and more effective in terms of maintaining knee function.

The average follow-up of the cases studied was 3.2 years, and the authors carefully defined “extensive instrumentation.” Among the 56 patients who were managed with I&D and suppression and the 31 who were managed with the initiation of 2-stage exchange (average age in both groups approximately 67 years), no significant differences were found in the rates of reoperation for infection or mortality. However, 9 of the 31 patients (29%) in the 2-stage group never underwent the second-stage reimplantation. Among those 9, 3 died prior to reimplantation and 2 underwent amputation due to failure of infection control.

Moreover, at the time of the latest follow-up, a significantly higher percentage of patients in the I&D group were ambulatory (76.8% vs 54.8% in the 2-stage group) and were able to functionally bend their knee (85.7% vs 45.2% in the 2-stage group). The authors surmise that these 2 findings are related to the soft-tissue damage and bone loss that typically occur during stage-1 removal of rTKA components.

Barry et al. conclude that in similar situations “deviating from the so-called gold standard of 2-stage exchange and accepting the modest results of I&D may be in the best interest of the patient,” as long as there are no loose implants in the existing construct. But the “sobering” mortality rates in the study (39.3% in the I&D group and 38.7% in the 2-stage group) remind us that this clinical scenario is extremely challenging for patients and surgeons, no matter which option is selected.

Click here to view an “Author Insights” video about this study with co-author Jeffrey Barry, MD.

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

Balancing Antibiotic Perfusion and Tourniquet Usage

Antibiotics are an integral part of infection prophylaxis in orthopaedic surgery, and tourniquets are widely used during many of those same surgeries. The timing of antibiotic administration in relation to tourniquet use has long been debated. Hanberg et al. explore this “balancing act” in the November 4, 2020 issue of The Journal in a carefully performed animal study.

The researchers anesthetized 24 female pigs and surgically exposed both of their hind calcanei. They then placed microdialysis catheters through drill holes in each calcaneus and also into the subcutaneous adipose tissue in the hind feet. Tourniquets were applied to one hind leg on each animal, and each pig was then randomized into 1 of 3 groups, based on when the animal received 1.5 gm of cefuroxime intravenously:

  • Group A –15 minutes prior to tourniquet inflation
  • Group B – 45 minutes prior to tourniquet inflation
  • Group C – At the time of tourniquet release

Hanberg et al. inflated the tourniquets for 90 minutes in all 3 groups, and then they measured the concentrations of cefuroxime and ischemic markers at regular intervals between the time of tourniquet inflation and up to 480 minutes afterward.

The authors found that in both Groups A and B, cefuroxime concentrations were maintained above the minimum inhibitory concentration (MIC) for Staphylococcus aureus in cancellous bone and adipose tissue throughout the 90 minutes of tourniquet inflation. In addition, injecting cefuroxime at the time of tourniquet deflation (Group C) kept the tissue-antibiotic levels above the MIC on the tourniquet side for 3.5 hours after tourniquet release.

There were no differences in the time above MIC in bone or adipose tissue between the 3 groups, but the researchers noted a trend toward shorter time above MIC in bone in Group A vs. Group C (p=0.08). There was also a tendency toward higher time above MIC in bone on the tourniquet side compared to no-tourniquet side in Group B (p=0.08) and Group C (p=0.06). The researchers also found that, in all the animals, tissue ischemia persisted for 2.5 hours after tourniquet deflation in bone, while the adipose tissue recovered immediately.

This animal study provides useful data and prompts us to ponder ideas for further investigation regarding the interplay between tourniquets and antibiotic perfusion. For example, I think the prolonged ischemia in cancellous bone is a topic that warrants further investigation, and I am also curious whether adding antibiotics at the time of tourniquet release might help combat the potentially negative effects of that ischemia.

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

Detecting Pathogens in Pediatric Infections: Swab, Tissue, or Bottle?

Identifying the pathogenic microorganism in childhood osteomyelitis and septic arthritis is essential to tailoring appropriate treatment. But the traditional methods of swab and tissue culturing have subpar success rates in pediatric patients, identifying the pathogen in only 40% to 60% of cases. In the October 21, 2020 edition of The Journal, Shin et al. report their findings comparing microbial identification rates using pediatric blood culture bottles (BCBs), typical culture swabs, and tissue specimens.

Over 3 years, the authors prospectively collected intraoperative specimens from 40 pediatric patients (mean age of 7.2 years) who underwent surgery for a presumed osteoarticular infection. Half of the patients had received oral or intravenous antibiotics in the 3 weeks prior to surgery, while the other half had received intravenous cefazolin after culture specimens were obtained in the operating room. Intraoperative culture specimens were obtained in 3 different manners for all patients:

  1. Four 21-gauge needles were dipped into the infected fluid and were used to inoculate 4 pediatric BCBs – 2 aerobic and 2 nonaerobic.
  2. Two swabs were placed in direct contact with the infected tissue.
  3. Two solid tissue samples were collected and placed in 2 sterile containers.

In these 40 cases, the microbial identification rate of the BCB method was 68%, compared to 45% with the swab method and 38% with the tissue method—all statistically significant differences. In 9 patients (23%), the pathogen was only identified with the BCB method. No samples showed positive culture growth with the other 2 methods if the BCB culture was negative. Interestingly, in a subgroup analysis of 15 patients with methicillin-susceptible Staphylococcus aureus (MSSA), the authors found no difference in detection rates between the 3 methods, but in cases involving organisms other than MSSA, detection with BCBs was significantly higher than with both swab and tissue cultures.

The apparent superiority of BCBs to detect microbial organisms could be due to the characteristics of pediatric BCBs, which enhance microorganism growth in a small amount of liquid. Although there are some concerns that this enhanced BCB detection could lead to increased rates of false-positives from contaminants, I think the risk of false positives is a viable tradeoff if we can more quickly and accurately identify pathogens in pediatric infections. As Shin et al. emphasize, “Sequelae resulting from these infections are particularly unfortunate for pediatric patients.”

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

Sustained Fevers After Spinal Fusion: A Sentinel for Infection?

Postoperative fevers occur frequently. During the first 2 to 3 days after surgery, these fevers are often due to atelectasis or the increased inflammatory response that arises from tissue injury during surgery. However, persistent postoperative fevers should be cause for concern. In the August 19, 2020 issue of The Journal, Hwang et al. examine the relationship between sustained fevers after spine instrumentation and postoperative surgical site infection.

The authors retrospectively reviewed 598 consecutive patients who underwent lumbar or thoracic spinal instrumentation. They excluded patients who underwent surgery to treat tumors or infections and those with other identified causes of fever, such as a urinary tract infection or pneumonia. Sustained fevers were defined as those that began on or after postoperative day (POD) 4 and those that started on POD 1 to 3 if they persisted until or beyond POD 5.

Sixty-eight patients (11.4%) met the criteria for a sustained fever after spinal instrumentation. Nine of those 68 (13.2%) were diagnosed with a surgical site infection. Of the 530 patients who did not have a sustained fever, only 5 (0.9%) developed a surgical site infection (p<0.001 for the between-group difference).

Further analysis revealed 3 diagnostic clues for surgical site infections among the patients with sustained fevers:

  • Continuous fever (rather than cyclic or intermittent)
  • Levels of C-reactive protein (CRP) >4 mg/dL after POD 7
  • Increasing or stationary patterns of CRP level and neutrophil differential

In addition, the authors found that CRP levels >4 mg/dL between PODs 7 and 10 had much greater sensitivity for discriminating surgical site infection than gadolinium-enhanced magnetic resonance imaging data obtained within 1 month of the surgical procedure.

Although a vast majority (87%) of patients with sustained postoperative fevers in this study did not develop an infection, persistent fever after spine instrumentation surgery is something to be mindful of. The authors describe their findings as “tentative” and advise readers to interpret them with caution. Those caveats notwithstanding, I consider this information to be valuable because it might help prevent delays in the diagnosis of a potentially serious perioperative complication.

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