Tag Archive | TKA

More Work, Less Pay for Revision TKAs

Time is a valuable commodity for everyone. Most physicians have spent long hours in the clinic or hospital, away from our families, sometimes missing important life events. We accept those aspects of our chosen profession. But everyone, including surgeons, wants to be appropriately reimbursed for their time. It’s logical that more complex surgical cases take more time to perform correctly and safely. But does Medicare (and the private insurers who base their physician payments on Medicare rates) adequately reimburse for that extra time?

The short answer is “no,” at least in terms of revision surgery for infected total knee arthroplasties (TKAs). Samuel et al. tackle that topic in the February 5, 2020 issue of The Journal. The authors reviewed records from the NSQIP database to identify cases of aseptic revision TKA, 1-stage septic revision TKA, and 2-stage septic revision TKA. Using propensity-score matching that controlled for age, sex, race, BMI, and ASA classification, the authors established 4 cohorts that allowed for comparison of the following types of revision TKA:

  • 1-stage, 2-component aseptic revisions (n=1,096)
  • 1 stage, 2-component septic revisions (n=274)
  • First stage of a 2-stage septic revision (n=274)
  • Second stage of a 2-stage septic revision (n=274)

The authors then compared the relative value units (RVUs) for each type of revision TKA. (Medicare uses RVU-based algorithms to reimburse physicians for their services.) The authors also identified operative times for the surgery types and made RVU-per-minute and dollars-per-minute calculations.

The mean operative times were statistically different between each cohort (149 minutes for the aseptic group, 160 minutes for the 1-stage septic group, 138 minutes for the first-stage of the 2-stage septic group, and 170 minutes for the second-stage of the 2-stage septic group). The dollar-per-minute calculation in the “easiest case” of aseptic revision was $7.74 per minute, while in the “hardest case” of a 2-stage septic revision, reimbursement was $5.66 per minute for the first stage and $5.19 per minute for the second stage.

The fact that Medicare’s current reimbursement system does not account for the complexity of treating an infected TKA harms not only surgeons. Financially discouraging physicians from taking complex cases could lead to patients having a difficult time finding a doctor to treat their infected knee replacement. This entire predicament warrants further investigation, possible adjustments to the RVU system, and more realistic valuations of time in the OR.

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

Virtual PT Noninferior to and Less Expensive than Usual Care

OrthoBuzz occasionally receives posts from guest bloggers. In response to a recent study in The Journal of Bone & Joint Surgerythe following commentary comes from Jaime L Bellamy, DO.

The most common complication arthroplasty surgeons worry about after total knee arthroplasty (TKA) is stiffness, which occurs in a reported 15.98% of cases.1 The notion of TKA patients doing their postoperative physical therapy (PT) on their own at home with a “virtual avatar” gives me pause because it might increase the risk of stiffness. However, if patients could save money, make satisfactory progress in the comfort of their own home, and not experience undue knee stiffness, virtual PT technology would be worth it.

In the January 15, 2020 issue of The Journal, Bettger et al. report on a randomized controlled trial that compared virtual to traditional PT after TKA. The authors hypothesized that virtual PT would cost less and would be clinically noninferior to traditional PT. The  FDA-approved Virtual Exercise Rehabilitation Assistant (VERA) studied in this trial uses 3-D technology to track patient movement and an avatar (digitally simulated coach) to assist patients through PT exercises. Virtual PT technology like this not only has the potential to reduce costs (particularly travel costs incurred by patients who live in rural areas), but also to help address current and expected therapist shortages.

There were 143 patients in the virtual PT group and 144 in the traditional PT group. Patients randomized to virtual PT had the technology set up in their home prior to surgery. In addition to avatar-assisted home exercises, virtual PT patients had weekly “video visits” with a human therapist.

Bettger et al. found the median 12-week costs for virtual and traditional PT to be $1,050 and $2,805, respectively. Additionally, at 6 weeks, virtual PT was found to be noninferior to traditional PT in terms of patient outcome measures, knee range of motion, and gait speed. At 12 weeks, virtual PT was found to be noninferior to usual care in terms of pain and hospital readmissions.

I am relieved that virtual PT has the potential to provide cost savings, without apparently increasing the risk of knee stiffness. The cost savings and at-home convenience may be especially important for elderly TKA patients who are living on a fixed income and for whom transportation issues are often vexing. I hope technology like VERA continues to contribute to improved patient satisfaction and easier access to PT.

Jaime L. Bellamy, DO (@jaimelbellamyDO) is an orthopaedic surgeon specializing in hip and knee reconstruction in Fort Bragg, NC and a member of the JBJS Social Media Advisory Board.


  1. Can administrative data be used to analyze complications following total joint arthroplasty? Clair AJ, et al. J Arthroplasty, 2015;30(9 Suppl):17-20. http://dx.doi.org/10.1016/j.arth.2015.01.060

Highly Cross-Linked Poly Adds No Benefit to Most TKAs

The preponderance of published orthopaedic evidence supports the use of highly cross-linked polyethylene (HXLPE) in acetabular components for patients undergoing total hip arthroplasty (THA). (See related OrthoBuzz post.) But the literature is filled with conflicting findings about the benefits of HXLPE for those undergoing total knee arthroplasty (TKA). Seeking clarity, in the January 15, 2020 issue of The Journal of Bone & Joint Surgery, Partridge et al. report findings from a registry-based cohort analysis of more than a half-million TKAs, comparing revision rates among those using conventional polyethylene (CPE) with those using HXLPE.

The authors analyzed TKA data captured by the National Joint Registry for England, Wales, and Northern Ireland during the period from 2003 to 2014. Of the >550,000 procedures examined, only about 10% utilized HXLPE. When the authors compared adjusted aseptic revision rates per 100 years observed within the three most common TKA systems in the database (NexGen by Zimmer, PFC Sigma by DePuy, and Triathlon by Stryker), they found no significant differences between HXLPE and CPE after a maximum follow-up of 12 years.

The only notable difference between the two polyethylene types was found in patients <60 years old and/or those with BMI >35 kg/m2, in whom the second-generation Stryker X3 HXLPE showed significantly better survival than its CPE counterpart. In explaining why the benefits of HXLPE seen in THA might not translate to TKA, Partridge et al. contrast the “ball and socket” hip joint with the wear mechanisms in TKA, which involve “rolling, sliding, and rotational motion that potentially put the polyethylene insert at greater risk of wear by delamination, pitting, and fatigue failure.”

The authors conclude that the extra costs of HXLPE bearings for TKA may not be justified for most TKA patients in the intermediate term, but commentator Remy Simon Nizard, MD notes that “other uncontrolled or insufficiently controlled parameters [such as quality of component positioning] may have had an influence on the results.”  While Partridge et al. call for “additional follow-up,” Dr. Nizard questions whether full-blown clinical trials investigating alternative bearings in TKA are justified, “given the emerging subject of the burden of research waste.”

What do you think? Comment using the “Leave a comment” button in the box next to the title.

What’s New in Adult Reconstructive Knee Surgery 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 OrthoBuzz summaries of these “What’s New” articles. This month, author Michael J. Taunton, MD selected the 5 most clinically compelling findings from the more than 130 studies summarized in the January 15, 2020 “What’s New in Adult Reconstructive Knee Surgery.

Unicompartmental Knee Arthroplasty (UKA)
—A prospective cohort study of 1,000 Oxford cementless UKAs indicated by standard Kozinn and Scott criteria found that revision-free survivorship at 10 years was 97%. Progression of lateral osteoarthritis and dislocation of the bearing were the most common reasons for revision.1

Pain Management
—Authors of a double-blinded, prospective, randomized study assigned 60 primary total knee arthroplasty (TKA) patients to receive either a continuous adductor canal block or a single-injection adductor canal block with adjuvant agents. They found no between-group differences in pain scores up to 42 hours postoperatively.2

Post-TKA Physical Therapy (PT)
—A prospective, randomized, noninferiority trial demonstrated that 290 post-TKA patients who were randomized to either outpatient PT, unsupervised web-based PT at home, or unsupervised printed-instruction-based PT at home had no difference in knee range of motion or in patient-reported outcomes at 4 to 6 weeks or 6 months postoperatively.3

Infection Prevention
—In a retrospective review of 29,695 total joint arthroplasties, preoperative penicillin allergy testing led to a 1.19% higher rate of infection-free survival at 10 years, principally by allowing more routine use of the prophylactic antibiotic cefazolin.4

Revision TKA
—A retrospective case series found that patients undergoing revision TKA at an age of < 50 years had a survivorship free of re-revision of 66% at 10 years. Regardless of the reason for revision, this population also had a higher risk of mortality than the general population at 10 years.5


  1. Campi S, Pandit H, Hooper G, Snell D, Jenkins C, Dodd CAF, et al. Ten-year survival and seven-year functional results of cementless Oxford unicompartmental knee replacement: A prospective consecutive series of our first 1000 cases. Knee. 2018 Dec;25(6):1231-7. Epub 2018/08/29.
  2. Turner JD, Dobson SW, Henshaw DS, Edwards CJ, Weller RS, Reynolds JW, et al. Single-Injection Adductor Canal Block With Multiple Adjuvants Provides Equivalent Analgesia When Compared With Continuous Adductor Canal Blockade for Primary Total Knee Arthroplasty: A Double-Blinded, Randomized, Controlled, Equivalency Trial. J Arthroplasty. 2018 Oct;33(10):3160-6 e1. Epub 2018/06/16.
  3. Fleischman AN, Crizer MP, Tarabichi M, Smith S, Rothman RH, Lonner JH, et al. 2018 John N. Insall Award: Recovery of Knee Flexion With Unsupervised Home Exercise Is Not Inferior to Outpatient Physical Therapy After TKA: A Randomized Trial. Clin Orthop Relat Res. 2019 Jan;477(1):60-9. Epub 2019/02/23.
  4. Wyles CC, Hevesi M, Osmon DR, Park MA, Habermann EB, Lewallen DG, et al. 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. Epub 2019/05/31.
  5. Chalmers BP, Pallante GD, Sierra RJ, Lewallen DG, Pagnano MW, Trousdale RT. Contemporary Revision Total Knee Arthroplasty in Patients Younger Than 50 Years: 1 in 3 Risk of Re-Revision by 10 Years. J Arthroplasty. 2019 Jul;34(7S):S266-S70. Epub 2019/03/03.

3 Reference Axes Help Ensure Rotational Alignment During TKA

Rotational malalignment of the femoral component during total knee arthroplasty (TKA) is associated with poor outcomes, but how best to assess femoral component rotation intraoperatively remains an unanswered question for arthroplasty surgeons. Now, in the largest study of its kind, Jang et al. conclude in the December 4, 2019 issue of JBJS that combining 3 reference axes is the optimal strategy for ensuring accurate femoral component positioning, sex/ethnic generalizability, and intraoperative efficiency.

The authors compared 5 reference axes commonly used for intraoperative assessment of femoral component rotation by mapping them to >2,100 entire-femur CT scans from patients with nonarthritic knees. Using the surgical transepicondylar axis (sTEA) as the gold-standard reference, Jang et al. found that no single other axis was both highly accurate and relatively immune to ethnic and sex variability. Based on their findings, they instead recommend using a combination of 3 axes—posterior condylar axis externally rotated 3° (PCA + 3° ER), the Whiteside or sulcus line, and the anatomical transepicondylar axis (aTEA)—to ensure rotational alignment.

The authors also suggest a straightforward intraoperative process for using these 3 axes:

  1. Start with the PCA + 3° ER, which most accurately approximates the gold-standard sTEA.
  2. Then use the Whiteside or sulcus line, neither of which is significantly affected by sex or ethnicity.
  3. Finally, palpate for the aTEA to narrow the margin of error.

Citing a limitation to this CT-based study of nonarthritic knees, the authors note that “we could not account for the effects of cartilage wear or other changes caused by degenerative arthritis.”

RCT: Single IV Dose of TXA Is Safe, Effective for TKA

Along the spectrum of early and late adopters in medicine, most orthopaedic surgeons fall in the middle. They wait for science to prove the efficacy and safety of an innovation, carefully review the published studies regarding that innovation, and adopt it if it will improve their patients’ outcomes.

In the December 4, 2019 issue of JBJS, Jules-Elysee et al. compare tranexamic acid (TXA) administered intravenously (IV) versus topically in a double-blinded, randomized controlled trial (RCT) of patients undergoing primary total knee arthroplasty (TKA).  Level-I evidence is rare in the orthopaedic literature, so when a well-performed RCT comes out, we should closely evaluate its findings.

A potent antifibrinolytic, TXA has been shown in multiple studies to decrease blood loss associated with major orthopaedic procedures. However, there are persistent (but not necessarily evidence-based) concerns about its potential to cause thrombogenic complications,  and the safest and most effective route of TXA administration remains an open question.

In this study, the IV group received TXA once before tourniquet inflation and again 3 hours later, along with a topical placebo given 5 minutes before tourniquet release.  The topical group received an IV placebo at the same time intervals as the IV group, along with TXA delivered topically in the wound prior to tourniquet release. The authors found lower systemic levels of plasmin-anti-plasmin (PAP, a measure of fibrinolysis) in both groups 1 hour after tourniquet release, but PAP levels remained significantly lower in the IV group (indicating higher antifibrinolytic activity) 4 hours after tourniquet release, which was likely related to the second IV dose of TXA.

The authors also found no between-group difference in systemic or wound levels of prothrombin fragment 1.2 (PF1.2, a marker of thrombin generation), indicating there was no increase in thrombogenicity in the IV group.  Interestingly, Jules-Elysee also found that the IV group had significantly higher hemoglobin and hematocrit levels 1 and 2 days after surgery, and those patients had a significantly shorter hospital stay.

Finding no major between-group differences in the mechanism of action, coagulation, or fibrinolytic profile, the authors concluded that a single IV dose of TXA may be the most simple protocol for hospitals to adopt if they are still concerned about TXA safety. Perhaps these Level-I findings will help some of the late adopters get over their fears about the safety of IV TXA.

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

Meta-Analysis Quality Improving, But Issues Remain

Hip and knee arthroplasty are common procedures worldwide and are increasing annually as demographics change and the technical aspects of these surgeries become more accessible to a broader swath of surgeons. The sheer number of these procedures makes them an appropriate focus for randomized controlled trials (RCTs). The aggregation of RCT data into more powerful statistical frameworks is the job of a meta-analysis.

Not surprisingly, we have seen an increasing number of meta-analyses related to hip and knee replacement published across all major orthopaedic journals during the last two decades. Authors have two common motivations for conducting meta-analyses. The first, to summarize data from carefully conducted RCTs into clinically relevant and important recommendations, is hopefully the most common motivation—and certainly the most justifiable. The second, to merely use previously published data as an analytic exercise to advance one’s academic career without investing the time and effort to do prospective research, is not justifiable, in my estimation.

In the December 4, 2019 issue of The Journal, Park et al. conduct quality and usefulness assessments of 114 published meta-analyses about hip and knee arthroplasty that appeared in 3 major orthopaedic journals (one of which was JBJS) from 2000 to 2017. They document a nearly 4-fold increase in the number of meta-analyses published on these topics when comparing 2000 to 2009 with 2010 to 2017. Based on Oxman-Guyatt Index scores of overall study quality, only 12 of the 114 studies were assessed as high quality, 87 as moderate quality, and 15 as low quality.

Here are some additional findings:

  • The majority of these meta-analyses were not performed in accordance with established PRISMA (Preferred Reporting Items for Systematic Reviews and Meta-Analyses) guidelines.
  • Only 39% of these articles showed the risk of bias.
  • Many of these meta-analyses covered redundant topics within the same year or within a few years of each other.
  • A review by expert attending surgeons of the 24 studies determined to be high quality per PRISMA found that 71% were either clinically unimportant or inconclusive.

It is a positive step to highlight for our readers the important quality issues surrounding meta-analyses, and I agree with James Stoney, who commented on these findings: “The onus is on surgeons to carefully scrutinize meta-analyses…and come to individual conclusions about the quality of the research rather than accept the conclusions at face value.”

But I am discouraged to see the number of problematic meta-analyses that have appeared in our literature, and I suspect most of these quality problems arise from the second, unjustifiable motivation noted above. We need to do better as a research community, as peer reviewers, and as journal editors to improve the quality of published meta-analyses so that we can favorably impact patient care and advance the clinical practice of hip and knee arthroplasty.

Marc Swiontkowski, MD
JBJS Editor-in-Chief

What’s New in Orthopaedic Rehabilitation 2019

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 summaries.

This month, co-author Nitin B. Jain, MD, MSPH selected the most clinically compelling findings from the 40 studies summarized in the November 20, 2019 “What’s New in Orthopaedic Rehabilitation.

Pain Management
–A randomized controlled trial compared pain-related function, pain intensity, and adverse effects among 240 patients with chronic back, hip, or knee pain who were randomized to receive opioids or non-opioid medication.1 After 12 months, there were no between-group differences in pain-related function. Statistically, the pain intensity score was significantly lower in the non-opioid group, although the difference is probably not clinically meaningful. Adverse events were significantly more frequent in the opioid group.

–A series of nested case-control studies found that the use of the NSAID diclofenac was associated with an increase in the risk of myocardial infarction in patients with spondyloarthritis and osteoarthritis, relative to those taking the NSAID naproxen.2

–Intra-articular injections of corticosteroids or hyaluronic acid are often used for pain relief prior to an eventual total knee arthroplasty (TKA). An analysis of insurance data found that patients who had either type of injection within three months of a TKA had a higher risk of periprosthetic joint infection (PJI) after the operation than those who had injections >3 months prior to TKA.

Partial-Thickness Rotator Cuff Tears
–A randomized controlled trial of 78 patients with a partial-thickness rotator cuff compared outcomes of those who underwent immediate arthroscopic repair with outcomes among those who delayed operative repair until completing 6 months of nonoperative treatment, which included activity modification, PT, corticosteroid injections, and NSAIDs.3 At 2 and 12 months post-repair, both groups demonstrated improved function relative to initial evaluations. At the final follow-up, there were no significant between-group differences in range of motion, VAS, Constant score, or ASES score. Ten (29.4%) of the patients in the delayed group dropped out of the study due to symptom improvement.

Stem Cell Therapy
–A systematic review that assessed 46 studies investigating stem cell therapy for articular cartilage repair4 found low mean methodology scores, indicating overall poor-quality research. Only 1 of the 46 studies was classified as excellent, prompting the authors to conclude that evidence to support the use of stem cell therapy for cartilage repair is limited by a lack of high-quality studies and heterogeneity in the cell lines studied.


  1. Krebs EE, Gravely A, Nugent S, Jensen AC, DeRonne B, Goldsmith ES, Kroenke K, Bair MJ, Noorbaloochi S. Effect of opioid vs nonopioid medications on pain-related function in patients with chronic back pain or hip or knee osteoarthritis pain: the SPACE randomized clinical trial. JAMA. 2018 Mar 6;319(9):872-82.
  2. Dubreuil M, Louie-Gao Q, Peloquin CE, Choi HK, Zhang Y, Neogi T. Risk ofcmyocardial infarction with use of selected non-steroidal anti-inflammatory drugs incpatients with spondyloarthritis and osteoarthritis. Ann Rheum Dis. 2018 Aug;77(8): 1137-42. Epub 2018 Apr 19.
  3. Kim YS, Lee HJ, Kim JH, Noh DY. When should we repair partial-thickness rotator cuff tears? Outcome comparison between immediate surgical repair versus delayed repair after 6-month period of nonsurgical treatment. Am J Sports Med. 2018 Apr;46(5):1091-6. Epub 2018 Mar 5.
  4. Park YB, Ha CW, Rhim JH, Lee HJ. Stem cell therapy for articular cartilage repair: review of the entity of cell populations used and the result of the clinical application of each entity. Am J Sports Med. 2018 Aug;46(10):2540-52. Epub 2017 Oct 12.

Surgeon Volume Matters for TKA Alignment

The retrospective multicenter study of 1,570 primary total knee arthroplasties (TKAs) by Kazarian et al. in the October 2, 2019 issue of JBJS focused on evaluating the impact of surgeon volume and training status on implant alignment. But the most surprising (and concerning) finding was that even among high-volume attendings—the best-performing of the three surgeon cohorts studied—the proportion of TKA alignment “outliers” was still high.

The authors radiographically measured 3 postoperative TKA alignment parameters: medial distal femoral angle (DFA), medial proximal tibial angle (PTA), and posterior tibial slope angle (PSA). Using established thresholds for “outliers” and “far outliers” for those 3 measurements, the authors compared the radiographic findings among surgeries performed by high-volume attendings (≥50 TKAs/year), low-volume attendings (<50 TKAs/year), and trainees (supervised residents or fellows).

As has been shown in similar studies of total hip arthroplasty (THA), the group of high-volume attendings outperformed the low-volume attendings and the trainee group on nearly all measurements assessed in this study. Interestingly, in terms of TKA alignment, the low-volume attending group and the trainee group performed similarly.

Kazarian et al. express concern that “even the most accurate cohort in our study, [the high-volume attendings], placed only 69.0% of knees in optimal alignment for all 3 measurements.” While the authors admit that implant alignment is not a perfect proxy for clinical outcomes, they argue that “gross alignment outliers are likely to have an impact on knee function, kinematics, and wear characteristics.” Citing literature suggesting that the use of robotic-arm assistance may improve TKA alignment, the authors surmise that employing such technology to assist low-volume surgeons or trainees might optimize alignment and improve outcomes, despite the added up-front cost of the technology.

Patient Discharge after Knee Replacement: How Soon Is Safe?

For most patients and payers, getting out of the hospital quickly after a knee replacement is very important. For orthopaedic surgeons, excellent patient outcomes are the top priority. The latest one-hour complimentary webinar from JBJS on Tuesday, October 1, 2019 at 8:00 pm EDT will reveal clinical practices that increase the odds of achieving both of those goals.

Co-authors Nelson SooHoo, MD and Armin Arshi, MD will explore data from their JBJS study comparing complication rates after outpatient and inpatient knee-replacement, emphasizing that outpatients must receive the same attention to infection prevention, thromboprophylaxis, and rehabilitation as inpatients.

Kurt Spindler, MD and Robert Molloy, MD will then delve into their JBJS study, which suggests that hospital site, surgeon, and day of the week are more accurate predictors of length of hospital stay after knee replacement than patient age, BMI, and comorbidities.

Moderated by Daniel Berry, MD of the Mayo Clinic, the webinar will also feature expert commentaries by Joseph Moskal, MD and Ronald Delanois, MD. The webinar will conclude with a 15-minute live Q&A session during which attendees can ask questions of all the panelists.

Seats are limited, so Register Now!