Tag Archive | total knee arthroplasty

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.

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

Predictors of Prolonged Analgesic Use after Joint Replacement

OrthoBuzz occasionally receives posts from guest bloggers. This guest post comes from Eric Secrist, MD in response to a recent study in Arthritis Research & Therapy.

There has been a proliferation of research regarding postoperative opioid usage after joint arthroplasty due to the widespread opioid epidemic. But Rajamäki and colleagues from Tampere University in Finland took the unique approach of also analyzing acetaminophen and NSAID usage in addition to opioids. The authors used robust data from Finland’s nationwide Drug Prescription Register, which contains reliable information on all medications dispensed from pharmacies, including over-the-counter drugs.

After excluding patients who underwent revision surgery or had their knee or hip replaced for a diagnosis other than osteoarthritis, the authors analyzed 6,238 hip replacements in 5,657 patients and 7,501 knee replacements in 6,791 patients, all performed between 2002 and 2013. The mean patient age was 68.7 years and the mean BMI was 29.

One year postoperatively, 26.1% of patients were still filling prescriptions for one or more analgesics, including NSAIDs (15.5%), acetaminophen (10.1%), and opioids (6.7%). Obesity and preoperative analgesic use were the strongest predictors of prolonged analgesic medication usage 1 year following total joint arthroplasty. Other predictors of ongoing analgesic usage included older age, female gender, and higher number of comorbidities. Patients who underwent knee replacement used the 3 analgesics more often than those who underwent hip replacement.

This study had all of the limitations inherent in retrospective database analyses. Additionally, it was not possible for the authors to determine whether patients took analgesic medications for postoperative knee or hip pain or for pain elsewhere in their body. Finally, the authors utilized antidepressant reimbursement data as a surrogate marker for depression and other medications as a surrogate for a Charlson Comorbidity Index.

Figure 2 from this study (shown below) reveals 2 important findings. First, total joint arthroplasty resulted in a significant decrease in the proportion of patients taking an analgesic medication, regardless of BMI. Second, patients in lower BMI categories were less likely to use analgesics both preoperatively and postoperatively.

The findings from this study may be most useful during preoperative counseling for obese patients, who often present with severe joint pain but are frequently told they need to delay surgery to lose weight and improve their complication-risk profile. Based on this study, those patients can be counseled that losing weight will not only decrease their complication risk, but also decrease their reliance on medications for the pain that led them to seek surgery in the first place.

Eric Secrist, MD is a fourth-year orthopaedic resident at Atrium Health in Charlotte, North Carolina.

TKA Cost Efficiency Is Improving, But We Can Do Better

Wide variability in the cost and quality of health care in the US has led some to describe our system as “uniquely inefficient.” Consequently, we continue to study variability intensely, especially in the realm of joint arthroplasty. In the June 3, 2020 issue of The Journal, Schilling et al. elegantly analyze the variations in 90-day episode payments made by Medicare Part A for total knee arthroplasty (TKA) from 2014 to 2016. In so doing, they provide a snapshot of hospital cost performance and, just as importantly, they offer a methodology by which to measure future hospital-level cost performance with this very popular surgery.

The authors reviewed >700,000 TKAs in the Medicare population at a time prior to the full implementation of the Comprehensive Care for Joint Replacement (CJR) model, and they ranked >3,200 hospitals within 9 US regions to determine cost performance.  Schilling et al. found that during those 3 years, the mean Medicare episode payment for TKA decreased significantly, due almost entirely to a >$1,500 per-case decrease in post-acute care payments, which included lower costs for skilled nursing facilities and inpatient rehabilitation. Also decreasing during that same period were length of hospital stay and 90-day readmission rates.

These findings highlight the improvements in care and cost efficiency that were occurring even before implementation of the CJR. In a Commentary on this study, Susan Odum, PhD suggests that “the improved value of TKA illustrated by Schilling et al. includes the successful impacts of the BPCI [Bundled Payments for Care Improvement] program,” an alternative payment model that Medicare rolled out beginning in 2013.

On the other hand, the authors also reveal a persistently high degree of variability in episode payments and resource utilization both across and within geographic regions. This strongly suggests the possibility of further improvement. Regardless of which, if any, alternative payment model we participate in, everyone in the orthopaedic community should think about how to become more efficient in our delivery of musculoskeletal care. And this study provides a conceptual framework and benchmarks for identifying where the room for improvement is.

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

Stronger Hands Related to Better Outcomes in THA and TKA

This post comes from Fred Nelson, MD, an orthopaedic surgeon in the Department of Orthopedics at Henry Ford Hospital and a clinical associate professor at Wayne State Medical School. Some of Dr. Nelson’s tips go out weekly to more than 3,000 members of the Orthopaedic Research Society (ORS), and all are distributed to more than 30 orthopaedic residency programs. Those not sent to the ORS are periodically reposted in OrthoBuzz with the permission of Dr. Nelson.

Up to 33% of patients are dissatisfied with their outcome after a knee or hip replacement. It’s evident that successful recovery from lower-limb joint replacement is aided by leg strength and stamina, but handgrip strength has been proposed as a proxy for a person’s overall muscle strength. A recent prospective cohort study1 of 226 patients who underwent total hip arthroplasty (THA) and 246 patients who underwent total knee arthroplasty (TKA) investigated the association between handgrip strength measured preoperatively with a dynamometer and changes in preoperative versus 1-year postoperative patient-reported outcome scores. Researchers analyzed the data after adjusting for sex, body mass index, and baseline scores.

For both THA and TKA patients, handgrip strength was positively associated with most physical function, symptom, and quality-of-life scores measured with HOOS, KOOS, and SF-36 questionnaires. On the other hand, there was no association between grip strength and mental-component scores in either the THA or TKA group.

Based on a review of the literature and this study’s findings, the authors conclude that the association between handgrip strength and THA/TKA outcomes is partly dependent on the joint site. Although the mechanism to explain the association has not been elucidated, translating these findings into an informal dynamometer-based tool could help clinicians counsel prospective joint-replacement patients about the value of preoperative conditioning.

1. Meessen JMTA, Fiocco M, Tordoir RL, Sjer A, Verdegaal SHM, Slagboom PE, Vliet Vlieland TPM, Nelissen RGHH. Association of handgrip strength with patient-reported outcome measures after total hip and knee arthroplasty. Rheumatol Int. 2020 Apr;40(4):565-571. doi: 10.1007/s00296-020-04532-5. Epub 2020 Feb 18. PMID: 32072233

Impressive Long-term Outcomes in Revision TKA with Constrained Prostheses

Time is an enemy of all orthopaedic implants, just as it is the bane of native joints. It is therefore helpful to accurately measure how long and well specific implant types last. That is what Kim et al. have done with their 19-year follow up of 90 patients (107 knees) who underwent total knee arthroplasty (TKA) with a constrained condylar knee prosthesis. Their findings appear in the April 15, 2020 issue of The Journal of Bone & Joint Surgery.

Knee arthroplasty surgeons often choose constrained prostheses to improve joint stability in patients with ligament dysfunction, and the typically longer stems of these implants can also compensate for poor bone stock. Kim et al. evaluated the same patient population (mean age of 65 years; mean BMI of 26.9 kg/m2) that they reported on in an earlier study, finding the following outcomes after a mean follow-up of 19 years:

  • 96% survival in terms of mechanical failure
  • 91% survival in terms of reoperation for any reason
  • Patient-reported outcome scores that remained significantly improved from pre-revision values
  • Only 1 knee with osteolysis around a component

Among the few knees that required re-revision, 5 such operations were performed due to aseptic loosening and 4 due to infection. The authors note that these very good long-term results are similar to those in previous studies of revision TKAs using various implant types. Kim et al. attribute these findings to several possible factors:

  • Low prevalence of comorbidities, including obesity, among the patients
  • Excellent surgical technique, including good cementing and correct flexion and extension gaps
  • Use of compression-molded polyethylene

Does Computer-Assisted Surgery Drive Better TKA Outcomes?

Computer-assisted surgery (CAS) for total knee arthroplasty (TKA) has become popular largely based on claims that the technology improves accuracy of component positioning and alignment. Theoretically, that leads to superior patient-reported outcomes. However, the use of CSA has not reliably yielded improvements in implant survival or clinical outcomes. A large registry study by Roberts et al. in the April 1, 2020 issue of The Journal sheds additional light on this perplexing question.

An earlier study by the same author group used data from the same New Zealand Joint Registry and showed no difference in functional outcomes or implant survival between TKAs performed with and without CAS.1 However, that study did not account for the potential bias introduced by surgeons who use CAS only for complex cases.

In this study, Roberts et al. analyzed data from 2 carefully selected groups of surgeons: those who used CAS in 90% of their TKAs (“routine CAS” surgeons) and those who used CAS in <10% of their TKAs (“routine conventional” surgeons). Further limiting their analysis to surgeons with >50 TKAs recorded in the registry between 2006 and 2018, Roberts et al. identified 25 “routine CAS” surgeons and 22 “routine conventional” surgeons. This allowed a comparison between 9,501 TKAs performed by routine CAS surgeons and 7,672 TKAs performed by routine conventional surgeons.  While analyzing revision rates and Oxford Knee Scores (OKS) at 6 months, 5 years, and 10 years, the authors also controlled for confounding variables such as age, body-mass index, and implant type.

With a mean follow-up of 4.5 years, the authors found a revision rate per 100 component-years of 0.437 in the group operated on by routine CAS surgeons, compared to a mean 4.9-year revision rate of 0.440 in the group operated on by routine conventional surgeons (p=0.724).  When stratifying outcomes of patients <65 years old, the authors again found no statistical difference in revision rates. They also found no between-group differences in OKS within the full and <65 cohorts at 6 months, 5 years, or 10 years.

The findings prompt the authors (and I) to wonder whether continually improving design and durability of modern implants make it difficult to discern any advantage from computer assistance in implant positioning.

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


  1. Roberts TD, Clatworthy MG, Frampton CM, Young SW. Does computer assisted navigation improve functional outcomes and implant survivability after total knee arthroplasty? J Arthroplasty. 2015 Sep; 30(9)Suppl: 59-63.

What Is a “High-Priority” Knee Replacement?

This post comes from Fred Nelson, MD, an orthopaedic surgeon in the Department of Orthopedics at Henry Ford Hospital and a clinical associate professor at Wayne State Medical School. Some of Dr. Nelson’s tips go out weekly to more than 3,000 members of the Orthopaedic Research Society (ORS), and all are distributed to more than 30 orthopaedic residency programs. Those not sent to the ORS are periodically reposted in OrthoBuzz with the permission of Dr. Nelson.

The coronavirus epidemic has caused all of us to “rethink” many things. Several days ago, a radiologist asked me whether 3 of my requested imaging studies were high priority in light of the pandemic. My response was, “God bless you. No, none of those is urgent.”

I am 79 years old and think back to my first year of orthopaedic residency, 1968. In 2020, the expectation among many patients is for immediate relief, and many orthopaedists try to deliver that. Whatever “new normal” emerges after the COVID-19 surge subsides, how will patients and physicians work together to arrive at a decision when to proceed to a knee replacement? Although knee replacement can result in pain and function salvation for patients with end-stage knee osteoarthritis, as many as 20% of patients report “unsatisfactory” results.

A recent “appropriateness” analysis of data from 2 multicenter cohort studies classified 3,417 potential knee replacements as follows:

  • Timely—total knee replacement took place within 2 years after the procedure had met “potentially appropriate” criteria
  • Potentially Appropriate but Not Replaced (for >2 years after the procedure had met appropriateness criteria)
  • Premature—a replacement that the authors deemed inappropriate but was performed anyway.

The authors found that surgery for 9% of the knees for which replacement was potentially appropriate took place in a “timely” manner. But overall, there was a high prevalence of both delayed and premature surgery. Specifically, 91% of the knees for which replacement was potentially appropriate were not replaced, and 26% of the 1,114 total knee replacements that were performed were considered to be “likely inappropriate” and therefore “premature.”

The likelihood of a knee being classified as potentially appropriate but not undergoing replacement was greater among black patients, and the likelihood of having premature total knee replacement was lower among participants with a body mass index of >25 kg/m2 and those with depression.

In a Commentary on this study, Michael G. Zywiel, MD noted that the Escobar appropriateness criteria used in the analysis focuses predominantly on physician-assessed rather than patient-assessed factors. This all begs the question: Now that we have joint-replacement tools that we could not even dream of in 1968, how do we as responsible surgeons help guide our patients in deciding when the time is right to use them?