Based on available data, it appears that most arthroplasty surgeons in the United States (myself included) usually resurface the patella during total knee arthroplasties (TKAs). This strategy is supported by much of the orthopaedic literature, but there is no universal consensus on which approach is best. Internationally, surgeons in some countries resurface the patella <20% of the time.
Amid this debate, the March 6, 2019 JBJS study by Maney et al. utilizes the New Zealand Joint Registry to shine a little more light on the issue. After analyzing close to 60,000 primary TKAs performed by 203 surgeons, the authors found that patients who underwent knee arthroplasty by surgeons who “usually” (>90% of the time) resurfaced the patella had significantly higher patient-reported Oxford Knee Scores at both 6 months and 5 years postoperatively, compared to those who had their knee replacements performed by surgeons who “selectively” (≥10% to ≤90% of the time) or “rarely” (<10% of the time) resurfaced the patella. However, only 7% of the surgeons in the study fell into the usually-resurface category. That fact, along with the authors’ inability to account for possible confounding patient or surgeon factors, imparts some fragility to the study’s data. Just as (or even more) importantly, the authors did not find any differences in revision rates per 100 component years between the three resurfacing strategies, with >92% survival for all implants at 15 years postoperatively.
This study seems to support previously published data suggesting that resurfacing the patella yields functional outcomes that are at least as good as, if not slightly better than, those with not resurfacing the patella. Still, added costs and potential complications are associated with patellar resurfacing, and these results could also be used to support the strategy of surgeons who do not routinely perform that part of a total knee arthroplasty.
While we still don’t know the “best” strategy, this study adds further credence to the notion that there is not a “wrong” technique when it comes to resurfacing the patella, and surgeons should continue to use whichever technique they feel is best for individual patients.
Chad A. Krueger, MD
JBJS Deputy Editor for Social Media
The main advantage of joint registries is their large number of recorded procedures, ideally with very few patient “types” not represented in the database. This is the case with the Australian Orthopaedic Association National Joint Replacement Registry, which includes data on almost 100% of all joint replacements performed in Australia since 2002. In the February 20, 2019 issue of The Journal, Jorgenson et al. analyze almost 6,000 major aseptic total knee arthroplasty (TKA) revisions from a cohort of 478,000 primary TKAs registered between 1999 and 2015. This analysis provides robust benchmark data for patients and surgeons, although it comes too late for the 3% of patients who required such a revision surgery within the 15-year study period.
The authors found that fixed bearings were revised for aseptic reasons at a significantly lower rate than mobile bearings (2.7% vs 4.1%, respectively) and that patients <55 years old had an almost 8-fold higher revision rate compared to patients ≥75 years old ( 7.8% versus 1.0%, respectively). The study also found lower aseptic revision rates with minimally stabilized total knee prostheses compared to posterior-stabilized prostheses, and higher aseptic revision rates with completely cementless fixation relative to either hybrid or fully cemented fixation. These are valuable data for arthroplasty surgeons in terms of selecting implants and surgical techniques and for preoperative counseling of patients—especially younger ones. While many of these findings have been previously reported, these registry-based results add significant strength to published data.
Ideally, data such as these would be controlled for confounding variables such as surgeon experience and additional patient-specific variables such as activity demands and medical comorbidities. Still, these data provide useful prosthesis-specific factors for shared decision making with patients. We look forward to more helpful information from this and other national joint registries and encourage the continued growth of similar registries in other subspecialties.
Marc Swiontkowski, MD
The anticipation of postoperative pain associated with a large operation such as a total knee arthroplasty (TKA) scares many patients. Some worry to the point of “catastrophizing” pain prior to surgery. As orthopaedic surgeons, we try to assuage our patients’ fears through preoperative education and multimodal pain-management modalities after surgery, but there are still some patients in whom the fear of pain—and the pain itself that inevitably accompanies arthroplasty— negatively affect their outcome. Preparing such patients for surgery and helping them recover afterward despite this high anxiety are big challenges for the orthopaedic care team. Some data suggest that cognitive behavioral therapy (CBT) might help.
However, a multisite randomized trial by Riddle et al. published in the February 6, 2019 issue of JBJS did not find any differences in pain or function among patients with moderate to high preoperative pain catastrophizing scores who underwent a form of CBT focused on pain coping skills, when their outcomes were compared to those of similar patients in “usual care” or “arthritis education” arms of the study. Each group had similar WOMAC pain scores and pain catastrophizing scores to start, and all patients were found to have significant but very similar decreases in their pain scores at 2, 6, and 12 months postoperatively. Independent assessors determined that the quality of the intervention in the coping-skills and arthritis-education arms was high, suggesting that it was not poor-quality interventions that accounted for the consistent similarities among the 3 groups.
While there are many physiological and psychological factors contributing to an individual’s experience of pain, the results of this study ran surprisingly counter to prior evidence. The authors speculate that differences between the 3 groups may have been masked by the fact that all patients had such a large decrease in pain after the TKA. While that would appear to be good news, we know that there is a stubbornly large subset of patients (cited in this article as 20%) who undergo a technically and radiographically ”successful” knee arthroplasty only to have continued pain without an obvious cause. (See related OrthoBuzz Editor’s Choice post.)
These findings lead me to believe a statement that probably cannot be proven: there are some patients who will experience function-limiting pain no matter what surgery is performed, no matter which drugs are administered, and no matter what rehabilitative therapy is provided. Learning how to identify those patients and clearly communicating expectations to them pre- and postoperatively might help improve their satisfaction with their procedure.
Chad A. Krueger, MD
JBJS Deputy Editor for Social Media
Every month, JBJS publishes a review of the most pertinent and impactful studies published in the orthopaedic literature during the previous year in one of 13 subspecialties. Click here for a collection of all OrthoBuzz subspecialty summaries. This month, Michael J. Taunton, MD, author of the January 16, 2019 “What’s New in Adult Reconstructive Knee Surgery,” selected the five most compelling findings from among the more than 100 noteworthy studies summarized in the article.
Cementless vs Cemented TKA Fixation
—A matched case-control study of 400 primary total knee arthroplasties (TKAs) found that cementless TKAs had a 0.5% rate of aseptic loosening over a mean follow-up of 2.5 years, while cemented TKAs had an aseptic loosening rate of 2.5%.1
TKA Component Size in Obese Patients
—Among 35 revision-TKA patients with a varus collapse of the tibia, 29 weighed >200 lbs. Fehring et al. found that patients with implants at the small end of the range of the manufacturer’s tibial size offering and with >5° of preoperative varus were at increased risk of tibial-component failure.2
—A retrospective multivariate analysis of >4,300 patients who underwent outpatient TKA and >128,900 patients who underwent inpatient TKA found that, within 1 year, those who had outpatient procedures were more likely to experience a tibial and/or femoral component revision due to a noninfectious cause, irrigation and debridement, explantation of the prosthesis, and stiffness requiring manipulation under anesthesia.
—In a randomized trial of patients undergoing TKA, one group received 15 mg/kg of systemic intravenous vancomycin, and a second group received intraosseous regional administration of 500 mg vancomycin into the tibia. Mean tissue concentrations of the antibiotic were 34.4 mg/g in the intraosseous group and 6.1 mg/g in the intravenous group, suggesting that intraosseous administration provides a significantly higher tissue concentration of that antibiotic. 3
TKA Anesthesia Protocol
—A retrospective review of 156 consecutive patients who underwent primary TKA found that procedures performed with mepivacaine spinal anesthesia led to fewer episodes of urinary catheterization and shorter mean length of stay compared with procedures performed with bupivacaine spinal anesthesia.4
- Miller AJ, Stimac JD, Smith LS, Feher AW, Yakkanti MR, Malkani AL. Results of cemented vs cementless primary total knee arthroplasty using the same implant design. J Arthroplasty.2018 Apr;33(4):1089-93. Epub 2017 Dec
- Fehring TK, Fehring KA, Anderson LA, Otero JE, Springer BD. Catastrophic varus collapse of the tibia in obese total knee arthroplasty. J Arthroplasty.2017 May;32(5):1625-9. Epub 2017 Jan 30.
- Chin SJ, Moore GA, Zhang M, Clarke HD, Spangehl MJ, Young SW. The AAHKS Clinical Research Award: intraosseous regional prophylaxis provides higher tissue concentrations in high BMI patients in total knee arthroplasty: a randomized trial. J Arthroplasty.2018 Jul;33(7S):S13-8. Epub 2018 Mar 15.
- Mahan MC, Jildeh TR, Tenbrunsel TN, Davis JJ. Mepivacaine spinal anesthesia facilitates rapid recovery in total knee arthroplasty compared to bupivacaine. J Arthroplasty.2018 Jun;33(6):1699-704. Epub 2018 Jan 16.
When Medicare’s Comprehensive Care for Joint Replacement (CJR) program was implemented in 2016, the health care community—especially orthopaedic surgeons— had 2 major concerns. First, would the program actually demonstrate the ability to decrease the costs of total joint replacements while maintaining the same, or improved, outcomes? Second, would CJR promote the unintended consequence of participating hospitals and surgeons ”cherry picking” lower-risk patients and steering clear of higher-risk (and presumably higher cost) patients? Both of these questions were at the heart of the study by Barnett et al. in a recent issue of the New England Journal of Medicine.
The authors evaluated hip and knee replacements at 75 metropolitan centers that were mandated to participate in the CJR program and compared the costs, complication rates, and patient demographics to similar procedures at 121 control centers that did not participate in CJR. The authors found significantly greater decreases in institutional spending per joint-replacement episode in institutions participating in the CJR compared to those that did not. Most of these savings appeared to come from CJR-participating institutions sending fewer patients to post-acute care facilities after surgery. Furthermore, the authors did not find differences between centers participating in the CJR and control centers in terms of composite complication rate or the percentage of procedures that were performed on high-risk patients.
While this 2-year evaluation does not provide the level of detail necessary to make far-reaching conclusions, it does address two of the biggest concerns related to CJR implementation from a health-systems perspective. There may be individual CJR-participating centers that are not saving Medicare money or that are cherry picking lower-risk patients, but overall the program appears to be doing what it set out to do—successfully motivating participating hospitals and healthcare facilities to look critically at what they can do to decrease the costs of a joint-replacement episode while simultaneously maintaining a high level of patient care. The Trump administration shifted CJR to a partly voluntary model in March 2018, and I hope policymakers consider these findings if further changes to the CJR model are planned.
Chad A. Krueger, MD
JBJS Deputy Editor for Social Media
Many older patients present to orthopaedic surgeons with clinical knee pain suggestive of osteoarthritis (OA) but with little or no radiographic evidence of disease. And a substantial proportion of those patients do not respond adequately to the recommended, first-line nonsurgical treatment approaches to knee OA. A prognostic study by Everhart et al. in the January 2, 2019 issue of The Journal of Bone & Joint Surgery helps explain why that might be.
The authors evaluated baseline knee radiographs and MRIs from >1,300 older adults (mean age of 61 years) who were enrolled in the Osteoarthritis Initiative, a multicenter observational cohort study with a median of 9 years of follow-up data. They sought to determine independent risk factors for progression to total knee arthroplasty (TKA) among this cohort, all of whom showed Kellgren-Lawrence grade 0 to 3 OA on knee radiographs. MRIs taken at baseline revealed that 38% of those patients had a full-thickness knee-cartilage defect. After the authors adjusted for various confounders (including age, weight, and symptom severity), they found that regardless of radiographic grade, the presence of a full-thickness cartilage defect was a strong independent risk factor for subsequent TKA. Moreover, patients with a defect ≥2 cm2 had twice the risk of arthroplasty compared with patients with defects <2 cm2.
According to the authors, the findings highlight the “greater importance of full-thickness cartilage loss over radiographic OA grade as a determinant of OA severity, specifically regarding the risk of future knee arthroplasty in older adults.” In his commentary on this study, Drew A. Lansdown, MD emphasizes that Everhart et al. “do not advocate for the routine use of MRI in the diagnosis of knee osteoarthritis,” but he says the findings “do suggest that early MRI may have a diagnostic role for patients who are not responding as expected to nonoperative measures.” Noting that the patients in this cohort would probably not be ideal candidates for current cartilage-restoration procedures, Dr. Lansdown encourages further research focused on identifying “patient-specific factors that can match patients with the treatment…that will provide the greatest likelihood of symptom relief and functional improvement.”
Somewhere between 10% and 15% of patients are unsatisfied with their outcome after primary total knee arthroplasty (TKA). In some cases, dissatisfaction is related to poor range of motion, but more often it is related to residual—or even intensified—pain in the knee several weeks after surgery.
In the January 2, 2019 issue of The Journal, Koh et al. report the results of a prospective randomized trial assessing the effects of duloxetine (Cymbalta) in TKA patients who were screened preoperatively for “central sensitization.” In central sensitization, a hyperexcitable central nervous system becomes hypersensitive to stimuli, noxious and otherwise.
Koh et al. randomized 80 centrally sensitized patients (mean age of 69 years), 40 of whom received a multimodal perioperative pain management protocol plus duloxetine, and 40 of whom received the multimodal protocol without duloxetine. During postoperative weeks 2 through 12, patients taking duloxetine reported better results in terms of pain and functional and emotional outcome measures than those not receiving the drug. Patients in the duloxetine group expressed greater satisfaction with pain control (77% vs 29%) and daily activity (83% vs 52%) at postoperative week 12, compared with those in the control group.
This research represents an important advance in identifying and treating patients who are prone to poor outcomes after TKA. The concept of central sensitization is relatively new to the orthopaedic community, and this pharmacologic intervention is likely to be just the first among many that will help these patients. I think it is probable that other, nonpharmacological interventions will eventually be as or even more successful in helping TKA patients with central sensitization. Koh et al. make a valuable contribution in this article by educating us as to the neurophysiologic basis of this condition, and their work should pave the way for more important research in this area.
Marc Swiontkowski, MD
It is well established that obese patients who undergo total joint arthroplasty have increased risks of complications and infections. But what about folks who are not obese, but are just generally large? Do they also have increased post-arthroplasty complications, compared to their smaller counterparts? That is the question Christensen et al. explored in a registry-based study in the November 7, 2018 edition of JBJS.
In addition to BMI, the authors examined 3 other physical parameters—body surface area, body mass, and height—to determine whether these less-studied characteristics (all contributing to “bigness”) were associated with an increased rate of various adverse outcomes, including mechanical failure and infection, after primary total knee arthroplasty (TKA). They evaluated data from more than 22,000 TKAs performed at a single institution and found that the risk of any revision procedure or revision for a mechanical failure was directly associated with every 1 standard deviation increase in BMI (Hazard Ratio [HR], 1.19 and 1.15, respectively), body surface area (HR, 1.37 and 1.35, respectively), body mass (HR, 1.30 and 1.27, respectively), and height (HR, 1.22 and 1.23, respectively). In this study, 1 standard deviation was equivalent to 6.3 kg/m2 for BMI, 0.3 m2 for body surface area, 20 kg for body mass, and 10.5 cm for height.
These findings, while not all that surprising, are enlightening nonetheless. The study shows that increasing height has a greater negative impact on TKA outcomes than previously thought. While I spend a lot of time counseling patients with high BMIs about the increased risks of undergoing a TKA (and while such patients can take certain actions to lower their BMI prior to surgery), I do not spend nearly as much time counseling patients who are much taller than normal about their increased risks (and height is not a modifiable risk factor). Nor do I spend much time thinking about a patient’s overall body mass or body surface area in addition to their BMI. This study will remind me not to overlook these less commonly examined physical parameters when discussing TKA with patients in the future.
Chad A. Krueger, MD
JBJS Deputy Editor for Social Media
Surgical treatment for knee osteoarthritis (OA) has become increasingly common. The many people who have damage to only one part of their joint (unicompartmental knee OA) are faced with three options—total knee arthroplasty (TKA), unicompartmental knee arthroplasty (UKA), or nonsurgical treatment. A study by Kazarian et al. in the October 3, 2018 issue of The Journal estimates the lifetime cost-effectiveness for those three options in patients from 40 to 90 years of age.
The authors used sophisticated computer modeling to estimate both direct costs (those related to medical/surgical care) and indirect costs (such as missed workdays) of the three options as a function of patient age at the time of treatment initiation. Here are the key findings:
- The surgical treatments were less expensive and provided patients from 40 to 69 years of age with a greater number of quality-adjusted life years (QALYs) than nonsurgical treatment.
- In patients 70 to 90 years of age, surgical treatments were still cost-effective compared with nonsurgical treatment, albeit less so than in younger patients. In this older age group, “cost-effectiveness ratios” of surgical treatment remained below a “willingness to-pay” threshold of $50,000 per QALY.
- When the two surgical treatments were compared to one another, UKA beat TKA decisively in cost-effectiveness among patients of any age.
After crunching more numbers, Kazarian et al. estimated that, by 2020, if all of the patients with unicompartmental knee OA who were candidates for UKA or TKA (a projected total of 120,000 to 210,000 people) received UKA, “it would lead to a lifetime cost savings of $987 million to $1.5 billion.
From these findings, the authors conclude that patients with unicompartmental knee OA should receive surgical treatment, preferably UKA, instead of nonsurgical treatment until the age of 70 years. After that age, all three options are reasonable from a cost-effectiveness perspective.
But perhaps the most important thing to remember about these findings is that they add information to—but should not replace—clinical decision-making based on complete and open communication between doctor and patient.
Annual volume projections for total joint arthroplasty (TJA) have been cited frequently and applied broadly, often to estimate future costs. But with a slowdown in the growth of the annual incidence of total knee arthroplasty (TKA), updated projections are needed, and that’s what Sloan et al. provide in the September 5, 2018 issue of JBJS.
Using the National Inpatient Sample to obtain TJA incidence data, the authors first analyzed the volume of primary TJA procedures performed from 2000 to 2014. They then performed regression analyses to project future volumes of TJA procedures. Here are the numbers based on the 2000-to-2014 data:
- Primary total hip arthroplasty (THA) is projected to grow 71%, to 635,000 annual procedures by 2030.
- Primary TKA is projected to grow 85%, to 1.26 million annual procedures by 2030.
However, the TKA procedure growth rate has slowed in recent years, and models based on 2008-to-2014 data project growth to only 935,000 annual TKAs by 2030—325,000 fewer procedures relative to the 2000-to-2014 models.
Earlier studies, notably one by Kurtz et al. in 2007, obviously could not account for the reduced growth rate in TKA after 2008. A 2008 analysis by Wilson et al., based on the Kurtz et al. data, estimated that annual Medicare expenditures on TJA procedures would climb from $5 billion in 2006 to $50 billion in 2030. “Using our projections,” say Sloan et al., “we predict that Medicare expenditures on these procedures in 2030 will be less than half of that predicted by Wilson et al.”
These findings lend credence to the authors’ observation that “it is imperative that projections of orthopaedic procedures be regularly evaluated and updated to reflect current rates.”