Patients with diabetes have an increased risk of postoperative complications following total joint arthroplasty (TJA). Additionally, perioperative hyperglycemia has been identified as a common and independent risk factor for periprosthetic joint infection, even among patients without diabetes. Therefore, knowing a patient’s glycemic status prior to surgery is very helpful.
In the November 15, 2017 edition of The Journal of Bone & Joint Surgery, Shohat et al. demonstrate that serum fructosamine, a measure of glycemic control obtainable via a simple and inexpensive blood test, is a good predictor of adverse outcomes among TJA patients—whether or not they have diabetes.
Researchers screened 829 patients undergoing TJA for serum fructosamine and HbA1c—a common measure, levels of which <7% are typically considered good glycemic control. Patients with fructosamine levels ≥292 µmol/L had a significantly higher risk of postoperative deep infection, readmission, and reoperation, while HbA1c levels ≥7% showed no significant correlations with any of those three adverse outcomes. Among the 51 patients who had fructosamine levels ≥292 µmol/L, 39% did not have HbA1c levels ≥7%, and 35% did not have diabetes.
In addition to being more predictive of postsurgical complications than HbA1c, fructosamine is also a more practical measurement. A high HbA1c level during preop screening could mean postponing surgery for 2 to 3 months, while the patient waits to see whether HbA1c levels come down. Fructosamine levels, on the other hand, change within 14 to 21 days, so patients could be reassessed for glycemic control after only 2 or 3 weeks.
While conceding that the ≥292 µmol/L threshold for fructosamine suggested in this study should not be etched in stone, the authors conclude that “fructosamine could serve as the screening marker of choice” for presurgical glycemic assessment. However, because the study did not examine whether correcting fructosamine levels leads to reduced postoperative complications, a prospective clinical trial to answer that question is needed.
In the November 15, 2017 issue of The Journal, Courtney et al. carefully evaluate CMS data to compare TKA and THA costs, complications, and patient satisfaction between physician-owned and non-physician-owned hospitals. The authors used risk-adjusted data when comparing complication scores between the two hospital types, in an attempt to address the oft-rendered claim that surgeons at physician-owned facilities “cherry pick” the healthiest patients and operate on the highest-risk patients in non-physician-owned facilities.
In general, the findings suggest that, for TKA and THA, physician-owned hospitals are associated with lower costs to Medicare, fewer complications and readmissions, and superior patient-satisfaction scores compared with non-physician-owned hospitals. These findings should come as no surprise to readers of The Journal. One fundamental principle of health care finance is that physicians control 70% to 80% of the total cost of care with their direct decisions. When physician incentives are aligned with those related to the facility, the result is better care at lower cost.
Nevertheless, many policymakers remain convinced that physician-owners are completely mercenary and base every decision on maximizing profit margins—even if that includes ordering unnecessary tests, performing unnecessary procedures, or using inferior implants. We need more transparency among physician-owners at local and national levels to address these usually-erroneous assumptions, which are frequently repeated by local non-physician-owned health systems. For example, we should be transparent with the percentage of the margin that ends up in the physician-owner’s pocket. Whatever the “right” percentage is, I believe it should not be the dominant factor in a physician’s total income..
The findings from Courtney et al. should spur further debate on this issue. I am confident that the best outcomes for individual patients and the public result when physicians (and their patients) stay in direct control of decision making regarding care, when surgeons are appropriately motivated to be cost- and outcome-effective, and when we all do our part to care for the under- and uninsured.
Marc Swiontkowski, MD
This basic science tip 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.
Over the decades, the meaning of the term “phenotype” has changed. In the past it was solely applied to inherited disorders and was based on physical appearance or clinical presentation. Similarly, the term “penetrance” was applied to the variations in phenotype severity relative to normal. Over time, it has been found that penetrance is usually a reflection of different mutations for the same gene at different parts of the allele, or a mutation in one of several specific genes that could contribute to a similar phenotype.
Now, both terms have been applied to a variety of genetic and environmental circumstances that may affect physical appearance and function. In osteoarthritis research, the term “phenotype” has increasingly been used to define physical, genetic, environmental, and other variables, both past and present.
The authors of a recent abstract use a modern application for the term phenotype to systematically review the literature for studies using knee characteristics relevant for phenotyping osteoarthritis (OA).1 A comprehensive search was performed limited to observational studies of individuals with symptomatic knee OA that identified phenotypes based on OA characteristics, and then the authors assessed phenotypic association with clinically important outcomes.
Based on their abstract, 34 of 2777 citations were included in a descriptive synthesis of the data. Clinical phenotypes were investigated most frequently, followed by laboratory, imaging, and etiologic phenotypes. Eight studies defined subgroups based on outcome trajectories (pain, function, and radiographic progression). Most studies used a single patient or disease characteristic to identify subgroups, while five included characteristics from multiple domains.
Evidence from multiple studies suggested that pain sensitization, psychological distress, radiographic severity, BMI, muscle strength, inflammation, and comorbidities are associated with clinically distinct phenotypes. Gender, obesity and other metabolic abnormalities, the pattern of cartilage damage, and inflammation may delineate distinct structural phenotypes. However, only a few of the 34 studies reviewed investigated the external validity of the chosen phenotypes or their prospective validity using longitudinal outcomes.
While the authors remarked on the heterogeneity of the data included in studies investigating knee OA phenotypes, they say that the phenotypic characteristics identified in their review could form a classification framework for future studies investigating OA phenotypes.
It should be noted that the FRAX score used to calculate fragility fracture risk could be considered a phenotypically based system, the validation of which is continuing.
- Deveza LA, Melo L, Yamato TP, Mills K, Ravi V, Hunter DJ. Knee osteoarthritis phenotypes and their relevance for outcomes: a systematic review. Osteoarthritis 2017 Aug 25. pii: S1063-4584(17)31156-1. doi: 10.1016/j.joca.2017.08.009. [Epub ahead of print].
Osteochondral allograft transplantations (OCAs) are becoming a mainstay of treatment for knee-cartilage injuries. To help ensure that the allograft plug is transplanted with <1 mm of step-off from the surrounding recipient cartilage, many surgeons restrict themselves to orthotopic OCAs—matching the graft-recipient condyles in a lateral-to-lateral or medial-to-medial fashion.
However, in the October 4, 2017 issue of The Journal of Bone & Joint Surgery, Wang et al. demonstrated that both orthotopic and non-orthotopic (e.g., lateral condyle-to-medial condyle) OCA resulted in significantly improved outcomes in 77 cases followed for a mean of 4.3 years. The authors found that reoperation rates and pre- and postoperative scores in physical functioning and pain did not differ significantly between the orthotopic (n=50) and non-orthotopic (n=27) groups. These results suggest that condyle-specific matching may not be necessary.
One problem with orthotopic OCA is that 75% of the available allograft is supplied in the form of lateral condyles, while most full-thickness cartilage lesions presenting for treatment occur in the medial condyle. Consequently, surgeon preferences for orthotopic OCA limit the number of available matches and lead to an estimated 13% of available grafts being discarded.
Noting that many factors contribute to successful resurfacing of cartilage defects in the knee, the authors say that “it may be overly simplistic to assume that a conventionally matched orthotopic allograft will ensure a smooth surface contour at the recipient site.” They go on to conclude that “if surgeons forewent condyle-specific matching, more allografts would be readily available, which would shorten wait times, provide fresher grafts with increased chondrocyte viability, and lower procedure costs.”
Minimizing perioperative blood loss during total knee arthroplasty (TKA) helps curtail the risks and costs of allogeneic blood transfusions. Currently, the most popular pharmacological approach to blood conservation is the antifibrinolytic agent tranexamic acid (TXA). But in a randomized trial published in the October 4, 2017 edition of The Journal of Bone & Joint Surgery, Boese et al. found that a similar and much less expensive compound, epsilon-aminocaproic acid (EACA), performed almost as effectively and just as safely as TXA in patients undergoing unilateral knee replacement.
Although the 98 patients in the study who received TXA averaged less estimated blood loss than the 96 patients who received EACA, no transfusions were required in either group, and there were no statistically significant or clinically relevant between-group differences in the change in hemoglobin levels. On the safety/complication side, there were no statistically significant between-group differences in any measured parameter, including postoperative serum creatinine levels or renal, bleeding, or thrombotic complications. However, there were 3 pulmonary emboli in the EACA group compared with only 1 in the TXA group. While that was not a statistically significant difference, “an observed difference of this magnitude could limit the usefulness of EACA in TKA,” the authors caution.
This study did not compare the current cost of the two compounds, but back in 2012, when the authors’ institution added antifibrinolytics to their blood management program, TXA cost $43/g, compared with $0.20/g for EACA. The cost differential is striking, even when you consider that TXA is at least 7 times more potent than EACA on a molar basis, so less of the former drug is required.
Boese et al. conclude that “TXA does not have superior blood conservation effects or safety profile compared with EACA in TKA,” but they cite a need for future equivalence, superiority, and noninferiority trials with these drugs.
The percentage of periprosthetic joint infections (PJIs) among patients requiring revision arthroplasty of the hip and knee is increasing. PJIs have important clinical implications both for revision surgical procedures as well as pre- and postoperative management. Any extra help we can get making a PJI diagnosis outside of the obvious (where the patient presents with a draining wound) would be most welcome.
In the September 6, 2017 issue of The Journal, Shahi et al. present compelling data from a prospective study suggesting that serum D-dimer levels may help diagnose PJI—and thereby help determine the optimal timing of component reimplantation. The authors determined that 850 ng/mL was the optimal threshold value for D-dimer in diagnosing PJI. Moreover, with sensitivity of 89% and specificity of 93%, this test outperformed the widely used ESR and CRP tests, which until now have proven to be the “best” tools we have at our disposal.
Ideally, after these results are confirmed in larger populations of patients undergoing revision arthroplasty, the serum D-dimer test—inexpensive and almost universally available—will be used in all high-volume joint replacement centers. The continued pursuit of diagnostic and treatment methodologies for patients with suspected PJI is definitely warranted, given the increasing number of patients requiring arthroplasty and combined lifetime knee- and hip-replacement revision rates hovering around 10% to 12%. The identification of D-Dimer elevation as a potentially more accurate diagnostic tool than our currently available tests is a welcome contribution.
Marc Swiontkowski, MD
The phrase “adverse event” has been defined variably in the orthopaedic literature, which is one reason identifying the factors associated with such events can be tricky. In the August 16, 2017 edition of The Journal of Bone & Joint Surgery, Millstone et al. go a long way toward pinpointing modifiable factors that boost the risk of adverse events.
Using an institution-wide adverse-event reporting system called OrthoSAVES, the authors analyzed adverse events among 2,146 patients who underwent one of three elective orthopaedic procedures: knee replacement, hip replacement, or spinal fusion. They found an overall adverse event rate of 27%, broken down by surgical site as follows:
- 29% for spine
- 27% for knee
- 25% for hip
The most common adverse events had a low severity grade (1 or 2); the authors suggest that including events typically not viewed as severe (such as urinary retention) is one reason the overall adverse event rate in this study was higher than most previously reported.
The unique finding from this study was that two modifiable factors—length of stay and increasing operative duration—were independently associated with a greater risk of an adverse event. More specifically, the authors found that, regardless of surgical site, each additional 30 minutes of surgery increased the adjusted odds for an adverse event by 13%.
The authors were quick to point out that their findings should not be interpreted as an admonition for surgeons to hurry up. “While operative duration may be a modifiable factor, operating more quickly for spinal or any other procedures may, itself, lead to increased complications,” they wrote. Rather, Millstone et al. suggest that the multiple factors comprising “procedural efficiency” during a surgical hospitalization warrant further investigation.
Analgesia after total knee arthroplasty (TKA) is a multimodal affair these days. Main goals include maintaining adequate patient comfort while limiting opiate use and permitting early mobilization.
In the August 2, 2017 issue of JBJS, Sogbein et al. report on a blinded randomized study comparing the performance of two types of analgesia often used in multimodal TKA pain-management protocols: preoperative motor-sparing knee blocks and intraoperative periarticular infiltrations.
Prior to surgery, the 35 patients in the motor-sparing block group received a midthigh adductor canal block under ultrasound guidance, combined with posterior pericapsular and lateral femoral cutaneous injections. The 35 patients in the periarticular infiltration group received study-labeled local anesthetics intraoperatively, just prior to component implantation.
Defining the “end of analgesia” as the point at which patient-reported pain at rest or activity rated ≥6 on the numerical rating scale and rescue analgesia was administered, the authors found that the duration of analgesia was significantly longer for the motor-sparing-block group compared with the periarticular-infiltration group. The infiltration group had significantly higher scores for pain at rest for the first 2 postoperative hours and for pain with knee movement at 2 and 4 hours. There were no between-group differences in time to mobilization, length of hospital stay, opiate consumption, or functional recovery.
In 2015, JBJS launched an “article exchange” collaboration with the Journal of Orthopaedic & Sports Physical Therapy (JOSPT) to support multidisciplinary integration, continuity of care, and excellent patient outcomes in orthopaedics and sports medicine.
During the month of August 2017, JBJS and OrthoBuzz readers will have open access to the JOSPT article titled “Clinical Prediction Models for Patients With Nontraumatic Knee Pain in Primary Care: A Systematic Review and Internal Validation Study.”
This systematic review yielded two new prognostic models for function and recovery in patients with nontraumatic knee pain. A longer duration of complaints predicted poorer function.
More than 900,000 patients every year undergo knee arthroscopy in the US. Many of those procedures involve a partial meniscectomy to address symptomatic meniscal tears. Surgeons “scoping” knees under these circumstances often encounter a chondral lesion—and most proceed to debride it.
However, in the July 5, 2017 issue of JBJS, Bisson et al. report on a randomized controlled trial that suggests there is no benefit to arthroscopic debridement of most unstable chondral lesions when they are encountered during partial meniscectomy. With about 100 patients ≥30 years old in each group, the authors found no significant differences in function and pain outcomes between the debridement and observation groups at the 1-year follow-up. In fact, relative to the debridement group, the observation group had more improvement in WOMAC and KOOS pain scores at 6 weeks, better SF-36 physical function scores at 3 months, and increased quadriceps circumference at 6 months.
The authors conclude that these findings “challenge the current standards” of typically debriding chondral lesions in the setting of arthroscopic partial meniscectomy. They also surmise that, in conjunction with declining Medicare reimbursements for meniscectomies with chondral debridement, these results “may lead to a reduction in the rate of arthroscopic debridement.”