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More Data on Outpatient vs Inpatient Joint Replacement

TKA for OBuzzIn addition to the Pearl Diver-based retrospective study by Arshi et al. on one-year complications after outpatient knee replacement, the December 6, 2017 issue of JBJS contains a NSQIP-based retrospective study by Basques et al. that compares 30-day adverse events and readmissions among 1,236 patients who underwent same-day-discharge hip or knee (total or unicompartmental) arthroplasty with an equal number of propensity score-matched patients who were discharged at least 1 calendar day after the procedure.

When analyzing all three procedures together, the authors found no overall between-group differences in the rates of any adverse event (severe or minor) or readmission. However, when authors analyzed individual adverse events, the same-day group had decreased thromboembolic events and increased 30-day reoperations compared to inpatients. Analysis of individual procedures revealed an increased 30-day reoperation rate for same-day total knee arthroplasty (TKA), compared with inpatient TKA. Overall, infection was the most common reason for reoperation and readmission following same-day procedures.

As with the Arshi et al. study, the limitations of the database prevented these authors from accounting for physician or hospital volume. However, they did identify several preoperative patient characteristics that increased the risk of 30-day readmission among same-day patients, and from those findings Basques et al. concluded that “obese patients, older patients [≥85 years of age], and those with diabetes mellitus may not be appropriate candidates for same-day procedures.”

Modern Irrigation/Debridement Yields Good Results for Early Post-THA Infection

Hip Debridement for OBuzzNowadays, chronic deep periprosthetic joint infections (PJIs) are typically treated with 2-stage exchange arthroplasty, but what about acute PJIs? In the December 6, 2017 edition of JBJS, Bryan et al. report on a retrospective cohort study of acute infections after hip arthroplasty. The results suggest we’ve come a long way in identifying patients with early infections and that contemporary irrigation-and-debridement protocols are more successful than older methods.

The researchers studied 6-year outcomes in 90 hips that had undergone either total or hemiarthroplasty and that were determined to have either acute early postoperative infections (n=66) or acute hematogenous infections (n=24). All the infected hips were managed with either irrigation, debridement, and modular head and liner exchange (70%) or with irrigation and debridement alone (30%). The authors stratified the patients into those without comorbidities (A), those with 1 or 2 comorbidities (B), and those with >2 comorbidities (C). Postoperatively, patients were treated with broad-spectrum intravenous antibiotics, followed by targeted therapy administered by infectious disease specialists.

Of the 90 acute infections, failure—defined as uneradicated infection, subsequent removal of any component for infection, unplanned second wound debridement for ongoing infection, or infection-related mortality—occurred in 15 hips (17%). Of those 15, 9 required component removal. The chances of treatment failure were slightly higher in cases of hematogenous infection (21%), compared with acute early postoperative infection (15%), but that difference was not statistically significant. Significant comorbidity-related failure-rate differences were found: failure occurred in 8% of the grade-A patients, 16% of grade-B patients, and 44% of grade-C patients. The most common infecting organism was methicillin-sensitive Staphylococcus aureus (MSSA).

From this overall 6-year success rate of 83%, the authors conclude that “with modern inclusion criteria for acute infection, modern surgical techniques, and modern antibiotic therapy…the rate of success was higher than in most historic reports.”

December 2017 Article Exchange with JOSPT

JOSPT_Article_Exchange_LogoIn 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 December 2017, JBJS and OrthoBuzz readers will have open access to the JOSPT article titled “Hip Abductor Muscle Volume and Strength Differences Between Women With Chronic Hip Joint Pain and Asymptomatic Controls.

This cross-sectional study demonstrated that women with chronic hip joint pain had larger gluteal muscle volume but decreased hip abductor strength, compared to asymptomatic controls.

Fructosamine Bests HbA1c for Preop Glycemic Screening

Fructosamine for OBuzzPatients 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.

High Value Joint Replacements at Physician-Owned Hospitals

H image for OBuzzIn 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
JBJS Editor-in-Chief

Certain Comorbidities Boost Risk of Acute Kidney Injury after THA

AKI Risk for OBuzzThe relationship between chronic kidney disease (CKD) and acute kidney injury (AKI) is circular: surgical patients with preexisting CKD are at increased risk of AKI, and even mild or transient AKI is associated with future development of CKD.

In the November 1, 2017 JBJS, Gharaibeh et al. report findings from a retrospective cohort study with a nested case-control analysis that assessed the rate and risk factors associated with AKI after total hip arthroplasty (THA).

From a total of 10,323 THAs analyzed, AKI developed postoperatively in only 114 cases (1.1%). A multivariate analysis of the entire cohort identified four preoperative comorbidities that increased the risk of AKI by 2- to 4-fold: CKD, heart failure, diabetes, and hypertension. In addition to those risk factors, an analysis of the case-control cohort found that increasing BMI and perioperative blood transfusions were also associated with a higher risk of AKI.

Using data from the entire cohort, the authors developed an AKI risk calculator focused on presurgical variables (see graph). Based on that model, which will require independent validation, a 65-year-old man with either CKD or heart failure would have a 2% risk of AKI; the risk would increase to 4% if that patient had CKD and hypertension and to 16.1% in the presence of CKD, hypertension, and heart failure.

The anticipated increase in demand for joint replacements could lead to US surgeons performing approximately 572,000 THAs during the year 2030. A certain (and possibly increasing) proportion of those future procedures will occur in patients who have hypertension, diabetes, heart failure, and/or chronic kidney disease. The findings from Gharaibeh et al., especially the yet-to-be-validated AKI risk score, could help hip surgeons better counsel patients and identify those who might benefit from heightened postsurgical monitoring of kidney function.

What’s New in Hip Replacement 2017

THA for OBuzzEvery month, JBJS publishes a Specialty Update—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 OrthoBuzz Specialty Update summaries.

This month, James T. Ninomiya, MD, MS, lead author of the September 20, 2017 Specialty Update on Hip Replacement, selected the five most clinically compelling findings from among the more than 50 studies covered in the Specialty Update.

Obesity and THA Outcomes
–Obesity is a well-established risk factor for perioperative THA complications. A prospective registry-based study found that reoperation and implant revision or removal rates increased with increasing BMI. More specifically, increasing BMI was associated with increased rates of early hip dislocation and deep periprosthetic infection.

Infection Prevention
–Two studies 1, 2 demonstrated that patients who have intra-articular injections within 3 months prior to THA experienced nearly double the risk of periprosthetic infection in the first postoperative year, compared with those in noninjection control groups.

Surgical Approaches to THA
–A study of >2,100 patients revealed that, despite claims to the contrary, there were no differences in dislocation rates between those who underwent THA using the direct anterior approach and a propensity-score matched cohort who underwent THA using a posterior approach.3

OR Temperature
–What is the optimal temperature for an orthopaedic operating room? Anecdotes are often used to justify keeping operating rooms at uncomfortably high temperatures, which leads to discomfort and fatigue for members of the surgical team. A comprehensive literature review led authors to suggest that preoperative patient warming, intraoperative patient warming with forced-air devices, and keeping OR temperature at ≤19° C is the ideal combination for comfort while still maximizing patient safety and outcomes.

Return to Driving
–Following joint replacement, patients often ask when it will be safe to return to driving. A meta-analysis of 19 studies concluded that the mean time for return to baseline reaction time for braking was 2 weeks following a right-sided hip replacement and 4 weeks following a right-sided knee replacement.4 The authors stressed, however, that return-to-driving recommendations should be individualized for each patient.


  1. Schairer WW, Nwachukwu BU, Mayman DJ, Lyman S, Jerabek SA. Preoperative hip injections increase the rate of periprosthetic infection after total hip arthroplasty. J Arthroplasty. 2016 ;31(9)(Suppl):166–169.e1. Epub 2016 Apr 22.
  2. Werner BC, Cancienne JM, Browne JA. The timing of total hip arthroplasty after intraarticular hip injection affects postoperative infection risk. J Arthroplasty. 2016 ;31(4):820–3. Epub 2015 Sep 1.
  3. Maratt JD, Gagnier JJ, Butler PD, Hallstrom BR, Urquhart AG, Roberts KC. No difference in dislocation seen in anterior vs posterior approach total hip arthroplasty. J Arthroplasty. 2016 ;31(9)(Suppl):127–30. Epub 2016 Mar 15.
  4. van der Velden CA, Tolk JJ, Janssen RPA, Reijman M. When is it safe to resume driving after total hip and total knee arthroplasty? A meta-analysis of literature on post-operative brake reaction times. Bone Joint J. 2017 ;99-B(5):566–76.

Has Conventional Polyethylene Become Obsolete in THA?

XLPE for OBuzzHighly cross-linked polyethylene (XLPE) has been in clinical use for nearly 15 years. In acetabular components for total hip arthroplasty (THA), XLPE’s superior wear characteristics and lower revision rates, relative to conventional polyethylene (PE), have been demonstrated in numerous studies. Here is one more: a 10-year Level I study in the October 18, 2017 issue of The Journal of Bone & Joint Surgery by Devane et al.

In this double-blinded, randomized trial, authors measured 2-D, 3-D, and volumetric wear (in mm or mm2), along with wear rates (mm/year), presence or absence of osteolysis, and revision rates in 91 patients at specified time intervals, up to a minimum of 10 years. The following results corroborate the general findings from most other studies on this topic:

  • The mean 3-D wear rate among patients with the XLPE acetabular liner was 0.03 mm/yr, versus 0.27 mm/yr among patients with conventional PE.
  • Eight percent of patients in the XLPE group showed radiographic evidence of osteolysis, versus 38% of patients in the PE group.
  • Patients with the conventional PE liner had a significantly higher revision rate (14.6%) than those with the XLPE liner (1.9%).

There were no significant between-group differences in clinical outcome scores, including the Oxford Hip Score and SF-12 physical well-being score.

The authors note that “the longer-term implications of these findings are unclear,” but their calculations indicated that, through 20 years, none of the XLPE liners would wear through, but 6 of the conventional PE liners would require revision due to wear-through.

Long-term Results Show No Advantage to “Minimalist” THA

Minimal Incision THA for OBuzzThe debate regarding minimally invasive/minimal incision total hip arthroplasty (THA) has been simmering for a decade and a half. When assessing the impact of adult reconstruction procedures, patients and treating physicians alike are most interested in longer-term results. Improved return of function in the first 3 to 6 weeks is of some value to all patients—and perhaps of great value to younger patients—and that has been one of the purported advantages of the “minimalist” approach. But it is the long-term results that really matter.

In the October 18, 2017 issue of The Journal, Stevenson et al. provide 10-year results from a 2005 randomized trial of small-incision posterior hip arthroplasty, and they confirm it adds no clinical, radiographic, or implant-survivorship benefit when compared with a standard posterior approach. An extra caveat here is that these procedures, originally done in 2003-2004, were undertaken by a highly experienced surgeon who had performed >300 minimal-incision THAs. In the hands of surgeons with less experience, smaller incisions may result in suboptimal component positioning and other complications, a point emphasized by Stevenson et al. and by Daniel Berry in his JBJS editorial accompanying the original study.

This long-term data is of great value to patients and surgeons alike. It is my hope that such high-quality evidence will temper the claims used in marketing materials that hype minimally invasive approaches, to which hip surgeons are routinely subjected.

Marc Swiontkowski, MD
JBJS Editor-in-Chief

D-Dimer Levels May Help with PJI Diagnoses

D-dimer for OBuzzThe 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
JBJS Editor-in-Chief