Quantitative Guidance for Treating Patients with Spinal Epidural Abscess
Any patient presenting with a spinal epidural abscess is in a high-risk situation, but decisions about operative versus nonoperative management in such cases are influenced largely by the presence, absence, or imminent risk of a motor deficit. This is why the identification by Shah et al. of 8 independent predictors of pre-treatment motor deficit and 7 independent predictors of 90-day mortality among patients with spinal epidural abscess is so important. The findings appear in the June 20, 2018 issue of JBJS.
The authors retrospectively analyzed data from 1,053 patients admitted with spinal epidural abscess at 2 tertiary medical centers and 3 regional community hospitals. Using multivariable logistic regression, they identified the following 8 significant risk factors for pre-treatment motor deficits in these patients:
- Diabetes
- Sensory changes
- Urinary incontinence/retention
- Fecal incontinence/retention
- Abscess location proximal to conus medullaris
- Abscess location dorsal to the thecal sac
- Abscess in multiple locations
- White blood cell (WBC) count >12 X 109 cells/L
Similarly, the authors identified the following 7 significant risk factors for 90-day mortality:
- Diabetes
- Age >65 years
- Active malignancy
- Renal disease requiring hemodialysis
- Pre-treatment motor deficit
- Endocarditis
- WBC count >15 X 109 cells/L
By themselves, these predictors are not prognostic, but the authors provide an algorithm that clinicians can use to generate an individualized probability of pre-treatment motor deficit or 90-day mortality for a given patient. The authors express hope that the resulting quantitative information will help guide management decisions for patients with spinal epidural abscess.
When Is a Fracture Good to Go?
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.
Determining when a fracture has healed enough for functional use can be difficult. The Radiographic Union Score for Tibia fractures (RUST) assesses fracture healing on a continuous scale from 4 to 12 points. Based on an evaluation of anteroposterior and lateral radiographs, RUST accounts for callus without visible fracture line (3 points), callus with visible fracture line (2 points), or absence of any callus (1 point) for each of four cortices. The modified RUST (mRUST) score subdivides the second parameter into two categories (callus present and bridging callus), creating a score ranging from 4 to 16 points. This tool has demonstrated high intraclass correlation coefficients (ICCs). However, until now, the correlation of these scores to mechanical properties of healed bone had not been demonstrated.
Cooke et al.1 evaluated both scores against the physical properties of bone healing by using a model of closed, stabilized femur fractures in 8- to 12-week-old male mice. Control mice received a normal diet and an experimental group received a phosphate-restricted diet. The physical properties of bone healing were determined with micro-computed tomography (µCT) and torsion testing on postoperative days 14, 21, 35, and 42. There were 10 to 16 mice in each group at any given time-point.
RUST scores from five raters were determined from anteroposterior and lateral radiographic views constructed from the µCT scans. ICCs were 0.71 (mRUST) and 0.63 (RUST). Both RUST scores were positively correlated with callus bone mineral density, bone volume fraction, callus strength, and rigidity. Radiographically healed calluses with an mRUST score of ≥13 and a RUST score of ≥10 had excellent relationships to structural and biomechanical metrics.
Mechanical properties revealed the effects of delayed healing due to phosphate dietary restrictions at later time points, but no such distinctions were found in the RUST scores. Both the RUST and mRUST scores have high correlation to physical properties of bone healing, but this tool may not be reliable for detecting poor bone quality due to nutrient deficiencies.
Reference
- Cooke ME, Hussein AI, Lybrand KE, Wulff A, Simmons E, Choi JH, Litrenta J, Ricci WM, Nascone JW, O’Toole RV, Morgan EF, Gerstenfeld LC, Tornetta P 3rd. Correlation between RUST assessments of fracture healing to structural and biomechanical properties. J Orthop Res. 2018 Mar;36(3):945-953. doi: 10.1002/jor.23710. Epub 2017 Sep 20. PMID: 28833572 PMCID: PMC5823715 DOI: 10.1002/jor.23710
Using Tranexamic Acid: Not If, But How
Most surgeons agree that tranexamic acid (TXA) is effective at reducing blood loss associated with a variety of surgical procedures, including total joint arthroplasty. The question is no longer whether it works but, more specifically, how is TXA most safely and effectively used. That was the main question Abdel et al. set out to answer in their study in the June 20, 2018 edition of The Journal. The authors completed a two-center randomized trial that compared blood loss, drain output, and transfusion rates among 320 total knee arthroplasty (TKA) patients who received intravenous (IV) TXA and 320 TKA patients who received topical TXA.
Statistically, the results of the study are clear: Patients who received intravenous TXA had significantly less blood loss (271 mL vs 324 mL; p=0.005) than those who received topical TXA. Furthermore, after authors controlled for several patient characteristics, they found that those who received topical TXA were 2.2 times more likely to receive a transfusion than those who received intravenous TXA. Still, both modalities resulted in very low transfusion and complication rates of <2% each.
Although IV TXA seems to be more effective at decreasing blood loss than topical TXA in the setting of TKA, Abdel et al. question whether the 53 mL difference is “clinically important,” considering the very low transfusion rates in both groups. What might be more clinically meaningful is the fact that the topical TXA group experienced a 5-minute delay during the procedure so the TXA could stay in contact with the tissues prior to suction and wound closure. Such a delay (which could account for about 5% of total surgical time) could put some patients at risk for other complications and is questionable without an appreciable benefit.
So, will every knee-replacement surgeon now use IV TXA instead of topical TXA? Of course not. Although the authors emphasize that there does not appear to be an increased risk of blood-clot-related complications when using IV TXA, some surgeons will still shy away from using that route of administration in certain patients. Also, some surgeons may question this study’s generalizability because of the number of perioperative variables described in the methods.
Still, I commend the authors on performing such a large, well-designed study. It is easy to pick apart data from the viewpoint of external validity, but these results are statistically steadfast. While we probably do not need more studies looking at the efficacy of TXA in total joint arthroplasty, further studies looking at the optimal manner in which the medication can be administered are welcomed.
Chad A. Krueger, MD
JBJS Deputy Editor for Social Media
JBJS 100: THA Registries, Bone-Repair Growth Factors
Under one name or another, The Journal of Bone & Joint Surgery has published quality orthopaedic content spanning three centuries. In 1919, our publication was called the Journal of Orthopaedic Surgery, and the first volume of that journal was Volume 1 of what we know today as JBJS.
Thus, the 24 issues we turn out in 2018 will constitute our 100th volume. To help celebrate this milestone, throughout the year we will be spotlighting 100 of the most influential JBJS articles on OrthoBuzz, making the original content openly accessible for a limited time.
Unlike the scientific rigor of Journal content, the selection of this list was not entirely scientific. About half we picked from “JBJS Classics,” which were chosen previously by current and past JBJS Editors-in-Chief and Deputy Editors. We also selected JBJS articles that have been cited more than 1,000 times in other publications, according to Google Scholar search results. Finally, we considered “activity” on the Web of Science and The Journal’s websites.
We hope you enjoy and benefit from reading these groundbreaking articles from JBJS, as we mark our 100th volume. Here are two more, both from 2002:
The Swedish Total Hip Replacement Register
H Malchau, P Herberts, T Eisler, G Garellick, P Soderman: JBJS, 2002 November; 84 (Suppl 2): S2
In this 19-page analysis of data from the Swedish Total Hip Replacement Register, which was initiated in 1979, Malchau et al. pinpoint the striking clinical and socioeconomic effects of the Register’s first 20 years. The information captured by joint registries, especially in regions that provide universal health care coverage and thus maintain robust databases, has helped orthopaedic surgeons refine indications, surgical techniques, and implant choices.
The Role of Growth Factors in the Repair of Bone: Biology and Clinical Applications
J R Lieberman, A Daluiski, T A Einhorn: JBJS, 2002 June; 84 (6): 1032
Countless studies related to tissue engineering and the musculoskeletal system have been published in the 16 years since this Current Concepts Review appeared in JBJS. Yet this article remains an essential primer for understanding how growth factors affect cells and tissues—and the possible applications for using growth factors to accelerate fracture healing, treat nonunions, and enhance spinal fusion.
Linking Registry and Claims Data—Not as Boring as it Sounds
It is not often that The Journal of Bone & Joint Surgery publishes an article about data-linkage efforts. To even raise the topic with most readers of The Journal would elicit a yawn and quick dismissal of the abstract without a second thought. With this fact duly noted, the possibility of linking health-system joint-replacement registries with Medicare claims data is a first step in a potentially game-changing approach to achieving the long-term clinical research our specialty needs.
In the June 20, 2018 issue of JBJS, Raman et al. detail their successful linkage of a total ankle arthroplasty (TAA) registry with Medicare data without the use of unique patient identifiers. Among 280 TAA patients over the age of 65, 250 had their registry data linked with their Medicare record with exact matches for date of procedure, date of birth, and sex. Of the linked records, 214 (76.4%) had ≥3 years of postoperative claims data.
Why are these findings so important? The answer is follow-up. Every clinician and/or researcher who has attempted to follow patients beyond the first year after a procedure understands how difficult long-term follow-up is. We live in a mobile society in which informative posttreatment data is easily lost. The younger the patient group, the more difficult it usually is to locate patients as time passes. If patients are doing well, many stop coming to our offices, no matter how strongly we recommend annual follow-ups. Everyone is busy—including retirees—and most have better things to do than drive to their surgeon’s office or even complete a web-based questionnaire. Additionally, some patients care only about their own outcomes; they are not as focused as we are on contributing to the advancement of the profession and improving outcomes at the population level.
By linking patient data from a local health-system registry to nationwide claims data, we can gain a better understanding of long-term patient progress. We can use the patient- and implant-specific data housed in the registry and essentially substitute the information from follow-up visits that did not take place within the registry system with the data contained within the Medicare system, which follows beneficiaries wherever they live.
The marriage of registry and claims data is not perfect, though, because patients who are still working probably have private insurance coverage that is not captured by the Medicare system. (Of course, if universal coverage were to come to pass, that issue would be eliminated.) Furthermore, any time claims data are used, uncertainty about the accuracy of coding must be considered. These real-world limitations notwithstanding, the linkage of registry data with claims data does have great potential for enhancing our ability to analyze—and improve—long-term orthopaedic outcomes.
Marc Swiontkowski, MD
JBJS Editor-in-Chief
Virtual Reality Makes Foray into Orthopaedics
Virtual reality (VR) is the computer-generated simulation of a three-dimensional environment that people can interact with in a seemingly real or physical way using special electronic equipment. Though I typically think of its impact on the video game world, the possibilities and applications of this technology are seemingly endless.
In fact, according to a recent article in MedCity News, VR is now being used to help train orthopaedic surgeons. Osso VR, a virtual-reality surgical training platform, hopes to change the way surgeons get trained by harnessing the possibilities of VR. The platform delivers realistic interactive surgical training environments that include the latest procedures and technology. According to pediatric orthopaedist and former game developer Justin Barad, co-founder and CEO of Osso VR, teams and individuals can practice and objectively measure their performance without needing a cadaver or putting any patients at risk while they learn. The technology also helps medical device companies help surgeons gain proficiency in a particular procedure or with a specific technology more quickly than otherwise possible.
Barad cites many problems with the way surgeons currently learn new surgical techniques. They often have to travel to remote cadaver courses for the opportunity to practice in a hands-on way. That model leaves few or no options to practice the procedure and become proficient with it. Barad claims that the model offered by Osso VR provides a new way to practice modern surgical techniques in a hands-on way and has the potential to positively impact surgical outcomes.
VR technology is still new, and orthopaedic educators are just starting to figure out how best to integrate it into orthopaedic education. But those details will likely work themselves out as the technology becomes more familiar to members of the orthopaedic community. Regardless, it is an appealing new tool that may help further bridge the gap between abstract book learning and the reality of patient care.
Nick Schepis
JBJS Social Media & Analytics Specialist
Shoulder Arthroplasty: Doxy + Cefazolin No Better than Cefazolin Alone Against P. Acnes
OrthoBuzz occasionally receives posts from guest bloggers. This guest post comes from Andrew D. Duckworth, MSc, FRCSEd(Tr&Orth), PhD, in response to a recent study in JBJS.
Propionibacterium acnes (now called Cutibacterium acnes, according to an updated classification) is a ubiquitous microbe in the setting of shoulder surgery and is a well-established cause of indolent infection and prosthetic loosening1,2. In 2016, JBJS published a study by Hsu et al. investigating single-stage revision shoulder replacement in patients with subclinical infection, and the authors reported that almost half of the patients had >2 positive cultures for P. acnes3. However, the exact consequence of positive cultures at the time of primary surgery is unknown, and the efficacy of specific antibiotic prophylaxis against this microbe remains unclear.
In the June 6, 2018 issue of JBJS, Rao et al. randomised 56 patients scheduled to undergo a primary anatomic or reverse total shoulder replacement to receive either preoperative cefazolin alone (n=27) or a combination of cefazolin and doxycycline (n=29) 4. All patients had standard skin preparation at the time of surgery with both alcohol and chlorhexidine.
The primary outcome measure was ≥1positive culture after 14 days of incubation from either superficial and/or deep-tissue samples taken intraoperatively. The authors deemed that a decrease of 50% in the positive culture rate would be clinically significant. However, they found no significant difference between the groups in terms of the primary outcome measure (p=0.99). The authors carried out a secondary analysis to determine which other factors might be associated with ≥1 positive P. acnes culture and found that younger age, male sex, and a lower Charlson Comorbidity Index were predictive. Although this study was potentially underpowered, it demonstrated that in patients undergoing primary shoulder arthroplasty, preoperative doxycycline does not significantly reduce the prevalence of positive culture rates for P. acnes.
These findings are similar to those found in previous research and should lead us to question whether preoperative antibiotics aimed specifically at preventing P. acnes infection associated with shoulder arthroplasty are truly useful. P. acnes infections are difficult to detect both clinically and via culture—which makes any intervention difficult to measure, especially in a potentially underpowered study. Consequently, larger studies in this area would help to more definitively determine whether preoperative antibiotics aimed specifically at P. acnes decrease infection rates or, instead, may be adding to the growing problem of bacterial resistance. In particular, such trials seem most useful when they focus on patients who are at higher risk of these specific infections—in this case, younger, healthy males.
Finally, as Rao et al. wisely observed, doxycycline is a bacteriostatic agent, which slows the growth and production of bacteria, rather than a bactericidal agent, which kills bacteria. Given that antimicrobial limitation, doxycycline might not be the most appropriate prophylactic drug to be investigating for these cases.
Andrew D. Duckworth, MSc, FRCSEd(Tr&Orth), PhD is a consultant orthopaedic trauma surgeon at Edinburgh Orthopaedic Trauma, Royal Infirmary of Edinburgh, and he is a member of the JBJS Social Media Advisory Board.
References
- Gausden EB, Villa J, Warner SJ, Redko M, Pearle A, Miller A, Henry M, Lorich DG, Helfet DL, Wellman DS. Nonunion After Clavicle Osteosynthesis: High Incidence of Propionibacterium acnes. J Orthop Trauma. 2017 Apr;31(4):229-235.
- Chuang MJ, Jancosko JJ, Mendoza V, Nottage WM. The Incidence of Propionibacterium acnes in Shoulder Arthroscopy. 2015 Sep;31(9):1702-7.
- Hsu JE, Gorbaty JD, Whitney IJ, Matsen FA III. Single-Stage Revision Is Effective for Failed Shoulder Arthroplasty with Positive Cultures for Propionibacterium. J Bone Joint Surg 2016;98:2047-2051.
- Rao AJ, Chalmers PN, Cvetanovich GL, O’Brien MC, Newgren JM, Cole BJ, Verma NN, Nicholson GP, Romeo AA. Preoperative Doxycycline Does Not Reduce Propionibacterium acnes in Shoulder Arthroplasty. J Bone Joint Surg Am. 2018 Jun 6;100(11):958-964.
Minimum Five-Year Outcomes of Hip Arthroscopy for the Treatment of Femoroacetabular Impingement and Labral Tears in Patients with Obesity
Obesity is a negative prognostic factor for various surgical procedures. https://bit.ly/2JKUj4C #JBJSInfographics #VisualAbstract
Inability of Older Adult Patients with Hip Fracture to Maintain Postoperative Weight-Bearing Restrictions
For elderly trauma patients, a basic goal is early mobilization, as immobilization can trigger various complications, such as venous thromboembolism, pneumonia, urinary tract infections, and pressure ulcers. https://bit.ly/2JIILyU #JBJSInfographics #JBJSVideoSummaries #VisualAbstract
Sarcopenia: An Independent Predictor of Mortality in Geriatric Acetabular Fractures
OrthoBuzz occasionally receives posts from guest bloggers. This guest post comes from Matthew Herring, MD, in response to a recent study in the Journal of Orthopaedic Trauma.
Fractures in the elderly are a growing problem in developed countries and generally carry a significant morbidity and mortality burden. When considering treatment strategies and making prognoses in this patient population, our ability to stratify patient frailty may be just as or more important than classifying the fracture. In a recent study in the Journal of Orthopaedic Trauma, Mitchell et al. evaluate the role of sarcopenia, an age-related loss of muscle mass, in predicting 1-year mortality among elderly patients with acetabular fractures.1
The authors performed a retrospective review of nearly 150 patients >60 years of age who sustained an acetabular fracture between 2003 and 2014. The authors used the lowest quartile of the psoas:lumbar vertebral index (PLVI) in the cohort as a surrogate for sarcopenia. The PLVI is calculated by measuring the cross-sectional area of the psoas muscle bellies at the L4 level and dividing that number by the cross-sectional area of the L4 vertebral body measured at the superior endplate (see image). Lower PLVIs represent greater loss of muscle mass.
After controlling for confounding variables, the authors found that sarcopenia was an independent risk factor for 1-year mortality. Specifically, patients with sarcopenia had a 32.4% 1-year mortality rate compared to a rate of 11.0% in patients without sarcopenia. Age and injury severity score (ISS) were also predictive of 1-year mortality, and patients with all 3 factors (age >75 years, ISS >14, and sarcopenia) had a mortality rate of 90%.
This article highlights the importance of risk-stratifying patients in ways that account for more than their presenting injuries. In the elderly population, chronologic age is only one of many indicators of frailty. Sarcopenia may be another marker that we can use to better understand the general well-being of our patients. As Mitchell et al. mention, more research must be done to precisely define a PLVI cutoff for sarcopenia to make this index a clinically useful tool. Ultimately, doing so will allow us to offer elderly patients and their families more thoughtful and evidence-based counseling regarding treatment and prognosis.
Matthew Herring, MD is a senior orthopaedic resident at the University of Minnesota and a member of the JBJS Social Media Advisory Board.
Reference
- Mitchell, Phillip M., et al., Sarcopenia is Predictive of 1-year Mortality After Acetabular Fractures in Elderly Patients.” Journal of Orthopaedic Trauma, June 2018; 32 (6) : 278-282.
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