Quick and accurate: that’s what orthopaedic surgeons want in diagnostic tools to help them determine whether patients presenting with pain after total joint arthroplasty have an infection. A prospective Level I study by Gehrke et al. in the January 3, 2018 issue of The Journal of Bone & Joint Surgery determined that a new lateral flow version of the Synovasure Alpha Defensin Test meets those requirements.
Alpha defensin is a protein secreted by neutrophils in response to bacterial infection, prior to the development of specific immune responses. Earlier research established alpha defensin in synovial aspirates to be an excellent biomarker for periprosthetic joint infection (PJI). The original ELISA-based alpha defensin test is usually sent out for 24-hour processing, limiting its intraoperative utility. However, the lateral flow version of the test (akin to an over-the-counter pregnancy test) was approved for use in Europe—and its results are available in 10 to 15 minutes.
Gehrke et al. compared the rapid test’s results to the diagnostic criteria promulgated by the Musculoskeletal Infection Society (MSIS). According to MSIS criteria, there were 76 joints with PJI among 191 study subjects on whom 195 joint aspirations were performed. Using that as the benchmark for diagnosis, the authors analyzed results from the rapid alpha defensin tests and found the following performance:
- 92.1% sensitivity
- 100% specificity
- 100% positive predictive value
- 95.2% negative predictive value
- 96.9% overall accuracy
Although the rapid test does not provide information about the identity of specific pathogens, the authors conclude that it “enables surgeons to start proper therapy without delay.” That ability comes at a price, however. In Germany, where this study was performed, each rapid test costs about 400 Euros, which is nearly $500 US.
In a commentary on the study, Garth Ehrlich and Michael Palmer cite another possible cost with the rapid-test scenario. Prior to using any alpha defensin test, physicians must rule out metallosis with MRI, because that non-infectious entity triggers false-positive results.
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 January 2018, JBJS and OrthoBuzz readers will have open access to the JOSPT article titled “Hip and Knee Strengthening Is More Effective Than Knee Strengthening Alone for Reducing Pain and Improving Activity in Individuals With Patellofemoral Pain: A Systematic Review With Meta-analysis.”
This study, the findings of which are summarized in the title, found that the positive pain and activity outcomes were achieved without concurrent changes in strength.
Time is perhaps today’s most valuable commodity, and to save JBJS readers time while still providing them with accurate scientific information, The Journal has introduced two new “quick-take” features: infographics and video summaries.
Two articles in the January 3, 2018 edition include an infographic, which encapsulates all the information of a written abstract in one rich, easy-to-digest poster-like image. Click on the titles below to see our first two infographics:
- Randomized Trial Comparing Suture Button with Single Syndesmotic Screw for Syndesmosis Injury
- Long-Term Outcomes of Distal Femoral Extension Osteotomy and Patellar Tendon Advancement in Individuals with Cerebral Palsy
In addition, the January 3, 2018 issue contains a video summary of the syndesmosis-injury study cited above. These 2-minute videos clearly and concisely explain the research question investigated, how it was examined, and what the findings were.
Please let the JBJS editorial team know what you think of these new features by commenting on this post.
Long-term population-based research has documented associations between high BMI and decreased longevity and increased risk of developing diabetes and cardiac complications. Musculoskeletally speaking, the risk of developing osteoarthritis of the knee has been strongly associated with elevated BMI, although the impact of high BMI on the development of hip osteoarthritis has been less clearly defined.
To detail the impact of increased BMI on the developing hip, in the January 3, 2018 issue of The Journal, Novais et al. painstakingly evaluated 128 pelvic CT images from a group of adolescents presenting with abdominal pain but no prior history of hip pathology. The authors found a significant association between increasing BMI percentiles and femoral head-neck alterations, including:
- Increased alpha angle
- Reduced head-neck offset and epiphyseal extension, and
- More posteriorly tilted epiphyses.
Taken together, these morphological anomalies resemble, in the authors’ words, “a post-slip or mild slipped capital femoral epiphysis [SCFE] deformity.”
While the association between elevated body mass and the risk of SCFE has long been known, the impact of high BMI on the morphology of the “normal” hip had not, until now, been described in detail. It makes intuitive mechanical sense that Novais et al. found no impact of high BMI on acetabular anatomy, but because of the orientation of the proximal femoral growth plate, it does make sense that high BMI affects the growing femoral head-neck junction.
It is my hope that consolidating these data with the abundance of other evidence about the health risks of high BMI in growing children will further coalesce worldwide efforts to lower the intake of sugar and “empty carbs” among growing children, and will further spur investment in programs to increase physical activity among this vulnerable age group.
Marc Swiontkowski, MD
The new year of 2018 brings with it the indexing of JBJS Case Connector on PubMed, going back to Volume 1, Issue 1.
Co-edited by Thomas W. Bauer, MD and Ronald W. Lindsey, MD, JBJS Case Connector currently compiles nearly 700 peer-reviewed orthopaedic case reports, empowering surgeons to identify emerging trends and find commonalities between cases to help them provide the best possible care for their patients.
In addition, monthly “Case Connections” essays explore the clinical relationships between recent and prior case reports, further helping surgeons to identify patterns. And JBJS Case Connector “Image Quizzes” provide interactive challenges based on recent Case Connector articles.
To learn more about JBJS Case Connector, click here.
The randomized controlled trial (RCT) may be the gold standard of clinical research, but not all RCTs are created equal. In the December 20, 2017 issue of The Journal, Kay et al. set out to determine the historical quality of more than 400 RCTs relating to anterior cruciate ligament (ACL) reconstruction published between 1985 and 2016.
The authors evaluated the studies using the Detsky quality index (on which a score of ≥75% is considered “high” methodological quality) and the CONSORT checklist. Fifty-two percent of the studies analyzed were surgical trials (graft choice, femoral fixation method, and single- vs double-bundle techniques), while 48% were nonsurgical trials (analgesic and rehabilitation regimens).
The mean Detsky score across all studies was 68.9% ± 13.2%. Forty-two percent of the studies were considered high-quality according to Detsky scores. There was no significant difference in mean Detsky scores between surgical and nonsurgical trials.
The authors noted a substantial increase in the number of ACL RCTs over time, although that number has not changed significantly since 2009, which is coincidentally the year that JBJS and many other journals required authors to use the CONSORT flow diagram. Notably, the reporting of methodologically sound randomization processes and the prospective calculation of sample sizes have also improved significantly in recent years.
Both the inclusion of a CONSORT flow diagram and the year published were significant predictors of the quality score. A mere 5% of trials published in 2008 or prior included the CONSORT flow diagram, while >40% of trials published since 2009 had a flow diagram.
While the authors are encouraged that “close to 50% of trials in this study reported blinding of outcome assessors,” they say areas for improvement include better “descriptions of allocation concealment and intent-to-treat analyses.”