Vancomycin Powder May Thwart Spinal Fusion
Prompted by relatively high infection rates associated with surgical treatment of pediatric spinal conditions such as scoliosis and spinal-deformity surgery in immunocompromised adults, spine surgeons have led “deep dive” clinical research into the possible benefits of local, intrawound antibiotic therapy. Consequently, the administration of antibiotic powder around the spine’s posterior elements and internal-fixation devices has become fairly widespread. But are there possible downsides to this approach that can impact patient outcomes?
This important question is addressed in the basic-science study by Ishida et al. in the October 2, 2019 issue of The Journal. The authors analyzed the fusion-specific impact of varying concentrations of intrawound vancomycin and tobramycin in a well-characterized rat model of posterolateral fusion performed with syngeneic iliac-crest allograft plus clinical bone-graft substitute. Ishida et al. found that a high dose of vancomycin (71.5 mg/kg, about 5 times higher than spine surgeons typically use) but not tobramycin had detrimental effects on fusion-mass formation in this model, as demonstrated by micro-computed tomography and histological analysis.
We now need further clinical research from the spine community to determine the optimal doses and types of intrawound antibiotics in this setting. Based on the currently available data, power calculations should be performed when designing future trials focused on this question. There seems to be little remaining doubt that locally delivered antibiotics help limit surgical-site and deep infections in spinal surgery. The impact of antibiotics on fusion rates must now be investigated further.
Marc Swiontkowski, MD
JBJS Editor-in-Chief
Elite Reviewer Spotlight: Eeric Truumees
JBJS is pleased to highlight our Elite Reviewers. The Elite Reviewers Program recognizes our best reviewers for their outstanding efforts. All JBJS reviewers help us maintain the highest standards for quality orthopaedic publishing.
Name: Eeric Truumees, MD
Affiliation: University of Texas at Austin, Dell Medical School / Ascension Seton Brain & Spine Institute, Austin, Texas
Years in practice: 20
How did you begin reviewing for other journals and for JBJS in particular?
The first part of my career was spent in a “privademic” setting. I saw peer review as a means of keeping up with the latest ideas in orthopaedic surgery (and spine surgery in particular). These reviews, while time consuming, both felt rewarding and were a solid contribution to the larger field. Since then, I have served several journals, including at the Deputy Editor level. The chance to serve at JBJS is a great honor.
What is your top piece of advice for those reviewers who aspire to reach Elite status?
First, your reviews should be systematic. There are lots of guides available, but you have to find a system that works well for you. Once you do, your reviews will both offer more value for the authors and editors and become more efficient to perform. Know your bandwidth and respond quickly whether you are able to provide the review or not. Then, as with anything, a big part of success lies in being reliable.
Aside from orthopaedic manuscripts, what have you been reading lately?
As someone with an interest in healthcare re-design and working in the highly contentious field of spine surgery, I have been reading books on program building, leadership, and other business topics.
Learn more about the JBJS Elite Reviewers program.
Glycation and Rotator Cuff Degeneration
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.
Advanced glycation end products (AGEs) form through a nonenzymatic process by which reducing sugars undergo Maillard rearrangement with amino acids. During rearrangement, the carbonyl group of the sugar reacts with the amino group of the amino acid, producing N-substituted glycosylamine and water.
During cooking, glycation occurs at 140° to 165° C (280° to 330° F), resulting in the browning of foods such as bread and French fries. This nonenzymatic reaction also occurs at human body temperature over decades. AGE formation can decrease the viscoelasticity and tensile strength of human tissue, resulting in increased mechanical stiffness that affects bone, ligaments, cartilage, and menisci. In cartilage, the excessive accumulation of AGEs leads to a more brittle matrix that is susceptible to fatigue and failure. AGEs also contribute to the etiology of several diabetic complications, including adhesive capsulitis of the shoulder.
Rotator cuff degeneration and tears become more common with age. Accumulated mechanical loads and anatomic variation play a large role. The role of AGEs in rotator cuff degeneration and tears has been suspected, but the exact mechanisms remain in question. Investigators recently showed that AGEs have detrimental effects on human rotator cuff-derived cells in vitro and on intact rat infraspinatus tendons ex vivo.1
In Vitro Findings
Rotator cuff-derived cells were obtained from 12 torn cuff edges during supraspinatus tendon repairs in patients with an average age 64.8 years. The cells were cultured in (1) regular medium with 500 μg/mL AGEs (high-AGE group), (2) regular medium with 100 μg/mL AGEs (low-AGE group), and (3) regular medium alone (control group). Cell viability was significantly suppressed in the high-AGE group relative to the control group. Vascular endothelial growth factor secretion was significantly greater in the high- and low-AGE groups than in the control group. Immunofluorescence stain demonstrated enhancement of hypoxia-inducible factor-1α, reactive oxygen species expressions, and cell apoptosis in the high- and low-AGE groups compared with the control group.
Ex Vivo Findings
Four upper limbs with intact rotator cuff tendons were harvested from 10-week old rats and cultured in regular medium or regular medium with 500 μg/mL AGEs. Mechanical testing showed significantly higher tensile strength in the control group than in the AGE group.
These results beg the question as to whether reduction of AGEs might delay or prevent rotator cuff senescence-related degeneration.
Reference
- Mifune Y, Inui A, Muto T, Nishimoto H, Kataoka T, Kurosawa T, Yamaura K, Mukohara S, Niikura T, Kokubu T, Kuroda R. Influence of advanced glycation end products on rotator cuff. J Shoulder Elbow Surg. 2019 Aug;28(8):1490-1496. doi: 10.1016/j.jse.2019.01.022. Epub 2019 Apr 10. PMID: 30981546
Expanded Indications for Medial UKA?
Along with recently renewed interest in unicompartmental knee arthroplasty (UKA) has come debate as to whether the preoperative presence of patellofemoral osteoarthritis (OA) and/or abnormal patellofemoral alignment should be considered UKA contraindications. Findings from a retrospective review of 639 knees by Burger et al. in the September 18, 2019 issue of The Journal of Bone & Joint Surgery strongly suggest that the answer is “no.”
After examining preoperative radiographic OA and alignment characteristics and postoperative patient-reported outcomes among patients who underwent fixed-bearing medial UKA, the authors concluded that “neither the [radiographic] presence of preoperative mild to moderate [patellofemoral] osteoarthritis nor abnormal patellar tilt or congruence compromised [patient-reported knee and patellofemoral-specific] outcomes at intermediate-term follow-up [mean of 4.3 ±1.6 years].”
Expanding the surgical inclusion criteria for UKA based on these findings could increase the number of patients eligible for UKA by 20% to 40%, estimated Burger et al. In the practice of the senior author (Andrew D. Pearle, MD), patients with symptoms of patellofemoral OA (such as anterior knee pain with prolonged sitting or stair-climbing) are considered ineligible for UKA, prompting the authors to suggest that “the presence of such symptoms may be better than radiographic criteria for determining which patients are eligible for medial [UKA].”
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