The Genetic Origins of Spinal Stenosis
Researchers from the University of Hong Kong are advancing our understanding of the etiology of spinal stenosis. Their work, “Etiology of Developmental Spinal Stenosis: a Genome-Wide Association Study,” appears in the October 6, 2017 edition of the Journal of Orthopaedic Research.
Jason Cheung, M.D. clinical assistant professor in the Department of Orthopaedics and Traumatology, The University of Hong Kong, and his colleagues set out to examine the relationship between developmental spinal stenosis and symptomatic spinal stenosis.
Dr. Cheung told OTW, “It is not uncommon to see patients with short pedicles. Anecdotally these patients have more difficult surgical decompression due to narrow canals but they also have multiple level stenosis and tend to have symptom recurrence after surgery. Through a series of studies including x-ray/MRI [magnetic resonance imaging] phenotyping and study of ligamentum flavum paradoxical changes, we have enough evidence to suggest that patients with developmental spinal stenosis have a very different pathophysiology as compared to those with degenerative spinal stenosis, and that the former condition is likely genetic in origin.”
The study was a southern Chinese population of volunteers who were assessed (age range: 18-55 years) for developmental spinal stenosis (DSS). For study purposes, DSS was defined as the anteroposterior bony spinal canal diameter on T1-weighted axial MRI of L1 to S1. The researchers performed genotyping using the Illumina HumanOmniZhongHua-8 BeadChip. Using the canal diameter as the quantitative trait, the team performed genomic statistical analyses. In total, 469 subjects were recruited for the study.
“Following through with our previous work, this was the first study to examine the genetic origins of developmental spinal stenosis based on a genome-wide association study (GWAS). Our study focused on the development of the bony canal, which is a clearer and more specific phenotype of ‘pre-existing’ spinal canal stenosis.”
“Oftentimes, spinal stenosis simply contributes to dural sac compression and is highly influenced by disc degeneration. Hence, based on a true phenotype of the spinal canal in relation to clinically relevant stenotic parameters, this study identifies several potential causative genes. One of which was the Wnt signaling pathway genes important for bone development.”
“Developmental spinal stenosis is an important pathology that contributes to an increased risk of ‘symptomatic spinal stenosis.’ It has apparent genetic origins and this should be further investigated with deep sequencing. The diameter of the bony spinal canal can be measured on MRI and X-rays, and is a diagnostic marker for developmental spinal stenosis. These patients are at-risk of multiple level stenosis and may require more extensive surgery.”
“Pre-existing canal narrowing has a large genetic influence and may contribute to multiple level stenosis, poor surgical outcomes, and difficulties in decompression surgery. There is maldevelopment of not only the bony architecture but also the fibrotic content of the ligamentum flavum. Although further research is necessary to understand the natural history of disease and the impact of this disease regarding long-term outcomes, these patients should be properly counseled regarding their risk. These patients may require a lower threshold for surgical treatment as with pre-existing narrowed canals, a smaller degree of disc herniation or ligamentum flavum hypertrophy may already cause stenotic symptoms.”
Co-author Dino Samartzis, M.D. commented to OTW, “This study represents a tremendous leap forward in understanding the etiology of spinal stenosis. Our findings have immense implications in discovering new biological pathways for such conditions and moving us towards a more ‘personalized’ approach to spine care.
Robust New Steroid Study for Knee OA
A team of researchers from Boston Medical Center (BMC), Brigham and Women’s Hospital, and Tufts University School of Medicine wanted to know what affects patient response to intra-articular corticosteroid injections for knee osteoarthritis (OA). “Efficacy and Treatment Response of Intra-articular Corticosteroid Injections in Patients With Symptomatic Knee Osteoarthritis,” was published in the October 2017 edition of the Journal of the American Academy of Orthopaedic Surgeons.
Eric L. Smith, M.D., a co-author on the study, is an orthopedic surgeon with Boston Medical Center. Dr. Smith commented to OTW, “The AAOS [American Academy of Orthopaedic Surgeons] practice guidelines on treatment of osteoarthritis of the knee has a neutral recommendation for the use of intra-articular corticosteroids due to the lack of robust studies. Our group felt that since this is a common practice to many orthopaedic surgeons, a more robust study was warranted.”
The authors wrote, “This prospective, multicenter cohort study had 100 participants with radiographic evidence of knee OA enrolled. Participants received one corticosteroid injection into the affected knee and were evaluated before the injection (baseline) and a 3 weeks, 6 weeks, 3 months, and 6 months after the injection.”
Dr. Smith told OTW, “This study was designed utilizing office practices from two separate centers. We wanted a heterogeneous patient base to more broadly apply our results. We did not establish a control group as all patients presenting to the clinics were symptomatic and there is not a comparable injectable based on the AAOS Practice guidelines. We utilized blinded reviewers to administer the patient reported outcome measures as well as performing radiographic grading.”
“We were surprised by the overall benefits with reduction of pain and improved function. Results were better in non-obese patients with less advanced arthrosis based on standardized radiographic grading. However, even though results were not as good in obese patients with advanced arthrosis, this patient population did significantly improve compared to their baseline.”
“Our results showed that intra-articular corticosteroid injections are a reliable intervention to reduce symptoms of knee osteoarthritis.”
“Orthopaedic surgeons should use this research study to help counsel patients with knee osteoarthritis about the benefits of reduction in pain and improved function with intra-articular corticosteroid injections. They should also use this study to better understand the benefits and limitations of performing injections in obese patients with advanced radiographic arthrosis.”
New Tool Improves Surgical Training
The study, “Knee Arthroscopy Simulation: A Randomized Controlled Trial Evaluating the Effectiveness of the Imperial Knee Arthroscopy Cognitive Task Analysis (IKACTA) Tool,” appears in the October 4, 2017 edition of The Journal of Bone and Joint Surgery.
Rahul Bhattacharyya (MBCHB (Hons), MRCS, MSc Surg), clinical research fellow in trauma and orthopedic surgery at Imperial College London and Chinmay Gupte, senior clinical lecturer in orthopedics at Imperial College London, told OTW, “Surgical training is under severe strain in recent times due to restriction in working hours, increasing senior involvement in service provision and greater application of surgical technology.”
“In this setting adjuncts to the traditional apprenticeship model are required to help meet training needs. Cognitive Task Analysis (CTA) is a technique that has been used very successfully in the airline industry to train pilots for many years. It has also been used to train musicians and military personnel. However, it has never been tested in orthopaedic training.”
The authors wrote, “Three expert knee surgeons were interviewed independently to generate a list of technical steps, decision points, and errors for diagnostic knee arthroscopy…”
Bhattacharyya told OTW, “We used an innovative multimedia design for our IKACTA (Imperial Knee Arthroscopy Cognitive Task Analysis) tool, where the learner can use written and audio-visual stimuli simultaneously to learn knee arthroscopy. A modified Delphi technique was used to ensure that the content of the learning tool was of high quality obtained from field experts.”
“The study showed that the IKACTA tool demonstrated significant improvement in objective validated scores (ASSET and TCS) for novice residents who were assessed on high fidelity phantom knee simulation. All residents also agreed that the tool was easy to use and they would like to use it prior to attending an operating theatre session on diagnostic knee arthroscopy.”
“CTA-based tools should be introduced in orthopaedic residency/training programs to help junior residents reduce their learning curves and improve utilization of operating theatre training time. The IKACTA is the first CTA tool described in orthopaedic training demonstrating significant objective benefits in training novice residents in diagnostic knee arthroscopy. It will provide trainees with a demonstrably strong foundation in diagnostic knee arthroscopy that will reduce learning curves in both technical skills and decision-making.”
