What’s New in Spine Surgery 2021
Every month, JBJS publishes a review of the most pertinent and impactful studies reported in the orthopaedic literature during the previous year in 14 subspecialties. Click here for a collection of all such OrthoBuzz specialty-update summaries.
This month, co-author Jacob M. Buchowski, MD, MS summarizes the 5 most compelling findings from the studies highlighted in the recently published “What’s New in Spine Surgery.”
Degenerative Cervical Myelopathy
–In a multicenter, double-blinded, placebo-controlled, randomized phase-3 trial, investigators found no additional benefit from riluzole use with regard to functional outcome scores among patients who underwent decompression and fusion for cervical myelopathy1. The primary outcome of interest was the change in the modified Japanese Orthopaedic Association (mJOA) score at 6 months.
Dysphagia After Multilevel ACDF
–A Level-I double-blinded randomized controlled trial demonstrated a significant decrease in the severity of dysphagia after multilevel anterior cervical discectomy and fusion (ACDF) among patients who received local intraoperative corticosteroids (56 in the treatment group vs 53 in the control group)2.
Preop. Epidural Steroid Injection and Postop. Infection
–A retrospective study of patients who underwent lumbar spine surgical procedures for radiculopathy and/or spinal stenosis3 found that:
- In the decompression group, there was no significant difference in the postoperative infection rate between those who had a preoperative epidural steroid injection (2,957 of 9,903) and those who did not.
- Among those who underwent fusion, there was a significantly higher rate of infection (2.68%) for those who had preoperative epidural steroid injection (1,383 of 5,108) vs those who did not (1.69%).
- In the fusion group, there was a significantly higher rate of infection for those who had a steroid injection within 30 days or >90 days preoperatively, but patients with injection between 30 and 90 days preoperatively had no increased risk of postoperative infection.
Adolescent Idiopathic Scoliosis (AIS)
–In a Level-IV study, investigators examined the relationship between thoracic morphology and pulmonary function in patients with AIS (mean age, 15.6 years)4. They found a strong positive correlation between the costophrenic angle distance and forced vital capacity, FEV1, vital capacity, and total lung capacity, suggesting that the costophrenic angle distance can be used to assess pulmonary function outcome. Their findings also suggest that an apical vertebral deviation ratio of >0.2 is associated with moderate to severe impairment of lung function.
Early-Onset Scoliosis (EOS)
–In a cross-sectional study of prospectively enrolled patients across multiple centers, investigators examined the influence of the classification of EOS etiology, radiographic parameters, and medical comorbidities on the Early Onset Scoliosis Questionnaire (EOSQ), a measure of health-related quality of life. Scores were lower in many EOSQ domains for patients with neuromuscular and syndromic etiologies. The total and subdomain scores were similar between patients with congenital and idiopathic EOS.
References
- Fehlings MG, Badhiwala JH, Ahn H, Farhadi HF, Shaffrey CI, Nassr A, Mummaneni P, Arnold PM, Jacobs WB, Riew KD, Kelly M, Brodke DS, Vaccaro AR, Hilibrand AS, Wilson J, Harrop JS, Yoon ST, Kim KD, Fourney DR, Santaguida C, Massicotte EM, Kopjar B. Safety and efficacy of riluzole in patients undergoing decompressive surgery for degenerative cervical myelopathy (CSM-Protect): a multicentre, double-blind, placebo-controlled, randomised, phase 3 trial. Lancet Neurol. 2021 Feb;20(2):98-106. Epub 2020 Dec 22.
- Kim HJ, Alluri R, Stein D, Lebl D, Huang R, Lafage R, Bennett T, Lafage V, Albert T. Effect of topical steroid on swallowing following ACDF: results of a prospective double-blind randomized control trial. Spine (Phila Pa 1976). 2021 Apr 1;46(7):413-20.
- Kreitz TM, Mangan J, Schroeder GD, Kepler CK, Kurd MF, Radcliff KE, Woods BI, Rihn JA, Anderson DG, Vaccaro AR, Hilibrand AS. Do preoperative epidural steroid injections increase the risk of infection after lumbar spine surgery? Spine (Phila Pa 1976). 2021 Feb 1;46(3):E197-202.
- Deng Z, Luo M, Zhou Q, Yang X, Liu L, Song Y. Relationship between pulmonary function and thoracic morphology in adolescent idiopathic scoliosis: a new index, the “apical vertebra deviation ratio”, as a predictive factor for pulmonary function impairment. Spine (Phila Pa 1976). 2021 Jan 15;46(2):87-94.
JBJS Author Insights: Dr. Toshiyuki Kawai
Co-author Toshiyuki Kawai, MD, PhD discusses the new JBJS study “Number of Levels of Spinal Fusion Associated with the Rate of Joint-Space Narrowing in the Hip.” Watch the video below.
Read the full report here.
Large Lytic Defects Produce Spinal Kinematic Instability
With the increasing effectiveness of immunotherapy and chemotherapy, patients with metastatic disease are surviving longer in much higher numbers. For many primary tumors (lung, breast, thyroid), a common site of metastases is the spine, giving rise to concomitant concerns regarding spine stability and the risk of neurologic compromise.
In the May 19, 2021 issue of JBJS, Alkalay et al. report the results of an in vitro study in which they simulated osteolytic defects in 3-level thoracic and lumbar segments of cadaveric spines. The simulations involved 2 patterns of lytic defects previously reported to be associated with increased risk of pathologic vertebral fracture: anterior-column compromise (40% of the vertebral body) and anterior plus middle-column compromise (extension of the model to include the ipsilateral pedicle and facet joint). The spinal segments were kinematically assessed in axial compression and axial compression with a flexion or extension moment, with testing before and after lesion simulation.
The authors concluded that “critical spinal lytic defects result in kinematic abnormalities and lower the compressive strength of the spine.” With greater lytic involvement, significantly higher translational motion along all 3 anatomic axes, and higher torsional and lateral-bending range of motion under axial compression with both flexion and extension moments were demonstrated.
The precision of the model in this cadaveric study was excellent. And the clinical implications of the findings are real: increasing lytic involvement of the vertebral body along with the pedicles could indicate impending instability, with the potential for neurologic injury. These data will be useful for surgeons and patients when formulating decisions regarding the need for intervention with fixation to limit flexion/extension forces in order to reduce pain and neurologic involvement. Future clinical data on the impact of these decisions in terms of pain and functional outcomes will be very valuable as we seek to optimize treatment of our patients with spinal metastatic disease.
Marc Swiontkowski, MD
JBJS Editor-in-Chief
Postop Dexamethasone Cuts Opioid Use after AIS Surgery
OrthoBuzz occasionally receives posts from guest bloggers. This guest post comes from Impact Science, in response to a recent article in JBJS.
Pain management is an important aspect of postoperative care after posterior spinal fusion for the treatment of adolescent idiopathic scoliosis (AIS). Opioid medications, while highly effective and commonly used for postoperative analgesia, have many well-documented adverse effects. Several recent studies have suggested that dexamethasone, a glucocorticoid, is an effective adjunct for postoperative pain management after many adult orthopaedic procedures, but its use after AIS surgery has not been well studied.
Beginning in 2017, doctors at Children’s Healthcare of Atlanta added dexamethasone to their postoperative pain control pathway for adolescent spinal-fusion patients. In the October 21, 2020 issue of The Journal of Bone & Joint Surgery, Fletcher et al. report findings from a cohort study that investigated the postoperative outcomes of 113 patients (median age of 14 years) who underwent posterior spinal fusion between 2015 and 2018. The main outcome of interest—opioid consumption while hospitalized—was determined by converting all postoperative opioids given into morphine milligram equivalents (MME).
Because dexamethasone entered their institution’s standardized pathway for this operation in 2017, it was easy for the authors to divide these patients into two groups; 65 of the study patients did not receive postoperative steroids, while 48 patients were managed with 3 doses of steroids postoperatively. Relative to the former group, the latter group showed a 39.6% decrease in total MME used and a 29.5% decrease in weight-based MME. Patients who received postoperative dexamethasone were also more likely to walk at the time of initial physical therapy evaluation. Notably, the authors found no differences between the groups with regard to wound dihescence or 90-day infection rates—2 complications that have been associated with chronic use of perioperative steroids.
In commenting on these findings, Amy L. McIntosh, MD from Texas Scottish Rite Hospital for Children writes that she was so impressed that she plans “on adding dexamethasone to our institution’s standardized AIS care pathway.”
Impact Science is a team of highly specialized subject-area experts (Life Sciences, Physical Sciences, Medicine & Humanities), who collaborate with authors, societies, libraries, universities, and various other stakeholders for services to enhance research impact. Through research engagement and science communication, Impact Science aims at democratizing science by making research-backed content accessible to the world.
Complex Technology Demands Conflict-Free Reporting
In the October 7, 2020 issue of The Journal, Du et al. report on a multicenter database-derived cohort of 167 patients with early-onset scoliosis treated with traditional growing rods and followed for ≥2 years after “final” fusion. These researchers report that 19% of those patients required a repeat surgery following fusion, most commonly for surgical-site infection and anchor-site failure. Multivariate analysis of risk factors for reoperation following final fusion revealed the following:
- Curve progression requiring revision surgery during the spine-lengthening process
- The number of levels spanned with the growing rods
- The duration of treatment
Du et al. report these results without spin in a way that is most useful for surgeons who are considering using these implants in their armamentarium. This is the way all new technology, especially complex advances in surgical care, should be reported.
Orthopaedic implants and instruments continue to evolve, almost always toward more sophisticated digital technology, complex engineering, and more numerous moving parts. The advent of magnetic growing rods for treating early-onset scoliosis is just one example. Often such advances are reported on by surgeons who are conflicted by personal and financial interests in the technology. This leads to all manner of potential bias–indication bias, reporting bias, selection bias, and detection bias to name just a few. Readers should evaluate this type of data with a high degree of suspicion.
What we need throughout orthopaedics are more multicenter, multisurgeon, “deconflicted” cohort studies and clinical trials. When such rigorous studies are conducted to investigate “high-tech” growing rods in patients with early-onset scoliosis, I will not be surprised if researchers find the same risk factors for reoperation after fusion that Du et al. found.
Marc Swiontkowski, MD
JBJS Editor-in-Chief
Hydrogel + Stem Cells Improve Disc Conditions in Goats
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.
One of the key changes leading to intervertebral disc degeneration is the loss of complex proteoglycans in the nucleus pulposus (NP), which leads to a loss of water avidity, physiologic dysfunction, NP tissue rigidity, and disruption of surrounding disc tissues. In humans, these changes can begin as early as the second decade of life. One of the difficulties in developing cellular therapies to address these changes is creating a hydrogel that can support effective delivery of mesenchymal stem cells (MSCs).
University of Pennsylvania researchers chemically induced degeneration in lumbar discs in adult male goats. After 12 weeks, some of the degenerating discs were injected with either a hydrogel alone (n=9 discs) or hydrogel with 10 million mesenchymal stem cells per ml (n=10 discs). The remaining discs received neither injection. Two weeks later, researchers analyzed disc height, hydrogel distribution, and MSC localization using green fluorescent protein (GFP) immunostaining.
After 12 weeks of disc degeneration, disc height was approximately 66% of pre-intervention levels. After 2 weeks of the treatment phase, researchers found an insignificant increase in height in the hydrogel-alone discs, and a significant 7.6% height increase in the hydrogel-with-MSCs discs. Imaging revealed that the majority of hydrogel was located in the NPs of the treated discs.
Treated discs exhibited improved overall histological grade compared to untreated discs, but the improvement was significant only in discs treated with hydrogel + MSCs. The fact that GFP-positive MSCs were identified both in the hydrogel itself and in the surrounding NP tissue suggests that MSCs migrated beyond the injection site.
The question remains whether we can similarly improve physiology in the wide spectrum of degenerative disc disease experienced by humans. Let’s hope that future investigations yield positive findings.
Teamwork Necessary When Treating Patients with Syringomyelia + Scoliosis
Most orthopaedic spine surgeons and neurosurgeons have come to understand that syringomyelia plays a role in some cases of scoliosis, and that the spinal-cord condition may increase the risk of cord injury during deformity-correction surgery. In the August 19, 2020 issue of JBJS, Tan et al. investigate whether radiographic and clinical outcomes after 1-stage posterior spinal fusion to correct scoliosis secondary to syringomyelia differ between patients with syringomyelia related to Chiairi-I malformation (CIM) and those with idiopathic syringomyelia.
The short answer is “no.” Although researchers found larger preoperative syringeal parameters in the CIM group, up through 2 years after scoliosis-correction surgery, they detected no significant between-group differences in coronal/sagittal parameters or in scores from the 5 domains of the Scoliosis Research Society-22 questionnaire. Moreover, the preoperative neurological status and intraoperative neuromonitoring signals were similar in both groups.
In commenting on these findings, Kent A. Reinker, MD, points out that patients who had received preoperative neurological treatment for the syrinx were excluded from the study, so “the results … do not necessarily apply to patients who have had neurological intervention prior to scoliosis surgery.” He strongly recommends that all patients with a syrinx be referred to a neurosurgeon for evaluation prior to any scoliosis surgery, concluding that “a working partnership between orthopaedic surgeons and their neurological colleagues is important when assessing these patients.”
Sustained Fevers After Spinal Fusion: A Sentinel for Infection?
Postoperative fevers occur frequently. During the first 2 to 3 days after surgery, these fevers are often due to atelectasis or the increased inflammatory response that arises from tissue injury during surgery. However, persistent postoperative fevers should be cause for concern. In the August 19, 2020 issue of The Journal, Hwang et al. examine the relationship between sustained fevers after spine instrumentation and postoperative surgical site infection.
The authors retrospectively reviewed 598 consecutive patients who underwent lumbar or thoracic spinal instrumentation. They excluded patients who underwent surgery to treat tumors or infections and those with other identified causes of fever, such as a urinary tract infection or pneumonia. Sustained fevers were defined as those that began on or after postoperative day (POD) 4 and those that started on POD 1 to 3 if they persisted until or beyond POD 5.
Sixty-eight patients (11.4%) met the criteria for a sustained fever after spinal instrumentation. Nine of those 68 (13.2%) were diagnosed with a surgical site infection. Of the 530 patients who did not have a sustained fever, only 5 (0.9%) developed a surgical site infection (p<0.001 for the between-group difference).
Further analysis revealed 3 diagnostic clues for surgical site infections among the patients with sustained fevers:
- Continuous fever (rather than cyclic or intermittent)
- Levels of C-reactive protein (CRP) >4 mg/dL after POD 7
- Increasing or stationary patterns of CRP level and neutrophil differential
In addition, the authors found that CRP levels >4 mg/dL between PODs 7 and 10 had much greater sensitivity for discriminating surgical site infection than gadolinium-enhanced magnetic resonance imaging data obtained within 1 month of the surgical procedure.
Although a vast majority (87%) of patients with sustained postoperative fevers in this study did not develop an infection, persistent fever after spine instrumentation surgery is something to be mindful of. The authors describe their findings as “tentative” and advise readers to interpret them with caution. Those caveats notwithstanding, I consider this information to be valuable because it might help prevent delays in the diagnosis of a potentially serious perioperative complication.
Matthew R. Schmitz, MD
JBJS Deputy Editor for Social Media
Owning the Bone in Spine Surgery
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.
Approximately 20% of patients who undergo spine surgery have osteoporosis, which has a significant impact on spine-surgery complications such as failure of fixation devices and collapse fractures following fusion procedures. In a recent critical analysis review, authors focus on improving outcomes by identifying and optimizing patients with osteoporosis prior to spine surgery. The multidisciplinary team involved in that process should include primary care providers, endocrinologists, physical therapists, and orthopaedic surgeons.
The predominant tool for assessing bone mineral density (BMD) is dual x-ray absorptiometry. The diagnosis is based on a T score, which represents the number of standard deviations between the patient’s BMD and that of a healthy 30-year-old woman. Standard deviations ≤─2.5 define osteoporosis. The Z score is similar to the T score but compares the patient to an age- and sex-matched individual.
A history of low-energy fracture, such as a wrist fracture following a fall from a standing height, is considered a sentinel event for suspicion of fragility fractures. The combination of a fragility fracture and low BMD is considered to be severe osteoporosis. The most common form of osteoporosis is associated with a postmenopausal decrease in mineralization, but there are other causes. These include advanced kidney disease, hypogonadism, Cushing disease, vitamin D deficiency, anorexia and/or bulimia, rheumatoid arthritis, hyperthyroidism, primary hyperparathyroidism, and some medications (e.g., anticonvulsants, corticosteroids, heparin, and proton pump inhibitors).
Forty-seven percent of patients undergoing spine deformity surgery and 64% of cervical spine surgery patients have low vitamin D levels. Postoperative bone health can be enhanced in women ≥51 years old with daily intake of 800 to 1,000 units of vitamin D and 1,200 mg of daily calcium. There is no solid evidence that pre- or postoperative bisphosphonates have a positive impact on bone healing. Conversely, some series have shown that teriparatide, an anabolic parathyroid hormone, may improve time-to-fusion and help reduce screw pull-out after lumbar fusion in postmenopausal women.
Calcitonin has been shown to reduce the incidence of vertebral compression fracture, but there is no concrete evidence that it supports spine-fusion healing. Similarly, there is no strong evidence for the use of estrogen or selective estrogen receptor modulators in this surgical scenario. There is evidence that when the human monoclonal antibody denosumab is combined with teriparatide, spine-fusion healing may be improved relative to the use of teriparatide alone. Finally, the review article identifies screw size, screw position, and other surgical considerations that can improve fixation strength.
Using the “Own the Bone” practices promulgated by the American Orthopaedic Association and the technical considerations described in this review, we should be able to mitigate osteoporosis-related postoperative complications in spine-surgery patients.
What’s New in Spine Surgery 2020
Every month, JBJS publishes 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 OrthoBuzz summaries of these “What’s New” articles. This month, co-author Jacob M. Buchowski, MD, selected the 5 most clinically compelling findings from the >30 studies summarized in the June 17, 2020 “What’s New in Spine Surgery.”
Adult Spinal Deformity
—A recent randomized controlled trial compared operative vs nonoperative treatment among 63 adult patients with symptomatic lumbar scoliosis. An additional 223 patients were included in an observational arm of the study. At 2 years, 64% of the randomized patients in the nonoperative group had crossed over to the operative group. In an as-treated analysis, surgery was associated with superior improvement, but the high crossover rate precludes making firm comparative conclusions.
Spinal Cord Injuries
—A small study of 3 subjects1 who had sustained a spinal cord injury investigated the delivery of spatially selective stimulation to posterior nerve roots innervating the lumbosacral spinal cord through an implantable pulse generator with real-time triggering capability. This method reestablished adaptive control over previously paralyzed muscles, and subjects were eventually able to walk or bike during spatiotemporal stimulation.
Cervical Myelopathy
—A prospective study of >700 patients with degenerative cervical myelopathy2 examined the impact of surgical management on neck pain outcomes. Using the Neck Disability Index at baseline and at 6, 12, and 24 months postoperatively, researchers found significant improvement in functional and pain scores that met or exceeded the minimum clinically important difference at all follow-up time points.
Lumbar Stenosis
—A retrospective study of >1,800 patients with symptomatic lumbar stenosis3 investigated whether pain improvements could be obtained surgically with decompression alone without fusion. At 1 year after surgery, decompression alone was associated with significant improvement in all patient-reported outcomes, suggesting that a concomitant fusion may not be required in such cases.
Opioid Consumption
—A retrospective study of nearly 29,000 patients4 examined the effects of chronic preoperative opioid therapy on medium- and long-term outcomes after lumbar arthrodesis surgery. Postoperatively, chronic opioid use prior to surgery was associated with an increased risk of 90-day emergency department visits and prolonged 1- and 2-year narcotic use.
References
- Wagner FB, Mignardot JB, Le Goff-Mignardot CG, Demesmaeker R, Komi S, Capogrosso M, Rowald A, Se´añez I, Caban M, Pirondini E, Vat M, McCracken LA, Heimgartner R, Fodor I, Watrin A, Seguin P, Paoles E, Van Den Keybus K, Eberle G, Schurch B, Pralong E, Becce F, Prior J, Buse N, Buschman R, Neufeld E, Kuster N, Carda S, von Zitzewitz J, Delattre V, Denison T, Lambert H, Minassian K, Bloch J. Courtine G. Targeted neurotechnology restores walking in humans with spinal cord injury. Nature. 2018 Nov;563(7729):65-71. Epub 2018 Oct 31.
- Schneider MM, Tetreault L, Badhiwala JH, Zhu MP, Wilson J, Fehlings MG. 42. The impact of surgical decompression on neck pain outcomes in patients with degenerative cervical myelopathy: results from the multicenter prospective AOSpine studies. Spine J. 2019 Sep;19(9):S21.
- Bech-Azeddine R, Fruensgaard S, Andersen M, Carreon LY. 215. Outcomes of decompression without fusion in patients with lumbar spinal stenosis with back pain. Spine J. 2019 Sep;19(9):S106.
- Eisenberg JM, Kalakoti P, Hendrickson NR, Saifi C, Pugely AJ. 142. Impact of preoperative chronic opioid therapy on long-term outcomes, reoperations, complications and resource utilization after lumbar arthrodesis. Spine J. 2019 Sep; 19(9):S68-9.
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