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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

Mehta Casting for Early-Onset Scoliosis: Predictors of Success

The treatment of early-onset scoliosis with Mehta casting is a long process, but if successful, it can delay or obviate the need for surgery. In the September 4, 2019 issue of JBJS, Fedorak et al. examine outcomes among 38 patients (mean age of 24 ± 15 months at time of first casting) who were treated with Mehta casting and followed for a mean of 8 ± 2 years. The retrospective review identified differences between patients who had a Cobb angle ≤15° (improvement group) at the most recent follow-up and those who had a Cobb angle of >15° (no-improvement group).

Forty-nine percent of children had achieved and maintained scoliosis of ≤15° at the time of the most recent follow-up, and 73% were improved by at least 20°, although 3 children ended up relapsing after meeting recommended criteria for discontinuation of casting. There was no significant difference in thoracic-height gain between the groups, demonstrating that even when scoliosis was not corrected, growth was maintained during cast treatment.

Patients in the improvement group had a mean age of 18.9 ± 12 months and scoliosis of 48.2° ± 14° at the initiation of treatment. Here are 3 additional factors that were associated with a greater likelihood of scoliosis of ≤15°:

  • A lower pre-treatment Cobb angle and traction Cobb angle
  • A smaller rib-vertebral angle difference on first-in-cast radiograph
  • A lower Cobb angle on first-in-cast radiograph

The authors note that although this study analyzed longer-term follow-up data than most other similar investigations, “treatment of early-onset scoliosis is not truly finished until skeletal maturity has been reached.”

Severe Congenital Scoliosis Lowers Exercise Capacity

The etiology and pathogenesis of adolescent idiopathic scoliosis (AIS) and congenital scoliosis are markedly different. Among the differences, progressive congenital scoliosis has the potential to cause much more severe impairment of pulmonary function than does AIS.

In an observational study in the June 19, 2019 issue of The Journal of Bone & Joint Surgery, Lin et al. investigate the precise extent to which pulmonary function and exercise capacity are affected by congenital scoliosis of varying severity. Sixty patients with congenital scoliosis (ranging from 10 to 39 years old) underwent spinal radiography, static pulmonary function testing (PFT), and dynamic cardiopulmonary exercise testing (CPET). From that data the researchers determined the impact of thoracic spinal deformity and rib anomalies on pulmonary function and exercise capacity.

Not surprisingly, PFT results, including total lung capacity, decreased as the severity of thoracic curves increased. In addition, patients with moderate or severe static pulmonary dysfunction had lower exercise tolerance than those with no or mild pulmonary dysfunction. CPET also revealed reduced ventilation capacity, faster respiratory rate, and smaller tidal volume in patients with more complex rib anomalies, although overall exercise tolerance did not differ among patients based on the severity of rib anomalies.

The authors observe that “although patients with thoracic deformities have the potential to compensate during increasing exercise,…exercise capacity (represented by work rate and maximal heart rate) declined greatly in patients with a thoracic curve exceeding 100°.” Because of the connection between congenital scoliosis with pronounced thoracic curves and loss of exercise capacity, Lin et al. recommend “early diagnosis, close follow-up, and timely treatment” for patients with this condition.

What’s New in Spine Surgery 2019

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 all OrthoBuzz Specialty Update summaries. This month, Jacob M. Buchowski, MD, MS, coauthor of the June 19, 2019 What’s New in Spine Surgery,” selected the five most clinically compelling findings from among the 47 noteworthy studies summarized in the article.

Predictive Analytics for Deformity Conditions
–A validated model for predicting outcomes after lumbar spine surgery1 found that patients with lower preoperative disability scores, those covered by Medicaid or Workers’ Compensation, and current and previous smokers were less likely to improve with lumbar fusion surgery. Invasiveness of surgery and surgeon and hospital type had lower predictive value.

Early-Onset Scoliosis (EOS)
–A 5-year direct-cost estimate2 comparing magnetic growing rods and conventional growing rods for the treatment of EOS found the total cost for magnetic growing rods to be £34,741 compared with £52,293 for conventional growing rods.

Pediatric Neuromuscular Scoliosis
–A Level-II study investigated patient factors associated with postoperative pulmonary complications among patients with neuromuscular scoliosis who underwent posterior spinal fusion.3 Patients with a history of pneumonia or gastrotomy tube at the time of surgery had an elevated risk of postoperative respiratory infections.

Opioid Consumption
–Findings from a retrospective study of >27,000 patients who underwent lumbar decompression with or without fusion revealed that the majority of patients using prescription opioids discontinued those medications postoperatively. However, among the patients with opioid use >90 days after surgery, the duration of preoperative opioid use was the most important predictor of postoperative opioid use.

Neurological Decline after Adult Spinal Deformity Surgery
–In a retrospective analysis of 265 patients who underwent corrective surgery for adult spinal deformity,4 23% of patients experienced a neurological injury; among those, 33% experienced a major neurological decline. Among the patients with major decline, full recovery was observed in 24% at 6 weeks and 65% at 6 months, but one-third of those patients experienced persistent neurological deficits at 24 months postoperatively. Among patients who experienced a minor neurological injury, 49% reported full recovery at 6 weeks and 70% reported full recovery at 6 months. About one-quarter of those patients showed no improvement at 24 months.

References

  1. Khor S, Lavallee D, Cizik AM, Bellabarba C, Chapman JR, Howe CR, Lu D, Mohit AA, Oskouian RJ, Roh JR, Shonnard N,Dagal A, Flum DR. Development and validation of a prediction model for pain and functional outcomes after lumbar spine surgery. JAMA Surg.2018 Jul 1;153(7):634-42.
  2. Harshavardhana NS, Noordeen MHH, Dormans JP. Cost analysis of magnet-driven growing rods for early-onset scoliosis at 5 years. Spine (Phila Pa 1976).2019 Jan 1;44(1):60-7.
  3. Luhmann SJ, Furdock R. Preoperative variables associated with respiratory complications after pediatric neuromuscular spine deformity surgery. Spine Deform.2019 Jan;7(1):107-11.
  4. Kato S, Fehlings MG, Lewis SJ, Lenke LG, Shaffrey CI, Cheung KMC, Carreon LY, Dekutoski MB, Schwab FJ, Boachie-Adjei O, Kebaish KM, Ames CP, Qiu Y, Matsuyama Y, Dahl BT, Mehdian H, Pellisé F, Berven SH. An analysis of the incidence and outcomes of major versus minor neurological decline after complex adult spinal deformity surgery: a subanalysis of Scoli-RISK-1 study. Spine (Phila Pa 1976).2018 Jul 1;43(13):905-12.

June 2019 Article Exchange with JOSPT

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 June 2019, JBJS and OrthoBuzz readers will have open access to the JOSPT article titled “Hybrid Approach to Treatment Tailoring for Low Back Pain: A Proposed Model of Care.”

The authors of this clinical commentary propose a hybrid, prognosis-based approach to low back pain management that includes psychologically informed treatments for those with medium risk and a predominantly central pain mechanism and motor-control approaches to exercise for individuals with medium risk and a nociceptive pain mechanism.

May 2019 Article Exchange with JOSPT

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 May 2019, JBJS and OrthoBuzz readers will have open access to the JOSPT article titled “Cervical Muscle Endurance Performance in Women With and Without Migraine.”

The authors of this cross-sectional laboratory study found that a group of 26 female patients with migraine exhibited a lower holding time for both neck-extensor and neck-flexor endurance than a group of 26 women without migraine. Both groups reported a similar level of neck pain, but only individuals in the migraine group reported pain referred to the head during testing.

Spine/Trauma 3D Navigation Software Recall

Brainlab AG is recalling its Spine & Trauma 3D Navigation software (version 1.0). The FDA has identified this as a Class I recall, the agency’s most serious category.

This navigation system provides images that help surgeons safely navigate instruments and implants used before and during minimally invasive surgeries. The software has been recalled because the displayed images may result in user misinterpretation and may prevent surgeons from accurately navigating surgical tools inside the patient.

In Chronic Sciatica, Gabapentin Quells Nerve Pain Better than Pregabalin

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. 

Orthopaedic surgeons may not be at the forefront of dealing with nonoperative nerve pain, but many of our patients who are not candidates for surgery suffer from spine-related nerve pain in their limbs, such as sciatica. Both gabapentin (GBP, Neurontin) and pregabalin (PGB, Lyrica) are used to treat chronic sciatica (CS).

Gamma-aminobutyric acid (GABA) is an important pain-related neurotransmitter, although neither GBP nor PGB affect the GABA receptor. Instead, both drugs associate with the ligand of the auxiliary α2δ-1 and α2δ-2 subunits of certain voltage-dependent calcium channels in nerves. Among other uses, Neurontin is prescribed to treat diabetic peripheral neuropathy, and Lyrica is commonly used to treat fibromyalgia.

Investigators reporting in JAMA Neurology sought to help guide practitioners in the initial choice of drug. Eighteen patients with MRIs corroborating single-sided nerve-root sciatic pain of at least 3 months duration were evaluated in an interim analysis as part of a randomized, double-blind, double-dummy crossover trial of PGB vs GBP (8 weeks of exposure to each drug with a 1-week washout in between). The primary outcome was pain intensity measured with a 10-point visual analog scale (VAS) at baseline and 8 weeks. Secondary outcomes included disability as measured with the Oswestry Disability Index and the severity and frequency of adverse events.

Relative to baseline, both drugs showed significant VAS pain reductions and disability-score improvements, However, head-to-head, GBP showed superior VAS pain reduction (mean [SD], GBP: 1.72 [1.17] vs PGB: 0.94 [1.09]; P = 0.035), regardless of the order in which it was given. There were no between-drug differences in disability scores, but adverse events for PGB were more frequent (PGB, 31 [81%] vs GBP, 7 [19%]; P = 0.002), especially when PGB was taken first.

The authors conclude that GBP was superior with fewer and less severe adverse events, and they suggest that gabapentin should be commenced before PGB to permit optimal crossover of medicines.

Reference
Robertson K, Marshman LAG, Plummer D, Downs E. Effect of Gabapentin vs Pregabalin on Pain Intensity in Adults WIth Chronic Sciatica: A Randomized Clinical Trial. JAMA Neurol. 2018 Oct 15. doi: 10.1001/jamaneurol.2018.3077. [Epub ahead of print] PMID: 30326006

Questionnaire Helps Identify Lumbar Patients Who Need Surgeon Consult

Only about 10% to 15% of patients with low back pain who are referred to a spine surgeon actually require a surgical procedure. And because low back pain is such a common presenting complaint, many such patients often wait a long time for a surgery consult. In the December 19, 2018 issue of JBJS, Coyle et al. demonstrate that a simple, 3-item patient-administered questionnaire can identify those better suited for nonoperative management—and thus increase the likelihood that surgical candidates are seen by spine surgeons in an acceptable time frame.

All 227 of the Canadian patients enrolled in this randomized controlled trial received the questionnaire, which elicited information to distinguish between patients with leg-dominant radicular pain and those with back-dominant pain. Evidence-based guidelines recommend nonoperative management for most back-dominant pain, while patients with leg-dominant pain are more likely to need surgery. Researchers randomized 116 patients into an intervention group; these patients were triaged by a spine surgeon and then had their triage status upgraded if responses to the questionnaire indicated leg-dominant symptoms. The 111 patients in the control group were triaged only by a spine surgeon.

After triage, 33 of the 227 patients (15%) were recommended for a surgical procedure—16 from the intervention group and 17 from the control group. Of the 16 surgical candidates identified from the intervention group, 9 (56%) were re-prioritized on the basis of questionnaire results.

The median wait time for a consultation among the 16 surgical candidates in the intervention group was 2.5 months, compared with 4.5 months for the 17 surgical candidates in the control group. A significantly greater percentage of patients in the intervention group than in the control group were seen for a consult with a spine surgeon within the “acceptable” time frame of 3 months. Another benefit of the questionnaire approach evaluated in this study is that it helps identify nonsurgical candidates early, so they can be directed toward more appropriate treatment (such as physical therapy) rather than delaying treatment while waiting for a consult with a spine surgeon.

Although this study was conducted in the setting of the “nationalized” Canadian health care system, wait times to see orthopaedic surgeons and neurosurgeons are also long for many patients in many regions of the US. This questionnaire enhancement to triage could therefore be viable throughout North America, and perhaps beyond.

Confirmed: TXA Works Well in Adolescent Scoliosis Surgery

The evidence favoring tranexamic acid (TXA) for reducing surgical blood loss is ample and growing, but until now robust data were sparse regarding its efficacy in the setting of adolescent idiopathic scoliosis surgery. In the December 5, 2018 issue of The Journal of Bone & Joint Surgery, Goobie et al. report on a randomized, blinded, placebo-controlled trial showing that, in that population, TXA reduced perioperative blood loss by 27%, compared with blood loss in a placebo group.

Even with recent advances in scoliosis surgical technique, blood transfusions are common. And, because transfusions are associated with significant morbidity and mortality, limiting operative blood loss and reducing the need for transfusion have become focal points for orthopaedic surgeons.

In this Level-I trial, >100 patients between the ages of 10 and 18 years undergoing elective posterior instrumented spinal fusion were randomized to receive either TXA (infusion of a 50-mg/kg loading dose and a 10-mg/kg/h maintenance dose) or normal saline (delivered in the same way and dose) during surgery. The TXA group demonstrated an overall 27% reduction in cumulative blood loss and a 2-fold reduction in the percentage of patients with clinically relevant blood loss (defined as >20 mL/kg).

The cumulative effect of reduced blood loss was enhanced over time, with the positive effect of TXA being most evident in procedures lasting >4 hours. None of the patients in the TXA group required a transfusion or developed side effects such as thromboembolism or seizures.

In an interesting sidenote, the authors asked the participating orthopaedic surgeons, who were blinded to the randomization, to guess which group each patient had been assigned to by evaluating the relative ooziness of the surgical field. The surgeons guessed correctly 72% of the time.

Overall, these findings prompted the authors to conclude that “the use of TXA as part of a multimodal blood management strategy, as was employed in this study, should be considered the standard of care for patients undergoing surgery for adolescent idiopathic scoliosis.”