Biomechanical assessment of the effect of sublaminar band tensioning on lumbar motion.

OBJECTIVE: Adjacent-segment disease (ASD) proximal to lumbosacral fusion is assumed to result from increased stress and motion that extends above or below the fusion construct. Sublaminar bands (SBs) have been shown to potentially mitigate stresses in deformity constructs. A similar application of SBs in lumbar fusions is not well described yet may potentially mitigate against ASD. METHODS: Eight fresh-frozen human cadaveric spine specimens were instrumented with transforaminal lumbar interbody fusion (TLIF) cages at L3-4 and L4-5, and pedicle screws from L3 to S1. Bilateral SBs were applied at L2 and tightened around the rods extending above the L3 pedicle screws. After being mounted on a testing frame, the spines were loaded at L1 to 6 Nm in all 3 planes, i.e., flexion/extension, right and left lateral bending, and right and left axial rotation. Motion and intradiscal pressures (IDPs) at L2-3 were measured for 5 conditions: intact, instrumentation (L3-S1), band tension (BT) 30%, BT 50%, and BT 100%. RESULTS: There was significant increase in motion at L2-3 with L3-S1 instrumentation compared with the intact spine in flexion/extension (median 8.78°, range 4.07°-10.81°, vs median 7.27°, range 1.63°-9.66°; p = 0.016). When compared with instrumentation, BT 100% reduced motion at L2-3 in flexion/extension (median 8.78°, range 4.07°-10.81°, vs median 3.61°, range 1.11°-9.39°; p < 0.001) and lateral bending (median 6.58°, range 3.67°-8.59°, vs median 5.62°, range 3.28°-6.74°; p = 0.001). BT 50% reduced motion at L2-3 only in flexion/extension when compared with instrumentation (median 8.78°, range 4.07°-10.81°, vs median 5.91°, range 2.54°-10.59°; p = 0.027). There was no significant increase of motion at L1-2 with banding when compared with instrumentation, although an increase was seen from the intact spine with BT 100% in flexion/extension (median 5.14°, range 2.47°-9.73°, vs median 7.34°, range 4.22°-9.89°; p = 0.005). BT 100% significantly reduced IDP at L2-3 from 25.07 psi (range 2.41-48.08 psi) before tensioning to 19.46 psi (range -2.35 to 29.55 psi) after tensioning (p = 0.016). CONCLUSIONS: In this model, the addition of L2 SBs reduced motion and IDP at L2-3 after the L3-S1 instrumentation. There was no significant increase in motion at L1-2 in response to band tensioning compared with instrumentation alone. The application of SBs may have a clinical application in reducing the incidence of ASD.

Predictors of Reduced Opioid Use With Spinal Cord Stimulation in Patients With Chronic Opioid Use.

OBJECTIVES: Spinal cord stimulation (SCS) has gained traction as an alternative to chronic opioid therapy in light of the opioid crisis. Prior reports vary widely in their estimates of its effect on opioid consumption. We therefore aimed to address the following questions: 1) Does chronic opioid use change after SCS? 2) Which patient characteristics predict reduced opioid consumption after SCS? MATERIALS AND METHODS: Claims from a private health insurance company were used to identify patients with SCS implantation from 2003 to 2014. We required 12 months of continuous data before and after surgery (i.e., a minimum total observation period of two years), and at least two opioid prescription fills in the six months before surgery. Daily morphine equivalent dose (MED) was calculated from prescription medication claims. Diagnosis codes identified common comorbidities. RESULTS: Hundred forty-five patients met inclusion criteria. MED of 65 was the most statistically meaningful preoperative dose threshold. Approximately half of patients decreased opioid use >20% after SCS implantation. Logistic regression analysis revealed age (p = 0.0362), gender (p = 0.0076), and preoperative daily MED < 65 (p = 0.0322) as predictors of meaningful reduction, which was defined as a 20% reduction in MED. CONCLUSIONS: With only half of chronic opioid users demonstrating meaningful opioid reduction after SCS implantation, we demonstrate that current SCS technology does not reliably help a larger number of patients reduce opioid usage. Women, older age, and preoperative MED < 65 are predictive of meaningful opioid reduction but only one of these is modifiable. As not all patients saw benefit from their therapies, there is still much room for improvement in the treatment of refractory chronic pain that is associated with failed back surgery syndrome and chronic regional pain syndrome.

Contemporary Approaches to Preventing and Treating Infections of Novel Intrathecal Neurostimulation Devices.

INTRODUCTION: Contemporary approaches to surgical site infections have evolved significantly over the last several decades in response to the economic pressures of soaring health care costs and increasing patient expectations of safety. Neurosurgeons face multiple unique challenges when striving to avoid as well as manage surgical implant infections. The tissue compartment, organ system, or joint is characterized by biological factors and physical forces that may not be universally relevant. Such implants, once rare, are now routine. Although the prevention, diagnosis, and treatment of surgical site infections involving neural implants has advanced, guidelines are ever changing, and the incidence still exceeds acceptable levels. We assess the impact of these factors on a new class of implantable neuromodulation devices. METHODS: The available evidence along with practice patterns were examined and organized to establish relevant groupings for continuing evaluation and to propose justifiable recommendations for the treatment of infections that might arise in the case of intradural spinal cord stimulators. RESULTS: Few studies in the modern era have systematically evaluated preventive behaviors that were applied to intradural neural implants alone. We anticipate that future efforts will focus even more on the investigation of modifiable factors along a continuum from bacterially repellant implants to weight management. Early diagnosis could offer the best hope for device salvage but to date has been largely understudied. CONCLUSIONS: Historically, prevention is the cornerstone to infection mitigation. However, immediate diagnosis and hardware salvage have not received the attention deserved, and that approach may be especially important for intradural devices.