Marco Cannella

Altered Trunk Motor Planning in Patients with Nonspecific Low Back Pain

ABSTRACT The authors investigated differences in trunk muscle activation timing between patients with chronic nonspecific low back pain (NSLBP) and asymptomatic controls during a self-initiated postural challenge. The authors compared 30 participants with NSLBP to 30 controls. Surface electromyographic data were collected from bilateral trunk muscles. Dependent variables were trunk muscle onset and offset relative to extremity muscle activation and duration of the trunk muscle burst and abdominal–extensor cocontraction. Patients with NSLBP demonstrated significantly delayed trunk muscle onset latency (p < .01), and shorter burst (p = .02) and cocontraction durations (p < .01). Results suggest that patients with NSLBP may be inefficient in regulating trunk posture during voluntary extremity movements. These alterations could also represent a compensatory control pattern imposed by the CNS to avoid pain.

23Na TQF NMR imaging for the study of spinal disc tissue

A method for acquiring triple quantum filtered (TQF) (23)Na NMR images is proposed that takes advantage of the differences in transverse relaxation rates of sodium to achieve positive intensity, PI, NMR signal. This PITQF imaging sequence has been used to obtain spatially resolved one-dimensional images as a function of the TQF creation time, tau, for two human spinal disc samples. From the images the different parts of the tissue, nucleus pulposus and annulus fibrosus, can be clearly distinguished based on their signal intensity and creation time profiles. These results establish the feasibility of (23)Na TQF imaging and demonstrate that this method should be applicable for studying human disc tissues as well as spinal disc degeneration.

2H double quantum filtered (DQF) NMR spectroscopy of the nucleus pulposus tissues of the intervertebral disc

Deuterium (2H) double‐quantum filtered (DQF) NMR spectroscopy of nucleus pulposus (NP) tissues from human intervertebral discs is reported. The DQF spectral intensities, DQ build‐up rates, and DQF‐detected rotating‐frame spin‐lattice relaxation times are sensitive to the degree of hydration of the NP tissue, and display a monotonous correlation with age between 15 and 80 years. The implications of this work are that the changes in water dynamics as detected via DQF NMR spectroscopy may be used as a probe of tissue degeneration in NP, particularly in the early stages of degeneration to which most standard NMR methods are not sensitive. Magn Reson Med 57:990–999, 2007.

The application of 23Na double‐quantum‐filter (DQF) NMR spectroscopy for the study of spinal disc degeneration

Degenerative disc disease is an irreversible process that leads to a loss of mechanical integrity and back pain in millions of people. In this report, 23Na double‐quantum‐filtered (DQF) NMR spectroscopy is used to study disc tissues in two stages of degeneration. Initial results indicate that the 23Na DQF signal may be useful for determining the degree of degeneration. The spectral analysis reveals the presence of sodium environments with different residual quadrupolar couplings and T2 relaxation times that we attribute to different regions, or compartments, corresponding to different biochemical regions in the tissue. In general it is found that there are compartments with no residual quadrupolar couplings, compartments with moderate couplings (200 to 1000 Hz), and compartments with couplings ranging from 1500 to 3000 Hz. The results indicate that 23Na DQF NMR spectroscopy provides a probe of the degenerative state of the intervertebral disc tissues, and might hold potential as a novel diagnostic method for detection of disc degeneration. Magn Reson Med 60:246–252, 2008.

Fill of the Nucleus Cavity Affects Mechanical Stability in Compression, Bending, and Torsion of a Spine Segment, Which Has Undergone Nucleus Replacement

Study Design. Axial loading, rotation, and bending were applied to human cadaveric lumbar segments to investigate the changes in disc mechanics with denucleation and incremental delivery of a novel hydrogel nucleus replacement. Objective. The purpose of this study was to investigate the effect of nucleus implant injection pressure/volume relationships on the quasi-static mechanical behavior of the human cadaveric lumbar intervertebral disc to determine if intact biomechanics could be reproduced with nucleus-implanted discs. Summary of Background Data. Previous studies have shown that volumetric filling of the nucleus cavity with a compliant nucleus replacement device will affect compressive stiffness of the implanted intervertebral disc, but data regarding restoration of mechanics through cavity pressurization are lacking. Methods. A total of 12 intact lumbar anterior column units were loaded in series in axial loading, axial rotation, lateral bending, and flexion/extension (FE). Each segment was fully denucleated and implanted with a hydrogel nucleus replacement using pressurization between 12 psi and 40 psi. Range of motion (ROM), neutral zone (NZ), energy dissipation (HYS), disc height (DH), and stiffness were compared among the intact, denucleated, and implanted conditions. Results. Denucleation significantly destabilized the segments compared to intact controls as shown by increased ROM, NZ, and HYS, and decreased DH and stiffness through the NZ. As the nucleus cavity was repressurized with increasing volumes of hydrogel implant, the segments were stabilized and DH was restored to the intact level. No significant differences from intact were observed in any loading direction for ROM, NZ, or DH after the segments were implanted with the nucleus replacement device using inflation pressures between 20 psi and 40 psi. Conclusion. Compliant nucleus replacement using inflation pressures of 20 to 40 psi resulted in restoration of intact mechanics. Mechanical function was dependent on the volume of implant injected into the nucleus cavity.

Nucleus Implantation: The Biomechanics of Augmentation Versus Replacement With Varying Degrees of Nucleotomy

Nucleus pulposus replacement and augmentation has been proposed to restore disk mechanics in early stages of degeneration with the option of providing a minimally invasive procedure for pain relief to patients with an earlier stage of degeneration. The goal of this paper is to examine compressive stability of the intervertebral disk after either partial nucleus replacement or nuclear augmentation in the absence of denucleation. Thirteen human cadaver lumbar anterior column units were used to study the effects of denucleation and augmentation on the compressive mechanical behavior of the human intervertebral disk. Testing was performed in axial compression after incremental steps of partial denucleation and subsequent implantation of a synthetic hydrogel nucleus replacement. In a separate set of experiments, the disks were not denucleated but augmented with the same synthetic hydrogel nucleus replacement. Neutral zone, range of motion, and stiffness were measured. The results showed that compressive stabilization of the disk can be re-established with nucleus replacement even for partial denucleation. Augmentation of the disk resulted in an increase in disk height and intradiskal pressure that were linearly related to the volume of polymer implanted. Intervertebral disk instability, evidenced by increased neutral zone and ranges of motion, associated with degeneration can be restored by volume filling of the nucleus pulposus using the hydrogel device presented here.

Nucleus Replacement of the Intervertebral Disc

This chapter focuses on the treatments for degenerative disc disease. The chapter also introduces several nucleus replacement design concepts prevalent in degenerative disc disease. Current treatment for degenerative disc disease focuses primarily on relieving back and leg pain. The most common surgical treatments, discectomy and spinal fusion, are performed to reduce pain, and not to restore disc function. Discectomy is employed when the disc has herniated and is impinging on nerve roots causing patient pain, but when the annulus degeneration is not severe. Surgical fusion, inducing bone growth across the functional spinal unit to eliminate disc loading and motion, is reserved for patients with chronic severely disabling pain. The replacement of the nucleus pulposus alone would result in a surgical technique that would offer a less invasive approach to pain relief while potentially restoring the functional biomechanics to the system. This approach could be most effective in patients with early diagnosis of disc disease, before the annulus has suffered significant degeneration. The chapter presents the surgical candidates for nucleus replacement, mechanical requirements of the nucleus replacements, and biocompatibility requirements for successful nucleus replacements.

Trunk Postural Muscle Timing Is Not Compromised In Low Back Pain Patients Clinically Diagnosed With Movement Coordination Impairments

Trunk muscle timing impairment has been associated with nonspecific low back pain (NSLBP), but this finding has not been consistent. This study investigated trunk muscle timing in a subgroup of patients with NSLBP attributed to movement coordination impairment (MCI) and matched asymptomatic controls in response to a rapid arm-raising task. Twenty-one NSLBP subjects and 21 matched controls had arm motion and surface EMG data collected from seven bilateral trunk muscles. Muscle onset and offset relative to deltoid muscle activation and arm motion, duration of muscle burst and abdominal-extensor co-contraction time were derived. Trunk muscle onset and offset latencies, and burst and co-contraction durations were not different (p > .05) between groups. Patterns of trunk muscle activation and deactivation relative to arm motion were not different. Task performance was similar between groups. Trunk muscle timing does not appear to be an underlying impairment in the subgroup of NSLBP with MCI.

Double and zero quantum filtered 2H NMR analysis of D2O in intervertebral disc tissue

The analysis of double and zero quantum filtered (2)H NMR spectra obtained from D2O perfused in the nucleus pulposus of human intervertebral disc tissue samples is reported. Fitting the spectra with a three-site model allows for residual quadrupolar couplings and T2 relaxation times to be measured. The analysis reveals changes in both the couplings and relaxation times as the tissue begins to show signs of degradation. The full analysis demonstrates that information about tissue hydration, water collagen interactions, and sample heterogeneity can be obtained and used to better understand the biochemical differences between healthy and degraded tissue.

Analysis of the mechanical behavior of the lumbar spine under high impact loading

High speed boat (HSB) crewman in the U.S. navy often suffer from lower back pain and accelerated intervertebral disc (IVD) degeneration, due to the high-G impacts experienced during typical missions, resulting in significant time on limited duty status. The relationship between high impact loads and disc biomechanics is not well understood. We seek to analyze the changes in mechanical behavior, particularly compressive stiffness, of anterior column units (ACU) of the lumbar spine as a function of duration of impact. Lumbar spine sections from four donors with mean age 63 ± 8.8 years were used, yielding n=5 ACUs. The discs were put under quasi-static loading to simulate normal loading conditions and determine the neutral zone and quasi-static loading stiffness. Each ACU then underwent an impact loading sequence, compressing a distance equal to its neutral zone. Each sequence consisted of six impact loads, with varying duration of compression-relaxation (10, 20, 40, 80, 160, and 320 ms). The data shows there is an increase in stiffness as the impact duration decreased. The sole exception was the 10-ms impact, which yielded stiffness values smaller than that of the 20- or 40-ms impacts. Stiffness values for all impact durations, however, were significantly higher (p < 0.05, Students t-test) than that of the quasi-static conditions. The data supports our theory that the IVD is more stiff under high impact loading conditions than normal loading, and that this stiffness increases with shortened impact duration. This shows that the highly demanding environment of naval crewman is deleterious to the IVD, and may provide insight into the high incidence of back pain and accelerated disc degeneration for this population.