Quantitative Shear Wave Speed Assessment for Muscles With the Diagnosis of Taut Bands and/or Myofascial Trigger Points Using Probe Oscillation Shear Wave Elastography: A Pilot Study.

OBJECTIVE: To use probe oscillation shear wave elastography (PROSE) with two vibration sources to generate two shear waves in the imaging plane to quantitatively assess the shear wave speeds (SWSs) of muscles with and without the diagnosis of taut bands (TB) and/or myofascial trigger points (MTrPs). METHODS: Thirty-three patients were scanned with the PROSE technique. Shear waves were generated through continuous vibration of the ultrasound probe, while the shear wave motions were detected using the same probe. SWSs for the sides with and without TBs and/or MTrPs were computed and compared. The pressure pain thresholds (PPTs) were measured as an indicator of maximum pain tolerance of patients. The statistical differences between the SWSs with and without TBs and/or MTrPs with different PPT values were analyzed using the nonparametric Wilcoxon rank-sum test. RESULTS: The mean SWSs for the sides with TBs and/or MTrPs are faster than that of the contralateral side without TBs and/or MTrPs. A significant difference was observed between mean SWSs with and without TBs and/or MTrPs without any information of PPT, with rank-sum test P < .005. Additionally, with the information of PPT, a significant difference was observed between mean SWSs for the sides with and without TBs and/or MTrPs, for PPT values between 0 and 50 N/cm2 (P < .005), but for PPT values between 50 and 90 N/cm2 , it was difficult to differentiate mean SWSs with and without TBs and/or MTrPs. CONCLUSION: Our preliminary results show that SWSs measured from patients had a significant difference between the mean SWSs with and without TBs and/or MTrPs.

Effect of Off-Axis Fluoroscopy Imaging on Two-Dimensional Kinematics in the Lumbar Spine: A Dynamic In Vitro Validation Study.

Spine intersegmental motion parameters and the resultant regional patterns may be useful for biomechanical classification of low back pain (LBP) as well as assessing the appropriate intervention strategy. Because of its availability and reasonable cost, two-dimensional (2D) fluoroscopy has great potential as a diagnostic and evaluative tool. However, the technique of quantifying intervertebral motion in the lumbar spine must be validated, and the sensitivity assessed. The purpose of this investigation was to (1) compare synchronous fluoroscopic and optoelectronic measures of intervertebral rotations during dynamic flexion-extension movements in vitro and (2) assess the effect of C-arm rotation to simulate off-axis patient alignment on intervertebral kinematics measures. Six cadaveric lumbar-sacrum specimens were dissected, and active marker optoelectronic sensors were rigidly attached to the bodies of L2-S1. Fluoroscopic sequences and optoelectronic kinematic data (0.15-mm linear, 0.17-0.20 deg rotational, accuracy) were obtained simultaneously. After images were obtained in a true sagittal plane, the image receptor was rotated in 5 deg increments (posterior oblique angulations) from 5 deg to 15 deg. Quantitative motion analysis (qma) software was used to determine the intersegmental rotations from the fluoroscopic images. The mean absolute rotation differences between optoelectronic values and dynamic fluoroscopic values were less than 0.5 deg for all the motion segments at each off-axis fluoroscopic rotation and were not significantly different (P > 0.05) for any of the off-axis rotations of the fluoroscope. Small misalignments of the lumbar spine relative to the fluoroscope did not introduce measurement variation in relative segmental rotations greater than that observed when the spine and fluoroscope were perpendicular to each other, suggesting that fluoroscopic measures of relative segmental rotation during flexion-extension are likely robust, even when patient alignment is not perfect.

Quantification of Myofascial Taut Bands.

OBJECTIVE: To assess the correlation of clinician-identified myofascial taut bands with their presence and characteristics on magnetic resonance elastography (MRE) imaging. DESIGN: Cross-sectional study. SETTING: A magnetic resonance imaging (MRI) research laboratory. PARTICIPANTS: A convenience sample of adults (N=65; 45 women, 20 men) identified by skilled musculoskeletal physicians as having upper trapezius myofascial pain-associated taut bands. INTERVENTIONS: Subjects had their taut bands outlined and were positioned within a 1.5T MRI machine. Shear waves were induced with a pneumatic transducer located over the belly of the involved muscle. Wave propagation was visualized with MRE images across a vibration cycle. Imaging data were assessed independently by 2 skilled MRE interpreters. MAIN OUTCOME MEASURES: The primary outcome measure was the determination of the intra- and interrater reliabilities of MRE taut band identification and their correlation with clinician identification of band presence. Secondary outcomes consisted of the elucidation of the physical characteristics of taut bands and their surrounding muscle tissue. RESULTS: MRE intra- and interrater reliability was excellent, with kappa coefficients and 95% confidence intervals (CIs) of .86 (.68-1.00) and .93 (.79-1.00), respectively. Stiffness in MRE-identified taut bands was elevated at a mean ± SD of 11.5±2.4 kPa and fell to 5.8±0.9 kPa in surrounding muscle tissue (P<.001); muscular tone in trapezius muscles without a taut band was relatively uniform at 6.6±2.1 kPa. Agreement between the physicians and the MRE raters, however, was relatively poor (63.1%; 95% CI, 50.2%-74.7%). CONCLUSIONS: Our findings suggest that while clinicians may overestimate, and current MRE techniques may underestimate, the presence of taut bands, these bands do exist, can be assessed quantitatively, and do represent localized areas of increased muscle stiffness.

Biomechanical and histological effects of augmented soft tissue mobilization therapy on achilles tendinopathy in a rabbit model.

OBJECTIVE: Augmented soft tissue mobilization (ASTM) has been used to treat Achilles tendinopathy and is thought to promote collagen fiber realignment and hasten tendon regeneration. The objective of this study was to evaluate the biomechanical and histological effects of ASTM therapy on rabbit Achilles tendons after enzymatically induced injury. METHODS: This study was a non-human bench controlled research study using a rabbit model. Both Achilles tendons of 12 rabbits were injected with collagenase to produce tendon injury simulating Achilles tendinopathy. One side was then randomly allocated to receive ASTM, while the other received no treatment (control). ASTM was performed on the Achilles tendon on postoperative days 21, 24, 28, 31, 35, and 38. Tendons were harvested 10 days after treatment and examined with dynamic viscoelasticity and light microscopy. RESULTS: Cross-sectional area in the treated tendons was significantly greater than in controls. Storage modulus tended to be lower in the treated tendons but elasticity was not significantly increased. Loss modulus was significantly lower in the treated tendons. There was no significant difference found in tangent delta (loss modulus/storage modulus). Microscopy of control tendons showed that the tendon fibers were wavy and type III collagen was well stained. The tendon fibers of the augmented soft tissue mobilization treated tendons were not wavy and type III collagen was not prevalent. CONCLUSION: Biomechanical and histological findings showed that the Achilles tendons treated with ASTM had better recovery of biomechanical function than did control tendons.

Lumbar trabecular bone mineral density distribution in patients with and without vertebral fractures: a case-control study.

PURPOSE: The proportion of load transmitted through the lumbar neural arch increases with aging, spinal degeneration, and lordosis, effectively shielding the lumbar vertebral bodies from load. This stress shielding may contribute to bone loss in the vertebral body, leading to increased fracture risk. To test his hypothesis, we performed a study to determine if vertebral body fractures were associated with a higher neural arch/vertebral body volumetric bone mineral density (vBMD) ratio. METHODS: Trabecular vBMD was calculated by quantitative CT in the L3 vertebral body and neural arch (pars interarticularis) of 36 women with vertebral compression fractures and 39 controls. Neural arch/vertebral body vBMD ratio was calculated, and its relationship to fracture status was determined using linear regression models adjusted for age and body mass index. RESULTS: Vertebral body trabecular vBMD was lower in fracture cases as compared to controls (mean ± SD, 49.0 ± 36.0 vs. 87.5 ± 36.8 mg/cm(3), respectively; P < 0.001), whereas trabecular vBMD of the neural arch was similar (96.1 ± 57.6 in cases vs. 118.2 ± 57.4 mg/cm(3) in controls; P = 0.182). The neural arch/vertebral body vBMD ratio was significantly greater in the fracture group than in controls (2.31 ± 1.07 vs. 1.44 ± 0.57, respectively; P < 0.001). CONCLUSION: These results support the hypothesis that stress shielding is a contributor to vertebral body bone loss and may increase fracture risk. Although further studies are needed, there may be a role for interventions that can shift vertebral loading in the spine to help prevent fracture.

Clinical effectiveness of single lumbar transforaminal epidural steroid injections.

OBJECTIVES: To assess the clinical effectiveness of single lumbar transforaminal epidural steroid injections (TFESIs) in subjects with radicular pain with or without radiculopathy. DESIGN: Retrospective observational series. SETTING: Single academic radiology pain management practice. SUBJECTS: Two thousand twenty-four subjects undergoing single lumbar TFESIs at the L4-5, L5-S1, or S1 neural foramina. METHODS / OUTCOME MEASURES: Subjects were assessed with a pain numerical rating scale (NRS, 0-10) and Roland-Morris disability questionnaire (R-M, 23-point Deyo modification) prior to TFESI and at 2 weeks and 2 months follow-up. Successful pain relief (responders) was defined as either ≥50% reduction in NRS or pain 0/10; functional success was defined as ≥40% reduction in R-M score. RESULTS: There were statistically significant (P < 0.0001) reductions in mean NRS and R-M scores at 2 weeks and 2 months postinjection. For NRS, 40.9% were responders at 2 weeks and 45.6% at 2 months. For R-M, 31.9% were responders at 2 weeks and 41.3% at 2 months. The proportion of responders for NRS and R-M was higher when there was <3 months of pain (odds ratio 2-month NRS = 2.42 [95% confidence interval: 1.82, 3.24], odds ratio 2-month R-M = 2.61 [1.96, 3.48]). For subjects with <3 months of pain, the proportion of responders was 62.4% (56.5, 68.3%) for NRS and 59.3% (53.3, 65.3%) for R-M scores. CONCLUSIONS: This retrospective observational study suggests TFESIs are clinically effective in the treatment of lumbar radicular pain. Subjects with a shorter duration of pain are more likely to achieve a successful outcome.

Transverse connectors providing increased stability to the cervical spine rod-screw construct: an in vitro human cadaveric study.

OBJECT: The object of this study was to determine if the addition of transverse connectors (TCs) to a rod-screw construct leads to increased stabilization of the cervical spine. METHODS: Eleven human cadaveric cervical spines (C2-T1) were used to examine the effect of adding connectors to a C3-7 rod-screw construct in 3 models of instability: 1) C3-6 wide laminectomy, 2) wide laminectomy and 50% foraminotomy at C4-5 and C5-6, and 3) wide laminectomy with full medial to lateral foraminotomy. Following each destabilization procedure, specimens were tested with no TC, 1 TC between the C-5 screws, and 2 TCs between the C-4 and C-6 screws. Testing of the connectors was conducted in random order. Specimens were subjected to ± 2 Nm of torque in flexion and extension, lateral bending, and axial rotation. Range of motion was determined for each experimental condition. Statistical comparisons were made between the destabilized and intact conditions, and between the addition of TCs and the absence of TCs. RESULTS: The progressive destabilization procedures significantly increased motion. The addition of TCs did not significantly change motion in flexion and extension. Lateral bending was significantly decreased with 2 connectors, but not with 1 connector. The greatest effect was on axial rotation. In general, 2 TCs were more restrictive than 1 TC, and decreased motion 10% more than fixation alone. CONCLUSIONS: Regardless of the degree of cervical destabilization, 1 or 2 TCs decreased motion compared with rods and screws alone. Axial rotation was most affected. Transverse connectors effectively increase the rigidity of rod-screw constructs in the cervical spine. Severe cervical instability can be overcome with the use of 2 TCs, but in cases in which 2 cannot be used, 1 should be adequate and superior to none.

Biomechanical evaluation of posterior lumbar dynamic stabilization: an in vitro comparison between Universal Clamp and Wallis systems.

Treatment of chronic low back pain due to degenerative lumbar spine conditions often involves fusion of the symptomatic level. A known risk of this procedure is accelerated adjacent level degeneration. Motion preservation devices have been designed to provide stabilization to the symptomatic motion segment while preserving some physiologic motion. The aim of this study was to compare the changes in relative range of motion caused as a result of application of two non-fusion, dynamic stabilization devices: the Universal Clamp (UC) and the Wallis device. Nine fresh, frozen human lumbar spines (L1-Sacrum) were tested in flexion-extension, lateral bending, and axial rotation with a custom spine simulator. Specimens were tested in four conditions: (1) intact, (2) the Universal Clamp implanted at L3-4 (UC), (3) the UC with a transverse rod added (UCTR), and (4) the Wallis device implanted at L3-4. Total range of motion at 7.5 N-m was determined for each device and compared to intact condition. The UC device (with or without a transverse rod) restricted motion in all planes more than the Wallis. The greatest restriction was observed in flexion. The neutral position of the L3-4 motion segment shifted toward extension with the UC and UCTR. Motion at the adjacent levels remained similar to that observed in the intact spine for all three constructs. These results suggest that the UC device may be an appropriate dynamic stabilization device for degenerative lumbar disorders.

Joint mobilization vs massage for chronic mechanical neck pain: a pilot study to assess recruitment strategies and estimate outcome measure variability.

OBJECTIVE: The purpose of this study was to determine the feasibility of a trial comparing cervical spine mobilization and massage as adjuncts to usual physical therapy treatments (superficial heat and head and neck posture education) for chronic neck pain. Specific objectives were to assess procedures and recruitment strategies and estimate the variability of the Neck Disability Index (NDI) and visual analog scale (VAS) in a population of subjects with chronic nonspecific neck pain and calculate a sample size for a definitive trial. METHODS: Subjects with nonspecific chronic neck pain (≥3 months) were randomized to receive either sedative massage or cervical spine joint mobilization in addition to postural education and home exercises. Neck Disability Index (primary outcome) and pain VAS scores were recorded for pretreatment, posttreatment, and change scores within each group to estimate effect size. Recruitment and follow-up success rates were tracked. RESULTS: Sixty potential subjects were screened: 34 were eligible and 23 were enrolled. The primary reason for not participating was the unwillingness to commit to the treatment schedule. Twenty subjects completed all (12) treatments. Three subjects discontinued treatment because they become asymptomatic. Pre and post mean NDI and VAS scores for the group receiving joint mobilization were 13.54/5.64 and 40.91/16.54, respectively. Pre and post mean NDI and VAS for the group receiving massage were 12.75/8.08 and 29.42/20.91, respectively. Several problems were encountered, and possible solutions were identified. Recruitment difficulties required alteration of the recruitment strategy. CONCLUSION: A full scale trial is feasible if appropriate changes are made in recruitment strategy including recruiting from a wider referral base, direct recruitment from the community, and/or expanding the study to multiple sites. A clinical trial will require 66 subjects per group to have a power of 80% to detect a 2-point difference in NDI score. This sample size will also provide more than 80% power to detect a 10-point difference in pain (VAS) between groups. Recruitment goals will be 76 per group to allow for dropouts.

NASS Contemporary Concepts in Spine Care: spinal manipulation therapy for acute low back pain.

BACKGROUND CONTEXT: Low back pain (LBP) continues to be a very prevalent, disabling, and costly spinal disorder. Numerous interventions are routinely used for symptoms of acute LBP. One of the most common approaches is spinal manipulation therapy (SMT). PURPOSE: To assess the current scientific literature related to SMT for acute LBP. PATIENT SAMPLE: Not applicable. OUTCOME MEASURES: Not applicable. DESIGN: Systematic review (SR). METHODS: Literature was identified by searching MEDLINE using indexed and free text terms. Studies were included if they were randomized controlled trials (RCTs) published in English, and SMT was administered to a group of patients with LBP of less than 3 months. RCTs included in two previous SRs were also screened, as were reference lists of included studies. Combined search results were screened for relevance by two reviewers. Data related to methods, risk of bias, harms, and results were abstracted independently by two reviewers. RESULTS: The MEDLINE search returned 699 studies, of which six were included; an additional eight studies were identified from two previous SRs. There were 2,027 participants in the 14 included RCTs, which combined SMT with education (n=5), mobilization (MOB) (n=4), exercise (n=3), modalities (n=3), or medication (n=2). The groups that received SMT were most commonly compared with those receiving physical modalities (n=7), education (n=6), medication (n=5), exercise (n=5), MOB (n=3), or sham SMT (n=2). The most common providers of SMT were chiropractors (n=5) and physical therapists (n=5). Most studies (n=6) administered 5 to 10 sessions of SMT over 2 to 4 weeks for acute LBP. Outcomes measured included pain (n=10), function (n=10), health-care utilization (n=6), and global effect (n=5). Studies had a follow-up of less than 1 month (n=7), 3 months (n=1), 6 months (n=3), 1 year (n=2), or 2 years (n=1). When compared with various control groups, results for improvement in pain in the SMT groups were superior in three RCTs and equivalent in three RCTs in the short term, equivalent in four RCTs in the intermediate term, and equivalent in two RCTs in the long term. For improvement in function, results from the SMT groups were superior in one RCT and equivalent in four RCTs in the short term, superior in one RCT and equivalent in one RCT in the intermediate term, and equivalent in one RCT and inferior in one RCT in the long term. No harms related to SMT were reported in these RCTs. CONCLUSIONS: Several RCTs have been conducted to assess the efficacy of SMT for acute LBP using various methods. Results from most studies suggest that 5 to 10 sessions of SMT administered over 2 to 4 weeks achieve equivalent or superior improvement in pain and function when compared with other commonly used interventions, such as physical modalities, medication, education, or exercise, for short, intermediate, and long-term follow-up. Spine care clinicians should discuss the role of SMT as a treatment option for patients with acute LBP who do not find adequate symptomatic relief with self-care and education alone.

Reduction in disk and fiber stresses by axial distraction is higher in cervical disk with fibers oriented toward the vertical rather than horizontal plane: a finite element model analysis.

OBJECTIVE: The purpose of this study was to quantify the biomechanical changes that occur in a compressed cervical disk with the application of axial distraction when the annular fiber orientation angles are varied between the horizontal and vertical planes. METHODS: A 3-dimensional finite element (FE) model of a cervical motion segment was developed. From this model, 3 FE models were developed and validated corresponding to 3 different fiber angles relative to the end plate-disk interface: +/-25 degrees (oriented toward the horizontal plane), +/-45 degrees (midway between the horizontal and vertical planes), and +/-65 degrees (oriented toward the vertical plane). Compression (50N), followed by an axial distraction (17N), was simulated. Annulus and nucleus stresses, von-Mises fiber stresses, annulus radial bulging, and nucleus radial displacement were computed. Hard tissue (cortical and cancellous bones and end plate) stresses were also quantified. RESULTS: With increasing fiber angle (toward vertical), axial segmental stiffness increased, whereas annulus and nucleus stresses, fiber stresses, annulus radial bulging, and nucleus radial displacement decreased. Similar outcomes were observed when axial distraction was applied to the compressed segment. Hard tissues were not affected with varying fiber angles; however, their mechanics changed when axial distraction was applied on the compressed segment. We noted lower disk stress in axial distraction than in compression. CONCLUSIONS: The results confirmed the hypothesis that fibers oriented toward the vertical plane reduce disk and fiber stresses and disk bulging. By aligning annular fibers toward the vertical plane axial distraction may help reduce disk and fiber stresses. Axial disk stresses decrease radially from outside to inside under compressive loading and that the anterior annulus is more stressed than the posterior-lateral annulus during both compression and distraction. Stresses decreased in both the annulus tissue matrix and fibers with increasing fiber angles and increasing fiber slope to 90 degrees (vertical fibers) is further anticipated to reduce the compressive disk stresses. The fibers in tension apply compression to the annulus tissue matrix, thus, decreasing annulus stresses in the axial and circumferential directions.

Junction kinematics between proximal mobile and distal fused lumbar segments: biomechanical analysis of pedicle and hook constructs.

BACKGROUND CONTEXT: Biomechanical studies have demonstrated increased motion in motion segments adjacent to instrumentation or arthrodesis. The effects of different configurations of hook and pedicle screw instrumentation on the biomechanical behaviors of adjacent segments have not been well documented. PURPOSE: To compare the effect of three different fusion constructs on adjacent segment motion proximal to lumbar arthrodesis. METHODS: Seven human cadaver lumbar spines were tested in the following conditions: 1) intact; 2) L4-L5-simulated circumferential fusion (CF); 3) L4-L5-simulated fusion extended to L3 with pedicle screws; and 4) L4-L5-simulated fusion extended to L3 with sublaminar hooks. Rotation data at L2-L3, L3-L4, and L4-L5 were analyzed using both load limit control (+/-7.5N.m) and displacement limit control (truncated to the greatest common angular motion of the segments for each specimen). RESULTS: Both the L3-L4 and L2-L3 motion segments above the L4-L5-simulated CF had significantly increased motion in all loading planes compared with the intact spine, but no significant differences were found between L3-L4 and L2-L3 motion. When the L3-L4 segment was stabilized with pedicle screws, its motion was significantly smaller in flexion, lateral bending, and axial rotation than when stabilized with sublaminar hooks. At the same time, L2-L3 motion was significantly larger in flexion, lateral bending, and axial rotation in the pedicle screw model compared with the sublaminar hook construct. CONCLUSIONS: The use of sublaminar hooks to stabilize the motion segment above a circumferential lumbar fusion reduced motion at the next cephalad segment compared with a similar construct using pedicle screws. The semiconstrained hook enhancement may be considered if a patient is at a risk of adjacent segment disorders.

Biomechanical evaluation of a new fixation device for the thoracic spine.

The technology used in surgery for spinal deformity has progressed rapidly in recent years. Commonly used fixation techniques may include monofilament wires, sublaminar wires and cables, and pedicle screws. Unfortunately, neurological complications can occur with all of these, compromising the patients' health and quality of life. Recently, an alternative fixation technique using a metal clamp and polyester belt was developed to replace hooks and sublaminar wiring in scoliosis surgery. The goal of this study was to compare the pull-out strength of this new construct with sublaminar wiring, laminar hooks and pedicle screws. Forty thoracic vertebrae from five fresh frozen human thoracic spines (T5-12) were divided into five groups (8 per group), such that BMD values, pedicle diameter, and vertebral levels were equally distributed. They were then potted in polymethylmethacrylate and anchored with metal screws and polyethylene bands. One of five fixation methods was applied to the right side of the vertebra in each group: Pedicle screw, sublaminar belt with clamp, figure-8 belt with clamp, sublaminar wire, or laminar hook. Pull-out strength was then assessed using a custom jig in a servohydraulic tester. The mean failure load of the pedicle screw group was significantly larger than that of the figure-8 clamp (P = 0.001), sublaminar belt (0.0172), and sublaminar wire groups (P = 0.04) with no significant difference in pull-out strength between the latter three constructs. The most common mode of failure was the fracture of the pedicle. BMD was significantly correlated with failure load only in the figure-8 clamp and pedicle screw constructs. Only the pedicle screw had a statistically significant higher failure load than the sublaminar clamp. The sublaminar method of applying the belt and clamp device was superior to the figure-8 method. The sublaminar belt and clamp construct compared favorably to the traditional methods of sublaminar wires and laminar hooks, and should be considered as an alternative fixation device in the thoracic spine.

Evidence-informed management of chronic low back pain with traction therapy.

The management of chronic low back pain (CLBP) has proven to be very challenging in North America, as evidenced by its mounting socioeconomic burden. Choosing among available nonsurgical therapies can be overwhelming for many stakeholders, including patients, health providers, policy makers, and third-party payers. Although all parties share a common goal and wish to use limited health-care resources to support interventions most likely to result in clinically meaningful improvements, there is often uncertainty about the most appropriate intervention for a particular patient. To help understand and evaluate the various commonly used nonsurgical approaches to CLBP, the North American Spine Society has sponsored this special focus issue of The Spine Journal, titled Evidence-Informed Management of Chronic Low Back Pain Without Surgery. Articles in this special focus issue were contributed by leading spine practitioners and researchers, who were invited to summarize the best available evidence for a particular intervention and encouraged to make this information accessible to nonexperts. Each of the articles contains five sections (description, theory, evidence of efficacy, harms, and summary) with common subheadings to facilitate comparison across the 24 different interventions profiled in this special focus issue, blending narrative and systematic review methodology as deemed appropriate by the authors. It is hoped that articles in this special focus issue will be informative and aid in decision making for the many stakeholders evaluating nonsurgical interventions for CLBP.

Effect of multiple freeze-thaw cycles on intervertebral dynamic motion characteristics in the porcine lumbar spine.

Fresh frozen spine specimens are commonly used in biomechanical investigations of the spine. Since many study designs require staged preparation and testing, the effect of multiple freeze-thaw cycles on motion behavior should be understood. The objective of this study was to investigate the effect of multiple freeze-thaw cycles on the biomechanical parameters measured during dynamic pure moment loading. Ten porcine lumbar motion segments were harvested immediately after death and potted in acrylic fixtures. Specimens were tested in continuous pure moment flexion-extension, lateral flexion, and rotation cycles up to a limit of +/-5Nm. Moment-angular displacement data were analyzed and parameters quantified including range of motion, elastic zone, transitional zone (neutral region) size and slope, and width of the hysteresis loop. All specimens were tested at baseline and after each of three subsequent cycles of freezing and thawing. The transitional zone size decreased and the transitional zone slope increased during flexion-extension and lateral bending after the initial freeze-thaw cycle. These parameters were not altered after subsequent cycles. No significant change was observed in the elastic zone or width of hysteresis loop. Although freezing porcine spine specimens increased the stiffness in the neutral region of motion, up to three subsequent cycles of freezing and thawing did not further affect these motion characteristics. This suggests that data obtained from porcine spines which have been frozen and thawed multiple times are stable after initial freezing.

Stress in lumbar intervertebral discs during distraction: a cadaveric study.

BACKGROUND CONTEXT: The intervertebral disc is a common source of low back pain (LBP). Prospective studies suggest that treatments that intermittently distract the disc might be beneficial for chronic LBP. Although the potential exists for distraction therapies to affect the disc biomechanically, their effect on intradiscal stress is debated. PURPOSE: To determine if distraction alone, distraction combined with flexion, or distraction combined with extension can reduce nucleus pulposus pressure and posterior annulus compressive stress in cadaveric lumbar discs compared with simulated standing or lying. STUDY DESIGN: Laboratory study using single cadaveric motion segments. OUTCOME MEASURES: Strain gauge measures of nucleus pulposus pressure and compressive stress in the anterior and posterior annulus fibrosus. METHODS: Intradiscal stress profilometry was performed on 15 motion segments during 5 simulated conditions: standing, lying, and 3 distracted conditions. Disc degeneration was graded by inspection from 1 (normal) to 4 (severe degeneration). RESULTS: All distraction conditions markedly reduced nucleus pressure compared with either simulated standing or lying. There was no difference between distraction with flexion and distraction with extension in regard to posterior annulus compressive stress. Discs with little or no degeneration appeared to distribute compressive stress differently than those with moderate or severe degeneration. CONCLUSIONS: Distraction appears to predictably reduce nucleus pulposus pressure. The effect of distraction therapy on the distribution of compressive stress may be dependent in part on the health of the disc.

The effect of loading rate and degeneration on neutral region motion in human cadaveric lumbar motion segments.

BACKGROUND: The quasistatic neutral zone is a surrogate for neutral region stiffness of spinal motion segments. No similar measure of dynamic stiffness has been validated. Because parameters related to stiffness are likely to be affected by loading rate and disc degeneration, we examined the effect of those factors on motion parameters derived from continuous motion data. METHODS: Fifteen human lumbar motion segments were tested with continuous flexion-extension pure moments at 0.5, 3.0 and 6.0 degrees /s. Range of motion, width of the hysteresis loop, transitional zone width, and slopes of the upper and lower arms of the hysteresis loop within the transitional zone were measured. Discs were then graded for degeneration. FINDINGS: As the loading rate increased from 0.5 degrees /s to 6.0 degrees /s there were significant increases in range of motion, hysteresis area, hysteresis loop width, and the upper and lower transitional zone slopes. At the same time transitional zone width decreased significantly. Degeneration had a significant effect on all parameters except hysteresis loop width. The transition zone slopes appeared to best discriminate between normal and degenerative discs. INTERPRETATION: Loading rate had a significant effect on all parameters. As degeneration increased consistent effects were observed indicating decreasing stiffness from grade 1 to grade 3 then slightly increased stiffness in grade 4 specimens. The slopes of the transitional zone have potential to be a useful measure of neutral region stiffness during dynamic motion testing.

Comparison of the Neck Disability Index and the Neck Bournemouth Questionnaire in a sample of patients with chronic uncomplicated neck pain.

OBJECTIVE: This study compares the sensitivity to change of the Neck Disability Index (NDI) and the Neck Bournemouth Questionnaire (NBQ) in patients with chronic uncomplicated neck pain. METHODS: This prospective longitudinal study was completed in an outpatient physical therapy clinic. Subjects, with uncomplicated neck pain (no concurrent shoulder pain or nerve root symptoms) for more than a 3-month duration, participated in a 4-week course of therapy that included moist heat, neck exercises, and either mobilization or massage. Outcome measures included standardized response means (sensitivity to change), Cronbach alpha (internal consistency), and 2-way Spearman correlations between the 2 questionnaires and between a pain Visual Analog Scale and each questionnaire (convergent validity). RESULTS: Mean (SD) score change of the NDI was 6.22 (5.12), and of the NBQ, 14.00 (11.99). Standardized response means were 1.21 and 1.17, respectively. Both questionnaires were more sensitive to change than the pain Visual Analog Scale (0.68). There was moderate correlation between the change scores of all 3 outcome tools (Spearman 0.46-0.57). The NBQ had higher internal consistency than the NDI. CONCLUSIONS: The NDI and the NBQ performed comparably in this group of patients with chronic uncomplicated neck pain. Both are sensitive to change and would be efficient outcome tools in studies of chronic neck pain. Both had acceptable internal consistency and are appropriate for use as single-outcome scales.

Sagittal plane motion in the human lumbar spine: comparison of the in vitro quasistatic neutral zone and dynamic motion parameters.

BACKGROUND: Disabling low back pain is often attributed to clinical instability but defining instability is problematic. The most common parameter used to characterize instability in the lab is the neutral zone which is measured with a quasi-static technique. But, it cannot be measured from continuous motion data. Our goal was to describe the relationship between the quasi-static neutral zone and dynamic motion parameters that might reflect laxity about the neutral position. We also sought to determine if dynamic parameters were correlated with disc degeneration. METHODS: Fifteen cadaveric lumbar motion segments were tested with both quasi-static and dynamic (continuous load) methods. Quasi-static range of motion and neutral zone were compared with dynamic range of motion, hysteresis loop width, and two parameters derived from the hysteresis data: transitional zone size and slope. Degeneration was graded macroscopically. FINDINGS: Neutral zone size was moderately correlated with hysteresis loop width (r=0.69) and strongly correlated with the transitional zone slope (r=-0.80). Degenerative grade had a significant effect on dynamic range of motion and transitional zone size and slope with differences found between grade 1 (normal) discs and higher grades. Only transitional zone slope was different between grades 1 and 2. INTERPRETATION: The transitional zone slope (representing the neutral region stiffness) had the strongest correlation with neutral zone and could best detect lower grades of degeneration. The transitional zone slope might be a useful parameter in dynamic studies investigating the association between degeneration and motion segment behavior.

Chronic lateral epicondylitis: comparative effectiveness of a home exercise program including stretching alone versus stretching supplemented with eccentric or concentric strengthening.

The objective of this study was to evaluate the effectiveness of eccentric strengthening. Ninety-four subjects (50 men) with chronic lateral epicondylitis were allocated randomly into three groups: stretching, concentric strengthening with stretching, and eccentric strengthening with stretching. Subjects performed an exercise program for six weeks. All three groups received instruction on icing, stretching, and avoidance of aggravating activities. The strengthening groups received instruction on isolated concentric and eccentric wrist extensor strengthening, respectively. At six weeks, significant gains were made in all three groups as assessed with pain-free grip strength, Patient-rated Forearm Evaluation Questionnaire, Disabilities of the Arm, Shoulder, and Hand questionnaire, Short Form 36, and visual analog pain scale. No significant differences in outcome measures were noted among the three groups. Although there were no significant differences in outcome among the groups, eccentric strengthening did not cause subjects to worsen. Further studies are needed to assess the unique effects of a more intense or longer eccentric strengthening program for patients with lateral epicondylitis.