Effects of tensioning the lumbar fasciae on segmental stiffness during flexion and extension - Young investigator award winner

Study Design. Biomechanical study of unembalmed human lumbar segments. Objective. To investigate the effects of tensioning the lumbar fasciae ( transversus abdominis [TrA]) aponeurosis) on segment stiffness during flexion and extension. Summary of Background Data. Animal and human studies suggest that TrA may influence intersegmental movement via tension in the middle and posterior layers of lumbar fasciae ( MLF, PLF). Methods. Compressive flexion and extension moments were applied to 17 lumbar segments from 9 unembalmed cadavers with 20 N lateral tension of the TrA aponeurosis during: 1) static tests: load was compared when fascial tension was applied during static compressive loads into flexion-extension; 2) cyclic loading tests: load, axial displacement, and stiffness were compared during repeated compressive loading cycles into flexion-extension. After testing, the PLF was incised to determine the tension transmitted by each layer. Results. At all segments and loads (< 200 N), fascial tension increased resistance to flexion loads by similar to 9.5 N. In 15 of 17, fascial tension decreased resistance to extension by similar to 6.6 N. Fascial tension during cyclic flexion loading decreased axial displacement by 26% at the onset of loading (0 - 2 N) and 2% at 450 N ( 13 of 17). During extension loading, fascial tension increased displacement at the onset of loading ( 10 of 17) by similar to 23% and slightly (1%) decreased displacement at 450 N. Segment stiffness was increased by 6 N/mm in flexion (44% at 25 N) and decreased by 2 N/mm (8% at 25 N) in extension. More than 85% of tension was transmitted through the MLF. Conclusions. Tension on the lumbar fasciae simulating moderate contraction of TrA affects segmental stiffness, particularly toward the neutral zone.

Factors influencing wound healing after surgery for metastatic disease of the spine

Study Design, The study group consisted of 53 patients who underwent 75 operations for spine metastases. Patient and tumor demographic factors, preoperative nutritional status, and perioperative adjunctive therapy were retrospectively reviewed. Objective, To determine the risk factors for wound breakdown and infection in patients undergoing surgery for spinal metastases. Summary of Background Data. Spinal Fusion using spine implants may be associated with an infection rate of 5% or more. Surgery for spine metastases is associated with an infection rate of more than 10%. Factors other than the type of surgery performed may account for the greater infection rate. Methods. Data were obtained by reviewing patient records. Age, sex, and neurologic status of the patient; tumor type and site; and surgical details were noted. Adjunctive treatment with corticosteroids and radiotherapy was recorded, Nutritional status was evaluated by determining serum protein and serum albumin concentrations and by total lymphocyte count. Results. Wound breakdown and Infection occurred in 75 of 75 wounds. No patient or tumor demographic factors other than intraoperative blood loss (P < 0.1) were statistically associated with infection; The correlation between preoperative protein deficiency (P < 0.01) or perioperative corticosteroid administration (P < 0.10) and wound infection was significant. There was no statistical correlation between lymphocyte count or perioperative radiotherapy and wound infection. Conclusions, The results indicate that preoperative protein depletion and perioperative administration of corticosteroids are risk factors for wound infection in patients undergoing surgery for spine metastases, Perioperative correction of nutritional depletion and cessation of steroid therapy may reduce wound complications.

In vivo measurement of the effect of intra-abdominal pressure on the human spine

In humans, intra-abdominal pressure (IAP) is elevated during many everyday activities. This experiment aimed to investigate the extent to which increased IAP-without concurrent activity of the abdominal or back extensor muscles-produces an extensor torque. With subjects positioned in side lying on a swivel table with its axis at L3, moments about this vertebral level were measured when IAP was transiently increased by electrical stimulation of the diaphragm via the phrenic nerve. There was no electromyographic activity in abdominal and back extensor muscles. When IAP was increased artificially to similar to 15% of the maximum IAP amplitude that could be generated voluntarily with the trunk positioned in flexion, a trunk extensor moment (similar to6 Nm) was recorded. The size of the effect was proportional to the increase in pressure. The extensor moment was consistent with that predicted from a model based on measurements of abdominal cross-sectional area and IAP moment arm. When IAP was momentarily increased while the trunk was flexed passively at a constant velocity, the external torque required to maintain the velocity was increased. These results provide the first in vivo data of the amplitude of extensor moment that is produced by increased IAP. Although the net effect of this extensor torque in functional tasks would be dependent on the muscles used to increase the IAP and their associated flexion torque, the data do provide evidence that IAP contributes, at least in part, to spinal stability. (C) 2001 Elsevier Science Ltd. All rights reserved.

The initial effects of a cervical spine manipulative physiotherapy treatment on the pain and dysfunction of lateral epicondylalgia

Manipulative therapy is frequently used in the management of musculoskeletal pain. A frequently reported clinical feature of this treatment is the immediacy with which it appears to initiate improvement in pain and function. A randomised, double blind, placebo controlled, repeated measures design was employed to study the initial effects of a cervical spine treatment technique in a group of 15 patients with lateral epicondylalgia. Pressure pain threshold, pain-free grip strength, upper limb neurodynamics, pain and function were assessed prior to and following application of either a treatment, placebo or control condition. All subjects received all three conditions. Differences between the pre-post measures were used as indicators of change in subject's symptom profiles. The treatment condition produced significant improvement in pressure pain threshold, pain-free grip strength, neurodynamics and pain scores relative to placebo and control conditions (P < 0.05). In summary, this study demonstrates that manipulative therapy is capable of eliciting a rapid hypoalgesic effect.

The effect of soft tissue deloading tape on thoracic spine pressure pain thresholds in asymptomatic subjects

The application of tape to deload soft tissue is used in the management of thoracic spine pain. A reported clinical feature of this treatment is reduced tenderness of the spine during postero-anterior mobilizations. A randomized, single blind, placebo controlled, repeated measures design study was employed to investigate the effects of deloading tape on pressure pain threshold measurements at the level of the T7 spinous process in an asymptomatic group of 24 subjects. Pressure pain thresholds were assessed prior to and following the application of deloading tape, placebo sham tape and no-tape control conditions. All subjects received all three conditions in a randomized order on three separate days. Differences between the pre- and post-measurements were used as indicators of change in a subject's pressure pain threshold. No significant change in pressure pain threshold measurements was found between conditions. In summary, this study demonstrated that deloading tape applied to the level of the T7 spinous process did not significantly change pressure pain threshold measurements in asymptomatic subjects, raising the possibility that any pain relieving effect may well be conditional upon pain being present. (C) 2002 Elsevier Science Ltd. All rights reserved.

Magnetic resonance imaging analysis of the upper cervical spine extensor musculature in an asymptomatic cohort: an index of fat within muscle

AIM: To establish a simple method to quantify muscle/fat constituents in cervical muscles of asymptomatic women using magnetic resonance imaging (MRI), and to determine whether there is an age effect within a defined age range. MATERIALS AND METHODS: MRI of the upper cervical spine was performed for 42 asymptomatic women aged 18-45 years. The muscle and fat signal intensities on axial spin echo T1-weighted images were quantitatively classified by taking a ratio of the pixel intensity profiles of muscle against those of intermuscular fat for the rectus capitis posterior major and minor and inferior obliquus capitis muscles bilaterally. Inter- and intra-examiner agreement was scrutinized. RESULTS: The average relative values of fat within the upper cervical musculature compared with intermuscular fat indicated that there were only slight variations in indices between the three sets of muscles. There was no significant correlation between age and fat indices. There were significant differences for the relative fat within the muscle compared with intermuscular fat and body mass index for the right rectus capitis posterior major and right and left inferior obliquus capitis muscles (p = 0.032). Intraclass correlation coefficients for intraobserver agreement ranged from 0.94 to 0.98. Inter-rater agreement of the measurements ranged from 0.75 to 0.97. CONCLUSION: A quantitative measure of muscle/fat constituents has been developed, and results of this study indicate that relative fatty infiltration is not a feature of age in the upper cervical extensor muscles of women aged 18-45 years. (C) 2005 The Royal College of Radiologists. Published by Elsevier Ltd. All rights reserved.

Intra-abdominal pressure increases stiffness of the lumbar spine

Intra-abdominal pressure (IAP) increases during many tasks and has been argued to increase stability and stiffness of the spine. Although several studies have shown a relationship between the IAP increase and spinal stability, it has been impossible to determine whether this augmentation of mechanical support for the spine is due to the increase in IAP or the abdominal muscle activity which contributes to it. The present study determined whether spinal stiffness increased when IAP increased without concurrent activity of the abdominal and back extensor muscles. A sustained increase in IAP was evoked by tetanic stimulation of the phrenic nerves either. unilaterally or bilaterally at 20 Hz (for 5 s) via percutaneous electrodes in three subjects. Spinal stiffness was measured as the force required to displace an indentor over the L4 or L2 spinous process with the subjects lying prone. Stiffness was measured as the slope of the regression line fitted to the linear region of the force-displacement curve. Tetanic stimulation of the diaphragm increased IAP by 27-61% of a maximal voluntary pressure increase and increased the stiffness of the spine by 8-31% of resting levels. The increase in spinal stiffness was positively correlated with the size of the IAP increase. IAP increased stiffness at L2 and L4 level. The results of this:study provide evidence that the stiffness of the lumbar spine is increased when IAP is elevated. (C) 2004 Elsevier Ltd. All rights reserved.