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PubMed2005

Fulcrum assisted soft stabilization system: a new concept in the surgical treatment of degenerative low back pain.

STUDY DESIGN: An experimental study on cadaver spine and spine model for biomechanical evaluation of a novel dynamic stabilization device. OBJECTIVES: First, to test the hypothesis that in dynamic stabilization of a lumbar spine using pedicle screws and ligament, addition of a fulcrum in front of the ligament can unload the disc. Second, to determine the relationship between the length and stiffness of the fulcrum and the ligament on disc unloading, lordosis and motion preservation. SUMMARY OF BACKGROUND DATA: Activity related low back pain may be attributable to abnormal disc loading or abnormal movement. Spinal fusion addresses both the mechanisms, but it has limitations. Soft stabilization with Graf ligament restricts abnormal movement but increases the disc pressure. The Dynesys system uses a plastic cylinder around the ligament to prevent overloading the disc, but it restricts extension and loses lordosis. METHODS: A novel dynamic stabilization system (fulcrum assisted soft stabilization or FASS) was developed in which a flexible fulcrum was placed in front of a ligament between the pedicle screws. It was hypothesized that the fulcrum should transform the compressive force of a ligament behind into a distraction force in front and unload the disc. Three spine models were developed using wooden blocks for vertebral bodies and neoprene rubber of different hardness for disc. Their load-deformation character was tested and compared with that of the cadaver spine in a spine tester. The spine model with the closest load-deformation property to cadaver spine was then tested for the effect of a FASS system, consisting of high density polythene rod as fulcrums and rubber "O" rings as ligaments. The disc pressure in the spine models were recorded with strain gauge in the center. RESULTS: Application of ligaments alone across the pedicle screws increased the disc pressure, produced a lordosis, and reduced the range of motion. Application of fulcrums reduced the disc pressure and maintained the lordosis. Increasing the fulcrum length resulted in progressive unloading of the disc but increased stiffness of the motion segment. As the fulcrum length approximated the height of the motion segment, the lordosis was lost, and the disc was completely unloaded. Decreasing the lateral bending stiffness of the fulcrum had minimal effect on disc unloading and motion-segment stiffness. CONCLUSION: The novel FASS system can unload the disc, control the range of motion, and maintain lordosis. These parameters may be controlled with a suitable combination of ligament and fulcrum system. The study provides an indication toward the desirable biomechanical properties of the fulcrum and ligament for future development of a clinically applicable prototype.

Aged↗
PubMed2005

Sexual receptivity is reduced in the female mu-opioid receptor knockout mouse.

Activation of mu-opioid receptors is critical to steroid regulation of female sexual behavior, lordosis, in rodents. Estrogen treatment activates mu-opioid receptors in the medial preoptic area inhibiting lordosis, but ultimately appears important for progesterone facilitation of lordosis. We investigated the role of mu-opioid receptors in the expression of sexual receptivity in mice lacking mu-opioid receptors. Although estrogen and progesterone facilitated lordosis in mu-opioid receptor knockout mice, they exhibited deficits in lordosis quotient and score compared with wild-type females, indicating reduced sexual receptivity. In contrast, wild-type and mu-opioid receptor knockout female mice did not differ in either active or passive avoidance of the male. These data are most consistent with the hypothesis that mu-opioid receptor activation is necessary for estrogen and progesterone to maximally facilitate lordosis.

Animals↗
PubMed1985

Presence of a neural mechanism for the expression of female sexual behaviors in the male rat brain.

Facilitatory and inhibitory neural mechanisms involved in the expression of female sexual behaviors in male rats were examined with a dual operation technique. Male rats were castrated and the preoptic area was dorsally deafferented (anterior roof deafferentation, ARD) in order to remove the forebrain lordosis-inhibitory system. Male rats with ARD displayed not only lordosis but also soliciting behaviors in response to 2 micrograms estradiol benzoate (EB) and 0.5 mg progesterone (P). The ARD male rat then received a second operation involving the hypothalamus or lower brain stem, i.e., the ventromedial nucleus and the adjacent area (ventromedial hypothalamus, VMH) were damaged by a radiofrequency lesion generator; the hypothalamus de-efferented anterolaterally by means of a Halász knife cut posterior to the suprachiasmatic nucleus (ADC) or lesions of the pontine periventricular gray and the adjacent area (dorsomedial tegmental lesion, DMTL). The DMTL effectively suppressed lordosis in EB-P-primed male rats with ARD. Only 1 of 14 ARD-DMTL males showed lordosis. In contrast, the VMH lesions or the ADC failed to interfere with the facilitatory effect of ARD on female sexual behaviors in male rats tested with the same dose of EB-P. Thus, the pontine periventricular gray plays a critical role for lordosis regulation in males. These results suggest that the male rat brain possesses the minimal neural mechanism for the expression of female sexual behaviors associated with the development of the strong forebrain lordosis-inhibiting system.

Afferent Pathways↗
PubMed1987

Possible role of alpha-2-noradrenergic receptors in modulation of sexual behavior in female guinea pigs.

These studies examine whether alpha 1-noradrenergic receptor stimulation alone is sufficient to facilitate lordosis behavior in ovariectomized, estrogen-primed female guinea pigs and to what extent alpha 2-noradrenergic receptors are involved in this steroid-dependent behavior. Neither of the alpha 1-agonists, phenylephrine or methoxamine, significantly facilitated lordosis in ovariectomized females primed with 10 micrograms of estradiol benzoate for 1 or 3 days. Animals exhibiting estrogen plus clonidine-facilitated lordosis showed a decrease in the behavior when given one of two alpha 2-antagonists (yohimbine or idazoxan). Idazoxan also attenuated lordosis in animals given estrogen plus progesterone. These findings, in combination with previous findings (that specific alpha 1-antagonists block lordosis), suggest that alpha 2-receptors, in addition to alpha 1-receptors play a role in modulation of lordosis behavior.

Adrenergic alpha-Antagonists↗
PubMed1976

The excitation and inhibition of sexual receptivity in female hamsters by progesterone: time and dose relationships, neural localization and mechanisms of action.

Ovariectomized hamsters were administered estradiol benzoate (EB) and 44 h later, progesterone (P.) Lordosis behavior was induced. When an additional dose of P was given up to 24 h prior to or 24 h after the EB, EB-P facilitation of lordosis was inhibited. Additional hamsters were given varying doses of P (25-200 mu) following EB using both excitatory and inhibitory paradigms. Inhibition of EB-induced lordosis was effected with a lower dose of P than was the facilitation of EB induced lordosis by P. Hamsters were also given intracerebral implants of P using excitatory and inhibitory paradigms. No excitatory loci were found. Inhibition of EB-induced lordosis was effected by implants in the posterior hypothalamus and anterior mesencephalon, but not by diencephalic implants. Other hamsters were administered tritiated estradiol (E2) plus P prior to, concurrent with, or shortly after the E2. P had no effect upon the accumulation of E2 by any brain sites, although E2 was found to concentrate to a greater degree in the diencephalon than in the mesencephalon or cortex. The estrogen-induced depletion and replenishment of hypothalamic cytosol estrogen receptors was also studied. Concurrent P treatment had no effect upon the receptor depletion-replenishment process. It was concluded that P can both facilitate and inhibit estrogen-induced lordosis and that the inhibitory effects of P are not upon estrogen-sensitive cells in the brain.

Animals↗
PubMed1996

Dopamine requires the unoccupied progesterone receptor to induce sexual behavior in mice.

Using the recently generated mutant mice strain (PRKO) carrying a null mutation for the progesterone receptor (PR) gene by gene targeting, we examined the critical role of PR as a coordinator of key regulatory events involved in the steroid hormone and dopamine-facilitated sexual behavior in female mice. In vitro one-point binding analyses of estradiol benzoate (EB)-induced cellular PRs and immunohistochemistry of PR in the mediobasal hypothalamus demonstrated a reduction in binding in the homozygous females, equivalent to background levels seen in EB-unresponsive tissue. The biochemical findings correlated well with the behavioral observations, with the wild type females exhibiting high levels of lordosis, while the homozygous females showed minimal lordosis in response to mating by male mice. As a critical validation of our earlier studies on ligand-independent activation of PRs by dopamine, we examined the facilitation of sexual behavior by a dopamine agonist in the null mutants. Wild type females having the full complement of PRs exhibited high levels of lordosis, while the homozygous females showed minimal lordosis in response to dopamine. To determine whether this reduced response was due to a general lack of ability to express lordosis, mice were treated with another neurotransmitter, serotonin. No significant difference in the serotonin-facilitated lordosis response was observed between the wild type and the homozygous females. We conclude that multiple signal transduction pathways coexist in the neuroendocrine system for reproductive behavior, with PR acting as a transcriptional mediator for dopamine, as well as progesterone, to achieve integration of neural communication in the central nervous system.

Animals↗
PubMed2005

Radiographic analysis of the sagittal alignment and balance of the spine in asymptomatic subjects.

BACKGROUND: There is an increasing recognition of the clinical importance of the sagittal plane alignment of the spine. A prospective study of several radiographic parameters of the sagittal profile of the spine was conducted to determine the physiological values of these parameters, to calculate the variations of these parameters according to epidemiological and morphological data, and to study the relationships among all of these parameters. METHODS: Sagittal radiographs of the head, spine, and pelvis of 300 asymptomatic volunteers, made with the subject standing, were evaluated. The following parameters were measured: lumbar lordosis, thoracic kyphosis, T9 sagittal offset, sacral slope, pelvic incidence, pelvic tilt, intervertebral angulation, and vertebral wedging angle from T9 to S1. The radiographs were digitized, and all measurements were performed with use of a software program. Two different analyses, a descriptive analysis characterizing these parameters and a multivariate analysis, were performed in order to study the relationships among all of them. RESULTS: The mean values (and standard deviations) were 60 degrees 10 degrees for maximum lumbar lordosis, 41 degrees +/- 8.4 degrees for sacral slope, 13 degrees +/- 6 degrees for pelvic tilt, 55 degrees +/-10.6 degrees for pelvic incidence, and 10.3 degrees +/- 3.1 degrees for T9 sagittal offset. A strong correlation was found between the sacral slope and the pelvic incidence (r = 0.8); between maximum lumbar lordosis and sacral slope (r = 0.86); between pelvic incidence and pelvic tilt (r = 0.66); between maximum lumbar lordosis and pelvic incidence, pelvic tilt, and maximum thoracic kyphosis (r = 0.9); and, finally, between pelvic incidence and T9 sagittal offset, sacral slope, pelvic tilt, maximum lumbar lordosis, and thoracic kyphosis (r = 0.98). The T9 sagittal offset, reflecting the sagittal balance of the spine, was dependent on three separate factors: a linear combination of the pelvic incidence, maximum lumbar lordosis, and sacral slope; the pelvic tilt; and the thoracic kyphosis. CONCLUSIONS AND CLINICAL RELEVANCE: This description of the physiological spinal sagittal balance should serve as a baseline in the evaluation of pathological conditions associated with abnormal angular parameter values. Before a patient with spinal sagittal imbalance is treated, the reciprocal balance between various spinal angular parameters needs to be taken into account. The correlations between angular parameters may also be useful in calculating the corrections to be obtained during treatment.

Adult↗
PubMed2001

Use of cylindrical titanium mesh and locking plates in anterior cervical fusion. Technical note.

After performing anterior cervical corpectomy or discectomy for cervical spondolytic myelopathy or radiculopathy, iliac crest bone graft and fibular auto- or allograft is often used to achieve arthrodesis in the cervical spine. The purpose of this study was to evaluate the use of a cylindrical titanium mesh and locking plate system as an alternative technique in achieving anterior cervical fusion and maintaining lordosis. Hospital records and radiographs of 38 patients who underwent anterior cervical discectomies (28 patients) or corpectomies (10 patients) from 1995 to 1997 were reviewed retrospectively. All patients had undergone arthrodesis in which autograft and a cylindrical titanium mesh and anterior locking plate fixation were used after discectomy or corpectomy. There were 20 men and 18 women (mean age 46.1 years; range 34-72 years). Presenting symptoms included radiculopathy (61%), myelopathy (37%), and neck pain (2%). Preoperative and postoperative radiographs were studied, and data were obtained on the following: overall lordosis or kyphosis of the cervical spine, segmental lordosis or kyphosis at each surgically treated level, and evidence of fusion. In all of the patients in whom lordosis was present preoperatively, lordosis was maintained during the follow-up period. The overall fusion rate was 100%. The average change in overall lordosis or kyphosis related to the fixation devices was 1.2 degrees (range 1-5 degrees) the average segmental change was 2.3 degrees (range 0-5 degrees); and the mean follow up was 16 months (range 12-36 months). Anterior cervical fusion with cylindrical titanium mesh and cervical locking plate system is an effective method of achieving arthrodesis and maintaining alignment in the cervical spine. The construct may provide additional load-sharing function, and it avoids the use of cadaveric bone or the need for harvesting tricortical iliac crest autograft.

Adult↗
PubMed2001

Progesterone and 3alpha,5alpha-THP enhance sexual receptivity in mice.

Progesterone (P) and its metabolites' effects on sexual receptivity (lordosis) of mice was examined. P dosages that produced normal circulating concentrations of P and 5alpha-pregnan-3alpha-ol-20-one (3alpha,5alpha-THP) enhanced lordosis of ovariectomized, sexually experienced C57BL/6J (C57), +/+ C57BL/6Jx129SvEv (C57x129), and -/- C57BL/6Jx129SvEv (PRKO) mice. Only C57 and C57x129 mice had increases in progestin receptor (PR)-immunoreactivity (PR-IR) in the hypothalamus. RU38486, a PR antagonist, attenuated lordosis of C57 and C57x129, but not PRKO, mice; epostane, a progestin biosynthesis inhibitor, reduced plasma progestins; and finasteride, a P metabolism inhibitor, reduced plasma 3alpha,5alpha-THP and attenuated lordosis of all mice. For sexually naive mice, greater lordosis on initial sexual experience corresponded to greater concentrations of plasma and central progestins and increased central binding of a GABAA agonist, muscimol, compared with that seen in mice with lower lordosis on initial mating. Thus, P-facilitated receptivity in mice involves P and 3alpha,5alpha-THP and their actions at PRs and GABAA receptors.

5-alpha-Dihydroprogesterone↗
PubMed1995

An analysis of sagittal spinal alignment in 100 asymptomatic middle and older aged volunteers.

STUDY DESIGN: A radiographic evaluation of 100 adult volunteers over age 40 and without a history of significant spinal abnormality was done to determine indices of sagittal spinal alignment. OBJECTIVES: To determine the sagittal contours of the spine in a population of adults older than previously reported in the literature and to correlate age and overall sagittal balance to other measures of segmental spinal alignment. SUMMARY OF BACKGROUND DATA: Previous studies of sagittal alignment have focused on adolescent and young adult populations before the onset of degenerative changes that may affect sagittal alignment. METHODS: Radiographic measurements were collected and subjected to statistical analysis. RESULTS: Mean sagittal vertical axis fell 3.2 +/- 3.2 cm behind the front of the sacrum. Total lumbar lordosis (T12-S1) averaged -64 degrees +/- 10 degrees. Lordosis increased incrementally with distal progression through the lumbar spine. Lordosis at L5-S1 and the position of the apices of the thoracic and lumbar curves were most closely correlated to sagittal vertical axis. Increasing age correlated to a more forward sagittal vertical axis with loss of distal lumbar lordosis but without an increase in thoracic or thoracolumbar kyphosis. CONCLUSIONS: The majority of asymptomatic individuals are able to maintain their sagittal alignment despite advancing age. Loss of distal lumbar lordosis is most responsible for sagittal imbalance in those individuals who do not maintain sagittal alignment. Spinal fusion for deformity should take into account the anticipated loss of lordosis that may occur with age.

Adult↗
PubMed2002

Sagittal morphology and equilibrium of pelvis and spine.

A prospective analysis of the sagittal profile of 100 healthy young adult volunteers was carried out in order to evaluate the relationship between the shape of the pelvis and lumbar lordosis and to create a databank of the morphologic and positional parameters of the pelvis and spine in a normal healthy population. Inclusion criteria were as follows: no previous spinal surgery, no low back pain, no lower limb length inequality, no scoliotic deviation. For each subject, a 30 x 90-cm sagittal radiograph including spine, pelvis and proximal femurs in standing position on a force plate was performed. The global axis of gravity was determined with the force plate. Each radiograph was digitized using dedicated software. The spinal parameters registered were values for thoracic kyphosis and lumbar lordosis. The pelvic angles measured were: pelvic incidence, sacral slope and pelvic tilt. The global axis of gravity was on average 9 mm anterior of the center of the femoral heads. The anatomic parameter of pelvic incidence angle varied from 33 degrees to 85 degrees (mean: 51.7 degrees, SD: 11 degrees). The average lumbar lordosis was 46.5 degrees. The average thoracic kyphosis was 47 degrees. We found a statistical correlation between incidence angle and lumbar lordosis (r=0.69, P<0.001) and between sacral slope angle and lumbar lordosis (r=0.75, P<0.001). Spine and pelvis balance around the hip axis in order to position the gravity line over the femoral heads. We propose a scheme of sagittal balance of the standing human body.

Adult↗
PubMed2001

Slight head extension: does it change the sagittal cervical curve?

It is commonly believed that slight flexion/extension of the head will reverse the cervical lordosis. The goal of the present study was to determine whether slight head extension could result in a cervical kyphosis changing into a lordosis. Forty consecutive volunteer subjects with a cervical kyphosis and with flexion in their resting head position had a neutral lateral cervical radiograph followed immediately by a lateral cervical view taken in an extended head position to level the bite line. Subjects were patients at a spine clinic in Elko, Nevada. All radiographs were digitized. Global and segmental angles of the cervical curve were compared for any change in angle due to slight extension of the head. The average extension of the head required to level the bite line was 13.9 degrees. This head extension was not substantially correlated with any segmental or global angle of lordosis. Subjects were categorized into those requiring slight head extension (0 degree-13.9 degrees) and those requiring a significant head extension (> 13.9 degrees). In the slight head extension group, the average change in global angle between posterior tangents on C2 and C7 was 6.9 degrees, and 80% of this change occurred in C1-C4. In the significant head extension group, the average change in global angle between posterior tangents on C2 and C7 was 11.0 degrees, and the major portion of this change occurred in C1-C4. Out of 40 subjects, only one subject, who was in the significant head extension group and had only a minor segmental kyphosis, changed from kyphosis to lordosis. The results show that slight extension of the head does not change a reversed cervical curve into a cervical lordosis as measured on lateral cervical radiographs. Only small extension angle changes (mean sum = 4.8 degrees) in the upper cervical segments (C2-C4) occur in head extension of 14 degrees or less.

Adult↗
PubMed2005

Concurrent validity of flexicurve instrument measurements: sagittal skin contour of the cervical spine compared with lateral cervical radiographic measurements.

OBJECTIVES: The aim of this study was to compare flexicurve surface contour measurements of the cervical spine with radiographic measurements of cervical lordosis. METHODS: One examiner evaluated 96 patients with chronic neck pain in neutral posture using a flexible ruler, flexicurve, to measure sagittal contour of the skin over the cervical spine from the external occipital protuberance to the vertebra prominens. The flexicurve skin contour and neutral lateral radiographs were digitized and compared. The flexicurve and radiographs were categorized into height-length ratio, curve angle, curve depth, sum of depths, modified Ishihara's index, and inverse of radius. Mean values, SDs, mean differences, and limits of agreement were calculated. The differences between flexicurve measurement mean values and x-ray mean values were deemed significant if the lower limit of agreement exceeded 15% of the mean values for the x-ray measurements. RESULTS: For all variables, except the height-length ratio, the mean values of the flexicurve variables differed significantly from the corresponding mean values of the radiographic measurements. All Pearson correlation coefficients were in the very poor range (r < 0.15). CONCLUSION: The flexicurve sagittal skin contour measurement has poor concurrent validity compared with established radiographic measurements of the cervical lordosis. The flexicurve tracings always predicted lordosis, overestimated the lordosis compared with x-ray values, and cannot discriminate between radiographic lordosis, straightened, S curves, and kyphotic alignments of the cervical curve.

Adult↗
PubMedDate not supplied

[Effects of inflammation-induced spinal fusion of the lumbar area on movement of the lumbar spine].

Lateral x-rays of the lumbar spine in standing position and functional flexion-extension roentgenograms of 21 patients with spontaneous fusion within the lumbar area after spondylitis were checked related to kyphosis of the block, lordosis and mobility of the lumbar spine and the single discs, and the appearance of degenerative spondylolisthesis. 76% demonstrated degenerative spondylolisthesis of the neighbouring discs, the half of them more than 5 mm with a significant higher number of segmental loosening of the disc caudal to the fusion. The kind of instability is a pseudo-spondylolisthesis (Junghans 1930) above and a retrolisthesis below the fused area. No higher mobility (no significant difference of mobility between the two cranial and the two caudal discs) can be seen as cause of this behaviour. The increased lordosis of the caudal segments is discussed to be the cause of the retrolisthesis distal the fusion. Altogether, kyphosis of the fused area leeds compensatory to a higher grade of lordosis in the mobile part of the lumbar spine without reaching the physiological lordosis of total lumbar spine. Kyphosis of the block does not influence mobility of the discs or the total lumbar spine, but increases significantly the rate of degenerative spondylolisthesis in the vicinal segments. These results suggest the operative reduction of lumbar lordosis in cases of kyphotic spondylitic destruction within the lumbar or thoracolumbar region in younger patients.

Adult↗
PubMed2000

Correlative analysis of the sagittal profile of the spine in patients with beta-thalassemia and in healthy persons.

This prospective study compares several roentgenographic parameters of the thoracic and lumbar spine in patients with beta-thalassemia and in healthy persons who served as controls. Eighty-four patients with beta-thalassemia and 84 age- and gender-matched healthy persons were examined clinically and radiologically (thoracic kyphosis, lumbar lordosis, and vertebral and sacral inclination). Although there was a significant difference in the vertebral inclination from T6 to L1, L4, and L5 between patients and controls, thoracic kyphosis and lumbar lordosis did not differ in the two groups. The apical vertebra of the thoracic kyphosis in patients and controls was T7 and T6, respectively, whereas L4 was the apical vertebra of the lumbar lordosis in both groups. There were no age- or gender-related differences in the magnitude of sacral inclination, thoracic kyphosis, or lumbar lordosis in the patients with beta-thalassemia compared with controls. Lumbar lordosis was significantly correlated with sacral inclination in both patients with beta-thalassemia and controls. Beta-thalassemia does not affect sagittal profile of the thoracic and lumbar spine but it is associated by structural changes on the frontal plane of the spine that are expressed as a high prevalence of scoliosis.

Adolescent↗
PubMed2002

Sagittal alignment of cervical flexion and extension: lateral radiographic analysis.

STUDY DESIGN: An analysis of lateral radiographs in the upright, flexion-extension position. OBJECTIVES: To document and define the differences in cervical flexion-extension kinematics as they relate to changes of alignment in upright cervical lordosis. SUMMARY OF BACKGROUND DATA: No previous study has reported the association between sagittal plane cervical rotation kinematics and changes of alignment in upright cervical lordosis. METHODS: Lateral radiographs were classified into five groups (Group A, lordosis; Group B, straight; Group C, kyphosis; Group D, S-curve with lordotic upper cervical and kyphotic lower cervical spine; and Group E, S-curve with kyphotic upper cervical and lordotic lower cervical spine) by changes of alignment in upright position. Sagittal cervical rotation angles were measured by a computer-assisted method in the fully flexed and extended positions. RESULTS: Group A revealed the largest angle of lordosis at extension and the smallest angle of kyphosis at flexion, whereas Group C revealed the smallest angle of lordosis at extension and the largest angle of kyphosis at flexion. When Group D adopted the flexion-extension position, the curvature of the upper cervical spine was the same as Group A, whereas the lower cervical spine showed the same curve as Group C. Similarly, the cervical rotation kinematics in Group E were a combination of motion of upper cervical spine in Group C and that of lower spine in Group A. CONCLUSION: The results suggest that alterations in the static alignment of the cervical curvature cause alterations in the dynamic kinematics of the cervical spine during cervical flexion-extension. This information should aid in the interpretation of kinematic studies of the cervical spine.

Adult↗
PubMed2003

Sagittal plane analysis of the spine and pelvis in adolescent idiopathic scoliosis according to the coronal curve type.

STUDY DESIGN: A retrospective study investigated the sagittal alignment in adolescent idiopathic scoliosis (AIS). OBJECTIVE: To evaluate the sagittal alignment of the spine and pelvis in adolescent idiopathic scoliosis on the basis of curve type. SUMMARY OF BACKGROUND DATA: The relation between the spine and pelvis highly influences the sagittal balance in adults. However, the sagittal alignment of the spine and pelvis in adolescent idiopathic scoliosis is poorly defined in the literature. METHODS: Five sagittal parameters were evaluated on lateral radiographs of 160 patients with adolescent idiopathic scoliosis: thoracic kyphosis, lumbar lordosis, sacral slope, pelvic tilt, and pelvic incidence. The patients were classified according to their coronal curve type. Analysis of variance was used to compare the parameters between the curve types, and Pearson coefficients were used to investigate the relation between all parameters (alpha = 0.05). RESULTS: The thoracic kyphosis was significantly lower for King I, II, and III curves than for lumbar curves. The lumbar lordosis was higher for lumbar curves, although not significantly. No significant change between the groups was observed for the sacral slope, pelvic tilt, or pelvic incidence. The pelvic incidence was significantly correlated with the lumbar lordosis, sacral slope, and pelvic tilt for all the groups. The lumbar lordosis was strongly related to the sacral slope in all cases, but not with the thoracic kyphosis, except in the case of thoracolumbar curves. CONCLUSIONS: Thoracic kyphosis depended mostly on the spinal deformity, whereas lumbar lordosis was influenced mainly by the pelvic configuration. The scoliotic curve type was not associated with a specific pattern of sagittal pelvic morphology and balance. The pelvic incidence found in this study was significantly higher than that reported in the literature for normal adolescents. The role of the pelvic incidence in the pathogenesis of adolescent idiopathic scoliosis needs to be explored in a longitudinal study involving patients with adolescent idiopathic scoliosis and normal adolescents.

Adolescent↗
PubMed2004

Effect of sagittal plane deformity of the lumbar spine on epidural fibrosis formation after laminectomy: an experimental study in the rat.

STUDY DESIGN: An animal model of postlaminectomy lumbar column sagittal plane deformity was designed in rats. OBJECTIVES: To analyze the effect of lumbar column deformity (lordosis and kyphosis) on postlaminectomy epidural fibrosis formation. SUMMARY OF BACKGROUND DATA: Incidence of peridural fibrosis formation after lumbar spinal surgery is considerably high. Instability and sagittal plane deformity of the lumbar spine has been implicated (not proven) as the factors for the development of epidural fibrosis. The effect of traction (kyphosis) or relaxation (lordosis) of the lumbar spine on epidural fibrosis formation is not known. METHODS: L4 laminectomies were performed in 30 rats. Three equal groups were formed. In the control group (group I), only laminectomy was performed. In other groups after laminectomy, lumbar lordosis (group II) and kyphosis (group III) was maintained with steel implants. The scar formation was evaluated both histologically and histomorphometrically on the 12th postoperative week. RESULTS: Kyphosis developed in group I. The mean amount of peridural scar tissue was significantly more evident in groups I and III than the lordosis group. The extent of adherence to the dura mater and the nerve roots was most apparent in group III. CONCLUSIONS: Kyphosis and consequent traction of the lumbar spine is one of the causes for increased epidural fibrosis formation after laminectomy. On the contrary, establishment of lordosis and relaxation of the lumbar spine decreased the scar tissue formation in rats.

Animals↗