Search PubMed⌕ Search

SEARCH · Search PubMed

Results for “LORDOSIS”

Search indexed PubMed citations on genomics, clinical trials, systematic reviews and public health. Explore titles, authors and supplied subject terms, then open the PubMed record.

Quote a phrase for an exact phrase match. Source license links do not imply unrestricted reuse.

At least 685 records · Page 38Linked to original sources
PubMed1996

Effects of posture and structure on three-dimensional coupled rotations in the lumbar spine. A biomechanical analysis.

STUDY DESIGN: A biomechanical lumbar spine model was constructed to simulate three-dimensional spinal kinematics under the application of pure moments. Parametric analysis of the model allowed for the estimation of how much of the coupled motions could be predicted by the lumbar lordosis and the intrinsic mechanical properties of the spine. OBJECTIVES: To evaluate the relative effects of lordosis and intrinsic mechanical spine properties on the magnitude and direction of coupled rotations. SUMMARY OF BACKGROUND DATA: Clinical evidence suggests that abnormal coupled motion in the lumbar spine may be an indicator of low back disorders. METHODS: The biomechanical lumbar spine model consisted of five vertebrae separated by intervertebral joints that provided three rotational degrees of freedom. In vitro experimental data, obtained from nine fresh-frozen (L1-S1) cadaveric specimens, were used to establish the mechanical properties of the intervertebral joints. Two different submodels were considered in simulating the three-dimensional intervertebral rotations in response to the applied moments. In the first, it was assumed that the coupled motions were generated solely as a result of the vertebral orientation caused by lordosis. In the second, additional intrinsic motion coupling was assumed. RESULTS: Intervertebral coupling was partially predicted by lumbar lordosis; however, the inclusion of intrinsic mechanical coupling dramatically improved the simulation of the intervertebral rotations (root mean square error < 1 degree). Comparison of the results from the two models demonstrated that the lumbar lordosis and intrinsic mechanical properties of the spine had about an equal effect in predicting the coupling between axial rotation and lateral bending. In contrast, coupled flexion, associated with lateral bending, was almost fully accounted for by the presence of lumbar lordosis. CONCLUSIONS: The lumbar lordosis and intrinsic mechanical properties of the spine were equally important in predicting the magnitude and direction of the coupled rotations.

Adult↗
PubMed1998

The lordotic effect of the OSI frame on operative adolescent idiopathic scoliosis patients.

STUDY DESIGN: A prospective evaluation of adolescent idiopathic scoliosis patients undergoing operative treatment on the Orthopedic Systems Incorporated (OSI; Jackson) frame. OBJECTIVES: To investigate prospectively thoracic, thoracolumbar, and lumbar sagittal alignments in patients with adolescent idiopathic scoliosis who undergo an instrumented posterior spinal fusion on the OSI frame. SUMMARY OF BACKGROUND DATA: In several studies, it has been shown that patient positioning on various operative frames is an important component of ultimate lumbar sagittal alignment. However, these studies have all concentrated on the lumbar spine, and no sagittal plane alignment data in adolescent idiopathic scoliosis patients have been reported in the thoracic and thoracolumbar junction as it relates to intraoperative positioning, correction maneuvers and correlative postoperative results. METHODS: Thirty-nine patients with operative adolescent idiopathic scoliosis treated with an instrumented posterior spinal fusion on the OSI frame were prospectively evaluated. Standing preoperative, intraoperative, and postoperative long-cassette lateral radiographs were reviewed with regional and segmental Cobb measurements of the thoracic, thoracolumbar junction, and lumbar spine obtained. RESULTS: Thoracic kyphosis (T1-T12) measured +34 degrees before surgery, +28 degrees during surgery, and +30 degrees after surgery, Thus, a statistically significant decrease was noted in thoracic kyphosis secondary to prone positioning on the OSI frame ( P < 0.05). Thoracolumbar spine measurements from T10 to L2 also showed a lordotic trend from +2 degrees before surgery, to -4 degrees during surgery, to -8 degrees after surgery, which was also statistically significant (P < 0.05). Total lumbar lordosis from T12 to S1 remained relatively unchanged from -60 degrees before surgery, to -59 degrees during surgery, to -60 degrees after surgery. However, segmental lumbar lordosis measured from T12 to the lowest instrumented vertebra showed a statistically significant increase in lordosis from -17 degrees before surgery, to -19 degrees during surgery, to -23 degrees after surgery (P < 0.05). Those patients in whom lumbar pedicle screws were used (vs. hooks alone) had the greatest increase in lumbar instrumented lordosis. CONCLUSIONS: Performing adolescent idiopathic scoliosis correction on the OSI frame tends to decrease thoracic kyphosis, increase thoracolumbar lordosis, and increase segmental instrumented lumbar lordosis, while it maintains total lumbar lordosis.

Adolescent↗
PubMed2001

The role of neurosteroids and nongenomic effects of progestins in the ventral tegmental area in mediating sexual receptivity of rodents.

Progesterone (P(4)) in the ventromedial hypothalamus (VMH) and ventral tegmental (VTA) is important for facilitation of lordosis; however, P(4)'s actions in these brain areas are different. Using lordosis in rodents as in vivo experimental models, we have examined the effects progestins exert in the midbrain and hypothalamus. Localization and blocker studies indicate that P(4)'s actions in the VMH require intracellular progestin receptors (PRs) but in the VTA they do not. Progestins that have rapid, membrane effects, and/or are devoid of affinity for PRs, facilitate lordosis when applied to the VTA. Manipulation of GABA and/or GABA(A)/benzodiazepine receptor complexes (GBRs) in the VTA alter lordosis, which suggests that progestins may interact with GBRs to facilitate receptivity by enhancing the function of GABAergic neurons. Interfering with P(4)'s metabolism to 5 alpha-pregnan-3 alpha-ol-20-one (3 alpha,5 alpha-THP), the most effective endogenous positive modulator of GBRs, or the biosynthesis of the neurosteroid 3 alpha,5 alpha-THP in the VTA attenuates female sexual behavior in rodents. Stimulation of mitochondrial benzodiazepine receptors (MBRs), which enhance neurosteroid production, by infusions of a MBR agonist to the VTA enhances lordosis. 3 alpha,5 alpha-THP is increased in the midbrain of mated > proestrous > diestrous rodents. These data suggest that 3 alpha,5 alpha-THP has a proximate modulatory role on lordosis. In summary, the actions of P(4) in the VTA are different from those in the VMH that involve PRs. In the VTA, P(4) may facilitate lordosis following metabolism to and/or biosynthesis of 3 alpha,5 alpha-THP, which may have subsequent actions at GBRs and/or MBRs to acutely modulate female sexual behavior in rodents.

Animals↗
PubMed1991

Midbrain central gray GABAA receptor activation enhances, and blockade reduces, sexual behavior in the female rat.

The inhibitory neurotransmitter, GABA, has been implicated in the control of lordosis behavior. Previous studies indicate that modulation of GABAA transmission can have dual effects on lordosis, being facilitative in the ventromedial hypothalamus and inhibitory in the preoptic area. The midbrain central gray (MCG) is also known to be an important neural site for regulating lordosis as well as defensive and escape behaviors, and plays an integral role in the control of nociception. Because of the multitude of behaviors regulated at the level of the MCG, we utilized a two-chamber testing apparatus that allowed simultaneous measurement of the females' proceptive (hopping and darting), receptive and rejection behaviors, as well as an index of nociception and general motor activity. We found that microinfusion of the GABAA antagonist, bicuculline, into the MCG of steroid-primed female rats resulted in a significant decrease in lordosis and proceptive behaviors at 5 min post-infusion. There was full recovery to pretest levels by 60 min. Furthermore, microinfusion of the GABAA agonist, muscimol, to estrogen-treated females that displayed low levels of receptivity and high levels of rejection behavior during a pretest, resulted in a significant increase in lordosis responding and a decrease in rejection behaviors. Neither drug significantly affected time spent in the vicinity of the male, motor activity or vocalizations. It is concluded that the decrease in lordosis resulting from blockade of GABA transmission is not solely due to the induction of antagonistic behaviors since there was no increase in rejections after bicuculline administration. The current findings are consistent with the interpretation that GABA facilitates lordosis in the MCG via disinhibition.(ABSTRACT TRUNCATED AT 250 WORDS)

Animals↗
PubMed2005

The effect of single-level, total disc arthroplasty on sagittal balance parameters: a prospective study.

A prospective radiographic study of the influence of total disc replacement on spinal sagittal balance. The goal of this study was to prospectively determine the effect of a single-level, total disc replacement on the sagittal balance of the spine, especially on sacral tilt (ST), pelvic tilt (PT), and lumbar lordosis. It has been shown that lumbar fusion may deleteriously alter the sagittal balance of the spine, including a decrease in the ST and lumbar lordosis. Clinically, postfusion pain has been shown to be significantly related to a decreased ST, increased PT, and decreased lumbar lordosis, independent of other factors such as pseudoarthrosis. To our knowledge, the influence of total disc replacement on spinal sagittal balance has not yet been reported in the literature. This is a prospective study of 35 patients who received a single level disc replacement using the Maverick Total Disc Arthroplasty system (Medtronic Sofamor Danek, Memphis, Tennessee) by a single surgeon at one institution from March 2002 to September 2003. The preoperative and postoperative radiographic evaluation included standing anteroposterior and lateral full spine films that included the femoral heads. The parameters studied were ST, PT, global and segmental lordosis, and global kyphosis. The average age of the 35 patients studied was 44.3 years (range 35-57). There were 18 females and 17 males. The disc arthroplasty was performed at the L4-L5 level in 19 patients and at the L5-S1 level in 16 patients. The average follow-up was 14 months (range 6-22 months). The preoperative values of global lordosis, ST, and PT were 51.5 degrees , 37.8 degrees , 16.9 degrees and, at last follow-up, they were 51.4 degrees , 37.4 degrees , and 17.5 degrees , respectively. These changes were not significantly different. When the groups were separated according to the level operated, there was still no statistical difference with regard to the overall lordosis, ST, PT or kyphosis from pre- to postoperative period or when the two groups were compared with each other. The level above the prosthesis has always significantly less lordosis. In the present study with use of a motion-preserving Maverick prosthesis, it appears that the patient is able to maintain the preoperative sagittal balance. The prosthesis has enough freedom of motion to allow the patient to maintain the natural sagittal and spinopelvic balance needed to prevent potential undue stress on the muscles and the sacroiliac joint. Although the number of patients is small, this is the first study to our knowledge that evaluates the sagittal balance after motion-preserving total disc arthroplasty.

Adult↗
PubMed1994

Intracerebral administration of antisense oligodeoxynucleotides to GAD65 and GAD67 mRNAs modulate reproductive behavior in the female rat.

Increased GABA activity in the medial hypothalamus (HYP) and midbrain central gray (MCG), but not the preoptic area (POA), facilitates sexual receptivity in the female rat [40]. In the current experiments, ovariectomized females were chronically treated with estrogen (via silastic capsules) to maintain a continuously high level of lordosis response. Administration of crystalline antisense oligodeoxynucleotide to the GABA synthetic enzyme, GAD67, into the HYP and MCG significantly and reversibly reduced lordosis response for 1-2 days, but did not inhibit lordosis when administered into the POA. Administration of a control oligonucleotide, consisting of the same nucleotide bases but in a scrambled sequence, did not significantly modulate behavior when infused into any brain areas. When oligodeoxynucleotide antisense to GAD67 was suspended in oil and then infused into the HYP or MCG it was more effective and resulted in less inter-animal variability. Subsequent experiments involving infusions into the MCG compared the effectiveness of antisense oligonucleotides to the two different forms of GAD, known as GAD65 and GAD67. Oligodeoxynucleotides antisense to the mRNA for either gene were effective at reducing lordosis behavior but with a different time course. Oligonucleotide antisense to GAD67 significantly reduced behavior within 24 h of infusion and there was full recovery by 4 days post-infusion. GAD65 antisense oligonucleotide did not significantly reduce behavior until 48 h post infusion and animals did not fully recover to pretest levels of lordosis until 5 days post-infusion. When antisense oligonucleotide for the two genes was administered simultaneously, the inhibition of lordosis was maximal at 24 h and stayed depressed for 4 days. There did not appear to be an additive effect of the two different antisense oligonucleotides when administered together. Tissue GABA levels in HYP and MCG of individual rats assayed by HPLC were no longer correlated with lordosis score after antisense oligonucleotide infusion but were after infusions of scrambled control oligos. Immunoblotting for the two forms of GAD revealed that GAD67 antisense oligonucleotide infusion led to significant decreases in both GAD67 and GAD65 protein levels as compared to infusions of scrambled control oligo. In addition, the levels of a neuronal marker, neuron-specific enolase, also decreased (although nonsignificantly) suggesting either a temporary shutdown of protein synthesis or a degeneration of GABAergic neurons after GAD67 antisense oligonucleotide infusion.

Animals↗
PubMed1988

Heterotypic sexual behavior in male rats after lesions in different amygdaloid nuclei.

Previous studies showed that different amygdaloid nuclei are involved in the control of lordosis behavior in female rats. The objective of the present study was to determine whether these nuclei played a role in the control of lordosis behavior in the male rat. Lesions were placed into different amygdaloid nuclei in male rats castrated as adults and primed with ovarian hormones. Lesions in the corticomedial amygdaloid nucleus completely suppressed lordosis behavior as expressed by the number of animals displaying lordosis responses to male mounts. By contrast extended lesions placed into the lateral amygdaloid nucleus (LN) remained without effects. Lesions placed in the very posterior part of the LN produced "hypersexuality" with a rise in the number of animals displaying lordosis responses and high LQ values. Lesions in the anterior part of the LN induced a decrease in the number of animals showing lordosis responses. The amygdala was then concluded to represent a functionally heterogeneous structure with different regions exerting opposite effects on the display of lordosis behavior in the male rat.

Amygdala↗
PubMed1982

Induction of female sexual behavior by GTP in ovariectomized estrogen primed rats.

The effect of both intrahypothalamic and systemic administration of guanosine triphosphate (GTP) on lordosis behavior was studied in ovariectomized and ovariectomized-adrenalectomized, estrogen-primed rats (estradiol benzoate, 4 micrograms). This estrogen dose per se induced only weak or no lordosis behavior. Injection of GTP into the medial hypothalamic area (100 micrograms in 2.5 microliters) elicited lordosis behavior with relatively short latency in 6 out of 7 rats. Systemic administration of GTP in a dose range of 0.8 mg to 5.0 mg to ovariectomized estrogen-primed rats, stimulated intense lordosis behavior in all subjects. Weak lordosis responses were displayed within the first 12 hr after GTP injection, but as 48 hr all rats were highly estrous. Lordosis behavior remained for up to eight days, its duration being related to the dose of GTP administered. GTP (2 mg) induced lordosis behavior in ovariectomized, adrenalectomized estrogen-primed rats, thus excluding the participation of adrenal steroids in this effect. The results are interpreted in terms of the stimulation of adenyl cyclase-cAMP systems by GTP.

Adrenalectomy↗
PubMed1986

Functional reconfiguration of midbrain neurons by ovarian steroids in behaving hamsters.

Previous studies have demonstrated the importance of the midbrain, especially the tectum, in the sensorimotor control of the sexually-receptive posture, lordosis, in female golden hamsters. In the present study, midbrain single unit activity was recorded during hormonal induction of lordosis, to identify neuronal activity mediating the sensorimotor control of the response and to observe functional changes in these neurons associated with the hormones' behavioral effect. Progesterone administration to estrogen-primed hamsters initiated pronounced changes in neuronal activity levels, somatosensory responsiveness and movement-related firing. These changes began in some neurons within 10 min of subcutaneous hormone injection and affected progressively more neurons until lordosis was elicitable 2-4 hr later. The pattern of these changes, including increased neuronal responsiveness to lumbosacral stimuli, appearance of lordosis-related firing (especially in the tectum) and reduced incidence of firing associated with lordosis-incompatible behaviors, constituted a transformation, or reconfiguration of midbrain sensorimotor function. It is proposed that this reconfiguration enables the elicitation and maintenance of lordosis by lumbosacral stimuli. Neural effects of comparable magnitude didn't result from control progesterone injections which failed to induce lordosis.

Animals↗
PubMed1992

Social modulation of behavioral reproductive senescence in female rats.

During aging, the lordosis reflex of female rats changes from a state of cyclic lordosis, when the lordosis reflex can be elicited by manual palpation only on proestrus, to a state of constant lordosis (CL), when it can be elicited daily. Social signals from other females altered this pattern of behavioral senescence. Group living decreased the lordosis reflex intensity in both old and young rats and delayed the onset of CL. Long-term group living delayed CL until late in the life span, while temporary group living delayed it only until rats returned to isolation. Long-term group living also changed the temporal relationship between CL and the acyclic, anovulatory state of estrus. Finally, the lordosis reflex intensity, measured by manual palpation, predicted the old rats' receptivity to a male, indicating that constant lordosis is a biomarker for other aspects of behavioral reproductive senescence.

Aging↗
PubMed1995

Ring A reduced progestins potently stimulate estrous behavior in rats: paradoxical effect through the progesterone receptor.

The effect of ring A reductions at C5 and C3 on the capacity of the progesterone (P) molecule to stimulate estrous behavior was studied in ovariectomized estrogen primed rats (5 micrograms estradiol benzoate, EB, 40 h before progestin administration). Dose-response curves (dose range: 0.75-200 micrograms) for the lordosis quotient (LQ), lordosis score (LS), and proceptivity were constructed for P and all its ring A reduced metabolites: 5 alpha-pregnanedione (alpha DHP), 5 beta-pregnanedione (beta DHP), 3 alpha,5 alpha-pregnanolone (3 alpha,5 alpha-Pgl), 3 alpha,5 beta-pregnanolone (3 alpha,5 beta-Pgl), 3 beta,5 alpha-pregnanolone (3 beta,5 alpha-Pgl), and 3 beta,5 beta-pregnanolone (3 beta,5 beta-Pgl). Progestins were dissolved in propylene glycol and IV injected through an indwelling jugular catheter. Tests for lordosis and proceptivity were made at 5, 30, and 120 min after progestin injection. Weak, though significant lordosis behavior was observed at 5 min following the injection of some of the progestins, particularly the pregnanolones. Maximal responses were obtained at 120 min postinjection for all progestins. Dose response curves of the LQ, LS, and proceptivity were dualistic for alpha DHP and both 3 alpha pregnanolones, smaller responses being observed with high doses. Relative potency analysis revealed that alpha DHP, 3 alpha,5 beta-Pgl, 3 beta,5 alpha-Pgl, and 3 alpha,5 alpha-Pgl were considerably more potent for eliciting lordosis than P (14, 13.7, 9, and 4-fold, respectively). The same order of relative potencies was found for both LS and proceptivity. 3 beta,5 beta-Pgl and beta DHP were only slightly more potent than P (2 and 1.5-fold, respectively). In a second study, the antiprogestin RU486 (5 mg, SC), injected 60 min before one of four selected progestins (alpha DHP, 3 alpha,5 alpha-Pgl, 3 alpha,5 beta-Pgl, and 3 beta,5 beta-Pgl), significantly inhibited their action on estrous behavior (lordosis and proceptivity) when tested at 60 and 120 min postinjection. On the other hand, RU486 failed to inhibit early lordotic responses obtained at 5 and 30 min following 3 alpha,5 alpha-Pgl and 3 alpha,5 beta-Pgl. Similarly RU486 was ineffective in inhibiting lordosis in ovariectomized rats treated only with estradiol (3 micrograms of EB/day for 7 days). Data suggest that: (i) ring A reduction of the P molecule plays an important role in the normal facilitation of estrous behavior in the rat; and (ii) ring A reduced progestins provoke this effect by acting, at least partially, through the progesterone receptor.

Animals↗
PubMed1987

Decreased rodent sexual receptivity after lindane.

Female rats were injected on the morning of proestrus with 25, 33, 50 or 75 mg/kg lindane or with 1, 2, 2.5 or 3 mg/kg picrotoxin. That evening, females were examined for lordosis behavior with a sexually experienced male. Picrotoxin had no inhibitory effects on lordosis behavior. There was a dose-dependent reduction in sexual receptivity (lordosis to mount behavior) with increasing doses of lindane. At none of the tested doses of lindane was there a total absence of lordosis behavior. However, lindane animals experienced a greater number of mounts before the first lordosis response was observed. Lindane-treated females may have required a greater amount of sensory stimulation to elicit the lordosis reflex. A majority of the lindane-treated females also failed to exhibit proceptive behavior (darting and hopping) during the mating test. The inhibitory effects of lindane on lordosis behavior are similar to previous reports of the effects of another chlorinated pesticide, chlordecone, on female sexual receptivity. Both compounds disrupt central nervous system neurotransmitters and this may account for their common attenuation of sexual behavior. Since both lindane and picrotoxin are recognized for their disturbance of the GABAergic system, these findings suggest that lindane's inhibition of sexual receptivity may not be mediated through its GABAergic action.

Animals↗
PubMedDate not supplied

[Sagittal alignment and segmental range of motion after total disc replacement of the lumbar spine].

AIM: To evaluate changes in static and dynamic values, X-rays of patients who underwent total disc replacement for degenerative disc disease were analyzed. METHOD: An analysis of pre- and postoperative lateral X-rays in 22 patients with 24 total disc replacements (Prodics, Spine Solutions) was performed. The total lumbar lordosis, the segmental lordosis angle, the disc height and the range of motion in the operated level were measured. RESULTS: Postoperatively a significant increase was observed for the following parameters: the anterior (pre: 9.0 +/- 3.4 mm; post: 16.7 +/- 2.4 mm; p < 0.001) and posterior (pre: 4.4 +/- 1.3 mm; post: 8.8 +/- 1.3 mm; p < 0.001) disc height and the segmental lordosis angle (pre: 20 degrees +/- 7.2 degrees; post: 27.7 degrees +/- 7.4 degrees; p < 0.001). Statistically no significant changes could be observed postoperatively for the total lumbar lordosis (pre: 56.2 degrees +/- 10.7 degrees; post: 58.6 degrees +/- 9.3 degrees; p = 0.196) and the range of motion (pre: 5.0 degrees +/- 4.0 degrees; post: 5.9 degrees +/- 3.5 degrees; p = 0.293). CONCLUSION: Total disc replacement for degenerative disc disease of the lumbar spine with the current concept does not alter the range of motion but significantly increases the disc height. The significant increase in segmental lordosis without a change in the total lumbar lordosis accounts for a change in lordosis in adjacent segments.

Adult↗
PubMed1994

Radiographic analysis of sagittal plane alignment and balance in standing volunteers and patients with low back pain matched for age, sex, and size. A prospective controlled clinical study.

STUDY DESIGN: A global and segmental study on standing lateral radiographs of 100 volunteers and 100 patients who had low back pain was undertaken to further define sagittal plane alignment and balance. The volunteer control group and the patient group were matched for age, sex, and size. METHODS: Measurements and determinations made on the standing radiographs included the following: segmental and total lordosis L1-S1 (Cobb method); thoracic kyphosis; thoracic apex; plumbline dropped from the center of C7; and sacral inclination measured between the plumbline and a line drawn along the back of the proximal sacrum. RESULTS: Segmental lordoses were significantly different between each motion segment in both groups. Approximately two-thirds of total lordosis occurred at the bottom two discs, i.e., L4-5 and L5-S1. Total lordosis was significantly less in the patients and was not age- or sex-related in either group. Patients tended to stand with less distal segmental lordosis, but more proximal lumbar lordosis, a more vertical sacrum and, therefore, more hip extension. This may be related to compensation as C7 sagittal plumb lines were comparable in both groups. Both groups had similar thoracic kyphosis. A much higher percentage of smokers was found in the low back pain patient population studied. Because of the significant amount of angulation in the lower lumbar spine, measurement of lordosis should include the L5-S1 motion segment and be done standing to better assess balance. Sacral inclination is a determinate of both standing pelvic rotation and hip extension. It is strongly correlated with segmental and total lordosis in both volunteers and patients. CONCLUSIONS: Definitions of sagittal balance are provided as well as additional sagittal plane data by which to compare corrections and fusions for different spinal disorders.

Adult↗
PubMed2004

Rigid, semirigid versus dynamic instrumentation for degenerative lumbar spinal stenosis: a correlative radiological and clinical analysis of short-term results.

STUDY DESIGN: Prospective comparative randomized clinical and radiologic study. OBJECTIVE: This study was conducted to compare the short-term effects of rigid versus semirigid and dynamic instrumentation on the global and segmental lumbar spine profile, subjective evaluation of the result, and the associated complications. BACKGROUND DATA: Lumbar spine fusion with rigid instrumentation for degenerative spinal disorders seems to increase the fusion rate. However, rigid instrumentation may be associated with some undesirable effects, such as increased low back pain following decrease of lumbar lordosis, fracture of the vertebral body and pedicle, pedicle screw loosening, and adjacent segment degeneration. The use of semirigid and dynamic devices has been advocated to reduce such adverse effects of the rigid instrumentation and thus to achieve a more physiologic bony fusion. MATERIALS AND METHODS: This study compared 3 equal groups of 45 adult patients, who underwent primary decompression and stabilization for symptomatic degenerative lumbar spinal stenosis. The patients of each group were randomly selected and received either the rigid (Group A), or semirigid (Group B), or dynamic (Group C) spinal instrumentation with formal decompression and fusion. The mean ages of the patients who received rigid, semirigid, and dynamic instrumentation were 65 +/- 9, 59 +/- 16, and 62 +/- 10 years, respectively. All patients had detailed roentgenographic study including computed tomography scan and magnetic resonance imaging before surgery to the latest follow-up observation. The following roentgenographic parameters were measured and compared in all spines: lumbar lordosis (L1-S1), total lumbar lordosis (T12-S1), sacral tilt, distal lordosis (L4-S1), segmental lordosis, vertebral inclination, and disc index. The SF-36 health survey and Visual Analogue Scale was used before surgery to the latest evaluation. RESULTS: All patients were evaluated after a mean follow-up of 47 +/- 14 months. Both lumbar and total lordosis correction did not correlate with the number of the levels instrumented in any group. Total lordosis was slightly decreased after surgery (3%, P < 0.05) in Group C. The segmentallordosis L2-L3 was increased after surgery by 8.5% (P < 0.05) in Group C, whereas the segmentallordosis L4-L5 was significantly decreased in Group Aand C by 9.8% (P = 0.01) and 16.2% (P < 0.01), respectively. The disc index L2-L3 was decreased after surgery in Group A and C by 17% (P < 0.05) and 23.5% (P < 0.05), respectively. The disc index L3-L4 was increased in Group C by 18.74% (P < 0.01). The disc index L4-L5 was after surgery decreased in all 3 groups: Group A by 21% (P = 0.01), Group B by 13% (P < 0.05), and Group C by 13.23% (P < 0.05). The disc index L5-S1 was significantly decreased in Group B by 13% (P < 0.05). The mean preoperative scores of the SF-36 before surgery were 11, 14, and 13 for Groups C, B, and A, respectively. In the first year after surgery, there was a significant increase of the preoperative SF-36 scores to 65, 61, and 61 for Groups C, B, and A, respectively, that represents an improvement of 83%, 77%, and 79%, respectively. In the second year after surgery and thereafter, there was a further increase of SF-36 scores of 19%, 23%, and 21% for Groups C, B, and A, respectively. The mean preoperative scores of Visual Analogue Scale for low back pain for Groups C, B, and A were 5, 4.5, and 4.3, respectively, and decreased after surgery to 1.9, 1.5, and 1.6, respectively. The mean preoperative scores of the Visual Analogue Scale for leg pain for Groups C, B, and A were 7.6, 7.1, and 6.9, respectively, and decreased after surgery to 2.5, 2.5, and 2.7, respectively. All fusions healed radiologically within the expected time in all three groups without pseudarthrosis or malunion. Delayed hardware failure (1 screw and 2 rod breakages) 1 year and 18 months after surgery without radiologic pseudarthrosis was observed in 2 patients in Group C. Asymptomatic radiolucent areas were shown around pedicle screws in the pedd pedicle screws in the pedicles L5 and S1 in 2, 3, and 4 cases in Group C, A, and B, respectively. There was no adjacent segment degeneration in any spine until the last evaluation. DISCUSSION AND CONCLUSION: This comparative study showed that all three instrumentations applied over a short area for symptomatic degenerative spinal stenosis almost equally after surgery maintained the preoperative global and segmental sagittal profile of the lumbosacral spine and was followed by similarly significant improvement of both self-assessment and pain scores. Hardware failure occurred at a low rate following dynamic instrumentation solely without radiologically visible pseudarthrosis or loss of correction. Because of the similar clinical and radiologic data in all three groups and the relative small number of patients that were included in each group, it is difficult for the authors to make any recommendation in favor of any instrumentation.

Aged↗
PubMed1979

Mesencephalic mechanisms for integration of female reproductive behavior in the rat.

Placement of bilateral electrolytic lesions in the mesencephalic central gray (CG) of estrogen-primed ovariectomized female rats produced an immediate decline in performance of the lordosis reflex. Lesions that destroyed the dorsal half of the CG and the adjacent subtectal region were effective. The decrease in individual animals in terms of the lordosis reflex score ranged from 20 to 100% of the prelesion performance. Such lesions abolished the facilitation of lordosis by electrical stimulation of the ventromedial nucleus of the hypothalamus. Similar abrupt losses of lordosis followed bilateral lesions of either a) the area between CG and the cuneiform nucleus of the mesencephalic reticular formation (NCf); or b) the ventrolateral quadrant of the NCf. The difference between these two lesions was that the effect of the latter could be overridden by electrical stimulation of the CG, whereas that of the former could not. We conclude that the CG is an important supraspinal component of the circuit for lordosis behavior, constituting a link between ascending somatosensory and descending motor systems for lordosis. It probably facilitates lordosis when activated by behaviorally relevant peripheral somatosensory and/or ventromedial hypothalamic inputs.

Animals↗
PubMed1999

Low back pain and posture.

This study was designed to analyse postural aberrations of the back and lower back region in patients with acute and chronic low back pain and to investigate the accordance of clinical and radiological assessments. Fifty patients with acute and 50 with chronic low back pain and 50 controls were studied and a detailed spinal physical examination was performed. In addition, the angles of thoracic kyphosis, lumbar lordosis and sacral inclination were assessed radiologically. Differences among the three groups, correlations of radiological parameters with each other and with clinical parameters such as age, gender and body mass index, and the accordance of clinical and radiological postural assessments were investigated. It was concluded that there were no statistically significant differences among the groups for angles of thoracic kyphosis, lumbar lordosis and sacral inclination; however, we found significant correlations among all radiological parameters, especially between lumbar lordosis and sacral inclination. Both lumbar lordosis and sacral inclination were increased with body mass index, and lumbar lordosis and thoracic kyphosis were increased with age. Clinical assessments of thoracic kyphosis and lumbar lordosis were not in accordance with radiological assessments.

Adult↗
PubMed1996

Comparison of lumbar sagittal alignment produced by different operative positions.

STUDY DESIGN: This study is a prospective evaluation of the effects of commonly used spinal tables on lumbar sagittal alignment. OBJECTIVES: The objective was to determine the differences, if any, in lumbar sagittal alignment produced by different positions on routinely used spinal operating tables. SUMMARY OF BACKGROUND DATA: Earlier studies have documented the advantages of the knee-chest position in lumbar decompressive procedures. When simultaneous fusion is performed and augmented with internal fixation, intraoperative position is the critical determinant of sagittal plane balance. Other investigators have documented an association between the knee-chest position and decreased lumbar lordosis. METHODS: Ten asymptomatic volunteers underwent a series of four lateral lumbar radiographs, as follows: standing, prone on the Jackson (Orthopaedic Systems, Inc., Hayword, CA) spinal table, and prone on the Andrews (Orthopaedic Systems, Inc.) table with the hips flexed 60 degrees and 90 degrees, respectively. Intervertebral body angle measurements were obtained from L1 to S1. Lordosis values were compared and analyzed for each of the positions. Standing lordosis was assumed to be physiologic. RESULTS: Physiologic lordosis values were produced only on the Jackson operative table. Both positions on the Andrews table resulted in a statistically significant decrease in lumbar lordosis. Decreasing hip flexion on the Andrews table from 90 degrees to 60 degrees produced a statistically significant increase in lumbar lordosis. However, this change did not reproduce physiologic values. CONCLUSION: When instrumentation is used to augment lumbar fusions, positions incorporating hip flexion should be avoided to ensure maintenance of sagittal plane balance.

Adult↗