Tuberculosis of the spine in the new millennium

Tuberculosis of the spine is probably one of the earliest diseases to have affected the human race. Over the past few decades, the epidemiology, pathology, natural history and diagnostic methodology have been well studied. The multinational prospective study on the efficacy of conservative chemotherapy and surgical treatment coordinated by the Medical Research Council has just completed a final 15-year follow-up report. Although it appears from this study that conservative treatment is as effective as surgical intervention for earlier and milder diseases, there are still reservations on the effect of such treatment at much longer follow-ups and for more severe diseases. Further developments in diagnosis using molecular genetic techniques, more effective antibiotics and more aggressive surgical protocols in the next millennium may help in solving the problems of late severe deformity and paraplegia in the debilitated immunocompromised patients.

Variability of somatosensory-evoked potentials in different stages of scoliosis surgery

STUDY DESIGN

A comparison of the latencies and amplitudes of the somatosensory-evoked potential in different stages of scoliosis surgery.

OBJECTIVES

To investigate the normal variability of the somatosensory-evoked potential at different stages of scoliosis surgery and to improve the reliability of spinal cord monitoring.

SUMMARY OF BACKGROUND DATA

False alarms in intra-operative spinal cord monitoring have been reported when the somatosensory-evoked potential measured before skin incision was used as the reference baseline value. However, the normal variability during different stages of surgery and the specificity of somatosensory-evoked potential is not well documented.

METHODS

The somatosensory-evoked potential of 90 patients who underwent surgical correction for idiopathic scoliosis was monitored intraoperatively, with stimuli applied to the posterior tibial nerve. The amplitudes and latencies of the somatosensory-evoked potential were recorded over Cz'-Fz and Cv-Fz. The values of latencies and amplitudes and their percentage variabilities were analyzed.

RESULTS

The values of latencies and their percentage variabilities did not differ significantly from each other in different stages of surgery. The values of amplitudes between different stages showed statistically significant differences. In particular, the amplitude of the somatosensory-evoked potential was found to be significantly decreased after exposure of the spine when compared with the amplitude before skin incision.

CONCLUSION

Some variability in latencies and amplitudes between different stages of scoliosis surgery is normal. These results suggest that the somatosensory-evoked potential when the spine is exposed may be used as the reference baseline to determine whether somatosensory-evoked potentials are subnormal at the subsequent stages of surgery.

Comparison of CMV, RSV, SV40 viral and Vlambda1 cellular promoters in B and T lymphoid and non-lymphoid cell lines

Determining the activity of viral and cellular regulatory elements in B or T lymphoid cell lines would facilitate appropriate utilization of the regulatory sequences for gene transfer- and expression-dependent applications. We have compared the activity of the CMV, RSV and SV40 viral promoter/enhancers as well as the Vlambda1 cellular promoter, in three B cell lines (REH, SMS-SB, C3P), three T cell lines (CEM, Jurkat, ST-F10), and two non-lymphoid cell lines (K-562, HeLa) using the luciferase reporter gene. In B cell lines, the activity of the CMV promoter/enhancer construct was the highest ranging from 10- to 113-fold greater than that of SV40. In contrast, in T cell lines the RSV promoter/enhancer activity was 11-65-fold higher than that of SV40. The Vlambda1 promoter activity was close to that of SV40 promoter/enhancer in most of the cell lines tested. We conclude that CMV and RSV promoter/enhancers contain stronger regulatory elements than do the SV40 and Vlambda1 for expression of genes in lymphoid cell lines.

Stability of the whole lumbar spine after multilevel fenestration and discectomy

STUDY DESIGN

An investigation of the in vitro biomechanical effects of multilevel fenestrations and discectomies on the behavior of whole lumbar spine motion, using a material testing system (Instron 1341, Instron Limited, High Wycombe, England) and Elite three-dimensional motion analysis system (BTS, Milano, Italy).

OBJECTIVES

To investigate the effects of multilevel fenestrations and discectomies on the stability of the whole lumbar spine, including segmental stiffness and sagittal (horizontal and vertical) translation.

SUMMARY OF BACKGROUND DATA

In the management of lumbar spinal stenosis, wide decompressive laminectomy with partial or total facetectomy has been the standard procedure for multilevel nerve decompression. Main complications with these procedures have been instability and chronic pain syndrome. Multilevel fenestration with undermining enlargement of the spinal canal has been selected for multilevel nerve decompression in recent years. However, the biomechanical effects of multilevel fenestration and discectomy have been controversial and difficult to validate. This study investigated the in vitro biomechanical effects of multilevel fenestrations and discectomies on motion behavior of the whole lumbar spine.

METHODS

Seven fresh human specimens from L1 to sacrum were used in this study. The fenestrations and discectomies consisted of L3-L4 bilateral fenestration, L4-L5 bilateral fenestration, L5-S1 bilateral fenestration, L4-L5 discectomy, and L5-S1 discectomy. Flexion, lateral bending, and axial rotation (torsion) loading were applied. Ranges of motion were determined two-dimensionally by the Elite system with an infrared camera. The postoperation results were compared with the intact conditions.

RESULTS

After multiple fenestrations, the sagittal ranges of motion at L4-L5 increased by 18% anteroposteriorly and 16% vertically under the flexion loads. At L5-S1, the motions increased by 19% and 45%, respectively. After fenestrations and discectomies, the ranges of motion in the sagittal plane increased by 28% horizontally and 71% vertically at L4-L5, and 14% and 166% at L5-S1. Motion increases were statistically significant (P < 0.05) in vertical translations. However, after the multilevel surgeries, no significant motions were found in each of the lumbar segments during lateral bending and axial rotation.

CONCLUSIONS

The results demonstrate that multilevel fenestrations and discectomies affect lumbar spinal stability in flexion, but have no effect on the stability of the lumbar spine in lateral bending or axial rotation.

Kinematics of the chest cage and spine during breathing in healthy individuals and in patients with adolescent idiopathic scoliosis

STUDY DESIGN

The lung function test by a Plethysmograph enabled calculations to be made of the total lung capacity and vital capacity. A Motion Analysis System (Elite, BTS Inc., Milano, Italy) was used to observe and record chest cage and spinal movements and as to correlate lung function with the chest cage and spine kinematics.

OBJECTIVES

To determine the three-dimensional kinematics and the shape and size changes of the chest cage and thoracic spine motion during deep breathing in healthy and scoliotic individuals.

SUMMARY OF BACKGROUND DATA

Lateral flexion plus rotation of the involved vertebrae around a vertical axis causing a decrease in lung function is the main disfigurement of scoliosis. Reports show that even after spinal fusion, reduced vital capacity associated with an increased residual volume are detected. Factors such as angle of scoliosis, length of the spinal column involved, and duration of the deformity influence pulmonary function but do not significantly affect its reduction. Mechanical inefficiency during breathing has not been studied.

METHODS

Three-dimensional kinematics of the chest cage and spine during breathing were studied in 41 scoliotic patients and in 20 healthy individuals. Three-dimensional chest cage motions relative to the spine and thoracic spine motions relative to T12 were calculated. To examine stiffness of the spine, lateral bending angles were calculated. The lung function test, which including spirometry and lung subdivision, also was performed for the scoliotic patients.

RESULTS

Significant differences (P < 0.05) were found in the movements of the upper level of the chest cage in anteroposterior and vertical directions, ranging from 16.7 to 28.6 mm in healthy individuals and from 12.1 to 24.2 mm in scoliotic patients. The thoracic spine displayed two-dimensional movements posteriorly and vertically during breathing, whereas less movement was seen in scoliotic patients. In addition, overall the scoliotic spine showed signs of stiffness in lateral bending.

CONCLUSIONS

The range of movement of the chest cage and spine is more limited in the scoliotic cases. This overall stiffness of the chest cage and the spine may contribute to the mechanical inefficiency and impairment of pulmonary function found in scoliotic patients.

Evaluation of a new calcaneal quantitative ultrasound system and determination of normative ultrasound values in southern Chinese women

Quantitative ultrasound (QUS) assessment at the calcaneus has been found to be a safe and reliable method for evaluating skeletal status. The present study aimed at evaluating the precision of the Sahara bone ultrasound densitometer and to determine the normative QUS data in healthy southern Chinese women. Broadband ultrasound attenuation (BUA), speed of sound (SOS) and qualitative ultrasound index (QUI) were determined. The long-term in vitro precision of the Sahara machine over 6 months was 4.6% for BUA and 0.39% for SOS. The short-term in vivo precision was 3.2 +/- 1.3% for BUA, 0.3 +/- 0.2% for SOS and 1.8 +/- 1.0% for QUI. The standardized precision for BUA, SOS and QUI was 4.4, 3.8 and 2.2 respectively. The normative data were determined in 1086 healthy subjects. Postmenopausal women had significantly lower BUA, SOS and QUI levels than the premenopausal women. Significant negative correlations were observed between QUS indices and age. Bone mineral density (BMD) assessments was performed on 349 of these subjects. BUA correlated significantly with lumbar spine BMD (r = 0.326) and femoral neck BMD (r = 0.395). Similar correlations were observed between SOS, QUI and BMD, with r values ranging between 0.446 to 0.522. Despite the fact that Chinese women have significantly lower BMD values than Caucasian women, the mean BUA values for pre- and postmenopausal Chinese women (73 +/- 18 and 59 +/- 18 dB/MHz respectively) were almost the same as those reported for Caucasian women. These normative data will be useful in the assessment of southern Chinese women with fracture risk.

Quantitative ultrasound and symptomatic vertebral fracture risk in Chinese women

Quantitative ultrasound (QUS) is emerging as a simple, inexpensive and noninvasive method for assessing bone quality and assessing fracture risk. We assessed the usefulness of a contact calcaneal ultrasonometer by studying normal premenopausal women (group I, n = 53), normal postmenopausal women (group II, n = 198), and osteoporotic women without (group III, n = 141) and with vertebral fractures (group IV, n = 53). The osteoporotic subjects had a T-score of the spine or hip neck bone mineral density (BMD) <-2.5 based on the local Chinese peak young mean values. When compared with postmenopausal controls, mean broadband ultrasound attenuation (BUA), speed of sound (SOS), and quantitative ultrasound index (QUI) were 26%, 2.1% and 25% lower in women with vertebral fractures (p all <0.005). The correlation coefficients between QUS parameters and BMD of the spine and hip ranged between 0.4 and 0.5. The ability of the QUS to discriminate between patients groups was determined based on the mean value of normal premenopausal women in group I. The mean T-score for women with fractures was -2.87 +/- 1.02 for BUA, -2.54 +/- 0.79 for SOS, -3.17 +/- 0.70 for QUI, -2.65 +/- 0.86 for L2-4 BMD and -2.53 +/- 0.66 for hip neck BMD. After adjustment for age and body mass index, the odds ratio of vertebral fracture was 1.71 (95% CI 1.2-2.6) for each 1 SD reduction in BUA, 2.72 (1.3-5.3) for SOS, 2.58 (1.4-4.6) for QUI, 2.33 (1.6-3.3) for L2-4 BMD, 2.09 (1. 37-3.20) for femoral neck BMD and 1.88 (1.34-2.92) for total hip BMD. The association between the QUS parameters and vertebral fracture risk persisted even adjustment for BMD. The area under the receiver operating characteristic curve for BUA for vertebral fracture was 0. 92, for SOS, QUI, L2-4 BMD and femoral neck BMD was 0.95, and for total hip was 0.91.

Age-related osteoporosis in Chinese: an evaluation of the response of intestinal calcium absorption and calcitropic hormones to dietary calcium deprivation

BACKGROUND

Age-related osteoporosis may be associated with inefficient intestinal calcium absorption and bone remodeling.

OBJECTIVE

We investigated the pathogenesis of age-related osteoporosis in Chinese women with habitual low calcium intakes.

DESIGN

We studied the response of intestinal calcium absorption, calcitropic hormones, and biochemical bone markers to graded dietary calcium deprivation.

RESULTS

The osteoporotic subjects (n = 25) had higher urinary calcium excretion (P < 0.05) and lower plasma 1,25-dihydroxyvitamin D concentrations (P < 0.02) than did age-matched control women (n = 25). Parathyroid hormone was not significantly different from that in age-matched control women but was significantly higher than in young women (n = 15, P < 0.05). Fractional 45Ca absorption was approximately 61% in all 3 groups when the diet was unmodified and increased to 71%, 69%, and 68% in the osteoporotic subjects, age-matched control women, and young women, respectively, when dietary calcium was reduced to 300 mg/d. When the osteoporotic women were calcium deprived, serum 1,25-dihydroxyvitamin D failed to increase but urinary calcium excretion persisted. In contrast, supplementation with 1200 mg Ca resulted in a lowering of parathyroid hormone (P < 0.005 compared with the unmodified diet) and 1,25-dihydroxyvitamin D (P < 0.01) and decreased fractional 45Ca absorption (P < 0.01), suggesting that the increased calcium intake was associated with a potent compensatory ability of the intestine and calcitropic hormones to adapt. Calcium supplementation lowered osteocalcin (P < 0.05) but not alkaline phosphatase, which remained elevated in the osteoporotic subjects at all stages.

CONCLUSIONS

Elderly osteoporotic women had reduced 1,25-dihydroxyvitamin D production, excessive urinary calcium loss, and high bone turnover. The Chinese women had exceptionally potent intestinal calcium absorption.

Assessment of scoliosis correction in relation to flexibility using the fulcrum bending correction index

STUDY DESIGN

A prospective study on adolescent idiopathic scoliosis to assess a new method of describing frontal plane correction.

OBJECTIVE

To assess the difference between using the correction rate and using the new fulcrum bending correction index when describing scoliosis correction.

SUMMARY OF BACKGROUND DATA

A description of the outcome of scoliosis surgery based on the correction rate does not take into account the curve's flexibility.

METHODS

The fulcrum bending correction index is calculated by dividing the correction rate by the fulcrum flexibility (based on the fulcrum bending radiograph) and is expressed as a percentage. The fulcrum bending correction index was compared with the correction rate in 35 patients with adolescent idiopathic scoliosis undergoing surgical correction. These patients were divided into a stiff and a flexible group based on a fulcrum flexibility of 50% to show the advantage of the fulcrum bending correction index over the correction rate.

RESULTS

The difference in correction rate between the flexible (66%) and the stiff group (45%) was significant (P < 0.05). The difference in the fulcrum bending correction index between the flexible (96%) and the stiff group (107%) was not significant (P = 0.2).

CONCLUSIONS

The fulcrum bending correction index takes into account the curve flexibility and is therefore better than the correction rate for comparing curve correction and use of instrumentation systems between different series of patients. A fulcrum bending correction index of close to 100% suggests that the instrumentation has taken up all the flexibility revealed by the fulcrum bending radiograph. It is recommended that the fulcrum bending correction index be used in the future as part of the postoperative assessment of frontal plane correction in cases of thoracic scoliosis.

Costal osteochondroma. A rare cause of spinal cord compression

STUDY DESIGN

Report of a rare cause of spinal cord compression: costal osteochondroma.

OBJECTIVE

To describe a very rare cause of spinal cord compression, costal osteochondroma, which was present in a 16-year-old girl with a history of hereditary multiple exostoses.

SUMMARY OF BACKGROUND DATA

Only four cases of expansion of costal osteochondroma into the spinal canal through an intervertebral foramen have been reported previously.

METHODS AND RESULTS

The origin of the osteochondroma at the head of the right 12th rib, the invasion of the spinal canal through the right T12-L1 intervertebral foramen, and the compression of the spinal cord were shown on computed tomography and magnetic resonance imaging. The exact extent of the osteochondroma, particularly the cartilage cap, was delineated accurately by magnetic resonance imaging. Complete excision followed by full recovery occurred 19 months after surgery.

CONCLUSION

Magnetic resonance imaging is the preferred method of investigation in cases of osteochondroma related to spine, because it allows for better pre-operative planning and helps to prevent incomplete excision of the tumor.

Radiographic assessment of pedicle hook placement

STUDY DESIGN

A cadaveric study of the changes in the radiographic morphology of the thoracic pedicle with vertebral rotation.

OBJECTIVE

To study the effect of vertebral rotation on the assessment of pedicle hook placement by determining the radiographic anatomy of the pedicle and its relation to the pedicle hook.

SUMMARY OF BACKGROUND DATA

It is commonly assumed that the oval pedicle shadow seen on spine radiographs is formed by the waist of the pedicle. The postoperative assessment of pedicle hook position is based on this assumption.

METHODS

Thoracic cadaveric vertebrae between T5 and T8 were studied, with wire markers placed at the waist, the pedicle-facet junction, and the pedicle-body junction. Thoracic pedicle hooks were placed in the correct position and offset to one side. Radiographs of the vertebral body were taken from 0 degree to 30 degrees of rotation with reference to the sagittal plane.

RESULTS

The radiographic morphology of the pedicle changes with vertebral rotation; it also differs between the concave and the convex side of a scoliotic spine. With rotation of less than 20 degrees, the pedicle shadow is formed by the waist on both sides. With 30 degrees of rotation, the concave pedicle shadow is formed by the pedicle-facet junction, whereas on the convex side, it is over-lapped by the transverse process shadow. A laterally misplaced hook on the convex side and a medially misplaced hook on the concave side can appear correctly located with vertebral rotation.

CONCLUSION

The oval pedicle shadow is not simply represented by the waist of the pedicle. An understanding of the changes in radiographic morphology with rotation is necessary for the assessment of thoracic pedicle hook location after surgery.

Prediction of correction of scoliosis with use of the fulcrum bending radiograph

We used a new method to assess spinal flexibility in thirty patients who were to be managed operatively for adolescent idiopathic scoliosis. The method involves placing the patient in the lateral decubitus position and bent over a fulcrum (a radiolucent padded cylinder) so that the spine is passively hinged open. For thoracic curves the fulcrum is centered under the rib corresponding to the apex of the curve, and for lumbar curves the fulcrum is placed directly under the apex. The preoperative workup for the thirty patients included an anteroposterior radiograph made with the patient standing, a lateral-bending radiograph made with the patient supine, and the new fulcrum bending radiograph. All patients were treated with posterior spinal arthrodesis with segmental spinal instrumentation. The degree of flexibility obtained with the traditional and new methods was compared with the degree of correction observed on the radiograph made, with the patient standing, one week after the operation. Preoperatively, the mean Cobb angle was 58 degrees on the anteroposterior radiograph made with the patient standing, 31 degrees on the lateral-bending radiograph made with the patient supine, and 24 degrees on the fulcrum bending radiograph. The mean angle was 25 degrees on the anteroposterior radiograph made one week postoperatively, so the mean correction was 57 per cent. The difference between the mean angle on the lateral-bending radiograph and that on the postoperative radiograph was significant (p < 0.001); however, the mean angle measured on the preoperative fulcrum bending radiograph and the postoperative angle were almost identical. We found the fulcrum bending radiograph to be more predictive of the degree of flexibility and correctability than the lateral-bending radiograph in this group of patients who had segmental spinal instrumentation for correction of idiopathic scoliosis.

Intervertebral disc autografting in a bipedal animal model

Fusion of the spine while restoring stability of the spinal segment, fails to preserve spinal mobility. Long term complications of accelerated degeneration in the neighboring segments have been reported. The present study explores the possibility of intervertebral disc autografting in a bipedal animal model by isolating a lumbar disc together with the adjacent end plates and repositioning it with minimal internal fixation. Fourteen Rhesus monkeys were sacrificed at 2, 4, 6, and 12 months after surgery and the grafted discs were examined radiologically, biochemically, pathologically, and biomechanically. Healing of the bony end plate was seen between 2 to 4 months postoperatively. There was early loss of disc height at 2 and 4 months but there was a suggestion of some reconstitution up to 12 months. There was minimal evidence of gross degeneration at all stages. Gradual loss of water content was found in the annulus and the nucleus. The nucleus pulposus seemed to be able to reaccumulate proteoglycan after an initial drop in the first 4 months. There was significant increase in hydroxyproline content in the annulus fibrosus and the nucleus pulposus. Biomechanically, the grafted disc showed hypermobility in the first 4 months but gradually became stabilized with time. Results from this study suggested that a fresh intervertebral disc autograft could survive a period of ischemia. Although the physiology of the disc was deranged, it was able to preserve a certain degree of segmental mobility without sacrificing stability. Further studies are required to validate these results and the field of disc allografting should be explored.

Applications of bone scintigraphy in ankylosing spondylitis

Eighteen bone scintisans performed in 14 patients with ankylosing spondylitis were reviewed. In young patients with low back pain, positive serology, and indeterminate radiographs, quantitative sacroiliac joint assessment and the presence of typical uptake patterns, particularly costovertebral, were useful in suggesting the diagnosis. Scintigraphy was helpful in the early detection of pseudoarthrosis complicating long-standing disease, especially in patients presenting with recurrent back pain. Selective application of bone scintigraphy aids the diagnosis of ankylosing spondylitis and its potential complications.

Spinal stenosis above a healed tuberculous kyphosis. A case report

STUDY DESIGN

This case report illustrates two patients with paraplegia of late onset resulting from cord compression in the hyperlordotic thoracic or thoracolumbar spine proximal to a healed tuberculous kyphosis.

OBJECTIVES

The objective of this paper is to highlight that degenerative stenosis of the thoracic spine proximal to a healed stable kyphosis can be a cause of paraplegia of healed disease.

SUMMARY OF BACKGROUND DATA

Paraplegia resulting from tuberculosis of the spine can be of early or late onset. Early onset paraplegia is usually a result of cord compression by active disease. Late onset paraplegia can be due to disease reactivation, bony ridge compression, or unstable kyphosis. To our knowledge, compression of the cord proximal to a healed, stable kyphosis giving rise to paraplegia has never been reported.

METHODS

Patient 1 presented with symptoms of spinal claudication and progressive paraparesis. He was found to have spinal stenosis in the hyperlordotic thoracolumbar spine proximal to a healed lumbosacral tuberculous kyphosis. Patient 2 presented with a 2-year history of progressive paraplegia. Imaging revealed cord compression at the hyperlordotic T10-11 segment by disc protrusion, and facet hypertrophy.

RESULTS

Laminectomy successfully relieved the first patient of all symptoms but the second patient had significant deterioration of the neurologic status after surgery.

CONCLUSION

Compensatory hyperlordosis of the thoracic or thoracolumbar spine commonly occurs in patients with severe tuberculous thoracolumbar or lumbosacral kyphosis. Degenerative spinal stenosis and cord compression at such hyperlordotic segment can cause late onset paraplegia. The blood supply of these chronically compressed cords is precarious and the risk of surgery is high.

Effects of short anterior lumbar interbody fusion on biomechanics of neighboring unfused segments

STUDY DESIGN

Segmental mobility and intradiscal pressure were measured and the data compared in six cadaveric lumbar spine specimens before and after in vitro simulated single level L4-5 and double level L4-5-S1 anterior interbody fusions.

OBJECTIVE

The experimental objective was to study the biomechanical effects of single level L4-5 and double level L4-5-S1 anterior interbody fusions on the neighboring unfused segments.

SUMMARY OF BACKGROUND DATA

The relationship between the local rigidity created by fusion mass and accelerated degeneration reported at the neighboring unfused intervertebral discs is not clear.

METHODS

Six cadaveric lumbar spine specimens were biomechanically tested in flexion and extension. Segmental mobility and intradiscal pressure of the specimens were measured before and after in vitro simulation of single level L4-5 and double level L4-5-S1 anterior interbody fusions.

RESULTS

The mobility of the motion segments immediately above and below an L4-5 fusion was increased in flexion. When the L5-S1 segment was also fused, the loss of segmental motion in both flexion and extension at the L4-5 and L5-S1 were compensated for by increased motion in all levels above the fusion. In both flexion and extension, the intradiscal pressures of all unfused intervertebral discs were increased after a single level L4-5 fusion and this increase was even more marked after a double level L4-5-S1 fusion.

CONCLUSIONS

There is no evidence that the neighboring unfused segments are loaded beyond their physiological limits due to the fusion. However, the neighboring unfused segments have to work more frequently toward the extremes of their functional ranges of motion after fusion and these effects will be more marked after a double level L4-5-S1 fusion.

A 68-year-old man with gradual onset of low-back pain

The following case is presented to illustrate the roentgenographic and clinical findings of a condition of interest to orthopedic surgeons. The initial history, physical findings, and roentgenographic examinations are noted on this page. The clinical and roentgenographic diagnoses are presented on the following pages.

Relation of spinal and thoracic cage deformities and their flexibilities with altered pulmonary functions in adolescent idiopathic scoliosis

STUDY DESIGN

Seventy patients (average age, 13.8 years) with adolescent idiopathic right thoracic scoliosis had full assessment of pulmonary functions and radiographic evaluation of spinal and thoracic cage deformities and their flexibilities.

OBJECTIVES

To determine how measurements of spinal and thoracic cage deformities related to pulmonary function.

SUMMARY OF BACKGROUND DATA

Pulmonary functions have been evaluated in relation to lateral curvature of the spine in most of the published studies. Scoliosis is a three-dimensional deformity. There is a need to evaluate these changes in pulmonary functions, reflecting not only spinal curvature but also rotational deformity, thoracic cage deformity, and their flexibilities.

METHODS

Radiographic measurements obtained from anteroposterior and lateral standing and anteroposterior supine bending radiographs included lateral curvature, vertebral rotation, kyphosis, maximum sternovertebral distance, and apical rib-vertebral angles. Using previous measurements, the flexibility of the curve, vertebral rotation, and rib-vertebral angle were calculated. A pulmonary function assessment was performed using a computerized pulmonary function system (5000V; Gould, Dayton, Ohio). We analyzed pulmonary functions in relation to deformity.

RESULTS

Measurements reflecting spinal deformities obtained from anteroposterior radiographs, such as Cobb angle, vertebral rotation, and vertebral rotation flexibility, were significantly correlated with the percent of predicted values of vital capacity and forced vital capacity, whereas kyphosis measured from lateral radiographs was significantly correlated with absolute values of residual volume, total lung capacity, functional residual capacity, and forced expiratory flow from 25-75% of the forced vital capacity (FEF25-75). Of the measurements reflecting thoracic cage deformity obtained from anteroposterior radiographs, rib-vertebral angle asymmetry (measured from supine bending radiographs) showed significant correlation with the percent of predicted values of vital capacity, forced vital capacity, and functional residual capacity, whereas the sternovertebral distance that was measured from lateral radiographs correlated significantly with absolute values of vital capacity, total lung capacity, forced vital capacity, and FEF25-75.

CONCLUSIONS

Deformities in coronal and transverse plane influence changes in pulmonary functions expressed as the percent of predicted values, whereas sagittal plane deformities influence mainly those absolute volumes in which residual volume is a component. It is suggested that rotational flexibility combined with other deformities could be evaluated in future studies on prediction of pulmonary function from the measurements of the deformity.

Evaluation of deformities and pulmonary function in adolescent idiopathic right thoracic scoliosis

Seventy patients with adolescent idiopathic right thoracic scoliosis had full assessment of their pulmonary function using a computerised pulmonary function system. Their mean age at evaluation was 13.8 years. The following measurements were obtained from anteroposterior and lateral standing and antero-posterior supine bending radiographs: lateral curvature, vertebral rotation, kyphosis, maximum sterno-vertebral distance and apical rib-vertebral angles. Using the above measurements, the flexibility of curve, vertebral rotation and rib-vertebral angle asymmetry were calculated. Patients were classified into three groups on the basis of their predicted vital capacity, to determine whether radiological features of deformity can help identify patients with compromised pulmonary function. The mean Cobb angle and vertebral rotation for the 70 patients were 50 degrees (range 35-100 degrees) and 22 degrees (range 1-44 degrees) respectively. The mean flexibility of curve and vertebral rotation were 52% and 49% respectively. Mean thoracic kyphosis was 25 degrees, ranging from -7 to 55 degrees. Of the patients with Cobb angle less than 90 degrees, 71% had vital capacity less than 80% of predicted values, and of these, 18% had marked compromise of vital capacity (less than 60% of predicted values). Mean values of Cobb angle, vertebral rotational flexibility, kyphosis, rib-vertebral angle asymmetry (in standing as well as supine bending radiographs) differed significantly between patients with more than 80% of predicted vital capacity and those with 60% or less of predicted values. Radiological features indicative of better pulmonary function were: rotational flexibility exceeding 55%, rib-vertebral angle asymmetry (standing) less than 25 degrees and kyphosis greater than 15 degrees. Two deformity parameters--that give a better prediction of pulmonary function than the widely used Cobb angle, vertebral rotational flexibility and rib-vertebral angle asymmetry--were identified in this study.

Cord compression caused by multiple disc herniations and intraspinal cyst in Scheuermann's disease

STUDY DESIGN

The design for this article is a case report.

OBJECTIVES

Reported is the case of a patient with Scheuermann's disease who experienced spastic paraparesis caused by multilevel disc herniations and intraspinal meningeal cyst occurring together.

SUMMARY OF BACKGROUND DATA

Although Scheuermann's disease is associated with disc degeneration and calcification, multilevel disc herniations causing neurologic deficit is exceedingly rare.

METHODS

A patient diagnosed with Scheuermann's disease was evaluated by laboratory tests and radiographs because of paresthesin in bilateral lower extremities.

RESULTS

Evaluation revealed a "cyst" that was separated from the proper subarachnoid space and a disc herniation.

CONCLUSIONS

Intraspinal cyst and multilevel disc herniations could coexist in Scheuermann's disease. Both could contribute to cord compression. Drainage of the cyst, anterior decompression of the disc herniations, and interbody fusion to stabilize the diseased segments produced good results after 2 years.

Sacral insufficiency fractures. Spectrum of radiological features

Clinical and radiological features of 22 Chinese patients with sacral insufficiency fractures were reviewed. Twenty-one were postmenopausal women. Other risk factors were external pelvic radiotherapy (eight) and total hip replacement (two). Severe low back pain was the most common presenting complaint. Fractures initially were demonstrated by bone scintigraphy in 21 and computed tomography (CT) in seven patients. Concomitant parasymphyseal and pubic rami fractures were detected in 17 and 10 patients, respectively. Follow-up assessment by CT and bone scintigraphy in five patients showed various stages of fracture healing. Recognition of the radiological patterns of this entity is emphasized.

Lumbar spinal mobility after short anterior interbody fusion

STUDY DESIGN

Segmental deformations of the lumbar spine in asymptomatic volunteers measured radiologically were compared with those in patients who underwent anterior interbody fusion.

OBJECTIVE

To determine the effects of anterior lumbar interbody fusion on the juxta-fused segments.

SUMMARY OF BACKGROUND DATA

Stiffness of a spinal segment after fusion was thought to be the cause of the degeneration process at the juxta-fused segments.

METHODS

Segmental deformations of the lumbar spine, from maximum extension to maximum flexion, in 30 asymptomatic volunteers and 52 pain-free patients who had single-level L4-L5 or double-level L4-S1 fusion were measured and compared.

RESULTS

The total flexibility of the lumbar spine was decreased after a single-level fusion and further decreased after double-level fusions. The segmental deformations of the juxta-fused segments also were decreased after either a single- or double-level fusion.

CONCLUSIONS

During normal flexion and extension of the lumbar spine, the juxta-fused segments were not deformed beyond their physiological limits after fusion. Thus, accelerated degeneration observed at a juxta-fused segment is unlikely to be attributable to hypermobility.

Radiologic case. Clinics in diagnostic imaging (1). Ankylosing spondylitis with complication of pseudoarthrosis

A 41-year-old Chinese woman with quiescent ankylosing spondylitis presented with increasingly severe, recurrent back pain. The thoracolumbar junction was focally tender on palpation. Radiographs and computerised tomography demonstrated T12/L1 pseudoarthrosis. Excision of pseudoarthrosis, followed by anterior and posterior spinal fusion were performed with good results. The clinical features, pathogenesis, and management of this complication are discussed. Imaging of pseudoarthrosis in ankylosing spondylitis is emphasized.

Vertebral growth after posterior spinal fusion for idiopathic scoliosis in skeletally immature adolescents. The effect of growth on spinal deformity

We studied 29 girls and one boy with adolescent idiopathic scoliosis who were at Risser grade 0 at the time of posterior spinal fusion and were followed until maturity (mean 7.8 years). We used serial radiographs to measure the ratio of disc to vertebral height in the fused segments and to detect differential anterior spinal growth and assess its effect on scoliosis, vertebral rotation, kyphosis, and rib-vertebral-angle difference (RVAD). From one year after surgery to the latest review, the percentage anterior disc height decreased by nearly one-half and the percentage posterior disc height by nearly one-third in the fused segments (p < 0.001). There was a 4 degree increase in mean Cobb angle (p < 0.001), 11 patients (37%) having an increase of between 6 degrees and 10 degrees. There was a significant increase in mean apical rotation by 2 degrees (p = 0.003), and four patients (13%) had an increase of between 6 degrees and 16 degrees. There was little change in kyphosis. There was an increase in mean RVAD by 4 degrees (p = 0.003), seven patients (23%) showing a reduction by 1 degree to 7 degrees, and 11 (37%) increases of between 6 degrees and 16 degrees. Spinal growth occurs after posterior fusion in adolescents who are skeletally immature, as a result of continued anterior vertebral growth. There is some progression of scoliosis, vertebral rotation, and RVAD, but little change in kyphosis. The increase in deformity is not enough to warrant the use of combined anterior and posterior fusion. The findings are relevant to the management of progressive curves, the timing and extent of surgery, and the prognosis for progression of deformity in this group of patients.