Cardiac fibroblasts inhibit β-adrenoceptor-dependent connexin43 expression in neonatal rat cardiomyocytes

Cardiac fibroblasts play an important role in adverse cardiac remodelling. As in many cardiac diseases connexin43 (Cx43) is altered, we wanted to elucidate whether fibroblasts may influence cardiac Cx43 expression. We used four different cell culture systems of neonatal rat cardiomyocytes (CM) and fibroblasts (FB): type 1, pure CM culture; type 2, co-culture of CM/FB; type 3, pure FB culture; type 4, Transwell® system: CM/FB co-cultured but separated by a microporous membrane. Stimulation of types 1-3 cell culture models with isoprenaline significantly enhanced Cx43-protein and Cx43-mRNA expression as well as phosphorylation of ERK and translocation of AP1 and CREB only in the CM cultures; whereas, the CM/FB co-cultures and the FB cultures did not respond to isoprenaline. Similarly, if CM and FB were separated by a microporous membrane (Transwell® system) the isoprenaline-induced increase in CM Cx43 was completely suppressed, suggesting the existence of a soluble factor responsible for the suppressant effect of FB. Angiotensin II determination in types 1 and 2 cell culture supernatants revealed that the CM/FB co-cultures exhibited a significant higher angiotensin II release than the CM cultures. Furthermore, we aimed to inhibit angiotensin II signal transduction pathway: blockade of AT1 receptors or PKC inhibition restored the responsiveness of CM/FB co-cultures to isoprenaline. Moreover, external addition of angiotensin II to CM cultures also resulted in suppression of isoprenaline-stimulated Cx43 expression in an AT1-receptor- and PKC-dependent manner. Thus, our study indicates that cardiac fibroblasts inhibit β-adrenoceptor-dependent Cx43 signalling in CM involving angiotensin II.

The signal transduction cascade regulating the expression of the gap junction protein connexin43 by beta-adrenoceptors

BACKGROUND AND PURPOSE

In mammalian heart, connexin43 (Cx43) represents the predominant connexin in the working myocardium. As the beta-adrenoceptor is involved in many cardiac diseases, we wanted to clarify the pathway by which beta-adrenoceptor stimulation may control Cx43 expression.

EXPERIMENTAL APPROACH

Cultured neonatal rat cardiomyocytes were stimulated with isoprenaline. Cx43 expression as well as activation of p38 mitogen-activated protein kinase (MAPK), p42/44 MAPK, JUN NH(2)-terminal kinase (JNK) and nuclear translocation of the transcription factors activator protein 1 (AP1) and CRE-binding protein (CREB) were investigated. Additionally, we assessed Cx43 expression and distribution in left ventricular biopsies from patients without any significant heart disease, and from patients with either congestive heart failure [dilated cardiomyopathy (DCM)] or hypertrophic cardiomyopathy (HCM).

KEY RESULTS

Isoprenaline exposure caused about twofold up-regulation of Cx43 protein with a pEC(50) of 7.92 +/- 0.11, which was inhibited by propranolol, SB203580 (4-(4-fluorophenyl)-2-(4-methylsulphinylphenyl)-5-(4-pyridyl)-1H-imidazole) (p38 inhibitor), PD98059 2-(2-amino-3-methoxyphenyl)-4H-1-benzopyran-4-one) (MAPK 1 kinase inhibitor) (Alexis Biochemicals, San Diego, CA, USA) or cyclosporin A. Similar findings were obtained for Cx43 mRNA. Furthermore, Cx43 up-regulation was accompanied by phosphorylation of p38, p42/44 and JNK, and by translocation of AP1 and CREB to the nucleus. Analysis of Cx43 protein and mRNA in ventricular biopsies revealed that in patients with DCM, Cx43 content was significantly lower, and in patients with HCM, Cx43 content was significantly higher, relative to patients without any cardiomyopathy. More importantly, Cx43 distribution also changed with more Cx43 being localized at the lateral border of the cardiomyocytes.

CONCLUSION AND IMPLICATION

Beta-adrenoceptor stimulation up-regulated cardiac Cx43 expression via a protein kinase A and MAPK-regulated pathway, possibly involving AP1 and CREB. Cardiomyopathy altered Cx43 expression and distribution.

Preoperative gait comparisons between adults undergoing long spinal deformity fusion surgery (thoracic to L4, L5, or sacrum) and controls

STUDY DESIGN

This investigation compared the gait of revision and primary spinal deformity patients about to undergo surgical reconstruction with that of a group of able-bodied controls.

OBJECTIVES

The hypothesis of the study was that both patient groups would have significantly compromised gait, spine motion, and gait endurance compared with the able-bodied group.

SUMMARY OF BACKGROUND DATA

There is a population of adults with degenerative changes superimposed on idiopathic scoliosis who present for reconstructive spinal surgery (primary patients). There is another group of adults who have already had spinal deformity surgery and present for revision surgery (revision patients).

METHODS

Twenty-seven women were recruited (8 primary, 13 revision, 6 able-bodied controls). A typical gait analysis was performed. Walking endurance was estimated from a submaximal graded treadmill exercise test. Three motion variables describing the orientation of the shoulders with respect to the pelvis in the three principal planes of the body were determined. Also, gait speed, stride length, cadence, and step width were calculated. The variable for the endurance test was the length of time walked on the treadmill.

RESULTS

Results for the revision group indicated a slower walking speed, greater sagittal plane trunk flexion, reduced range of motion in the coronal and transverse planes, and poorer endurance relative to age-matched controls. The primary group demonstrated a slower walking speed relative to age-matched controls. The revision group had poorer endurance scores relative to the primary group.

CONCLUSION

This investigation is an objective report describing the compromised gait and walking endurance of adult patients with spinal deformity before spinal fusion surgery. Results supported subjective observations regarding the preoperative gait of these patients and presented results difficult to observe in a clinical setting. The techniques appear useful in providing objective information regarding the gait abilities of these patients.

Minimum 2-year analysis of sacropelvic fixation and L5-S1 fusion using S1 and iliac screws

STUDY DESIGN

An analysis of lumbosacral fusions for high-grade spondylolisthesis fusions with reduction and long fusions to the sacrum in ambulatory adults.

OBJECTIVE

To assess the clinical and radiographic results of lumbosacral fusions using bilateral S1 and iliac screws.

SUMMARY OF BACKGROUND DATA

S1 screws often fail with lumbosacral fusions, whereas L5-S1 pseudarthrosis is common in patients with deformity.

MATERIALS AND METHODS

A total of 81 patients (38 revision, 43 primary) with minimum 2-year follow-up (average, 4.2 years; range, 2.0-7.1 years) underwent L5-S1 fusion using S1 and iliac screws (158 screws). Forty-nine of 81 constructs (61%) included an anterior load-sharing/fixation device. Group 1 included isthmic spondylolisthesis (n = 42), whereas Group 2 included long fusions (> or =3 levels) to the sacrum (n = 39). In Group 2, 15 patients (Group 2A) were fused from L1, L2, or L3 to the sacrum (3-5 levels, average 3.3 levels) and 24 patients (Group 2B) were fused from the thoracic spine to the sacrum (6-17 levels, average 11.5 levels). Twelve patients had pseudarthrosis at L5-S1. A patient questionnaire was completed.

RESULTS

A total of 36 of the 38 revision patients had previous iliac crest harvesting, yet iliac screws were placed in 34 of 36 patients. Overall, 78 of 80 patients had iliac crest harvesting (one not attempted). None had loss of screw fixation or iliac crest fracture after harvesting. Four of the 81 patients (4.9%) had pseudarthrosis at L5-S1 after reconstruction. This included solid fusion in 10 of 12 patients presenting with L5-S1 pseudarthrosis. Fourteen percent of patients experienced some discomfort over the iliac screws; however, only one patient required screw removal.

CONCLUSIONS

Bilateral iliac screws coupled with bilateral S1 screws provide excellent distal fixation for lumbosacral fusions with a high fusion rate (95.1%) in high-grade spondylolisthesis and long fusions to the sacrum. Previous iliac crest harvesting does not prevent ipsilateral screw placement (34 of 36 patients) or additional iliac harvesting (78 of 80 patients).

Adolescent idiopathic scoliosis: a new classification to determine extent of spinal arthrodesis

BACKGROUND

The lack of a reliable, universally acceptable system for classification of adolescent idiopathic scoliosis has made comparisons between various types of operative treatment an impossible task. Furthermore, long-term outcomes cannot be determined because of the great variations in the description of study groups.

METHODS

We developed a new classification system with three components: curve type (1 through 6), a lumbar spine modifier (A, B, or C), and a sagittal thoracic modifier (-, N, or +). The six curve types have specific characteristics, on coronal and sagittal radiographs, that differentiate structural and nonstructural curves in the proximal thoracic, main thoracic, and thoracolumbar/lumbar regions. The lumbar spine modifier is based on the relationship of the center sacral vertical line to the apex of the lumbar curve, and the sagittal thoracic modifier is based on the sagittal curve measurement from the fifth to the twelfth thoracic level. A minus sign represents a curve of less than +10 degrees, N represents a curve of 10 degrees to 40 degrees, and a plus sign represents a curve of more than +40 degrees. Five surgeons, members of the Scoliosis Research Society who had developed the new system and who had previously tested the reliability of the King classification on radiographs of twenty-seven patients, measured the same radiographs (standing coronal and lateral as well as supine side-bending views) to test the reliability of the new classification. A randomly chosen independent group of seven surgeons, also members of the Scoliosis Research Society, tested the reliability and validity of the classification as well.

RESULTS

The interobserver and intraobserver kappa values for the curve type were, respectively, 0.92 and 0.83 for the five developers of the system and 0.740 and 0.893 for the independent group of seven scoliosis surgeons. In the independent group, the mean interobserver and intraobserver kappa values were 0.800 and 0.840 for the lumbar modifier and 0.938 and 0.970 for the sagittal thoracic modifier. These kappa values were all in the good-to-excellent range (>0.75), except for the interobserver reliability of the independent group for the curve type (kappa = 0.74), which fell just below this level.

CONCLUSIONS

This new two-dimensional classification of adolescent idiopathic scoliosis, as tested by two groups of surgeons, was shown to be much more reliable than the King system. Additional studies are necessary to determine the versatility, reliability, and accuracy of the classification for defining the vertebrae to be included in an arthrodesis.

Prospective dynamic functional evaluation of gait and spinal balance following spinal fusion in adolescent idiopathic scoliosis

STUDY DESIGN

Prospective evaluation of gait and spinal-pelvic balance parameters in patients with adolescent idiopathic scoliosis undergoing a spinal fusion.

OBJECTIVE

To evaluate changes in gait and three-dimensional alignment and balance of the spine relative to the pelvis as a consequence of spinal fusion.

SUMMARY OF BACKGROUND DATA

Preoperative and postoperative spinal radiographs have been the major forms of outcome analysis of adolescent idiopathic scoliosis fusions. The use of optoelectronic analysis for posture and gait has gained acceptance recently. However, there is a paucity of data quantifying, comparing, and correlating structural and functional changes in patients undergoing scoliosis fusion surgery including upright posture and gait.

METHODS

Thirty patients with adolescent idiopathic scoliosis undergoing an instrumented spinal fusion were prospectively evaluated. Coronal and sagittal vertical alignment was evaluated on radiographs (CVA-R, SVA-R), during upright posture (CVA-P and SVA-P), and during gait (CVA-G, SVA-G). Transverse plane alignment was evaluated by the acromion-pelvis angle during gait.

RESULTS

Gait speed was significantly decreased (P < 0.05) between preoperative (129 +/- 16 cm/sec) and 2-year postoperative (119 +/- 16 cm/sec) testing sessions. Decreasing gait speed was the result of significantly reduced cadence and decreased stride length. There were no significant differences for lower extremity kinematics over the entire gait cycle. Spinal-pelvic balance parameters showed significant improvement in mean CVA-R, CVA-G (P < 0.05), then unchanged CVA-P at 2 years postoperation. CVA-P was relatively unchanged while the mean CVA-G also showed significant improvement from preoperation (2.2 +/- 2.4 cm) to 2 years postoperation (1.3 +/- 1.3 cm)(P < 0.05). The mean SVA-R, SVA-P, and SVA-G were unchanged at 2 years postoperation (P > 0.05). The acromion-pelvis angle during gait at maximum shoulder rotation was statistically improved at 1 year (P = 0.002) and 2 years (P = 0.001) after surgery. Importantly, CVA-P correlated with CVA-G, and SVA-P correlated with SVA-G to the P < 0.05 level.

CONCLUSIONS

Patients with adolescent idiopathic scoliosis undergoing spinal fusion show slightly decreased gait speed at 2 years postoperation without any change in lower extremity kinematics. Spinal-pelvic balance parameters are improved in the coronal plane and unchanged in the sagittal plane radiographically and during standing posture and gait. Transverse plane parameters also are improved at maximum shoulder rotation during gait.

Complications and results of long adult deformity fusions down to l4, l5, and the sacrum

STUDY DESIGN

This is a consecutive study of patients having undergone surgical treatment of adult lumbar scoliosis. Follow-up ranged from 2 to 13 years (average 5 years).

OBJECTIVES

To assess the complications and outcomes of patients with long fusions to L4 (n=23), L5 (n=21), or the sacrum (n=15) and determine if a "deeply seated" L5 segment is protective.

SUMMARY OF BACKGROUND DATA

Few studies assess outcomes and complications in adults fused from the thoracic spine to L4, L5, or the sacrum with minimum 2-year follow-up.

METHODS

Fifty-eight patients (59 cases; average age 43 years; range 21 to 60) with minimum 2-year follow-up were analyzed for subsequent spinal degeneration and complications. Outcomes were assessed from questionnaires administered at latest follow-up.

RESULTS

Sixteen percent of cases (7 of 44) fused short of the sacrum displayed subsequent postoperative distal spinal degeneration, although only three patients were symptomatic. Compared with the group with no subsequent degeneration, this group had a lower improvement in function and pain relief. Other complications for patients fused short of the sacrum included two cases with crosslink breakage, one with neurologic deficit, three with pseudarthroses, one with hook pullout, and one with L5 screw pullout. For cases fused to the sacrum, two cases with deep wound infections and one with loose iliac screw requiring removal were observed. Because two of four cases fused to L5 with subsequent degeneration at L5-S1 were observed to have "deeply seated" L5 segments and two of the four did not, the authors could conclude only that "deep seating" of L5 is not absolute protection.

CONCLUSIONS

Fusions short of the sacrum did not have predictable long-term results. Those fused short of the sacrum who developed distal spinal degeneration had worse outcomes. Patients fused to the sacrum did not have a higher complication rate. A "deeply seated" L5 segment does not necessarily protect the L5-S1 disc.

Prospective randomization of parenteral hyperalimentation for long fusions with spinal deformity: its effect on complications and recovery from postoperative malnutrition

STUDY DESIGN

A prospective randomized study of total parenteral nutrition for long spinal deformity fusions as well as its effect on complications and recovery from postoperative malnutrition was performed.

OBJECTIVES

To determine whether the administration of total parenteral nutrition to patients undergoing same-day or staged long spinal fusions has an effect on postoperative nutritional parameter depletion, time for return to preoperative nutritional baseline, and complication rate.

SUMMARY OF BACKGROUND DATA

Several studies have suggested, but only one has demonstrated, that perioperative administration of total parenteral nutrition to patients undergoing spinal reconstructive surgery may reduce postoperative nutritional depletion, thereby decreasing postoperative complications.

METHODS

In this study, 46 patients undergoing same-day or staged spinal reconstruction surgery (> or = 10 levels) were randomized to receive or not receive total parenteral nutrition after surgery. The nutritional parameters of albumin, prealbumin, transferrin, total protein, and absolute lymphocyte count were obtained before surgery and at regular intervals after surgery until at least four out of five parameters were within 10% of their preoperative baseline value. Perioperative data and complications were tallied.

RESULTS

There were no complications related to total parenteral nutrition administration. There was no statistical difference in total complications between those who did and those who did not receive total parenteral nutrition. However, there was a trend (P < 0.073) for the total parenteral nutrition group to return to nutritional baseline quicker. A significant increase in transferrin (P < 0.0082) and prealbumin (P < 0.015) depletion occurred in the patients who did not receive total parenteral nutrition. The anterior/posterior-same-day patients receiving total parenteral nutrition had more major complications (P < 0.033) and significantly more total protein depletion (P < 0.018) than the anterior/posterior-staged patients receiving total parenteral nutrition, possibly because the anterior/posterior-staged group received significantly more days(P < 0.0155) of total parenteral nutrition than the anterior/posterior-same-day group. In controlling for the number of days of total parenteral nutrition, no significant difference between type of surgery and complications was found.

CONCLUSIONS

The administration of postoperative total parenteral nutrition to patients with spinal deformity is safe. No statistical reduction in complications occurred in the total parenteral nutrition group despite a trend toward more rapid normalization of nutritional parameters and a decrease in postoperative nutritional depletion. The anterior/posterior-staged group with the administration of total parenteral nutrition had a lower overall complication rate and a decreased incidence of postoperative nutritional depletion than the one-stage reconstruction group. The difference in the complication rates between the two groups may relate as much to the staging as to the administration of total parenteral nutrition per se. For certain cases it may be more advisable to stage patients and deliver total parenteral nutrition than to manage the cases in a continuous (i.e., same-day) fashion.

Prospective pulmonary function evaluation following open thoracotomy for anterior spinal fusion in adolescent idiopathic scoliosis

STUDY DESIGN

Prospective study.

OBJECTIVES

To prospectively evaluate sequential pulmonary function tests (PFTs) at a minimum 2-year follow-up after an open anterior spinal fusion (ASF) with instrumentation for thoracic AIS.

SUMMARY OF BACKGROUND DATA

Anterior spinal fusion with instrumentation is currently undergoing evaluation as an alternative to posterior spinal fusion (PSF) for thoracic adolescent idiopathic scoliosis (AIS). However, the effect of an open thoracotomy on pulmonary function in these patients is unknown.

METHODS

Fifty-one patients with thoracic AIS with an average age of 15+0 (range 11+2 to 20+5) had PFTs consisting of volume (FVC), flow (FEV-1), and total lung capacity (TLC). Parameters were obtained preoperatively, and at 3 months, 1 year, and a minimum 2-year follow-up. All patients had a single or double open thoracotomy with the diaphragm kept intact. Fusion levels ranged from T4 (most proximal) to L1 (most distal). The average preoperative thoracic coronal Cobb measurement was 53 degrees (range 38 degrees to 80 degrees ), and the average postoperative coronal measurement was 24 degrees (range 7 degrees to 49 degrees ). The average preoperative thoracic sagittal kyphosis (T5-T12) averaged 22 degrees (range 10 degrees to 58 degrees ), and the average postoperative sagittal kyphosis measured 29 degrees (range 7 degrees to 67 degrees ).

RESULTS

There was a significant decline (P< or =0.05) in PFT absolute values (L) of 19%-FVC, 15%-FEV-1, and 11%-TLC at 3 months postoperatively with subsequent improvement and no statistical difference between preoperative and 2-year postoperative values. When evaluating percent predicted values, there was a statistical decline (P< or =0.05) at 3 months postoperatively averaging 19% FVC, 14% FEV-1, and 12% TLC. These values returned to within 94% to 96% of baseline by the 2-year follow-up visit, but were still statistically less than the preoperative values (P</=0.05).

CONCLUSIONS

Pulmonary function following thoracotomy with ASF with instrumentation demonstrated a significant decline of 3-month postoperative PFT values, but returned to preoperative baseline absolute values (L) by the 2-year follow-up visit. The percent predicted values returned to within 95% of baseline 2 years postoperatively. Scoliosis surgeons should be aware of these findings when deciding upon the approach (anterior versus posterior) utilized for thoracic AIS.

The effect of variation in arm position on sagittal spinal alignment

STUDY DESIGN

A prospective radiographic analysis of sagittal alignment in patients with and without previous spinal fusion.

OBJECTIVES

To evaluate the effect of variation of arm position on the segmental, regional, and global sagittal radiographic spinal alignment. In addition, to determine whether spinal fusion has any influence on the effect of variation in arm position on the sagittal spinal alignment.

SUMMARY OF BACKGROUND DATA

Importance of segmental, regional, and global sagittal alignment has been widely promoted. However, no mention has been made of arm positioning during a lateral spinal radiograph and the resultant effects it may have on sagittal alignment and balance.

METHODS

Prospective evaluation of 40 consecutive patients with and 40 consecutive patients without a previous spinal fusion was performed. The patients had lateral long cassette radiographs performed in a standardized fashion with the first radiograph obtained with the patient's arms raised horizontally forward at 90 degrees of flexion at the shoulder, and the second radiograph obtained with arms raised horizontally forward at 30 degrees of flexion at the shoulder. Standard segmental, regional, and global sagittal alignments were measured and statistically compared.

RESULTS

In comparing group 1 (patients with spinal fusion) to group 2 (patients without spinal fusion), there was no statistically significant difference in segmental and regional sagittal alignments. However, positioning the arms at 90 degrees versus 30 degrees resulted in a negative shift of the sagittal vertical axis (SVA) in patients that was statistically significant (P = 0.038) for those with (-6 mm at 90 degrees vs +4 mm at 30 degrees ), but not (P = 0.119) for those patients without (-8 mm at 90 degrees vs -4mm at 30 degrees ) a previous spinal fusion.

CONCLUSIONS

Based on the findings in this study, the authors recommend positioning the arms at 30 degrees of forward flexion from the vertical when obtaining a long cassette lateral radiograph of the entire spine.

Do radiographic parameters correlate with clinical outcomes in adolescent idiopathic scoliosis?

STUDY DESIGN

A radiographic assessment has been developed to include coronal, sagittal, and axial parameters.

OBJECTIVE

To determine the correlation of postoperative radiographic results and percentage postoperative radiographic improvement with patient clinical self-assessment.

SUMMARY OF BACKGROUND DATA

With the increasing interest in outcome studies, the authors wanted to determine whether Scoliosis Research Society clinical questionnaire results would correlate with objective radiographic improvement.

METHODS

INCLUSION CRITERIA

adolescent idiopathic scoliosis treated with anterior or posterior instrumentation, a solid fusion, minimum 2-year follow-up, and a completed postoperative Scoliosis Research Society questionnaire. Seventy-eight patients met the criteria. Measurements included in the radiographic score: Cobb angles of the coronal curve, C7 to the center sacral vertical line, apical translation, apical vertebral rotation, T1 rib angle, end-instrumented vertebrae angulation, angulation of the disc below the end-instrumented vertebra, and curve type. Sagittal measurements included T2-T12, T5-T12, T2-T5, T12-L2, and L1-S1.

RESULTS

The preoperative radiographic score of these 78 patients was mean 60.1 +/- 9.7 (range 41-88, maximum radiographic score, 100). The 2-year postoperative radiographic score was mean 83.8 +/- 8.8 (range, 65-100). The median Scoliosis Research Society questionnaire score was 98 +/- 12.3 (range, 58-116, maximum score, 125, showing that the patient is highly satisfied and asymptomatic). The postoperative radiographic score versus the questionnaire score showed a Spearman rank correlation of 0.04 (P = 0.68, little or no correlation throughout). Percentage improvement of the radiographic score versus the questionnaire score showed a Spearman rank correlation of 0.1 (P = 0.38, little or no correlation throughout).

CONCLUSION

In this initial group of patients, the radiographic assessment shows a significant improvement between preoperative and 2-year postoperative scores. However, little correlation between the radiographic assessment and the questionnaire scores was found in this adolescent population, suggesting that separate analyses of radiographic and clinical outcome data are required when evaluating results of postoperative scoliosis surgery.

Process measures and patient/parent evaluation of surgical management of spinal deformities in patients with progressive flaccid neuromuscular scoliosis (Duchenne's muscular dystrophy and spinal muscular atrophy)

STUDY DESIGN

Fifty-four consecutive patients with flaccid neuromuscular scoliosis (33 with Duchenne's muscular dystrophy, 21 with spinal muscular atrophy) who had undergone surgery for their disorder between 1985 and 1995 were sent questionnaires to evaluate function, self-image, cosmesis, pain, pulmonary status, patient care, quality of life, and satisfaction. Forty-eight patients returned the questionnaires.

OBJECTIVE

To assess patient/parent satisfaction and clinical/functional ways in which spinal fusion helped or did not benefit these patients and to assess complications and the ultimate radiographic result.

SUMMARY OF BACKGROUND DATA

There are only a few reports of results of spinal fusion and segmental instrumentation for flaccid neuromuscular disorders. There are no published reports regarding patient/parent evaluation of the procedure.

METHODS

Results of the questionnaire were tallied, graded, and divided into eight categories. The questionnaire was validated by a Cronbach's alpha analysis, a test-retest, and a comparison with questionnaire answers from patients with idiopathic scoliosis. Radiographic data and complications also were accumulated. The follow-up periods after surgery ranged from 2 to 12.6 years (average, 7.8 years).

RESULTS

Except for two patients who died within 3 months of surgery, all patients seemed to have benefited from the surgery. Cosmesis, quality of life, and overall satisfaction rated the highest.

CONCLUSION

These data indicate that spinal fusion with segmental spinal instrumentation benefits most patients with Duchenne's muscular dystrophy or spinal muscular atrophy with spinal deformities in terms of all categories assessed, even though these diseases have a progressively deteriorating course.

Complications of pediatric thoracolumbar and lumbar pedicle screws

STUDY DESIGN

This was a retrospective review of 223 consecutive cases (1986-1996) from one institution where 759 thoracolumbar and lumbar pedicle screws were used in the treatment of various pediatric spinal disorders in patients less than 18 years of age.

OBJECTIVES

To determine the incidence of short- and long-term (> 2 years follow-up) complications in this group of patients-specifically, complications related to instrumentation and those directly attributable to pedicle screws in these pediatric patients.

SUMMARY OF BACKGROUND DATA

Although much has been written regarding the use of pedicle screws in the adult population, no published study has examined complication rates with regard to thoracolumbar and lumbar pedicle screws placed for pediatric spinal disorders.

METHODS

A retrospective review of 223 consecutive cases involving 759 pedicle screws placed for a variety of pediatric spinal disorders was performed. Complications were divided into short term and long term (> 2 years follow-up) and into those relating to instrumentation and those relating to pedicle screws specifically.

RESULTS

Short-term complication occurred in 5 patients (2.2%) for a total of 17 screws ultimately removed. Only two of these patients had screws removed for lumbar radicular complaints. No residual sequellae resulted. No long-term (> 2 years postoperative) complications were noted.

CONCLUSION

Low short- and long-term complication rates specific for pediatric pedicle screws suggests that for properly trained spinal surgeons, pedicle screws fixation in the pediatric population can be performed safely to treat a variety of spinal disorders.

Radiographic results of arthrodesis with Cotrel-Dubousset instrumentation for the treatment of adolescent idiopathic scoliosis. A five to ten-year follow-up study

We evaluated the radiographic results of posterior spinal arthrodesis with use of Cotrel-Dubousset instrumentation in seventy-six patients who had adolescent idiopathic scoliosis. At an average of six years (range, five to ten years) postoperatively, the fusion appeared to be solid in all patients. Comparison of radiographs that had been made immediately postoperatively with those that had been made at the time of the latest follow-up showed that no patient had lost any correction in the coronal plane at the levels with instrumentation and seventy-five had had no change in the thoracic or lumbar sagittal alignment at the levels with or without instrumentation. In the remaining patient, a kyphosis had developed at the junction of the segments with instrumentation and those without instrumentation, necessitating additional operative treatment. Sixty-three patients completed a questionnaire for assessment of the clinical status. Their responses were favorable with regard to function, cosmetic appearance, and general satisfaction with the operative result. Twenty-four (38 per cent) of the sixty-three patients reported occasional pain in the spine that did not interfere with work or school activities. Sixty-two patients stated that, given the hypothetical situation of reverting to the preoperative status, they would have the operation again.

Major intraoperative neurologic deficits in pediatric and adult spinal deformity patients. Incidence and etiology at one institution

STUDY DESIGN

A retrospective study of 1,090 patients undergoing corrective spinal deformity surgery for scoliosis (n = 920), kyphosis (n = 77), or a combination of the two (n = 93) at one institution.

OBJECTIVES

To ascertain the etiologies and incidence of neurologic deficits occurring at the time of surgery.

SUMMARY OF BACKGROUND DATA

Potential etiologies of intraoperative neurologic deficits include cord compression, overdistraction, purely vascular, or a combination.

METHODS

The study group included only patients with useful function of their lower extremities and normal bowel and bladder control, and patients whose surgeries were in spinal cord territory as opposed to purely cauda equina territory.

RESULTS

There were four major neurologic deficits that occurred during surgery. Three of the four deficits were purely vascular in etiology. The fourth may have had a vascular and mechanical etiology. All four patients had anterior and posterior surgery with harvesting of the unilateral convex segmental vessels, and each had a component of hyperkyphosis, as well as intraoperative controlled hypotension. All four patients showed marked improvement of motor weakness with time.

CONCLUSIONS

Significant risk factors were combined anterior and posterior surgery (P = 0.009) and hyperkyphosis (P = 0.0006).

Posterior arthrodesis in the skeletally immature patient. Assessing the risk for crankshaft: is an open triradiate cartilage the answer?

STUDY DESIGN

Thirty-three skeletally immature patients younger than 12 years of age and having posterior arthrodesis and evidence of solid posterior fusion without "adding on" were retrospectively reviewed. All patients had a minimum of 5 years of follow-up.

OBJECTIVES

To ascertain factors associated with crankshaft and to determine how accurate a marker the triradiate cartilage was.

SUMMARY OF DATA

All patients had Risser Stage 0 curves and all of the girls were premenarchal preoperatively. The average age was 9 years 3 months (range, 2 years-11 years 11 months). Preoperative diagnoses consisted of 14 idiopathic, 11 congenital, five dysplastic, and three neuromuscular etiologies.

METHODS

Preoperatively, within 3 months after surgery, and at 2-year, 5-year, and final postoperative follow-up, the following radiographic parameters were reviewed: coronal Cobb, apical vertebral rotation, apical vertebral translation, rib vertebral angle difference, and trunkshift.

RESULTS

The triradiate cartilage was open in 24 patients at the time of operation. Of those 24, only nine (37.5%) had documented proof of crankshaft. Patients with closed triradiate cartilage had no significant postoperative increase in radiographic parameters (0 of 9). The subgroup of patients with idiopathic scoliosis had an average age of 11 years 3 months (range, 9 years 2 months-11 years 11 months). Five of 14 patients had an open triradiate cartilage. All were followed up to skeletal maturity. None had significant progression in postoperative radiographic parameters.

CONCLUSION

This study did not find an open triradiate cartilage to be an absolute prognostic indicator for the occurrence of crankshaft. Additional refinement of markers of maturity are needed to determine who requires anterior arthrodesis.

The use of pedicle screw fixation to improve correction in the lumbar spine of patients with idiopathic scoliosis. Is it warranted?

STUDY DESIGN

A retrospective assessment of coronal, sagittal, and axial correction using convex lumbar pedicle screw constructs compared with hook constructs in patients with idiopathic scoliosis.

OBJECTIVE

To determine if pedicle screw constructs can improve coronal, sagittal, and axial correction without increased complications and therefore warrant their use in the lumbar spine.

SUMMARY OF BACKGROUND DATA

Although hooks have been the traditional fixation choice for posterior scoliosis correction of the lumbar spine, pedicle screws may offer advantages for improved correction of lumbar spinal deformity.

METHODS

Twenty-two patients constituted Group A (hooks), in which 17 were double major and five were King Type IV curves. These patients had a minimum follow-up period of 2 years and an average of one hook per lumbar fusion segment. Twenty-two patients constituted Group B (screws), in which 20 were double major and two were King Type IV curves. These patients had a minimum follow-up period of 2 years, and screw configuration consisted of pedicle fixation on the convex side for correction and at times on the concave side for fixation.

RESULTS

Pedicle screw fixation constructs had improved lumbar Cobb correction (P < 0.05), lowest instrumented vertebra tilt (P < 0.05), lowest instrumented vertebra translation (P < 0.01), and segmental sagittal alignment from T12 to lowest instrumented vertebra (P < 0.01). There was no significant change in axial rotation using either surgical method.

CONCLUSIONS

The use of pedicle screw fixation on the convex portion of the lumbar spine in patients with double major idiopathic scoliosis allows for improved correction of the lumbar Cobb measurement, horizontalization and translation of the lowest instrumented vertebra, and improved segmental lordization over the instrumented levels without increased complications.

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.

Prospective analysis of nutritional status normalization after spinal reconstructive surgery

STUDY DESIGN

A prospective analysis of nutritional status after surgery in 57 spinal reconstructive surgery patients.

OBJECTIVES

To determine the length of time required for patients to return to their preoperative nutritional baseline and to investigate risk factors for patients with prolonged normalization.

SUMMARY OF BACKGROUND DATA

The preoperative nutritional status of spinal reconstructive surgery patients appears to be an important parameter of surgical morbidity, complication rates (especially wound healing), patient acceptance, and overall surgical success.

METHODS

The nutritional parameters of albumin, pre-albumin, total protein, transferrin, and the absolute lymphocyte count were investigated before surgery and at various time points after surgery.

RESULTS

Forty-four patients (Group A) with an average 6.4 fusion levels returned to their preoperative baseline nutritional values by 6 weeks after surgery, whereas 13 patients (Group B) with a statistically increased number of fusion levels of 13.8 (P = 0.0009) took 12 weeks or longer to return to their preoperative baseline. Risk factors for prolonged normalization (Group B) included increased total number of fusion levels, especially 10 or more (P < 0.05); patients undergoing circumferential fusions (P < 0.05); and, to a lesser extent, older patients undergoing multiple fusion levels (P = 0.055).

CONCLUSIONS

These data are important when counseling spinal reconstructive surgery patients before surgery and provides information to those patients who may benefit from perioperative nutritional supplementation.

Analysis of pulmonary function and chest cage dimension changes after thoracoplasty in idiopathic scoliosis

STUDY DESIGN

A prospective study of 19 adolescents and seven adults with idiopathic scoliosis undergoing posterior spinal fusion with segmental spinal instrumentation and a concomitant thoracoplasty had pulmonary function evaluation before surgery and at selected time points up to a minimum 2 years after surgery.

OBJECTIVES

The objectives were to determine the effects thoracoplasty had on pulmonary function and chest cage dimension changes at a minimum 2-year follow-up in idiopathic scoliosis patients.

SUMMARY OF BACKGROUND DATA

The cosmetic benefits of thoracoplasty on the rib hump deformity are well accepted. The rib resection procedure allowed for procurement of autogenous bone used for the arthrodesis. Short- and long-term pulmonary function evaluation was necessary to determine proper patient selection and any potential sequelae from the rib resection procedure.

METHODS

All patients had pulmonary function tests consisting of forced vital capacity, forced expiratory volume in 1 second, and total lung capacity performed before surgery and 3 months, 1 year, and 2 years after surgery. Ten adolescents also had computed tomographic scans before and after surgery to evaluate chest cage dimension changes after the procedure.

RESULTS

The 3-month postoperative pulmonary function test values of the 19 adolescents experienced a statistically significant decline, averaging 16% (P < 0.05), however, the mean values for each parameter returned to just slightly below the preoperative value at 2-years follow-up. The pulmonary function test values of the seven adults experienced a 27% initial decline 3 months after surgery and a residual 23% decline 2 years after surgery; both values were statistically significant (P < 0.05).

CONCLUSIONS

We reserve the thoracoplasty procedure for adolescents and adults with preoperative pulmonary function values that will tolerate the morbidity associated with the rib resection. Adolescent patients appear to normalize their pulmonary function tests by 2 years follow-up, whereas long-term pulmonary function in the adult patient remains a concern.

Anterior fresh frozen structural allografts in the thoracic and lumbar spine. Do they work if combined with posterior fusion and instrumentation in adult patients with kyphosis or anterior column defects?

STUDY DESIGN

This was a prospective study of 24 adult patients with kyphosis or anterior column spinal defects treated with anterior fresh frozen allograft for anterior column defects and posterior instrumentation and autogenous grafting.

OBJECTIVES

The objectives of the study were to assess the effectiveness of the anterior allograft in maintaining sagittal correction and to assess anterior incorporation.

SUMMARY OF BACKGROUND DATA

Twenty-four patients were followed for a minimum of 2 years (range, 2 + 0-5 + 4 years).

METHODS

Upright radiographs were analyzed before surgery, immediately after surgery, and at the final follow-up examination to assess success of anterior fusion and maintenance of correction. A strict four-point grading system was used. Two independent observers analyzed the radiographic results.

RESULTS

Only two patients showed some collapse of their anterior allograft. The other 22 patients maintained correction, attaining a Grade I or Grade II fusion. Semiconstrained instrumentation ws used posteriorly in the two patients who had graft collapse.

CONCLUSIONS

Anterior structural allograft worked effectively to maintain correction of kyphosis if combined with posterior instrumentation and autogenous grafting. Rigid forms of posterior instrumentation were preferred.

Posterior spinal fusion supplemented with only allograft bone in paralytic scoliosis. Does it work?

STUDY DESIGN

The authors prospectively evaluated 40 patients with paralytic scoliosis treated from 1985 to 1990 with bilateral posterior segmental instrumentation, facet fusions, local bone graft, and allograft (mostly fresh frozen) bone supplementation only.

OBJECTIVES

The authors report the fusion results for these patients, and any complications referable to the use of bank bone.

SUMMARY OF BACKGROUND DATA

Acceptable correction was obtained and maintained in the coronal and sagittal planes for all but two patients (the third patient with a pseudarthrosis had not lost correction). The definite pseudarthrosis rate was 7.5%. One patient had a deep wound infection.

METHODS

The radiographs were graded as definitely solid, definitely a pseudarthrosis, or no instrumentation failure but difficult to visualize the whole fusion mass. The patients selected for fusion without autogenous harvesting were especially frail and had reduced pulmonary and nutritional reserve. Follow-up ranged from 2 + 2 years to 7 + 6 years, with an average of 3 + 9 years.

RESULTS

In the 40 surgical patients, there were three known pseudarthroses. In 28 patients, there was a definite fusion. In the remaining nine patients (five with flaccid disease, four with spastic disease), the quality of their bone precluded definitive determination, but there was no obvious instrumentation failure or loss of correction.

CONCLUSION

This study suggests that allograft bone graft is a suitable substitute for autogenous bone graft harvesting in select patients with paralysis in whom autogenous harvesting is not feasible.

Preoperative spinal canal investigation in adolescent idiopathic scoliosis curves > or = 70 degrees

STUDY DESIGN

This is a prospective evaluation of a consecutive series of patients with adolescent idiopathic scoliosis (AIS) with curves > or = 70 degrees.

OBJECTIVE

The authors investigated the possibility that large curve size may constitute an atypical presentation of idiopathic scoliosis suggestive of underlying neurologic pathology, which would warrant preoperative investigation.

SUMMARY OF BACKGROUND DATA

The potential for intraspinal pathology to cause scoliosis is well accepted. The incidence of spinal canal abnormalities in congenital or atypical scoliosis may be as high as 30-60%. Identification of clinical neurologic deficits, congenital abnormalities, or atypical features of scoliosis are often helpful in identifying the subpopulation of scoliosis patients at risk for spinal canal pathology.

METHODS

Thirty-three consecutive patients with large (> or = 70 degrees) adolescent idiopathic scoliosis (AIS) and without evidence of neurologic or congenital abnormalities, were evaluated with either computed tomography/myelogram (n = 3) or magnetic resonance imaging (n = 30) to assess the entire spinal canal.

RESULTS

None of the studies revealed any pathology of the neuraxis, and all 33 patients were treated with surgery without any neurologic sequelae.

CONCLUSIONS

Preoperative investigation of the central neuraxis is not mandatory in large (> or = 70 degrees) but otherwise typical AIS curves. These large curves do not appear to suggest associated spinal canal anomalies.

Recognition and treatment of the proximal thoracic curve in adolescent idiopathic scoliosis treated with Cotrel-Dubousset instrumentation

STUDY DESIGN

A retrospective radiographic and clinical review of a consecutive series of patients with adolescent idiopathic scoliosis (AIS) instrumented/fused with Cotrel-Dubousset instrumentation (CDI) was undertaken.

OBJECTIVE

The authors determined criteria when the upper thoracic curve should be instrumented/fused in AIS treated with CDI and assessed the results of surgical treatment.

SUMMARY OF BACKGROUND DATA

Failure to recognize and include the upper left thoracic curve in the instrumentation/fusion of a lower right thoracic idiopathic scoliosis may produce shoulder imbalance and coronal decompensation. Patients with an elevated left shoulder clinically or a positive T1 tilt radiographically usually require instrumentation/fusion of the proximal thoracic curve. However, the upper left thoracic curve may be structural and require inclusion in the instrumentation/fusion when the shoulders clinically are level or even if the right shoulder is elevated preoperatively when using CDI.

METHODS

The authors compared 27 patients with AIS with structural upper thoracic curves that were instrumented with CDI to T2 (Group I) to 27 patients with King Type III curves treated with CDI that did not have the upper thoracic curve instrumented/fused (Group II).

RESULTS

The distinguishing Group I preoperative criteria indicating a structural upper thoracic curve included a proximal thoracic curve greater than 30 degrees that corrected to no better than 20 degrees on sidebending; > or = Grade I rotation or > or = 1 cm translation present at the apex of this curve; any elevation of the left shoulder or tilt of T1 into the concavity of the upper thoracic curve; or when the transitional vertebra between the two curves is at T6 or below.

CONCLUSIONS

When these aforementioned criteria are present and surgical correction with CDI is planned, we recommend extending the instrumentation up to T2 to produce level shoulders and maintain coronal balance.

Ability of Cotrel-Dubousset instrumentation to preserve distal lumbar motion segments in adolescent idiopathic scoliosis

Between 1985 and 1990, 44 patients with adolescent idiopathic scoliosis were treated with Cotrel-Dubousset instrumentation when Harrington instrumentation would have extended into the distal lumbar spine (L3, L4, or L5) for these curve patterns. Twenty-four of these 44 (group I) patients had one distal fusion level preserved using Cotrel-Dubousset instrumentation, whereas the other 20 patients (group II) were instrumented/fused with Cotrel-Dubousset instrumentation to the expected Harrington instrumentation level in the lower lumbar spine. All patients have a minimum 2-year follow-up, and the average follow-up is 39 months (range 24-74). The characteristics of the group I curves that allowed us to stop the instrumentation a level short included minimal rotation and tilt of the anticipated lowest instrumented vertebra, overall coronal curve flexibility, and nonstructural components to the lumbosacral region of the spine. There were no major differences between these two groups when comparing postoperative coronal and sagittal balance parameters at the most recent follow-up. In select cases, dependent on the preoperative criteria to be discussed, Cotrel-Dubousset instrumentation (vs. traditional Harrington instrumentation) does allow distal lumbar fusion levels to be saved while maintaining acceptable coronal and sagittal balance.

Preventing decompensation in King type II curves treated with Cotrel-Dubousset instrumentation. Strict guidelines for selective thoracic fusion

Between 1985 and 1988, 50 adolescent idiopathic scoliosis patients with either King Type II (n = 19) or III (n = 31) curves were treated with Cotrel-Dubousset instrumentation and had a minimum of 2-year follow-up. Five of these patients had early postoperative decompensation, and have provided important lessons for the future prevention and treatment of these imbalances. Most problematic was distinguishing between King Type II and double major curve patterns. Proper identification of King Type II curves, which may be successfully treated with selective thoracic fusion, requires careful analysis of the standing preoperative coronal radiograph as well as the side benders. Thus, we now define Type II curves based on the differential between the thoracic and lumbar curve magnitude, apical vertebral deviation from the midline, and apical vertebral rotation on the standing coronal radiograph in addition to a positive flexibility index.

Cotrel-Dubousset instrumentation for adolescent idiopathic scoliosis

We evaluated the results of segmental fixation of the spine with Cotrel-Dubousset instrumentation in ninety-five patients who had adolescent idiopathic scoliosis. The instrumentation was used in an attempt to achieve three-dimensional correction of the scoliosis, maintain lumbar lordosis, create thoracic kyphosis, and avoid the need for a postoperative cast or brace. The patients were followed for twenty-four to sixty-four months (average, thirty-five months). Cotrel-Dubousset instrumentation provided an average correction of the coronal curve of 48 per cent at the time of the most recent follow-up. The normal sagittal curves at the thoracolumbar junction and in the lumbar spine were maintained, and the thoracic kyphosis was increased slightly (average, +7 degrees). Apical translation improved an average of 60 per cent, and apical rotation improved an average of 11 per cent. Forced vital capacity improved an average of 21 per cent, and the one-second forced expiratory volume improved an average of 18 per cent. There were no major neurological deficits. A symptomatic pseudarthrosis developed in one patient. Postoperatively, decompensation of the spine developed in five of the first twenty-six patients who had a Type-II or Type-III curve. This complication was avoided in the last twenty-four patients who had a Type-II or Type-III curve by means of a stricter adherence to the definition of a Type-II curve, and reversal of the bend of the rod and the hooks between the caudal neutral and stable vertebrae. The major advantages of Cotrel-Dubousset instrumentation are the stable fixation that is achieved and the preservation of segmental lumbar lordosis.

Analysis of pulmonary function and axis rotation in adolescent and young adult idiopathic scoliosis patients treated with Cotrel-Dubousset instrumentation

Forty-eight patients with idiopathic scoliosis underwent posterior spinal fusion with Cotrel-Dubousset instrumentation (CDI). Each patient was given preoperative and postoperative pulmonary function tests (PFTs). Pulmonary volume improved a mean 0.40 L (16%), and pulmonary flow improved a mean 0.33 L (15%). Differences between preoperative and postoperative PFT values were shown to be statistically significant and correlated well with coronal side-bending correction. Twenty patients had preoperative and postoperative CT scans through the apical vertebra. Vertebral rotation was assessed on CT scan by the method of Aaro and Dahlborn (1,2). At the apex, the mean percentage improvements in the longitudinal axis rotation relative to the midline (16%) and to the sagittal plane (10%), the rib hump index (8%), and the kyphosis-lordosis index (0%) were minimal. Radiographically, the 66% mean improvement in apical vertebral translation was more substantial and consistent than the 10% mean improvement in apical vertebral rotation. Therefore, at the apex the CDI "derotation maneuver" may be more of a "translational maneuver."