Comparative analysis of pedicle screw versus hook instrumentation in posterior spinal fusion of adolescent idiopathic scoliosis

STUDY DESIGN

A retrospective matched cohort study.

OBJECTIVE

To comprehensively compare the 2-year postoperative results of posterior correction and fusion with segmental pedicle screw instrumentation versus those with hook constructs in adolescent idiopathic scoliosis (AIS) treated at a single institution.

SUMMARY OF BACKGROUND DATA

Despite the reports of satisfactory correction and maintenance of scoliotic curves by pedicle screw instrumentation compared to hook constructs, few reports on the comprehensive comparison of segmental pedicle screw instrumentation versus hook instrumentation exist.

MATERIALS AND METHODS

A total of 52 patients with AIS at a single institution who underwent a posterior spinal fusion with segmental pedicle screw (26) or hook (26) instrumentation were sorted and matched according to four criteria: similar age at surgery (14.8 years in pedicle screw group and 14.2 years in hook group), identical Lenke curve types, same number of fused vertebrae (11.7 in each group), and identical operative methods (18 posterior spinal fusions with thoracoplasty, 4 posterior spinal fusions with iliac crest bone graft, and 4 anterior and posterior spinal fusions in each group). Patients were evaluated before surgery, immediate after surgery, and at the 2-year follow-up according to radiographic changes in curve correction, pulmonary function tests, operative time, intraoperative blood loss, implant costs, and SRS-24 scores.

RESULTS

After surgery, the average major curve correction was 76% in the screw group and 50% in the hook group (P < 0.001). At the 2-year follow-up, loss of the major curve correction was less in the screw group (5.4%) compared with the hook group (8.0%) (P = 0.35). Postoperative global coronal and sagittal balance was similar in both groups. An average of 0.8 levels from the distal end vertebra was saved using pedicle screws compared with hook constructs (P = 0.002). Postoperative 2-year proximal junctional change in the sagittal plane (angle between uppermost instrumented vertebra and two vertebral bodies above the uppermost-instrumented vertebra) was 9 degrees in the screw group and 6 degrees in the hook group (P = 0.19). Postoperative 2-year distal junctional change in the sagittal plane was similar in both groups. Operative time averaged 341 minutes in the screw group and 338 minutes in the hook group (P = 0.86), and intraoperative blood loss was similar in both groups (879 mL in screw group vs. 896 mL in hook group) (P = 0.12). Average implant cost in the hook group (11.8 fixation points; 5,816 U.S. dollars) was significantly lower than that of the screw group (17.1 fixation points; 11,508 U.S. dollars) (P < 0.001). Two years following surgery, the screw group demonstrated improved percent predicted pulmonary function values compared with that of the hook group (FVC, 80%--> 79% in screw group vs. 82%--> 74% in hook group, P = 0.0056; FEV-1, 73%--> 76% in screw group vs. 80%--> 79% in hook group, P = 0.017). Postoperative 2-year SRS-24 scores were similar in both groups (screw group [97] vs. hook group [101]) (P = 0.15). There were no neurologic or visceral complications related to hook or pedicle screw instrumentation.

CONCLUSION

Pedicle screw instrumentation, although more expensive, offers a significantly better major and minor curve correction without neurologic problems and improved pulmonary function values in the operative treatment of AIS and enables a slightly shorter fusion length than segmental hook instrumentation.

Selection of instrumentation and fusion levels for scoliosis: where to start and where to stop

Object. Although there are several papers in the literature regarding selection of fusion levels in the adolescent patient, fewer articles pertain to this in the adult patient. The author reviewed his experience and the literature and reports on the choice of fusion levels in the adolescent and adult patient.

Methods. After a review of available data, the author determined that the proximal and distal extent of the fusion should be based on defining curves as either major or minor in the adolescent patient. It is often possible to exclude minor curves from the fusion. Relative Cobb measurement, apical deviation from the plumb line, and apical rotation are the most useful means of distinguishing a major from a minor curve. Otherwise, the proximal and distal extent of a fusion should be performed in such a way that the proximal and distal vertebrae are both neutral and stable (bisected by the center sacral line) postoperatively. Additional segments may need to be included in the adult patient in whom extensive degenerative changes and subluxations are present. The decision of whether to terminate a long fusion at L-5 or the sacrum in an adult degenerative lumbar curve is complex and many factors have to be considered.

Conclusions. Guidelines exist for fusion levels in both adolescent and adult patients. Not all curves require fusion. There are many coronal and sagittal considerations that have to be analyzed when making the final decision.

Pedicle subtraction osteotomy for the treatment of fixed sagittal imbalance. Surgical technique

BACKGROUND

Fixed sagittal imbalance (a syndrome in which the patient is only able to stand with the weight-bearing line in front of the sacrum) has many etiologies. The most commonly reported technique for correction is the Smith-Petersen osteotomy. Few reports on pedicle subtraction procedures (resection of the posterior elements, pedicles, and vertebral body through a posterior approach) are available in the peer-reviewed literature. We are aware of no report involving a substantial number of patients with coexistent scoliosis who underwent pedicle/vertebral body subtraction for the treatment of fixed sagittal imbalance.

METHODS

Twenty-seven consecutive patients in whom sagittal imbalance was treated with lumbar pedicle subtraction osteotomy at one institution were analyzed. Radiographic analysis included assessment of thoracic kyphosis, lumbar lordosis, lordosis through the pedicle subtraction osteotomy site, and the C7 sagittal plumb line. Outcomes analysis was performed with use of a before-and-after pain scale, items from the Oswestry questionnaire, and the Scoliosis Research Society (SRS) questionnaire after a minimum duration of follow-up of two years. Complications and radiographic findings were also analyzed for the entire group.

RESULTS

Overall, the average increase in lordosis was 34.1 degrees and the average improvement in the sagittal plumb line was 13.5 cm. One patient had development of a lumbar pseudarthrosis through the area of pedicle subtraction osteotomy, and six patients had development of a thoracic pseudarthrosis. Two patients had development of increased kyphosis at L5/S1, caudad to the fusion, resulting in some loss of sagittal correction. There were significant improvements in the overall Oswestry score (p < 0.0001) and the pain-scale score (p = 0.0002). Most patients reported improvement in terms of pain and self-image as well as overall satisfaction with the procedure.

CONCLUSIONS

Pedicle subtraction osteotomy is a useful procedure for patients with fixed sagittal imbalance. A worse clinical result is associated with increasing patient comorbidities, pseudarthrosis in the thoracic spine, and subsequent breakdown caudad to the fusion.

Selective thoracic fusion for adolescent idiopathic scoliosis with C modifier lumbar curves: 2- to 16-year radiographic and clinical results

STUDY DESIGN

Retrospective clinical and radiographic review with functional outcome assessment.

OBJECTIVES

To evaluate outcome of selective thoracic fusion for adolescent idiopathic scoliosis in the presence of widely deviated compensatory lumbar curves.

SUMMARY OF BACKGROUND DATA

Previous reports on the results of selective thoracic scoliosis fusion have not specifically focused on deformities with widely deviated lumbar curves. Whether these challenging deformities are best treated with selective thoracic fusion or fusion of both curves remains unclear.

METHODS

Forty-four consecutive patients with adolescent idiopathic scoliosis with main thoracic, compensatory minor lumbar "C" modifier curves underwent selective thoracic fusion at a single institution (1987-2000). Radiographs were analyzed before surgery, at 1 week, 2 years, and latest follow-up (2-16 years; mean 5.0 years).

RESULTS

A mean 36% thoracic correction was closely matched by a 34% lumbar correction at latest follow-up. A majority of spontaneous lumbar correction occurred at its cephalad segments (P = 0.001). Spontaneous correction of lumbar apical translation occurred in a majority of patients (prognostic factors identified). Global coronal imbalance (2-5 cm) was common before surgery and was a significant risk factor (P = 0.04) for global imbalance at latest follow-up. Postoperative bracing was not utilized, and there were no reoperations. Patients with coronal imbalance (2-5 cm) at latest follow-up had slightly inferior SRS-24 results.

CONCLUSIONS

Satisfactory results are achieved with selective thoracic fusion of properly selected C modifier lumbar curves. Correction of the lumbar curve results principally from a decrease in the tilt of its upper vertebrae, but not necessarily improved apical translation. Mild coronal imbalance was well tolerated and has not necessitated distal extension of the fusion.

Can we predict the ultimate lumbar curve in adolescent idiopathic scoliosis patients undergoing a selective fusion with undercorrection of the thoracic curve?

STUDY DESIGN

Retrospective review of anterior and posterior fusions for treatment of adolescent idiopathic thoracic scoliosis.

OBJECTIVES

To delineate the best factors determining final lumbar curve magnitude in patients with adolescent idiopathic scoliosis undergoing a selective thoracic anterior or posterior spinal fusion at or proximal to the first lumbar vertebra.

SUMMARY OF BACKGROUND DATA

Although spontaneous lumbar curve correction occurs consistently following a selective thoracic anterior or posterior spinal fusion, the degree of correction is somewhat unpredictable.

METHODS

One hundred consecutive patients with major thoracic-compensatory lumbar adolescent idiopathic scoliosis treated by a single surgeon with either selective posterior spinal fusion (n = 44) or anterior spinal fusion (n = 56) of the main thoracic region with an unfused lumbar spine with a lumbar B modifier (lumbar apex touching the center sacral vertical line) or lumbar C modifier (lumbar apex completely lateral to the center sacral vertical line) were retrospectively reviewed.

RESULTS

Those patients who maintained excellent postoperative coronal balance, with spontaneous lumbar curve correction, had their thoracic Cobb corrected intraoperatively to a measurement very close to but not more than that of the preoperative thoracic push-prone Cobb. Stepwise multiple linear regression analysis was used to develop a formula to help predict lumbar response in those patients undergoing selective thoracic fusion. This is represented in the following formula: Final lumbar Cobb = 14.4 + 3.06 (lumbar modifier; 0 = B, 1 = C) + 0.30 (preoperative standing lumbar Cobb) - 0.18 (preoperative supine lower Cobb) + 0.81(preoperative push/prone lumbar Cobb) - 0.15(preoperative standing thoracic Cobb) - 0.16(% thoracic Cobb change from preoperative to immediate postoperative). Final model R2 = 0.72.

CONCLUSIONS

Of the preoperative measurements examined, the preoperative push-prone is the best preoperative flexibility radiograph to predict the final lumbar curve measurement and, along with other factors, can be used to formulate a model that will help the treating surgeon more confidently predict the final lumbar curve response in patients undergoing a selective thoracic fusion.

Comparison of SRS questionnaire results submitted by both parents and patients in the operative treatment of idiopathic scoliosis

STUDY DESIGN

A prospective, cross-sectional analysis of patients with operative idiopathic scoliosis comparing Scoliosis Research Society's Outcomes Instrument (SRS-24) scores from both parents and patients obtained separately on the same day along with pertinent radiographic data.

OBJECTIVE

To determine the correlation of parents' and patients' perspectives of the patients' preoperative and postoperative experience using the SRS-24 questionnaire emphasizing parent-patient disparities.

SUMMARY OF BACKGROUND DATA

No report to our knowledge has addressed the association between parent assessments of their child's presurgical and postsurgical outcome as verified by SRS-24 questionnaire data.

MATERIALS AND METHODS

A total of 101 patients with operative idiopathic scoliosis were analyzed based on paired parent-patient SRS-24 data and radiographs performed on the same day. Patients were analyzed by age at date of examination (9-23 years, mean 17 +/- 5 years), gender (16 male, 85 female), major curve magnitude (41-126 degrees ), procedure type [preoperative (22 pairs), anterior spinal fusion (49 pairs), anterior spinal fusion/posterior spinal fusion (19 pairs), posterior spinal fusion (46 pairs)], and time from surgery (preoperative, postoperative 1-93 months, mean 24 months). All questionnaire scores were classified based on domains of pain, self-image, function, overall satisfaction, and total score.

RESULTS

In overall time periods, parents consistently scored higher than their children in the self-image (P = 0.0001), satisfaction (P = 0.0001), and total score (P = 0.04), but not pain or function. Before surgery, parents overestimated patients' scores in self-image (P = 0.002) by 7.5% but not other domains. Satisfaction differences (P = 0.04) improved with increasing age of the patient, but not other domains. There were no significant differences with gender or preoperative/postoperative major curve magnitudes.

CONCLUSION

Based on SRS-24 data, parents typically scored higher than their children in the operative treatment of idiopathic scoliosis in total score, self-image, and overall satisfaction. Some parent-patient scores correlated better with increasing age of the patient, and later in the postoperative period.

Free hand pedicle screw placement in the thoracic spine: is it safe?

STUDY DESIGN

A retrospective study.

OBJECTIVE

To evaluate the safety of a free hand technique of pedicle screw placement in the thoracic spine at a single institution over a 10-year experience.

SUMMARY OF BACKGROUND DATA

Thoracic pedicle screw fixation techniques are still controversial for thoracic deformities because of possible complications including neurologic.

MATERIALS AND METHODS

Three hundred ninety-four consecutive patients who underwent posterior stabilization utilizing 3204 transpedicular thoracic screws by 2 surgeons from 1992 to 2002 were analyzed. The mean age was 27 + 10 years (range 5 + 3-87 + 0 years) at the time of surgery. Etiologic diagnoses were: scoliosis in 273, kyphosis in 53, other spinal disease in 68. Pedicle screws were inserted using a free hand technique similar to that used in the lumbar spine in which anatomic landmarks and specific entry sites were used to guide the surgeon. A 2-mm tip pedicle probe was carefully advanced free hand down the pedicle into the body. Careful palpation of all bony borders (floor and four pedicle walls) was performed before and after tapping. Next, the screw was placed, followed by neurophysiologic (screw stimulation with rectus abdominus muscle recording) and radiographic (anteroposterior and lateral) confirmation. An independent spine surgeon using medical records and roentgenograms taken during treatment and follow-up reviewed all the patients.

RESULTS

The number of the screws inserted at each level were as follows (total n = 3204): T1, n = 13; T2, n = 60; T3, n = 192; T4, n = 275; T5, n = 279; T6, n = 240; T7, n = 230; T8, n = 253; T9, n = 259; T10, n = 341; T11, n = 488; T12, n = 572. Five hundred seventy-seven screws inserted into the deformed thoracic spine were randomly evaluated by thoracic computed tomography scan to assess for screw position. Thirty-six screws (6.2%) were inserted with moderate cortical perforation, which meant the central line of the pedicle screw was out of the outer cortex of the pedicle wall and included 10 screws (1.7%) that violated the medial wall. There were no screws (out of the entire study group of 3204) with any neurologic, vascular, or visceral complications with up to 10 years follow-up.

CONCLUSIONS

The free hand technique of thoracic pedicle screw placement performed in a step-wise, consistent, and compulsive manner is an accurate, reliable, and safe method of insertion to treat a variety of spinal disorders, including spinal deformity.

Aprotinin reduces blood loss during spinal surgery in children

STUDY DESIGN

A prospective blinded, randomized controlled study compared the effect of a perioperative infusion of aprotinin versus placebo during long segment spinal fusions in children.

OBJECTIVES

To determine whether aprotinin decreases blood loss and transfusion requirements in pediatric patients with spinal deformities undergoing posterior spinal fusions of seven or greater segments.

SUMMARY OF BACKGROUND DATA

Blood loss is a major cause of morbidity during long segment spinal fusion. Several preoperative and intraoperative techniques are currently used to reduce blood loss and transfusion requirements. Aprotinin, an antifibrinolytic and anti-inflammatory agent, has been used to decrease blood loss in cardiac surgical patients. We designed a prospective, randomized, and blinded controlled study to evaluate aprotinin's efficacy in reducing bleeding during pediatric spine surgery.

METHODS

After obtaining informed written consent, we studied 44 children and adolescents who were anticipated to be at higher risk for major blood loss during posterior spinal fusion. Children were randomly assigned to receive high dose aprotinin or placebo infusion during the perioperative period. Patients were assessed for blood loss, transfusion requirements, days in the intensive care unit, and days in hospital.

RESULTS

Demographics in the two groups of patients were similar. The study demonstrated a significant reduction in estimated blood loss (aprotinin 545 cc, placebo 930 cc) and transfusion requirements (aprotinin 1.1 U, placebo 2.2 U). The duration of intensive care unit admission was similar in the two groups, as was the time until discharge.

CONCLUSIONS

This randomized, blinded study suggests that aprotinin significantly decreased blood loss and transfusion requirements in pediatric and adolescent scoliosis surgical patients at increased risk for intraoperative bleeding.

The Lenke classification of adolescent idiopathic scoliosis: how it organizes curve patterns as a template to perform selective fusions of the spine

STUDY DESIGN

Retrospective radiographic review.

OBJECTIVES

To analyze how the Lenke classification of adolescent idiopathic scoliosis provides a template of specific curve patterns that may be appropriate to perform selective fusion of the spine.

METHODS

A new triad classification system of adolescent idiopathic scoliosis has been developed. It consists of a curve type, a lumbar spine modifier (A, B, C), and a sagittal thoracic modifier (-, N, +). A selective fusion is termed when both the thoracic and thoracolumbar/lumbar curves deviate completely from the midline, but only the major curve (largest Cobb measurement) is fused, leaving the minor curve unfused and mobile. In this manner, selective thoracic fusions of the spine are potentially indicated for major main thoracic/minor lumbar curves (Types 1C and potentially 2C and 3C patterns) when the lumbar apex deviates off the center sacral vertical line. Conversely, selective thoracolumbar/lumbar fusions may be indicated for major thoracolumbar/lumbar-minor main thoracic curves, when the thoracic apex lies off the C7 plumbline (Type 5C and potentially 6C patterns). Importantly, additional analysis of ratios of structural characteristics between the main thoracic and thoracolumbar/lumbar curves are necessary to predict when a successful selective main thoracic or thoracolumbar/lumbar fusion will be feasible. Lastly, the clinical appearance of the patient's truncal alignment is essential to confirm the aspirations of performing a selective spinal fusion.

RESULTS

Successful selective thoracic fusion of 1C (n = 36) and 2C (n = 8) curves have been performed in 44 consecutive patients with adolescent idiopathic scoliosis. The average thoracic curve was 61 degrees before surgery and 39 degrees at final follow-up. The average preoperative lumbar curve was 48 degrees, decreasing to 32 degrees postoperatively. A group of 21 consecutive patients with Type 5C or 6C major thoracolumbar/lumbar-minor main thoracic curves underwent a selective thoracolumbar/lumbar fusion. The average preoperative thoracolumbar/lumbar curve was 56 degrees corrected to 22 degrees at the 2-year follow-up. The average minor main thoracic curve preoperative was 38 degrees, with spontaneous correction to 28 degrees at 2 years postoperative.

DISCUSSION

Selective thoracic or thoracolumbar/lumbar fusion can be successfully performed in a variety of adolescent idiopathic scoliosis curve patterns. Careful attention to the preoperative Lenke curve classification, analysis of structural characteristics between the planned instrumented and noninstrumented regions of the spine, as well as a documented clinical examination that confirms the planned instrumented and fused regions of the spine to be the most clinically prominent are essential features to determine before surgery. No patients undergoing selective thoracic fusion have required extension of the fusion to the lumbar spine, whereas one patient with a selective thoracolumbar fusion required extension of the fusion up to include the thoracic spine due to continued thoracic progression with growth.

CONCLUSIONS

Selective thoracic or thoracolumbar/lumbar fusions of the major curve can be successfully performed even when the minor curve completely deviates from the midline, based on the Lenke classification system, the analysis of structural criteria between the planned fused and unfused regions of the spine, and the clinical examination of the patient. Selective fusions, when successfully performed, will optimize mobile segments of the spine in patients with adolescent idiopathic scoliosis.

The pros and cons to saving the L5-S1 motion segment in a long scoliosis fusion construct

STUDY DESIGN

This is a review of the literature and personal experience as it pertains to whether a long fusion should be stopped at L5 or S1 in a patient with adult lumbar scoliosis and degenerative changes.

OBJECTIVES

To summarize the problems with decision-making and to point out the strengths and limitations of past studies.

SUMMARY OF BACKGROUND DATA

There is a paucity of data on this subject. Problems with stopping at L5 include fixation at that segment and subsequent breakdown at L5-S1. The problems with stopping at the sacrum include the additional surgical requirements and increased potential for pseudarthrosis.

METHODS

Summarized is past literature and, to some extent, personal experience of the author(s).

RESULTS

There are situations where it is clearly preferable to stop at the sacrum. However, there are many borderline circumstances in which whether it is better to stop at L5 or the sacrum is not clear cut.

CONCLUSIONS

The answer to this question requires further study. Multicenter data collection, consistency of approach, and potential randomization in a prospective fashion might help provide an answer.

Complications and outcomes of pedicle subtraction osteotomies for fixed sagittal imbalance

STUDY DESIGN

Radiographic analysis, outcomes analysis (pain scale, Oswestry, SRS-24), and accumulation of complications. Outcomes and complications collected prospectively. Radiographic analysis performed retrospectively.

OBJECTIVES

To assess the benefits and stress complications of pedicle subtraction osteotomies for patients with fixed sagittal imbalance.

SUMMARY OF BACKGROUND DATA

Few reports on pedicle subtraction osteotomies exist in the peer-review literature for conditions other than trauma and ankylosing spondylitis.

MATERIALS AND METHODS

Thirty-three consecutive patients with sagittal imbalance treated with lumbar pedicle subtraction osteotomy at one institution (minimum 2-year follow-up) were analyzed. Complications were also analyzed for the entire group of consecutive pedicle subtraction osteotomies done at our institution to date (n = 66).

RESULTS

For the 33 patients with minimum 2-year follow-up, there were significant improvements in the overall Oswestry score (P 0.0001) and pain score (P = 0.0001). Most patients reported improvement in pain and self-image and reported overall satisfaction based on ultimate SRS-24 questionnaire. There was one pseudarthrosis in the lumbar spine through an area of pedicle subtraction osteotomy (area of previous laminectomy and nonunion), and six patients had thoracic pseudarthroses (levels other than the osteotomy level) and one patient had a pseudarthrosis at L5-S1. Two patients had acute angular kyphosis at the thoracolumbar junction at the proximal end of the construct. Five patients who experienced transient neurologic deficits resolved their deficits after central canal enlargement.

CONCLUSIONS

The clinical result with pedicle subtraction osteotomy is reduced with pseudarthrosis in the thoracic or lumbar spine and subsequent breakdown adjacent to the fusion. For patients with a degenerative sagittal imbalance etiology the results were worse and the complications were higher. Central canal enlargement is critical.

Thoracolumbar deformity arthrodesis to L5 in adults: the fate of the L5-S1 disc

STUDY DESIGN

A retrospective clinical and radiographic analysis of long adult deformity fusions terminating at L5.

OBJECTIVES

To define the results of thoracolumbar fusions to L5 in adult deformity patients with critical evaluation for potential subsequent L5-S1 disc degeneration and L5 implant loosening.

SUMMARY OF BACKGROUND DATA

Few studies have reported the results of long adult fusions to L5 and the potential for subsequent advanced L5-S1 disc degeneration is unknown.

MATERIALS AND METHODS

Thirty-four consecutive patients fused from the thoracic spine to L5 at a single institution were evaluated at a mean follow-up of 5.6 years (2.1-14.3 years). SRS-24 functional outcome questionnaire results were obtained for all patients at most recent follow-up.

RESULTS

By latest follow-up, subsequent advanced L5-S1 disc degeneration (SAD) developed in 19 of 31 patients (61%) assessed as having "healthy" discs before surgery. SAD was associated with a forward shift in sagittal balance (P = 0.02) and need for revision surgery (P = 0.02). Risk factors for the development of SAD were preoperative positive sagittal balance (P = 0.01), younger age (P = 0.03), and the presence of even mild radiographic degeneration before surgery (P = 0.004). Loss of L5 implant fixation occurred in six patients (18%) and was associated with deep seating of L5 within the pelvis (P = 0.0001). Inferior SRS-24 outcome measures were associated with preoperative advanced L5-S1 disc degeneration and the development of postoperative sagittal imbalance.

CONCLUSIONS

Subsequent L5-S1 DDD developed in 61% of patients after long adult fusions to L5 and was associated with a significant loss of sagittal alignment and an increased likelihood for or definite need for another operation. Loss of L5 implant fixation is not uncommon, especially in patients with a deep-seated L5 vertebra.

Staged posterior surgery for severe adult spinal deformity

STUDY DESIGN

Retrospective analysis with prospective outcomes.

OBJECTIVE

To analyze the strategy of dividing one prolonged, complex, posterior surgery into two smaller posterior procedures staged during one hospitalization.

SUMMARY OF BACKGROUND DATA

When operating on complex revision adult deformity, the posterior surgery alone can be unduly prolonged, placing patients at risk for hemodynamic complications associated with protracted same-day surgery.

MATERIALS AND METHODS

Forty-two consecutive adults with severe deformity and 2 years or more of follow-up were included. Thirty-three presented for revision surgery. Twenty-two had more than one previous fusion. During first-stage posterior surgery, existing implants were removed, decompressions performed, and new fixation points established. Five to 7 days later, patients underwent second-stage posterior surgery, consisting of osteotomies (34 patients), completion of instrumentation, and fusion. Anterior surgery was performed during either stage as necessary. Age at surgery was 47 (range 18-68); 4.8 (range 1-9) levels were fused anteriorly and 11.3 (range 4-17) levels posteriorly.

RESULTS

No major perioperative medical complications occurred (e.g., myocardial infarction, pulmonary embolus, death). All completed staged surgery as planned. Only five required any postoperative intubation. There was only one perioperative deep infection, one superficial infection, and one sterile seroma. No medical or surgical complication could be related to the staging of posterior surgery. SRS-24 and radiographic outcomes were excellent at >or=2-year follow-up.

CONCLUSION

Staged posterior surgery can be performed safely with few surgical complications and no major medical complications, as well as excellent outcomes in a population known to be at high risk. Such staging can be useful in performing complex posterior revision and osteotomy surgery while limiting hemodynamic stresses.

Prospective comparison of gait and trunk range of motion in adolescents with idiopathic thoracic scoliosis undergoing anterior or posterior spinal fusion

STUDY DESIGN

Prospective evaluation of gait and spinal range of motion (ROM) in adolescent idiopathic scoliosis (AIS) patients undergoing either an anterior or a posterior spinal fusion.

OBJECTIVE

Compare changes in gait and spine ROM between AIS patients undergoing either an anterior or posterior spinal fusion.

SUMMARY AND BACKGROUND DATA

Problems with AIS posterior spinal fusion and attempts to minimize the number of spinal segments fused have led to the promotion of anterior spinal fusion. Comparison of functional outcomes of the two surgeries has not been reported.

MATERIALS AND METHODS

Thirty-one patients with single or double thoracic AIS undergoing an anterior (n = 16) or posterior (n = 15) instrumented spinal fusion underwent gait and triplanar ROM tests before surgery and 24 months postoperative. Videography with reflective surface markers on the scapula, spine, and pelvis were used to quantify changes in gait and trunk ROM.

RESULTS

Surgical results indicated that an average of four fewer levels was fused and the lowest instrumented vertebrae were one level higher in the spine for the anterior group compared to the posterior group. Gait results showed no change in gait speed and no change in coronal and sagittal plane kinematics, regardless of group. Transverse plane motion during gait was reduced in both groups. Spinal ROM results indicated motion loss in all three planes, regardless of group, with the posterior group having less postoperative ROM than the anterior group. Unlinking surgical approach from number of fused levels and lowest instrumented vertebrae with a subset of subjects also indicated less postoperative ROM for the posterior group.

CONCLUSIONS

The surgical and ROM results seem to favor the anterior approach over the posterior approach for the classification of patients in this investigation. However, it should be noted that both groups had decreased postoperative ROM.

Gait changes as the result of deformity reconstruction surgery in a group of adults with lumbar scoliosis

STUDY DESIGN

This was a prospective analysis of adult spinal deformity patients having fusions from the thoracic spine down to L5 or the sacrum. Gait analysis was performed before surgery and 1 and 2 years postoperatively, as was questionnaire analysis.

OBJECTIVES

To compare the preoperative and postoperative gait of revision and primary patients having long fusions to the distal lumbar spine or sacrum with that of a group of able-bodied adults. The experimental hypothesis was that both patient groups would have significantly compromised preoperative gait and gait endurance compared to the able-bodied group and that significant changes would be noted in both groups at 1 and 2 years postoperation.

SUMMARY OF BACKGROUND DATA

Spinal reconstructive surgery is often performed on adults with progressive lumbar spinal deformities. These patients can be divided into two major groups. The first are those patients who have degenerative changes superimposed on idiopathic scoliosis (primary patients) without previous operative treatment; the second are those patients who have already had a long fusion to L4, L5, or the sacrum (revision patients).

METHODS

Twenty-nine women participated in the investigation (8 primary, 12 revision, 9 able-bodied controls). A gait analysis was performed before surgery and 1 and 2 years postoperation. Walking endurance (time) was estimated from a submaximal graded treadmill exercise test. Motion variables describing the gait of the subjects, as well as gait speed, were determined. The SRS, Oswestry questionnaires, and an analog pain scale were also administered.

RESULTS

The primary group showed no adverse changes in lower extremity kinematics after surgery, and their gait speed improved such that it was not significantly different from the able-bodied group at 2 years postoperation. The revision group displayed lower extremity gait kinematics that were significantly different from the able-bodied group before surgery, but were no longer different from the able-bodied 2 years after surgery. They also had a significant increase in gait endurance. Questionnaire data indicated significant improvements for both groups after surgery.

CONCLUSIONS

Objective gait data quantifying the efficacy of reconstructive spinal surgery in both primary and revision patients indicated improved gait. Gait endurance was improved in the revision group, and gait speed for the primary was not significantly different from able-bodied at 2 years postoperation. Clinically, it would appear that rehabilitation strategies to improve gait endurance and gait speed could be implemented to further improve the gait of these patients.

Evaluation and surgical treatment of high-grade isthmic dysplastic spondylolisthesis

In children and young adults who seek medical treatment for high-grade isthmic dysplastic spondylolisthesis, common clinical symptoms are referable to the lumbosacral spine and/or the lower extremities. Pain in the lumbosacral spine may be secondary to altered lumbosacral alignment and biomechanics. It also may be caused by malalignment of the entire spinal-pelvic axis as a result of anterior sagittal imbalance. Lower extremity radiculopathies involving the L5 nerve root(s) may be present, and in severe forms of spondylolisthesis crisis, marked entrapment of the cauda equina at L5-S1 may occur. High-grade isthmic dysplastic spondylolisthesis are treated surgically and should include appropriate central and foraminal decompressions at the L5-S1 level, followed by lumbosacral fusion. Partial reduction aiming at improving the slip angle (lumbosacral kyphosis) is more beneficial and provides less risk to the L5 nerve roots than complete reduction of the translational component of the slip. Solid anterior and posterior spinal fusion at L5-S1 appears to provide the best long-term results.

Pedicle subtraction osteotomy for the treatment of fixed sagittal imbalance

BACKGROUND

Fixed sagittal imbalance (a syndrome in which the patient is only able to stand with the weight-bearing line in front of the sacrum) has many etiologies. The most commonly reported technique for correction is the Smith-Petersen osteotomy. Few reports on pedicle subtraction procedures (resection of the posterior elements, pedicles, and vertebral body through a posterior approach) are available in the peer-reviewed literature. We are aware of no report involving a substantial number of patients with coexistent scoliosis who underwent pedicle/vertebral body subtraction for the treatment of fixed sagittal imbalance.

METHODS

Twenty-seven consecutive patients in whom sagittal imbalance was treated with lumbar pedicle subtraction osteotomy at one institution were analyzed. Radiographic analysis included assessment of thoracic kyphosis, lumbar lordosis, lordosis through the pedicle subtraction osteotomy site, and the C7 sagittal plumb line. Outcomes analysis was performed with use of a before-and-after pain scale, items from the Oswestry questionnaire, and the Scoliosis Research Society (SRS) questionnaire after a minimum duration of follow-up of two years. Complications and radiographic findings were also analyzed for the entire group.

RESULTS

Overall, the average increase in lordosis was 34.1 degrees and the average improvement in the sagittal plumb line was 13.5 cm. One patient had development of a lumbar pseudarthrosis through the area of pedicle subtraction osteotomy, and six patients had development of a thoracic pseudarthrosis. Two patients had development of increased kyphosis at L5/S1, caudad to the fusion, resulting in some loss of sagittal correction. There were significant improvements in the overall Oswestry score (p < 0.0001) and the pain-scale score (p = 0.0002). Most patients reported improvement in terms of pain and self-image as well as overall satisfaction with the procedure.

CONCLUSIONS

Pedicle subtraction osteotomy is a useful procedure for patients with fixed sagittal imbalance. A worse clinical result is associated with increasing patient comorbidities, pseudarthrosis in the thoracic spine, and subsequent breakdown caudad to the fusion.

LEVEL OF EVIDENCE

Therapeutic study, Level IV (case series [no, or historical, control group]). See Instructions to Authors for a complete description of levels of evidence.

Prevalence of neural axis abnormalities in patients with infantile idiopathic scoliosis

BACKGROUND

Although reports in the literature have demonstrated an approximately 20% prevalence of neural axis abnormalities in patients with juvenile idiopathic scoliosis who have a curve of >20 degrees, the prevalence of neural axis abnormalities in patients with infantile idiopathic scoliosis is not well documented. In two previous studies involving a total of only ten patients with infantile idiopathic scoliosis, five patients were noted to have a neural axis abnormality on magnetic resonance images.

METHODS

The records of forty-six consecutive patients who were seen between 1992 and 2000 at three spinal deformity clinics were retrospectively reviewed. The inclusion criteria included presumed idiopathic scoliosis at the time of presentation, an age of three years or less, a curve magnitude of > or = 20 degrees, normal neurological findings, no associated syndromes, and no congenital abnormalities. All patients were evaluated with a total spine magnetic resonance imaging protocol for examination of neural axis abnormalities from the skull to the coccyx.

RESULTS

Ten (21.7%) of the forty-six patients were found to have a neural axis abnormality on magnetic resonance imaging. This group included five patients with an Arnold-Chiari malformation and an associated cervicothoracic syrinx, three with syringomyelia, one with a low-lying conus, and one with a brainstem tumor. Eight of these ten patients needed neurosurgical intervention for treatment of the abnormality.

CONCLUSIONS

The 21.7% prevalence of neural axis abnormalities in this group of patients with infantile idiopathic scoliosis was found to be almost identical to that reported in the literature on patients with juvenile idiopathic scoliosis. Because of the high prevalence of abnormalities and the fact that eight of the ten patients with abnormal findings on magnetic resonance images required neurosurgical intervention, a total spine magnetic resonance imaging evaluation at the time of presentation is recommended for all patients with infantile idiopathic scoliosis who have a curve measuring > or = 20 degrees.

Sagittal plane analysis of adolescent idiopathic scoliosis: the effect of anterior versus posterior instrumentation

STUDY DESIGN

Radiographic analysis of anterior and posterior instrumentation for adolescent idiopathic scoliosis.

OBJECTIVES

To compare effects of anterior versus posterior instrumentation on sagittal plane parameters.

SUMMARY OF BACKGROUND DATA

The sagittal plane is critical to the long-term success of scoliosis surgery, but few studies have compared the effect of anterior versus posterior instrumentation.

METHODS

Standing, full spine lateral radiographs of 110 consecutive patients (mean age 14 years) who had surgery for adolescent idiopathic scoliosis between 1996 and 1998 at one institution with a minimum 24-month (mean 32 months) follow-up were evaluated. Fifty patients were instrumented anteriorly with single screw-rod constructs. Sixty patients were instrumented posteriorly with segmental implants (5.5 mm; hooks, wires, and/or pedicle screws).

RESULTS

At the final follow-up, the proximal junctional measurement (measured between the proximal instrumented vertebra and the segment two levels cephalad) increased most with posterior instrumentation (+7 degrees increase for posterior thoracic +1 degrees increase for anterior thoracic instrumentation, P= 0.02; +9 degrees increase for posterior thoracic and lumbar instrumentation vs. +4 degrees for anterior thoracolumbar instrumentation, P= 0.03). Thoracic kyphosis (T5-T12) increased significantly with anterior versus posterior thoracic instrumentation (+4 degrees vs. -2 degrees change, P= 0.04). Lumbar lordosis (T12-S1) was enhanced with either anterior or posterior instrumentation. No significant changes in distal junctional measurement (measured between the distal instrumented vertebra and the segment two levels caudal) were noted. The C7 sagittal plumbline remained negative in all groups at the final follow-up.

CONCLUSION

Anterior and posterior instrumentation had differential effects on the sagittal plane in patients with adolescent idiopathic scoliosis. However, the overall magnitude of the differences was small. Properly performed, both approaches can result in acceptable sagittal profiles.

A comprehensive study of patients with surgically treated lumbar spinal stenosis with neurogenic claudication

BACKGROUND

The relationship between objective measurements and subjective symptoms of patients with spinal stenosis and the degree of narrowing of the spinal canal is not clear. The purpose of this study was to evaluate patients undergoing surgery for lumbar spinal stenosis and intermittent neurogenic claudication with functional testing, quantitative imaging, and patient self-assessment.

METHODS

Sixty-two patients with lumbar spinal stenosis and neurogenic claudication were prospectively enrolled in the study. All underwent preoperative magnetic resonance imaging and/or computed tomography myelography, and all were treated with decompressive surgery and were followed for a minimum of two years. The evaluation included treadmill and bicycle exercise tests as well as patient self-assessment with use of the Oswestry Disability Index and a visual analog pain scale preoperatively and postoperatively.

RESULTS

Preoperatively fifty-eight (94%) of the patients had a positive result (provocation of symptoms) on the treadmill test and twenty-seven (44%) had a positive result on the bicycle test, whereas postoperatively six and twelve, respectively, had positive results. The mean preoperative scores on the Oswestry Disability Index and visual analog pain scale were 58.4 and 7.1, respectively. Postoperatively, these scores decreased to 21.1 and 2.3, respectively, and both decreases were significant (p < 0.05). Forty-seven (76%) of the patients were seen to have central stenosis on the preoperative imaging studies; forty-one of them had a cross-sectional area of the dural tube of <100 mm (2) at at least one level and twelve had a cross-sectional area of <100 mm (2) at at least two levels.

CONCLUSIONS

A positive treadmill test was consistent with a diagnosis of spinal stenosis and neurogenic claudication in >90% of the patients preoperatively. Following surgical decompression of the lumbar spinal stenosis, more functional improvement was demonstrated by the treadmill test than by the bicycle test. The scores on the Oswestry Disability Index and visual analog pain scale also improved postoperatively. The severity of central canal narrowing at a single level does not appear to limit the postoperative improvement in either functional ability or patient self-assessment. Patients with multilevel central stenosis were, on the average, older and walked a shorter distance preoperatively and postoperatively, although the improvement in their postoperative self-assessment scores was similar to that of patients with single-level stenosis.