[Ventrodorsal correction and instrumentation in idiopathic scoliosis]

Does Planned Staging for Posterior-Only Vertebral Column Resections in Spinal Deformity Surgery Increase Perioperative Complications?

STUDY DESIGN

Propensity-matched case control.

OBJECTIVES

To compare the perioperative complication rate between single- and two-stage posterior-only VCRs (2-pVCR).

SUMMARY OF BACKGROUND DATA

A vertebral column resection (VCR) for severe spinal deformity is a technically challenging and lengthy procedure with a potentially high complication rate. Planned staging has an advantage of distributing operative time into 2 smaller, more manageable, intervals.

METHODS

Adult and pediatric spinal deformity patients undergoing a VCR were retrospectively identified from a single institution's surgical database from 1985 to 2013. Propensity scoring was used to match 2-pVCR and single-staged patients. Each group was matched for 15 preoperative risk factors including demographic, operative, and radiographic characteristics. Perioperative complications were defined as occurring within 2 months of initial surgery. Additionally, a binary logistic regression analysis was performed with complications as the outcome.

RESULTS

A total of 183 consecutive patients were identified as undergoing a VCR, with 172 meeting the inclusion criteria (posterior-only). Forty-four patients underwent planned 2-pVCR whereas 124 had a single-staged VCR. Consistent with propensity-matching, no statistically significant difference between the single- and 2-pVCR cohorts existed for all matching parameters, except pulmonary function tests. There was no significant difference (p = .290) between complication rates for single-stage (12/35; 34%) and 2-pVCR (8/35; 23%) patients. Stepwise binary logistic regression analysis showed that age (p = .014; OR = 0.94, CI = 0.89-0.99) and body mass index (p = .030; OR = 1.13 CI = 1.01-1.26) influenced the occurrence of a complication.

CONCLUSION

Planned staging of posterior-only VCRs does not increase the occurrence of perioperative complications in adult and pediatric spinal deformity patients.

LEVEL OF EVIDENCE

III (Propensity-matched case control).

Comparison of anterior and posterior vertebral column resection versus anterior release with posterior internal distraction for severe and rigid scoliosis

PURPOSE

This study aimed to compare efficacy, safety, and cost between staged vertebral column resection (VCR) and anterior release with internal distraction in treating severe and rigid idiopathic scoliosis.

METHODS

We examined the records of 43 patients with severe and rigid idiopathic scoliosis treated in our hospital. Group A included 26 patients who underwent anterior VCR followed by posterior vertebral column resection and instrumentation from July 2007 to October 2009. Group B included 17 patients who underwent anterior release with temporary posterior internal distraction, followed by posterior fusion and instrumentation from November 2009 to June 2011. The average preoperative main curve for group A was 101.3° (range 90°-130°) and for group B was 104.8° (range 90°-136°). Minimum follow-up was 2 years. Radiographic and clinical outcomes were compared between the groups.

RESULTS

A t test demonstrated that the differences between the groups in preoperative and postoperative coronal and sagittal imbalance, thoracic kyphosis correction, and lumbar lordosis were not statistically significant. Patients in group B showed better postoperative (P = 0.031) and final (P = 0.030) main thoracic curve correction (76.8 and 75.6 %, respectively) than patients in group A (68.3 and 67.7 %, respectively). Patients in group B had better thoracolumbar or lumbar curve correction (85.8 %) than those in group A (76.8 %; P = 0.048). The differences in blood loss and operation time were not statistically significant (P = 0.094 and P = 0.060, respectively). Hospital stay was longer (P = 0.001) and patient cost was higher (P < 0.001) for patients in group B. One patient in group A required ventilator support for 12 h after anterior surgery. One transient dyspnea occurred in group B. No neurologic deficits occurred in either group.

CONCLUSION

Anterior release with posterior internal distraction produces better corrective effects than anterior and posterior VCR, though hospital stay and costs are greater.

Two-stage vertebral column resection for severe and rigid scoliosis in patients with low body weight

BACKGROUND CONTEXT

To date, there are no clinical series documenting the treatment of severe and rigid scoliosis in patients with low body weight. To optimize curve correction and minimize the risk of complications, we performed a two-stage vertebral column resection (VCR) with posterior pedicle screw instrumentation to treat patients with severe and rigid scoliosis and low body weight.

PURPOSE

The purposes of this study were to report the results of a two-staged VCR for patients with severe and rigid scoliosis and low body weight.

STUDY DESIGN

This was a prospective, longitudinal, and descriptive study with a minimum follow-up of 2 years.

PATIENT SAMPLE

Sixteen patients (nine women and seven men) with severe and rigid scoliosis and low body weight from the department of orthopedics, West China hospital, Sichuan University.

OUTCOME MEASURES

Clinical analysis included rib hump and lumbar hump. Radiographic analysis consisted of Cobb angle measurements of coronal curves, apical vertebral translation, coronal balance, sagittal balance, thoracic kyphosis, and lumbar lordosis. All measurements were taken before surgery, after surgery, and in the final follow-up period.

METHODS

For evaluation of surgical effectiveness, comparative analysis of rib hump, lumbar hump, Cobb angle of coronal curves, apical vertebral translation, coronal balance, sagittal balance, thoracic kyphosis, and lumbar lordosis before operation, after operation, and at the most recent follow-up was done.

RESULTS

The body weight of patients averaged 33.8 kg (range 27-40 kg). Mean operating time was 580.3 minutes, with a blood loss of 1,581.3 mL. The correction rates of rib hump and lumbar hump were 77% and 85%. Preoperative major curves ranged from 90° to 130° Cobb angle. Coronal plane correction of the major curve averaged 70.7%, with an average loss of correction of 1.8%. The apical vertebral translation of the major curve was corrected by 73.2%. The preoperative coronal imbalance of 0.6 cm (range 0-1.4 cm) was improved to 0.5 cm (range 0-1.4 cm) at the most recent follow-up. The preoperative sagittal imbalance of 0.9 cm (range -3.1 to 4.6 cm) was improved to 0.8 cm (range -1.0 to 3.0 cm) at the most recent follow-up. The preoperative thoracic kyphosis of 50.1° (range 6°-86°) was corrected to 28.9°±7.7° (range 18°-42°) at the most recent follow-up. The preoperative lumbar lordosis of -57.9° (range -85° to -32°) was corrected to -49.0° (range -62° to -40°) at the most recent follow-up. Complications were encountered in two patients. One patient required ventilator support for 12 hours after anterior surgery. Malposition of one pedicle screw was found in one patient. There were no neurologic complications or any deep wound infections. No complication of instrumentation was found at final follow-up.

CONCLUSIONS

The use of two-stage VCR for patients with severe and rigid scoliosis and low body weight can achieve a good correction of scoliosis without serious complications.

Anterior and posterior vertebral column resection for severe and rigid idiopathic scoliosis

A total of 16 patients with severe and rigid idiopathic scoliosis treated by anterior and posterior vertebral column resection (APVCR) were retrospectively reviewed after a minimum follow-up of 2 years. The indication for APVCR was scoliosis more than 90° with flexibility less than 20%. The radiographic parameters were evaluated, and clinical records were reviewed. All patients underwent APVCR with posterior pedicle screw instrumentation in a two-stage surgery. The rib hump was reduced from 7.2 cm preoperatively to 1.8 cm at final follow-up (75% correction). Preoperative curves ranged from 93° to 110° Cobb angle. Coronal plane correction of the major curve averaged 67% with an average loss of correction of 1.4%. The apical vertebral translation of the major curve was corrected by 63.5%. The preoperative coronal imbalance of 0.9 cm (range 0-2.4) was improved to 0.8 cm (range 0.1-1.7) at the most recent follow-up. The preoperative sagittal imbalance of 1.0 cm (range -3.1 to 4.6) was improved to 0.9 cm (range -2.6 to 3.0) at the most recent follow-up. Complications were encountered in four patients. One patient required ventilator support for 12 h after anterior surgery. Malposition of one pedicle screw was found in one patient. Malposition of titanium mesh cage happened to two patients. There were no neurological complications, deep wound infections or pseudarthrosis. APVCR is an effective alternative for severe and rigid idiopathic scoliosis.

Combined anterior and posterior instrumentation in severe and rigid idiopathic scoliosis

A prospective clinical and radiographic evaluation of 33 consecutive patients with severe and rigid idiopathic scoliosis (average Cobb angle 93 degrees, flexibility on bending films 23%) were treated with combined anterior and posterior instrumentation with a minimum follow-up of 2 years. All patients underwent anterior release and VDS-Zielke Instrumentation of the primary curve. In highly rigid scoliosis, this was preceded by a posterior release. Finally, posterior correction and fusion with a multiple hook and pedicle screw construct was performed. Thirty patients were operated in one stage, three patients in two stages. Preoperative curves ranged from 80 to 122 degrees Cobb angle. Frontal plane correction of the primary curve averaged 67% with an average loss of correction of 2 degrees . The apical vertebral rotation of the primary curve was corrected by 49%. In all but three patients, sagittal alignment was restored. There were no neurological complications, deep wound infections or pseudarthrosis. Combined anterior and posterior instrumentation is safe and enables an effective three-dimensional curve correction in severe and rigid idiopathic scoliosis.

A new operative classification of idiopathic scoliosis: a peking union medical college method

STUDY DESIGN

A retrospective radiographic study on the type of surgically treated idiopathic scoliosis, with a prospective study on the reliability of the type-related fusion guide.

OBJECTIVES

To identify and classify surgically treated idiopathic scoliosis, and define its related fusion levels by a new classification system.

SUMMARY OF BACKGROUND DATA

Some classification methods for idiopathic scoliosis have been suggested. However, poor intraobserver reproducibility and interobserver reliability were experienced in these studies, and were not appropriate for guiding surgical planning.

METHODS

A total of 427 surgically treated idiopathic scoliosis cases were reviewed. Preoperative and postoperative standing anteroposterior, lateral, and preoperative supine side-bending radiograph were analyzed using the Scoliosis Research Society definition of scoliosis and curve apex. The resulting classification was tested for intraobserver reliability and interobserver reliability, and by 6 surgeons. Apical frequencies were determined for each type, and prospective surgical testing of the new type and its related fusion guide was performed.

RESULTS

Three major types and 13 subtypes were identified, of which the Peking Union Medical College type I accounted for 56.62%, type II 42.16%, and type III 1.22%. The interobserver reliability testing was 85% (kappa coefficient 0.832), while intraobserver reproducibility was 91% (kappa coefficient 0.898). Each type had its corresponding fusion levels. A prospective study of 152 cases was performed according to the classification. All of these cases were followed over 18 months, and no postoperative decompensation was noted.

CONCLUSION

The Peking Union Medical College classification of idiopathic scoliosis is one system to combine each type with its corresponding fusion level, and it had much higher interobserver reliability and intraobserver reproducibility than the King system. Further prospectivestudies would help to clarify and expand this system.

Effect of different surgical strategies on screw forces after correction of scoliosis with a VDS implant

Pullout of the cranial end-vertebra screw following the correction of a scoliosis with the VDS implant is a common complication. Very little is known about the forces acting on the screws during ventral derotation spondylodesis (VDS) in ventral scoliosis surgery. These forces determine the risk of screw-loosening. The purpose of this study was to identify implant properties and to determine surgical correction strategies that reduce the risk of cranial end-vertebra screw pullout. For this aim, a three-dimensional nonlinear finite element model of a scoliotic thoracic spine was created with a Cobb angle of 61 degrees and 32 degrees rotation. The VDS implant was inserted between T5 and T9. The longitudinal rod diameter, the implant material and seven surgical correction strategies were examined to determine their influence on the Cobb angle as well as on derotation and on axial and transverse forces in the screws. A stiffer implant achieves a better correction but causes higher axial and transverse screw forces. Axial tensile forces act on the screws fixed to the cranial end vertebra and the middle vertebra, while axial compressive forces act on the other screws. A strong correction at the cranial segment leads to high axial and transverse screw forces in the farthest cranial screw and thus to a high risk of screw pullout. The resultant transverse force is often much higher than the axial force component. Simulation of local trunk muscle forces has only a minor effect on the results. The axial tensile forces and thus the risk of screw pullout are highest at the cranial end vertebra. A strategy in which surgical correction is strong in the middle segments and moderate in the outer ones leads to a good reduction of the Cobb angle, a wide derotation angle, and relatively low axial tensile forces at the cranial end vertebra screw.