Congenital thoracolumbar spine deformities

3D printing and spine surgery

Rapid prototyping (RP), also known as three-dimensional printing (3DP), allows the rapid conversion of anatomical images into physical components by the use of special printers. This novel technology has also become a promising innovation for spine surgery. As a result of the developments in 3DP technology, production speeds have increased, and costs have decreased. This technological development can be used extensively in different parts of spine surgery such as preoperative planning, surgical simulations, patient-clinician communication, education, intraoperative guidance, and even implantable devices. However, similar to other emerging technologies, the usage of RP in spine surgery has various drawbacks that are needed to be addressed through further studies.

Coronal Imbalance After Three-Column Osteotomy in Thoracolumbar Congenital Kyphoscoliosis: Incidence and Risk Factors

STUDY DESIGN

Retrospective radiographical clinical study.

OBJECTIVE

To investigate the incidence and risk factors of coronal imbalance (CI) after three-column osteotomy (3-CO) in patients with thoracolumbar congenital kyphoscoliosis (CKS).

SUMMARY OF BACKGROUND DATA

The incidence and risk factors of postoperative CI have been reported in adolescent idiopathic and degenerative lumbar scoliosis. However, limited data exists for patients with CKS after 3-CO.

METHODS

We reviewed a consecutive series of patients with CKS who underwent posterior-only 3-CO. Coronal curve patterns were classified according to absolute C7 translation values into: Type A, C7 translation is less than 30 mm; Type B, C7 translation more than or equal to 30 mm and C7 plumb line (C7PL) shifted to the concave side of the main curve; and Type C, C7 translation more than or equal to 30 mm and C7PL shifted to the convex side. CI was defined as C7 translation on either side more than or equal to 30 mm. According to C7 translation at the latest follow-up, patients was subdivided into an imbalanced group and a balanced group.

RESULTS

One-hundred-thirty patients (mean age, 17.7 ± 5.2 yr) were recruited. The mean follow-up was 41.3 ± 18.5 months. Twenty-six patients (20%) were identified as having CI at the latest follow-up. Compared with the balanced group, the imbalanced group had a larger proportion of preoperative Type C pattern, higher main curve correction, and greater lowest instrumented vertebra (LIV) tilt before and after surgery. Multiple logistic regression showed that risk factors for CI were preoperative type C pattern, preoperative LIV tilt more than or equal to 23.5° and immediate postoperative LIV tilt more than or equal to 12.3°.

CONCLUSION

The incidence of CI in patients with CKS after 3-CO was 20%. A preoperative type C pattern, preoperative LIV tilt more than or equal to 23.5°, and immediate postoperative LIV tilt more than or equal to 12.3° were found to be associated with CI at the latest follow-up.

LEVEL OF EVIDENCE

3.

Posterior unilateral pedicle subtraction osteotomy of hemivertebra for correction of the adolescent congenital spinal deformity

BACKGROUND CONTEXT

The treatment of adolescent congenital deformity (late-diagnosed congenital deformity) is still unknown. The best candidates for hemivertebra excision are young patients, typically between 4 and 6 years of age. Partial excision may be feasible for older children.

PURPOSE

The purpose of this study was to assess the effect of unilateral pedicle subtraction osteotomy of hemivertebra for correction of the adolescent congenital spinal deformity.

STUDY DESIGN

Retrospective analysis.

PATIENT SAMPLE

Twelve patients with adolescent congenital deformity who underwent posterior unilateral pedicle subtraction osteotomy and correction were evaluated. Mean age at the time of surgery was 17 years.

OUTCOME MEASURES

The charts, standing full-length posteroanterior and lateral view radiographs, and functional measures were reviewed.

METHODS

For evaluation of surgical effectiveness, comparative analysis of the parameters of the total main curve, the segmental curve, the compensatory cranial and caudal curves, the segmental kyphosis, and the trunk shift before and after operation and at the most recent follow-up was done.

RESULTS

The mean follow-up period was 40.5 months. Mean Cobb angles of the total main curve and the segmental curve were, respectively, 47.5° and 43.8° before surgery, 23.7° and 16.5° after surgery, and 22.6° and 17° at the last follow-up. The angle of segmental kyphosis was 11.8° before surgery, 6.2° after surgery, and 7.8° (range, -30° to 26°) at the final follow-up. The mean final global lordosis was within the normal range. No neurologic deficit occurred. Solid fusion was achieved for all cases.

CONCLUSIONS

Unilateral pedicle subtraction osteotomy with instrumentation from a posterior-only approach is indicated in older teenagers for an adolescent congenital spinal deformity. Compared with hemivertebra excision, corrective surgery with hemivertebra osteotomy has a lower intraoperative blood loss and shorter operation time.

Clinical application of computer-designed polystyrene models in complex severe spinal deformities: a pilot study

Surgical treatment of complex severe spinal deformity, involving a scoliosis Cobb angle of more than 90 degrees and kyphosis or vertebral and rib deformity, is challenging. Preoperative two-dimensional images resulting from plain film radiography, computed tomography (CT) and magnetic resonance imaging provide limited morphometric information. Although the three-dimensional (3D) reconstruction CT with special software can view the stereo and rotate the spinal image on the screen, it cannot show the full-scale spine and cannot directly be used on the operation table. This study was conducted to investigate the application of computer-designed polystyrene models in the treatment of complex severe spinal deformity. The study involved 16 cases of complex severe spinal deformity treated in our hospital between 1 May 2004 and 31 December 2007; the mean +/- SD preoperative scoliosis Cobb angle was 118 degrees +/- 27 degrees. The CT scanning digital imaging and communication in medicine (DICOM) data sets of the affected spinal segments were collected for 3D digital reconstruction and rapid prototyping to prepare computer-designed polystyrene models, which were applied in the treatment of these cases. The computer-designed polystyrene models allowed 3D observation and measurement of the deformities directly, which helped the surgeon to perform morphological assessment and communicate with the patient and colleagues. Furthermore, the models also guided the choice and placement of pedicle screws. Moreover, the models were used to aid in virtual surgery and guide the actual surgical procedure. The mean +/- SD postoperative scoliosis Cobb angle was 42 degrees +/- 32 degrees, and no serious complications such as spinal cord or major vascular injury occurred. The use of computer-designed polystyrene models could provide more accurate morphometric information and facilitate surgical correction of complex severe spinal deformity.