Three-dimensional translations following posterior three-column spinal osteotomies for the correction of severe and stiff kyphoscoliosis

Posterior Multisegment Apical Convex plus Concave Intervertebral Release Combined with Posterior Column Osteotomy for the Treatment of Rigid Thoracic/Thoracolumbar Scoliosis

BACKGROUND

Intervertebral release (IVR) in the apical region is critical for full release of a rigid spine. Previous studies have mainly reported IVR techniques using an anterior approach or posterior apical convex IVR. We first report the surgical procedure of posterior multisegment apical convex plus concave IVR combined with posterior column osteotomy (PCO) for treating rigid thoracic/thoracolumbar scoliosis.

METHODS

This study retrospectively analyzed clinical, radiologic outcomes and technique notes of 18 patients with rigid scoliosis treated with posterior multisegment convex plus concave IVR combined with PCO.

RESULTS

The preoperative, postoperative, and final follow-up mean sagittal Cobb angles of the main curve were 75.2° (58.7°-110.2°), 18.4° (9°-35.1°), and 19.0° (8.2°-36.3°), respectively. The mean correction rate was 75.3% (66.7%-86.7%). In cases of thoracolumbar kyphosis, the preoperative, postoperative, and final follow-up mean sagittal Cobb angles were 45.7° (40.5°-52.6°), 18.8° (10.2°-27.5°), and 19.8° (11.1°-29°), respectively. The mean correction rate was 57% (42.1%-72.6%). The mean axial vertebral rotation (AVR) in the IVR region was 24.4° (14.3°-46.3°) preoperatively and was corrected to 10.9° (10.9°-26.6°) postoperatively. The mean correction rate for AVR was 55.9% (41.1%-78.6%). The coronal and sagittal Cobb angles and AVR postoperatively were significantly lower than those preoperatively (P < 0.001). This case series reported 2 cases of pleural effusion and 1 case of wound infection.

CONCLUSIONS

Single posterior multilevel apical convex plus concave IVR combined with PCO is a safe and effective surgical method for treating rigid thoracic/thoracolumbar scoliosis that does not need 3-column osteotomy.

Center of rotation analysis for thoracic and lumbar 3-column osteotomies in patients with sagittal plane spinal deformity: insights in geometrical changes can improve understanding of correction mechanics

OBJECTIVE

Three-column osteotomy (3CO) is used for severe spinal deformities. Associated complications include sagittal translation (ST), which can lead to neurological symptoms. Mismatch between the surgical center of rotation (COR) and the concept of the ideal COR is a potential cause of ST. Matching surgical with conceptual COR is difficult with pedicle subtraction osteotomy (PSO) and vertebral column resection (VCR). This mismatch influences correction geometry, which can prevent maximum possible correction. The authors' objective was to examine the sagittal correction geometry and surgical COR of thoracic and lumbar 3CO.

METHODS

In a retrospective study of patients with PSO or VCR for severe sagittal plane deformity, analysis of surgical COR was performed using pre- and postoperative CT scans in the PSO group and digital radiographs in the VCR group. Radiographic analysis included standard deformity measurements and regional kyphosis angle (RKA). All patients had 2-year follow-up, including neurological outcome. Preoperative CT scans were studied for rigid osteotomy sites versus mobile osteotomy sites. Additional radiographic analysis of surgical COR was based on established techniques superimposing pre- and postoperative images. Position of the COR was defined in a rectangular net layered onto the osteotomy vertebrae (OVs).

RESULTS

The study included 34 patients undergoing PSO and 35 undergoing VCR, with mean ages of 57 and 29 years and mean RKA corrections of 31° and 49°, respectively. In the PSO group, COR was mainly in the anterior column, and surgical and conceptual COR matched in 22 patients (65%). Smaller RKA correction (27° vs 32°, p = 0.09) was seen in patients with anterior eccentric COR. Patients with rigid osteotomy sites were more likely to have an anterior eccentric COR (41% vs 11%, p = 0.05). In the VCR group, 20 patients (57%) had single-level VCR and 15 (43%) had multilevel VCR. COR was mainly located in the anterior or middle column. Mismatch between surgical and conceptual COR occurred in 24 (69%) patients. Larger RKA correction (63° vs 45°, p = 0.03) was seen in patients with anterior column COR. Patients with any posterior COR had a smaller RKA correction compared to the rest of the patients (42° vs 61°, p = 0.007).

CONCLUSIONS

Matching the surgical with the conceptual COR is difficult and in this study failed in one- to two-thirds of all patients. In order to avoid ST during correction of severe deformities, temporary rods, tracking rods, or special instruments should be used for correction maneuvers.

Three-dimensional translations following posterior three-column spinal osteotomies for the correction of severe and stiff kyphoscoliosis

BACKGROUND CONTEXT

Posterior three-column spinal osteotomies were shown to be effective to treat severe and stiff kyphoscoliosis. Translations at the site of osteotomy after deformity correction were commonly seen intraoperatively, which might cause potential neurologic deficits. However, this phenomenon was not thoroughly discussed in the current literature.

PURPOSE

This study aimed to evaluate the three-dimensional (3D) translations at the three-column osteotomy site and their effects on neurologic outcome in the surgical correction of severe and stiff kyphoscoliosis.

STUDY DESIGN/SETTING

A retrospective study was carried out.

PATIENT SAMPLE

Sixty-nine patients treated by posterior three-column spinal osteotomy for severe kyphoscoliosis of idiopathic, congenital, neuromuscular, neurofibromatosis, and tuberculosis origin were included.

OUTCOME MEASURES

General, coronal, and sagittal translations were graded three-dimensionally according to the theory of Meyerding.

METHODS

The charts of 69 clinical patients with severe and stiff kyphoscoliosis treated by posterior three-column osteotomy from January 2013 to June 2015 were reviewed. There were 35 male patients with an average age of 21.5 years and 34 female patients with an average age of 22.5 years. The etiologies of these spinal deformities were idiopathic, congenital, neuromuscular, neurofibromatosis, and tuberculosis. According to our classification system of spinal cord neurologic function, there were 41 type A, 13 type B, and 15 type C cases. The 3D spine models were reconstructed from thin-sliced computed tomography (CT) scan, and the 3D translations at the three-column osteotomy site were graded and analyzed.

RESULTS

The incidences of general translation (GT), frontal translation (FT), and sagittal translation (ST) were 62.3%, 52.2%, and 26.1%. The incidence of evoked potential (EP) change in cases with GT/FT being or more than grade II (GT, 42.9%; FT, 50.0%) was significantly higher than that with GT/FT being less than grade II (GT, 16.7%; FT, 18.2%), whereas the incidence of EP change in cases with ST being or more than grade I (33.3%) was significantly higher than that with ST being less than grade I (9.8%). No linear correlations were found between spine shortening distance, deformity correction rate, and the degree of translation.

CONCLUSIONS

The 3D translations are common in posterior three-column spinal osteotomies regardless of anterior strut graft placement. The increase of translation will increase neurologic risks, with GT or FT less than grade II and ST less than grade I being relatively safe.