The Deformity Angular Ratio: Does It Correlate With High-Risk Cases for Potential Spinal Cord Monitoring Alerts in Pediatric 3-Column Thoracic Spinal Deformity Corrective Surgery?

STUDY DESIGN: A retrospective analysis. OBJECTIVE: The purpose of this study was to determine whether the deformity angular ratio (DAR) can reliably assess the neurological risks of patients undergoing deformity correction. SUMMARY OF BACKGROUND DATA: Identifying high-risk patients and procedures can help ensure that appropriate measures are taken to minimize neurological complications during spinal deformity corrections. Subjectively, surgeons look at radiographs and evaluate the riskiness of the procedure. However, 2 curves of similar magnitude and location can have significantly different risks of neurological deficit during surgery. Whether the curve spans many levels or just a few can significantly influence surgical strategies. Lenke et al have proposed the DAR, which is a measure of curve magnitude per level of deformity. METHODS: The data from 35 pediatric spinal deformity correction procedures with thoracic 3-column osteotomies were reviewed. Measurements from preoperative radiographs were used to calculate the DAR. Binary logistic regression was used to model the relationship between DARs (independent variables) and presence or absence of an intraoperative alert (dependent variable). RESULTS: In patients undergoing 3-column osteotomies, sagittal curve magnitude and total curve magnitude were associated with increased incidence of transcranial motor evoked potential changes. Total DAR greater than 45° per level and sagittal DAR greater than 22° per level were associated with a 75% incidence of a motor evoked potential alert, with the incidence increasing to 90% with sagittal DAR of 28° per level. CONCLUSION: In patients undergoing 3-column osteotomies for severe spinal deformities, the DAR was predictive of patients developing intraoperative motor evoked potential alerts. Identifying accurate radiographical, patient, and procedural risk factors in the correction of severe deformities can help prepare the surgical team to improve safety and outcomes when carrying out complex spinal corrections. LEVEL OF EVIDENCE: 3.

Modified T4 hemivertebrectomy for persistent high left shoulder after surgery for double thoracic scoliosis.

STUDY DESIGN: Case report. OBJECTIVE: To surgically regain shoulder balance in patients with adolescent idiopathic scoliosis after loss of alignment after posterior fusion for Lenke II deformity correction. SUMMARY OF BACKGROUND DATA: Shoulder balance is known to have a large effect on patient satisfaction after deformity correction. Previous studies have outlined guidelines for determining levels of instrumentation to prevent postoperative high left shoulder. However, to our knowledge, no study has provided instructions on how to correct coronal imbalance in patients with previously fused scoliosis. We describe a case using a T4 unilateral pedicle subtraction osteotomy and contralateral Smith-Petersen osteotomy to treat high left shoulder in a patient who had previously undergone posterior instrumented fusion for adolescent idiopathic scoliosis. METHODS: The radiographs and clinical charts were reviewed for a 17-year-old female patient treated with a revision fusion and modified T4 hemivertebrectomy for a persistently high left shoulder after previous correction of a Lenke II idiopathic scoliosis. RESULTS: A reduction in the T1 tilt angle from 19.2° to 10.1° and an improvement in the coronal Cobb angle of the proximal thoracic curve from 37° to 17° were obtained. Shoulder balance was greatly improved. CONCLUSION: A proximal thoracic partial vertebrectomy with unilateral pedicle subtraction osteotomy and contralateral Smith-Petersen osteotomy is a technique that can be used to successfully correct fixed shoulder imbalance after posterior instrumented fusion of a double thoracic adolescent idiopathic scoliosis. LEVEL OF EVIDENCE: N/A.

Comparison of pedicle subtraction and Smith-Petersen osteotomies in correcting thoracic kyphosis when closed with a central hook-rod construct.

STUDY DESIGN: Retrospective analysis. OBJECTIVE: To demonstrate the effectiveness of hook-rod constructs in closing thoracic osteotomies safely and effectively. SUMMARY OF BACKGROUND DATA: The outcomes of hook-rod instrumentation in osteotomies for the correction of kyphosis at the lumbar region of the spine have been described. Little literature exists on the outcomes at the thoracic level. METHODS: The radiographs and clinical scores of 38 patients who underwent pedicle subtraction osteotomy or Smith-Petersen osteotomy in the thoracic spine with the osteotomies closed using a central rod were retrospectively reviewed. Measurements included osteotomy angle, thoracic kyphosis (T2-T12), and maximum kyphosis. Perioperative and long-term complications were reviewed. RESULTS: Thirty-eight patients underwent thoracic level osteotomies. There were 8 males and 30 females with a mean age of 51.9 years (range, 18-76 yr) at the time of surgery. The mean construct length was 13.2 levels (4-25). Kyphosis correction was equal in the 2 groups. In the pedicle subtraction osteotomy group, a mean of 24.7° (4°-47°) correction was obtained through the osteotomies compared with 24.0° (9°-65°) in the Smith-Petersen osteotomy group. Correction per osteotomy was 23.7° (4°-47°) in the pedicle subtraction osteotomy group compared with 11.8° (2.8°-46.0°) in the Smith-Petersen osteotomy group. No difference in the amount of correction achieved at the different regions of the thoracic spine was observed with either type of osteotomy with central rod closure. CONCLUSION: Central hook-rod constructs provide a safe and effective means of closing thoracic osteotomies and result in good correction of rigid sagittal plane deformities. LEVEL OF EVIDENCE: 4.

Tension Pneumothorax as a Complication of Inadvertent Pleural Tears During Posterior Spinal Surgery.

OBJECTIVE: To review and expose the occurrences of tension pneumothorax as a result of pleural tear during posterior spinal surgery. METHODS: Intraoperative reports were retrospectively reviewed for 2 patients who underwent posterior spinal fusion and experienced pleural tear and subsequent tension pneumothorax. Surgical decisions for recognition and treatment were also reviewed. RESULTS: Unrecognized pleural tearing led to the formation of tension pneumothorax in both patients studied. Onset of respiratory signs and symptoms were delayed, occurring in the recovery room for the first patient and intraoperatively for the second. Both patients were successfully treated with conversion to open pneumothorax and placement of chest tubes. CONCLUSIONS: Tension pneumothorax is a complication that can arise during posterior thoracic spinal surgery as a result of an inadvertent pleural tear. Awareness of this potentially fatal complication will greatly help in the timely recognition and treatment of this condition if this situation occurs. The authors recommend a low threshold for chest tube placement in patients with known or suspected pleural tears or in patients with undiagnosed respiratory failure undergoing posterior thoracic spine surgery.