Impact of Screw Type on Kyphotic Deformity Correction after Spine Fracture Fixation: Cannulated versus Solid Pedicle Screw

New technique and case report: Robot-assisted intralaminar screw fixation of spondylolysis in an adolescent

Introduction

Management of spondylolysis in adolescents is generally successful with conservative management. Uncommonly, surgical fixation is necessary for refractory cases. Direct repair with intralaminar screws is one commonly utilized technique. Recently, less invasive spinal procedures are becoming viable with the enabling of technologies, including robotics.

Case description

A 14-year-old baseball player and surfer presented with low back pain, diagnosed by MRI as bony edema and stress fractures of the posterior spinal elements. After 18 months, the pain was unresponsive to rest, physical therapy, and bracing. There was no radicular pain or neurologic symptoms. Computed tomography (CT) revealed bilateral, chronic nonhealing pars defects at L5. He underwent outpatient, robot-assisted percutaneous intralaminar fixation with hydroxyapatite-coated screws through a 2 cm skin incision.

Outcome

On postoperative day 1, the patient reported relief of his preoperative pain and he was ambulating without difficulty. At 2 weeks follow-up, the patient was completely pain free and surfing. At 2 months follow-up, low-dose CT demonstrated partial incorporation of the hydroxyapatite-coated screws, and the patient returned to sports. At 6 months follow-up, the patient had no pain and was swinging his baseball bat with full force. Low-dose CT revealed complete healing of the defects with full incorporation of the hydroxyapatite-coated screws.

Conclusions

A novel minimally invasive robotic percutaneous approach for direct spondylolysis repair using hydroxyapatite-coated screws is a potential surgical treatment option for non-healing pars defects in adolescent patients.

TREATMENT OF THORACOLUMBAR FRACTURES BY CLOSED REDUCTION VIA A PERCUTANEOUS SOLID PEDICLE SCREW

Objectives

Investigate the effect of closed reduction and per- cutaneous pedicle screw fixation in treating thoracolumbar fractures.

Methods

This retrospective study analyzed 12 cases of single-segment thoracolumbar spine fractures without spinal cord and nerve injury at our department from March 2016 to September 2017. Patients were treated with closed reduction, percutaneous reduction, and internal fixation with solid pedicle screws. The operation time, intraoperative blood loss, anterior vertebral body height ratio (AVHR), Cobb angle (CA) of sagittal kyphosis, and VAS of back pain were determined and statistically compared.

Results

The average operation time was 147.2 ± 45.6 min, and the average intraoperative bleeding was 67.8 ± 34.2 mL. All fractured vertebrae were completely reduced, their height was restored, and kyphosis was corrected. The average follow-up period was 10.6 ± 2.7 months, with significant improvements seen in the AVHR, CA of sagittal kyphosis, and VAS score (P < 0.01). One case had a broken rod after three months, and another had a postoperative infection. All the patients achieved bony healing.

Conclusion

The treatment of thoracolumbar fractures by closed reduction and internal fixation with a percutaneous solid pedicle screw is simple, effective, and economical. Level of Evidence VI; Therapeutic Study, Case Series .

Predicting development of severe clinically relevant distal junctional kyphosis following adult cervical deformity surgery, with further distinction from mild asymptomatic episodes

OBJECTIVE

This retrospective cohort study aimed to develop a formal predictive model distinguishing between symptomatic and asymptomatic distal junctional kyphosis (DJK). In this study the authors identified a DJK rate of 32.2%. Predictive models were created that can be used with high reliability to help distinguish between severe symptomatic DJK and mild asymptomatic DJK through the use of surgical factors, radiographic parameters, and patient variables.

METHODS

Patients with cervical deformity (CD) were stratified into asymptomatic and symptomatic DJK groups. Symptomatic: 1) DJK angle (DJKA) > 10° and either reoperation due to DJK or > 1 new-onset neurological sequela related to DJK; or 2) either a DJKA > 20° or ∆DJKA > 20°. Asymptomatic: ∆DJK > 10° in the absence of neurological sequelae. Stepwise logistic regressions were used to identify factors associated with these types of DJK. Decision tree analysis established cutoffs.

RESULTS

A total of 99 patients with CD were included, with 32.2% developing DJK (34.3% asymptomatic, 65.7% symptomatic). A total of 37.5% of asymptomatic patients received a reoperation versus 62.5% symptomatic patients. Multivariate analysis identified independent baseline factors for developing symptomatic DJK as follows: pelvic incidence (OR 1.02); preoperative cervical flexibility (OR 1.04); and combined approach (OR 6.2). Having abnormal hyperkyphosis in the thoracic spine, more so than abnormal cervical lordosis, was a factor for developing symptomatic disease when analyzed against asymptomatic patients (OR 1.2). Predictive modeling identified factors that were predictive of symptomatic versus no DJK, as follows: myelopathy (modified Japanese Orthopaedic Association score 12-14); combined approach; uppermost instrumented vertebra C3 or C4; preoperative hypermobility; and > 7 levels fused (area under the curve 0.89). A predictive model for symptomatic versus asymptomatic disease (area under the curve 0.85) included being frail, T1 slope minus cervical lordosis > 20°, and a pelvic incidence > 46.3°. Controlling for baseline deformity and disability, symptomatic patients had a greater cervical sagittal vertical axis (4-8 cm: 47.6% vs 27%) and were more malaligned according to their Scoliosis Research Society sagittal vertical axis measurement (OR 0.1) than patients without DJK at 1 year (all p < 0.05). Despite their symptomatology and higher reoperation rate, outcomes equilibrated in the symptomatic cohort at 1 year following revision.

CONCLUSIONS

Overall, 32.2% of patients with CD suffered from DJK. Symptomatic DJK can be predicted with high reliability. It can be further distinguished from asymptomatic occurrences by taking into account pelvic incidence and baseline cervicothoracic deformity severity.