Correction of L5 Tilt in 2-Row Vertebral Body Tethering Versus Posterior Spinal Fusion for Adolescent Idiopathic Scoliosis.

STUDY

DESIGN

Single-center retrospective cohort study.

OBJECTIVE

To compare the correction of fractional curve and L5 tilt in 2RVBT versus PSF with LIV in the lumbar spine.

SUMMARY OF BACKGROUND DATA: Vertebral body tethering, an AIS fusion-alternative, avoids rigid constructs, allowing for lower instrumented vertebra (LIV) selection. Single-tether constructs break, but mini-open thoracoscopic assistant double-row vertebral body tethering (2RVBT) reduces this. Limited comparative studies exist with posterior spinal fusion (PSF).

METHODS

Retrospective analysis of AIS correction surgeries with lumbar LIV using preoperative and minimum 2-year postoperative imaging. Patients were divided into 2RVBT or PSF groups. Data included age, Riser, UIV, LIV, instrumented levels, and revision rates. Radiographic analyses included preoperative and postoperative main curve Cobb (MCC), secondary curve Cobb (SCC), fractional curve Cobb (FCC), and L5 tilt.

RESULTS

Ninety-nine patients participated (49 in 2RVBT, 50 in PSF). Preoperatively, secondary CC differed significantly (2RVBT: 44.6±10.4 degrees vs. PSF: 39.5±11.8 degrees, P =0.026), but not L5 tilt, MCC, or FCC. Postoperatively, MCC (2RVBT: 25.7±12.3 degrees vs. PSF: 19.5±7.4 degrees, P =0.003) and SCC (2RVBT: 18.0±8.4 degrees vs. PSF: 14.5±6.6 degrees, P =0.012) varied. Preoperative to postoperative changes in MCC (2RVBT: -32.0±11.3 degrees vs. PSF: -37.2±13.3 degrees, P =0.044) and L5 tilt (-13.8±9.0 degrees vs. PSF: -8.1±6.8 degrees, P =0.001) differed. Revision rates were similar (2RVBT: 2.0%, PSF: 4.0%, P =0.57). In 2RVBT, 3 tethers broke, 1 revision occurred for a broken tether, and 1 pleural effusion needed thoracocentesis. In PSF, 1 superficial infection needed surgery, and 1 revision was for add-on phenomenon. After PSM for Lenke classification, 54 patients remained (27 in each group). At 2 years, 2RVBT showed less MCC correction (-30.8±11.8 degrees vs. -38.9±11.9 degrees, P =0.017), but greater L5 tilt correction (-14.6±10.0 degrees vs. -7.5±6.0 degrees, P =0.003).

CONCLUSIONS

This study with a minimum 2-year radiographic follow-up demonstrates that 2RVBT results in greater L5 tilt correction when compared with posterior spinal fusion after PSM for Lenke classification and similar rates of revision surgery.

LEVEL OF EVIDENCE: Level III.