P4.013: A New Option for the Surgical Treatment of Scoliosis, Second Generation Results of Vertebral Body Tethering.

Background: Adolescent Idiopathic scoliosis (AIS) is traditionally treated with posterior spinal fusion when curves approach 50 degrees. Vertebral Body Tether (VBT) surgery is a motion sparing, minimally invasive growth modulation procedure that is an alternate treatment. This study evaluates 2-4 yr results of VBT done after FDA approval in 2019, a second generation (2G) Cohort. To date all long-term data is from earlier first generation (1G) cohorts.

Methods: This retrospective review across 3 centers of consecutive AIS patients treated with VBT for scoliosis. Inclusion criteria matched FDA indications, curves of 35-65°, >2-year follow-up, adequate radiographs, and no prior spinal surgery. Skeletally mature patients and non-AIS cases were excluded. IRB approval and data use agreements were obtained.

Results: Included were 166 treated curves (142 patients) with an initial mean Cobb angle of 50° (35-65°) and average follow-up of 30 (24-55 months). 98 curves were thoracic, 20 thoracolumbar, and 24 double curves (thoracic and lumbar). Mean Cobb angles at post-op, one year, and two years were 25° (1-59°), 20° (-18-41°), and 21° (-10-49°) respectively. 40 subjects had >3-year follow-up, averaging 24° (-19-44°). In terms of the final Cobb angle, Excellent 0-25, or acceptable 26-39 results were seen in 96% of patients. Preoperative curve magnitude (p=.02) and Initial post-operative curve magnitude (p < 01) significantly influenced treatment success. Complications included no neurologic injuries or infections; 10% required reoperation (2 fusion, 4 reoperations for full or overcorrection, and 4 other reasons). Suspected tether rupture occurred in 27% of cases, but did not lead to subsequent surgery. SRS 22 Outcomes show improvement in Self Image, function, Satisfaction and total score (p <.01).

Conclusion: 2G VBT results show improved results with lower reoperation and complication rates compared to 1G VBT cohorts. Almost all current published data is based on earlier 1G Cohorts. Initial curve size and initial correction of the curve are key components of success. SRS patient reported outcomes support patient satisfaction. This data supports VBT integration as a standard of care options for eligible scoliosis patients. It would be beneficial for pediatricians and primary care providers to be aware of this minimally invasive and motion sparing option for treatment.