The Tether™ - Vertebral Body Tethering System Post Approval Study

While spinal fusion remains the standard surgical treatment for progressive idiopathic scoliosis, concerns about the long-term effects of spinal fusion have led to the investigation of growth-modulation techniques. Anterior Vertebral Body Tethering (AVBT) is one such technique that utilizes growth modulation to remodel the shape of the vertebra and straighten scoliotic curves in skeletally immature individuals. In this technique, screws are inserted at each vertebral level for the length of the convex side of the curve. A strong cord is connected through the screw tulip heads and used to initially straighten the curve as each level is fixed with a set screw. Following surgery and during the growth period the spine begins to remodel according to the Hueter-Volkmann Law, bone growth is relatively inhibited in areas of increased pressure (convex or tethered side) and relatively stimulated in areas of decreased pressure or tension (concave side). Following this principle, AVBT has been shown to alter spinal growth with the potential to correct scoliosis while maintaining spine flexibility.

The objective of the study is to assess the ongoing safety and probable benefit of The Tether HUD which was approved by the FDA under an HDE. Subject enrollment and data collection will be managed by the Harms Study Group (HSG) and Setting Scoliosis Straight Foundation (SSSF) Registry. Institutions that are HSG members or affiliates, with Investigators/surgeons that are trained and approved to perform surgeries with The Tether, will participate in the registry. Ten sites from this group will be identified as study sites specific to this Tether post-approval study (PAS). Consecutive subjects from these sites, that meet the eligibility criteria of this study, will be flagged in the registry as the PAS cohort and the study endpoints will be assessed across this population.

• Adverse Events [Time frame: AVBT surgery to five year post-op]
• Reoperation [Time frame: AVBT surgery to five year post-op]
• Number of participants with new curves that develop above or below the tethered portion of the spine. [Time frame: AVBT surgery to five year post-op]
• Number of participants with secondary curves that progress to the point of clinical significance. [Time frame: AVBT surgery to five year post-op]
• Number of participants with device integrity failures including cord breakage and screw migration. [Time frame: AVBT surgery to five year post-op]
• Mean (SD) and distributions of sagittal balance (mm) from pre-op through last visit [Time frame: Baseline to five year post-op]
• Mean (SD) and distributions of lumbar lordosis (degrees) from pre-op through last visit. [Time frame: Baseline to five year post-op]
• Mean score of Scoliosis Research Society 22r Patient Questionnaire [Time frame: Baseline to five year post-op]
• Number of participants with compromised lung function [Time frame: Baseline to five year post-op]
• Measurement (degrees rotation) of trunk shape by scoliometer device. Mean (SD) [min, max] will be reported. [Time frame: Baseline to five year post-op]
• Trunk flexibility as determined by distance (cm) of flexion and lateral bend using fingertip to floor method. [Time frame: Baseline to five year post-op]