Clinical Evidence

Clinical Data Summary

Spinal tethering is being studied in a 57-patient clinical trial of scoliosis patients. In this trial, one subject was found to not be eligible for the study, thus this subject was included in the safety analysis but excluded from other analyses. This study had 48 girls and 8 boys who had a spinal tethering surgery when they were around 12 years old. Their tethering was done using a different but similar device made up of screws and a tethering cord. The implants you may receive is a new device made specifically to be used in smaller patients. The patients enrolled in this study see their doctor regularly for follow up appointments until they are fully grown (approximately 18 years old).


A Cobb angle is a measurement of the curvature of the spine in degrees and is commonly used to evaluate how severe a particular case of scoliosis is. On average, patients in this study saw the Cobb angle of their curve reduce by more than 50%, from 40.4° to 17.6°. A Cobb angle of 10° is the minimum angle for a diagnosis of scoliosis. Patients also saw a reduction in the size of their rib hump prominence from an average of 13.6° to 8.7°. Following surgery, fewer patients on average reported unlevel shoulders and unlevel hips.


Spine surgery is serious, and complications are possible. The most common complications seen in this study were back pain, overcorrection of the curve, nausea/vomiting, pain in the arms or legs, the need for additional surgery, and temporary numbness along the side of the chest or hip. Overcorrection occurs following surgery when the curve becomes perfectly straight and then keeps correcting in the opposite direction. Your doctor will monitor your curve carefully with x-rays to determine if overcorrection is happening. If the overcorrection gets too large, an additional surgery can be performed to treat this problem by loosening or cutting the cord. This surgery is often less invasive than the original surgery and has a quicker recovery.

In this study 8 of the 57 patients had an additional surgery. Five (5) of the 8 patients had surgery to fix overcorrections, one surgery was performed because the cord broke before the patient finished growing, one surgery was due to the patient developing a new curve in another area of their spine, and one surgery was due to a slippage in the spine that was unrelated to the tethering procedure and caused the spinal canal to narrow.


This study shows that there is a likely benefit of surgery with The Tether - Vertebral Body Tethering System, however complications are possible. Should you have more questions, ask your doctor for more details about the clinical study and its results.