Vertebral body tethering may yield outcomes similar to posterior spinal fusion
SAN DIEGO — Results showed vertebral body tethering for treatment of adolescent idiopathic scoliosis may have outcomes comparable to that of posterior spinal fusion.
Baron S. Lonner, MD, and colleagues compared patients with adolescent idiopathic scoliosis who underwent vertebral body tethering with patients who underwent posterior spinal fusion. The groups were matched for curve type, age and kyphosis. Lonner noted he performed all operations.
“We had 25 matched pairs and we looked at radiographic outcomes, complication rates and operative statistics, like blood loss and operative time, and we assessed patient-reported outcomes with the Scoliosis Research Society Questionnaire,” Lonner, chief of minimally invasive scoliosis surgery at Mount Sinai Hospital in New York and professor of orthopedic surgery at Icahn School of Medicine, told Healio Orthopedics about research presented at the American Academy of Orthopaedic Surgeons Annual Meeting.
Patients in both groups had similar age and major (largest) curvature prior to surgery, according to Lonner. He added the groups also had similar corrections of the major structural curvature, as well as the secondary compensatory curvature. Although the groups had similar rotational correction, Lonner noted the spinal fusion group had slightly improved correction for thoracolumbar curves compared with the vertebral body tethering group.
“So, [there was] slightly more rotational correction for fusion,” Lonner said. “Although clinically similar, [the correction was] statistically slightly greater for the fusion patients.”
Complication rates included one infection and one screw requiring revision surgery in the fusion group compared with three patients with cord breakage in the vertebral body tether group, Lonner noted. Despite the cord breakages, Lonner said reoperation was not required. He added the two groups had no significant differences in patient-reported outcomes in the Scoliosis Research Society Questionnaire. However, Lonner said patients who underwent vertebral body tethering had one-fifth less blood loss compared with patients who underwent spinal fusion.
“We still have a lot of work to do in studying outcomes and finding the sweet spot, the best indications and the best timing for performing [vertebral body tethering] VBT, but I think it will have an increasingly prominent role in the treatment of the adolescent patient with scoliosis and will allow patients to have at least partial preservation of motion and flexibility,” Lonner said.
Perspective
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The study by Baron S. Lonner, MD, and colleagues addresses a timely and important question regarding two procedures for management of adolescent idiopathic scoliosis. The relatively new and relatively untested procedure, vertebral body tethering, which is gaining in popularity at some centers, was compared with a long established procedure, posterior spinal fusion, which is known to have very successful long-term outcomes with a low complication rate, even 10 years later.
A comparable cohort of patients in the two groups was compared retrospectively at 2 years after surgery. This study did show similar rates of curve correction in the coronal plane, which differs from previous work. Vertebral body tethering had slightly better correction of kyphosis, as anterior surgery can create some shortening of the anterior spinal column, but posterior spinal fusion had better axial plane correction, since posterior implants extend past the instantaneous axis of rotation and are stronger in this plane of rotational correction. In fact, three of the vertebral body tethering patients underwent thoracoplasty to assist with rib hump correction, while none of the posterior spinal fusion patients required it. Vertebral body tethering patients lost less blood intraoperatively and operative time was similar, as were patient-rated outcomes.
However, two important questions remain to be answered: Will the complication of broken cords increase over time, as patients are followed longer, and will this increase the need for reoperation? And, did patients actually benefit from the theoretical motion that was preserved by avoiding posterior spinal fusion? The early results are promising, but growing children need longer follow-up than 2 years to convince surgeons and families that this procedure will be reproducible and durable. The elusive goal of spinal curvature correction with motion preservation may be closer with vertebral body tethering, but what price must patients and families pay along the way?
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Lonner BS, et al. Paper 366. Presented at: American Academy of Orthopaedic Surgeons Annual Meeting. Aug. 31-Sept. 3, 2021; San Diego.
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