The Harms Study Group retrospectively compared anterior vertebral body tethering to posterior spinal fusion and published their results, “Anterior Vertebral Body Tethering Compared with Posterior spinal fusion for Major Thoracic Curves,” in the December 21, 2022 edition of The Journal of Bone and Joint Surgery.
“Vertebral body tethering has been a career long effort of mine beginning with animal research on the feasibility of modulating spinal growth initiated over 20 years ago,” stated co-author Peter Newton, M.D. to OTW.
Dr. Newton, chief of the Division of Orthopedics & Scoliosis at Rady Children’s Hospital in San Diego, California, added, “With now over a decade of clinical experience, this is an important paper for two reasons.
- It is the first large scale multicenter study of vertebral body tethering and
- secondly it provides a matched comparison to the gold standard posterior spinal fusion option that patients with operative idiopathic scoliosis are faced with choosing between.”
The researchers used two methods of propensity-guided matching, pairing patients with thoracic idiopathic scoliosis who had anterior vertebral body tethering (minimum 2-year follow-up) to posterior spinal fusion patients. A total of 237 patients treated with anterior vertebral body tethering were compared with 237 patients treated with posterior spinal fusion. The team compared radiographic, clinical, and Scoliosis Research Society 22-Item Questionnaire data both preoperatively and at the 2-year (or longer) follow-up.
According to the findings, patients in the anterior vertebral body tethering group were younger, had a smaller mean thoracic curve preoperatively (48 ± 9°; range, 30° to 74°; compared with 53 ± 8°; range, 40° to 78° in the posterior spinal fusion group), and had less initial correction (41% ± 16% correction to 28° ± 9° compared with 70% ± 11% correction to 16° ± 6° in the posterior spinal fusion group).
Dr. Newton and his team also found:
- deformity at the time of the latest follow-up was 27° ± 12° (range, 1° to 61°) for anterior vertebral body tethering and 20° ± 7° (range, 3° to 42°) for posterior spinal fusion.
- 76% of anterior vertebral body tethering patients had a thoracic curve of <35° at the latest follow-up compared with 97.4% of posterior spinal fusion
- A residual curve of >50° was present in seven anterior vertebral body tethering patients (3%), three of whom underwent subsequent posterior spinal fusion, and in none of the posterior spinal fusion patients (0%).
- Forty-six subsequent procedures were performed in 38 anterior vertebral body tethering patients (16%), including 17 conversions to posterior spinal fusion and 16 revisions for excessive correction, compared with 4 revision procedures in 3 posterior spinal fusion patients (1.3%).
Anterior vertebral body tethering patients had lower median preoperative Scoliosis Research Society-22 mental-health component scores and saw less improvement in the pain and self-image scores between preoperatively and the ≥2-year follow-up.
In the more strictly matched analysis (n = 108 each), 10% of patients in the anterior vertebral body tethering group and 2% of patients in the posterior spinal fusion group required further surgical intervention.
Dr. Newton told OTW, “Although this paper only reports the two-year postop outcomes, these results demonstrate what a patient can expect with regard to scoliosis correction and the risk of early revision surgery as well as the likelihood of avoiding a posterior spinal fusion if that is a strong desire of the patient.” “The additional research required for vertebral body tethering is substantial, the most obvious of which is longer term follow-up. The durability beyond two years is crucial to understand. Ongoing follow up of this cohort within the Harms Study Group continues and we hope to present five-year outcomes as the data becomes available.”
