Purpose
Vertebral body tethering (VBT) has shown promising results but also a high tether breakage rate, which has been reported in up to 48% of patients. Tether breakages can lead to loss of correction, and the most used definition for tether breakage is a loss of segmental correction of > 5°. However, there may also be some breakages that do not have a negative influence on curve correction. Analyzing the real breakage rate was the aim of this study.
Methods
All patients who underwent anterior revision surgery after VBT were included in this retrospective study. Real (intraoperatively confirmed) tether breakages were compared to preoperatively suspected tether breakages. The definition for a suspected tether breakage was an angular change of more than 5° between an early and the latest radiograph.
Results
Ten patients who received 11 revision surgeries with a total of 15 revised curves were analyzed. Of the 80 analyzed segments, 36 were found to have a breakage. Of these 36 segments, 20 were suspected to be broken preoperatively. Sixteen breakages were not identified on preoperative radiographs (44%). One suspected broken tether was intraoperatively found to be intact.
Conclusion
By using the > 5° rule, only 56% of the tether breakages could be diagnosed. On the other hand, many tether breakages will not result in a loss of correction.
