The rotation of preoperative-presumed lowest instrumented vertebra: Is it a risk factor for distal adding-on in Lenke 1A/2A curve treated with selective thoracic fusion?

Zhong He, Xiaodong Qin, Rui Yin, Zhen Liu, Bangping Qian, Yong Qiu, Zezhang Zhu

August 2020, Volume 29, Issue 8, pp 2054 - 2063 Original Article Read Full Article

First Online: 04 March 2020

Purpose

To investigate whether the rotation of preoperative-presumed lowest instrumented vertebra (LIV) is a risk factor for adding-on (AO) in adolescent idiopathic scoliosis (AIS) treated with selective posterior thoracic fusion (sPTF).

Methods

A total of 196 AIS patients of Lenke type 1A or 2A with minimum 2-year follow-up after sPTF with all pedicle screw instrumentation were included. Radiographical parameters were measured as follows: preoperative rotation angle of presumed LIV and LIV + 1, LIV + 1/LIV rotation difference, postoperative rotation angle of LIV and LIV derotation angle on CT scans. Patients were classified into AO group and non-AO group during the follow-up. The parameters were compared between the two groups to investigate risk factors for AO.

Results

Among 196 patients, 40 (20.4%) patients developed with AO at the final follow-up. Compared with non-AO group, patients with AO had significantly larger preoperative rotation angle of presumed LIV (8.8° ± 3.4° vs. 3.4° ± 2.9°, P

Conclusion

AIS patients with low Risser grade and large preoperative rotation angle of presumed LIV are more likely to develop with AO after sPTF. Moreover, for the patients with LSTV selected as LIV, preoperative rotation of presumed LIV might be still a risk factor associated with the occurrence of AO.

Level of Evidence

III

Graphic abstract

These slides can be retrieved under Electronic Supplementary Material.[graphic not available: see fulltext]

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