Methods

Radiological data of 93 patients (84 females, 9 males) who met the inclusion criteria were retrospectively evaluated. The relationship between the L3 vertebra and the central sacral vertebral line, the portion of the L3 vertebra in the stable zone of Harrington, the parallelism of the L3 with the sacrum, and the tilt and rotation of the L3 on TrUGA radiographs were evaluated for the selection of the lowest instrumented vertebrae (LIV). Clinical results were analyzed using the Scoliosis Research Society-22 (SRS-22) questionnaire.

Results

The mean follow-up period of the study group was 149.3 months. According to the Lenke classification, 29 patients had Type 3C, 33 had Type 5C, and 31 had Type 6C curves. The preoperative analysis was based on standing anteroposterior (AP), supine traction, and bending X-rays, and the L3 vertebra was selected as the LIV in 37 patients (40%). These X-rays suggested L4 as the LIV in 56 patients (60%); however, based on our study criteria, the L3 vertebra was selected. No significant loss of correction was observed nor additional surgery due to decompensation was required in the follow-up period.

Conclusion

The use of TrUGA radiographs with the identified criteria is an efficient alternative method in the selection of the LIV in patients with Lenke Type 3C, 5C, and 6C curves.