Experience of using uniplanar screws in combination with direct vertebral rotation for correction of Lenke type 5 and 6 scoliotic deformities

Objective. To evaluate the effectiveness of uniplanar pedicle screws in combination with direct vertebral rotation (DVR) and their impact on the choice of the lower instrumented vertebra in the correction of idiopathic scoliosis with a primary lumbar curve.

Material and Methods. A retrospective cohort study of 33 patients divided into two groups was conducted. Patients in Group 1 (n = 17) underwent correction using uniplanar screws and DVR, and those in Group 2 (n = 16) underwent correction using multiaxial pedicle screws according to the standard technique. Radiographic parameters (Cobb angle) and CT data (translation, axial rotation of the spine) and the SRS-22 questionnaire were used for the analysis.

Results. A clinically significant threshold for the initial Cobb angle of 60° was identified. For deformities ≤60°, the use of uniplanar pedicle screws with DVR provided statistically significantly better correction of the deformity (p = 0.037) and axial rotation (p < 0.001) with a shorter construct length. For deformities >60°, no significant differences in Cobb angle correction and translation between the groups were found, with the exception of better derotation achieved in Group 1. According to the SRS-22 questionnaire results, there were no significant differences in the patients’ subjective assessment of their condition, except for the “self-image” domain, where the score was higher in Group 1.

Conclusion. The use of uniplanar screws in combination with direct vertebral rotation (DVR) technique is effective for the correction of moderate lumbar scoliotic deformities (≤60° Cobb angle). This approach allows for three-dimensional correction and preserves motion segments due to a shorter construct (fixation up to L3). The 60° threshold serves as a practical guide for choosing the fixation type: for smaller angles, uniplanar pedicle screws with DVR are preferable, while for larger angles, the screw type does not have a decisive influence on the correction.

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