Clinical outcomes of tri-cortical pedicle screw oblique fixation technique in correction surgery of degenerative kyphoscoliosis in adult patients

English Keywords:Kyphoscoliosis  Tri-cortical pedicle screw  Proximal junctional kyphosis  Degenerative spinal deformity

English Abstract:

  【Abstract】 Objectives: To evaluate the clinical outcomes of tri-cortical pedicle screw(TPS) oblique fixation technique utilized in degenerative kyphoscoliosis. Methods: 93 patients treated in Nanjing Drum Tower Hospital between January 2020 and November 2022 were retrospectively reviewed. Among the patients, 42 underwent intraoperative O-arm navigation system guided bilateral TPS oblique fixation at upper instrumented vertebra(UIV) were enrolled in the TPS group, and the other 51 patients underwent traditional pedicle screw fixation were enrolled in the pedicle screw group. There were no statistical differences in baseline data such as age and preoperative imaging between the two groups(P>0.05). The follow-up period was 33.2±4.2 months in the TPS group and 32.1±9.0 months in the pedicle screw group, with no significant difference between the two groups(P=0.458). Cobb′s angle, regional kyphosis(RK), sagittal vertical axis(SVA), and coronal balance distance(CBD) were measured on X-ray images taken before operation, immediate after operation, and at final follow-up. The Scoliosis Research Society(SRS-22) questionnaires and Oswestry disability index(ODI) were utilized to evaluate the patient-reported outcomes. Complications during follow-up were also recorded. Result: 93 patients all successfully completed the surgery. In TPS group, the pre-operative Cobb angle was 39.9°±20.8°, and the immediate post-operative Cobb angle was 19.8°±10.8°; RK was 47.8°±19.6° and 23.6°±10.5°immediate post-operation. In pedicle screw group, the pre-operative Cobb angle was 36.8°±24.3°, and the immediate post-operative Cobb angle was 21.3°±13.0°; RK was 47.8°±19.6° and 23.6°±10.5° immediate post-operation. In both groups, the immediate postoperative Cobb angle, RK, SVA, and CBD all improved significantly compared with the preoperative values(P<0.05), while no statistical difference was observed between groups(P>0.05). At final follow-up, the SVA of pedicle screw group was increased significantly compared with that at immediate postoperation, which was significantly bigger than that of TPS group(P<0.05), while Cobb angle, RK, CBD of the pedicle screw group were not significantly different from those at immediate postoperation(P>0.05). Compared to preoperative scores, significant improvements were noted in the quality of life scores across multiple domains, including activity/functional status, self-image, pain, and mental health(P<0.05). Pain-related scores were significantly higher in the pedicle screw group than in the TPS group. There was no statistically significant difference in ODI score between the two groups at preoperation. The ODI score at final follow-up was improved significantly in both groups, while no significant difference was observed between groups(P>0.05). In the TPS group, 3 cases developed proximal junctional kyphosis(PJK) during follow-up(7.1%), with one patient undergoing revision surgery. In contrast, 14 patients in the pedicle screw group developed PJK(27.5%), indicating a significantly higher incidence compared to the TPS group(P=0.011). Conclusions: The TPS oblique fixation technique can obtain satisfying orthopedic effects in treating degenerative kyphoscoliosis in adult patients, and reduce the incidence of PJK significantly.