Analysis on the related factors of misplacement of freehand pedicle screws via posterior approach in degenerative scoliosis.

BACKGROUND

To study the risk factors associated with misplacement of freehand pedicle screws through a posterior approach for degenerative scoliosis.

METHODS

A total of 204 patients who underwent posterior pedicle screw-rod system surgery for degenerative scoliosis in our hospital from December 2020 to December 2023 were retrospectively analyzed. Patient demographics, radiographic accuracy, and surgery-related information were recorded.

RESULTS

A total of 204 patients were included. A total of 2496 screws were placed. 2373 (95.07%) were in good position. Misplacement screws were 123 (4.93%). None of the patients had postoperative spinal nerve symptoms due to screw malposition. The misplacement rate of thoracic (T10-T12) pedicle screws was 11.11% (60/540). Misplacement of pedicle screws in the lumbar spine (L1-L5) was 3.22% (63/1956). Age, gender, surgeon, and operation time had no significant effect on misplacement of pedicle screws (P>0.05). Body mass index, Hu value, number of screw segments, Cobb angle, vertebral rotation, and spinal canal morphology had some correlation with pedicle screw misplacement. Among them, BMI, Hu value, number of screw segments, Cobb angle, and vertebral rotation grade were independent risk factors for PS misplacement (P<0.05). The height of the posterior superior iliac spine had a significant effect on pedicle screw misplacement in the lower lumbar spine (L4/5) (P<0.05).

CONCLUSION

BMI, Hu value, number of screw levels, Cobb angle, and vertebral rotation grade were independent risk factors for pedicle screw misplacement in patients with degenerative scoliosis. Posterior superior iliac spine height has a large impact on PS placement in the lower lumbar spine. Patients with degenerative scoliosis should be preoperatively planned for the size and direction of the placed screws by X-ray and CT three-dimensional, to reduce the misplacement rate of pedicle screws.