Free hand pedicle screw placement in the thoracic spine: Is it safe?

Study Design. A retrospective study. Objective. To evaluate the safety of a free hand technique of pedicle screw placement in the thoracic spine at a single institution over a 10-year experience. Summary of Background Data. Thoracic pedicle screw fixation techniques are still controversial for thoracic deformities because of possible complications including neurologic. Materials and Methods. Three hundred ninety-four consecutive patients who underwent posterior stabilization utilizing 3204 transpedicular thoracic screws by 2 surgeons from 1992 to 2002 were analyzed. The mean age was 27 + 10 years ( range 5 + 3 - 87 + 0 years) at the time of surgery. Etiologic diagnoses were: scoliosis in 273, kyphosis in 53, other spinal disease in 68. Pedicle screws were inserted using a free hand technique similar to that used in the lumbar spine in which anatomic landmarks and specific entry sites were used to guide the surgeon. A 2-mm tip pedicle probe was carefully advanced free hand down the pedicle into the body. Careful palpation of all bony borders ( floor and four pedicle walls) was performed before and after tapping. Next, the screw was placed, followed by neurophysiologic ( screw stimulation with rectus abdominus muscle recording) and radiographic ( anteroposterior and lateral) confirmation. An independent spine surgeon using medical records and roentgenograms taken during treatment and follow-up reviewed all the patients. Results. The number of the screws inserted at each level were as follows ( total n = 3204): T1, n = 13; T2, n = 60; T3, n = 192; T4, n = 275; T5, n = 279; T6, n = 240; T7, n = 230; T8, n = 253; T9, n = 259; T10, n = 341; T11, n = 488; T12, n = 572. Five hundred seventy-seven screws inserted into the deformed thoracic spine were randomly evaluated by thoracic computed tomography scan to assess for screw position. Thirty-six screws (6.2%) were inserted with moderate cortical perforation, which meant the central line of the pedicle screw was out of the outer cortex of the pedicle wall and included 10 screws (1.7%) that violated the medial wall. There were no screws ( out of the entire study group of 3204) with any neurologic, vascular, or visceral complications with up to 10 years follow-up. Conclusions. The free hand technique of thoracic pedicle screw placement performed in a step-wise, consistent, and compulsive manner is an accurate, reliable, and safe method of insertion to treat a variety of spinal disorders, including spinal deformity.