The utility of preoperative computed tomography-guided screw marking in thoracic spine surgery

Abstract

Introduction: Wrong-level surgery (WLS) is a preventable yet severe complication in spinal surgery, particularly for pathologies located in the thoracic spine, where localizing the intended level is more challenging compared to the lumbar or cervical spine, which have more distinct landmark structures and fewer vertebral bodies.

Research question: Evaluate the impact of preoperative, computed tomography (CT)-guided screw marking on avoiding WLS and optimizing intraoperative workflows.

Material and methods: We conducted a retrospective case-control study at Bern University Hospital, enrolling all patients treated with thoracic spinal surgery between February 2017 and August 2022. Patients that received preoperative, CT-guided screw marking in the pedicle at the index level were compared to those without preoperative marking. Data included clinical features, radiological parameters, and complications. Primary endpoint: occurrence of WLS. Secondary endpoints: duration of intraoperative fluoroscopy, operating room (OR) occupancy time, and complications.

Results: A total of 117 patients were included: 71 in the screw group and 46 in the control group. The mean age was 54 (±16) years. Significant differences were found in the indication for surgery (p = 0.002). No significant differences were observed in duration of intraoperative fluoroscopy, effective dose, or total OR occupancy time. WLS occurred in only one patient in the control group and none in the screw group. Surgical complications were similar between groups.

Discussion and conclusion: We present a safe technique with a low complication rate for preoperative marking of the index vertebra before thoracic spinal surgery, allowing spine surgeons to eliminate the risk of WLS.

Keywords: Intraoperative fluoroscopy; Spine surgery; Spontaneous intracranial hypotension; Wrong-level surgery.

Fig. 1

Illustration of the CT-guided, percutaneous screw marking technique. The first step includes local anaesthesia of the skin, soft tissue, and the periosteum (A). Navigation of a K-wire to the index pedicle (B). The trocar is then introduced via the K-wire (C). After removal of the K-wire, the screw is inserted through the trocar into the bone (D). The final result is documented for operation planning (E).

Fig. 2

CT image documentation of screw marking in the thoracic spine. CT scan to locate the correct position (A). Positioning of the K-wire at the correct location (B). Documentation of the screw within the surgical trajectory (C). 3D-volume rendered reconstruction with the inserted screw in the index pedicle (D).

Fig. 3

Intraoperative fluoroscopy (A) and intraoperative images showing the inserted screw in relation to bony landmarks before (B) and after left-sided partial hemilaminectomy (C). The arrows point at the screw head.