Postoperative Assessment of Pedicle Screws and Management of Breaches: A Survey among Canadian Spine Surgeons and a New Scoring System

Abstract

Study design: This study was designed as a survey amongst Canadian spine surgeon to determine a scoring system to standardize pedicle screw placement assessment.

Purpose: This study aimed to obtain and analyze the opinions of spine surgeons regarding the assessment of pedicle screw accuracy, with the goal of establishing clinical guidelines for interventions for malpositioned pedicle screws.

Overview of literature: Accurate placement of pedicle screws is challenging, and misalignment can lead to various complications. To date, there is no recognized gold standard for assessing pedicle screw placement accuracy. The literature is lacking studies attempting to standardize pedicle screw placement accuracy assessment.

Methods: A survey of the clinical methods and imaging criteria that are used for assessing pedicle screw placement accuracy was designed and sent to orthopedic and neurosurgery spine surgeons from the Canadian Spine Society for their anonymous participation.

Results: Thirty-five surgeons completed the questionnaire. The most commonly used modalities for assessing pedicle screw position postoperatively were plain X-rays (97%) and computed tomography (CT, 97%). In both symptomatic and asymptomatic patients, the most and least worrisome breaches were medial and anterior breaches, respectively. The majority of surgeons tended not to re-operate on asymptomatic breaches. More than 60% of surgeons would re-operate on patients with new-onset pain and a ≤4-mm medial or inferior breach in both thoracic and lumbar regions. If a patient experienced sensory loss and a breach on CT, in either the thoracic or lumbar levels, 90% and 70% of the surgeons would re-operate for a medial breach and an inferior breach, respectively.

Conclusions: Postoperative clinical presentation and imaging findings are crucial for interpreting aberrant pedicle screw placement. This study presents a preliminary scoring system for standardizing the classification of pedicle screws.

Keywords: Canadian spine surgeon survey; Guidelines for pedicle screw revision; Pedicle screw accuracy; Pedicle screw grading; Scoring system for pedicle screw placement.

Fig. 1. Asymptomatic patients with a postoperative pedicle screw breach. The majority of surgeons tended not to re-operate on asymptomatic breaches. However, almost 25% of surgeons would remove the misplaced screw when there was a medial or inferior breach, even when patients were asymptomatic.

Fig. 2. New-onset weakness in patients with a postoperative pedicle screw breach. When a medial breach was identified on computed tomography in the lumbar or thoracic region, all surgeons would re-operate to correct the screw position if the patient presented with new weakness. However, 50% of surgeons would not operate on a patient with new-onset weakness and an anterior thoracic or lumbar breach.

Fig. 3. New-onset pain in patients with a postoperative pedicle screw breach. More than 60% of respondents would re-operate on patients with new-onset pain and a medial breach of ≤4 mm in the thoracic or lumbar regions.

Fig. 4. New-onset sensory loss in patients with a postoperative pedicle screw breach. For a patient with sensory loss and a medial or inferior breach on computed tomography at the thoracic or the lumbar level, 90% and 70% of the surgeons, respectively, would perform a corrective operation.