Incidence of lumbar spine pedicle breach after percutaneous screw fixation: a radiographic evaluation of 601 screws in 151 patients.

STUDY DESIGN: Prospective clinical study.

OBJECTIVES: Although percutaneous pedicle screw fixation continues to be increasingly practiced, there remain few reports specifically addressing the accuracy and clinical safety of this technique. The goal of this study is to evaluate the accuracy of fluoroscopically guided pedicle screw placement in the lumbar spine.

SUMMARY OF BACKGROUND DATA: Pedicle breach rates vary substantially in the literature. Pedicle breach rates have been reported to be as high as 29% with the traditional, open technique. With the use of computer-assisted 2-dimensional fluoroscopy, breach rates have been reported between 5% and 23%. Furthermore, in a series of 225 pedicles instrumented with 3-dimensional fluoroscopy, the reported breach rate was 1.8%.

METHODS: A total of 151 patients were evaluated after instrumented single-level or 2-level minimally invasive transforaminal lumbar interbody fusion with 601 screws placed for percutaneous fixation. The treated patients had an average age of 56.6 y (20-85 y) and there were 129 cases of single-level and 22 cases of 2-level. The levels of pedicle screw fixation included (level, patient numbers): L1/L2 (1), L2/L3 (2), L3/L4 (33), L4/L5 (101), L5/S1 (46). Radiographic results included postoperative computed tomographic scan. Patients were followed prospectively for potential clinical symptoms.

RESULTS: In a total of 601 instrumented pedicles, there were 37 pedicle breaches (6.2%). Of these, 22 (3.7%) were significant breaches (≥3 mm). The level of the breached pedicles were L3 (5/46, 10.2%), L4 (12/201, 7.0%), L5 (15/158, 9.5%), S1 (3/47, 3.4%). The side/location of breach was characterized as follows: medial (22), lateral (12), superior (2), and inferior (1). There were 2 symptomatic breaches, both associated with a medial breach at the L5 pedicle. Symptoms from these events were transient and did not require hardware repositioning. There were no other complications.

CONCLUSIONS: Percutaneous pedicle screw fixation in the lumbar spine continues to be a technique embraced by modern spinal surgeons. The use of intraoperative fluoroscopic guidance is both a clinically safe and accurate method for instrumentation and is of comparable accuracy to other techniques. Although trajectory errors may occur, they are of rare clinical significance.