A multi-level drill guide template improves the accuracy of pedicle screw placement in lumbar spine

D.-W. Ge, L. Yang, X. Chen, J. Tang, H.-T. Chen, H.-J. Li, T. Sui, Y. Zhuang, S.-N. Zheng, X.-J. Cao

Department of Orthopedics, the First Affiliated Hospital of Nanjing Medical University, Nanjing, China. xiaojiancao001@126.com

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• Orthopedics

OBJECTIVE: Free-hand technique is widely used in pedicle screw placement for lumbar spine and generally safe; however, screw malposition still occurs. To develop a novel multi-level drill guide template for pedicle screw placement in lumbar spine and evaluate its accuracy.

MATERIALS AND METHODS: Twelve lumbar cadaveric specimens were randomly allocated into guide template group (n=6) and free-hand group (n=6). Computed tomography (CT) scans were obtained for reconstruction of three-dimensional (3D) model of each lumbar vertebra, and further an individual guide template was designed. Then the templates and their corresponding vertebra were developed by rapid prototyping (RP) technology. With the guide of the templates, screws were inserted via mini-open Wiltse approach. The positions of the screws were assessed based on postoperative CT images.

RESULTS: In total, 120 pedicle screws inserted (guide template group: n=60 vs. free-hand group: n=60). For all 30 vertebras in the guide template group, all pre-designed personalized drill guide templates can be fitted into the facet joints of each vertebra well. Furthermore, our results revealed a significant improvement for the guide template group in the accuracy rate (p=0.026).

CONCLUSIONS: Armed with advantages of minimal invasion, enhanced accuracy and safety, the novel technique of multi-level drill guide template can be properly applied in pedicle screw placement for lumbar spine and promises to be a potential option in clinical application.

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