1. Introduction
Annually, more and more fusion spine surgeries are performed, which leads to a higher number of implant removal and revision procedures [1, 2]. Tulip-head screws, are among the many implant systems developed with advances in spinal surgery. Removing hardware can be quite a challenge, especially when screwdrivers are mismatched or implant sets are no longer available. If the proper screwdriver is not available, removing polyaxial screws can be extremely difficult because the tulip-head component rotates independently of the screw shaft. We propose a simple and practical method for retrieving tulip-head pedicle screws during revision spine surgery or implant removal.

2. Methods and Materials/Patients 
Technical note
An Allen key (hex-head wrench), an anti-torque wrench, and a one-inch-long rod are required for our technique. An Allen key is used to remove nuts from screws or connectors when a proper screwdriver is not available. A one-inch rod is short enough to avoid causing damage to the surrounding structures. The rod is inserted into the tulip of the screw and tightened with a nut so that the screw head moves as a single unit (Figure 1A). Then, the rod is turned counterclockwise with an anti-torque wrench to remove the pedicle screw (Figures 1B and 1C). The local Ethics Committee waived ethical approval because all procedures were part of routine care, and no identifying information about participants is available in the article. Using this simple and practical method, we were successful in removing tulip-head pedicle screws from patients undergoing revision spine surgery or implant removal (Figure 2). This procedure did not result in any complications.

3. Discussion
Spinal transpedicular screw fixation is a widely used spinal fixation technique for a wide range of spinal disorders. As the number of procedures performed grows each year, so does the need for these implants to be removed [2]. Some implant systems are only used for a limited time, and their use or import may cease after a certain period. For the removal of tulip-head pedicle screws, we recommend using our simple method, which requires only an anti-torque wrench, an Allen wrench, and a one-inch rod. 

4. Conclusion
Our simple and practical method helps retrieve polyaxial tulip-head pedicle screws during revision spine surgery to be replaced with a larger diameter screw or before different types of osteotomies.

Ethical Considerations
Compliance with ethical guidelines
Ethical approval was waived by the local Ethics Committee of the Hospital given the retrospective nature of the study and all the procedures were part of the routine care. There is no information (names, initials, hospital identification numbers, or photographs) in the submitted manuscript that can be used to identify patients.

Funding
This research did not receive any grant from funding agencies in the public, commercial, or non-profit sectors.

Authors' contributions
Conceptualization, methodology and supervision: Abolfazl Rahimizadeh; Investigation and writing: All authors.

Conflict of interest
The authors declared no conflict of interest. 


References

1. Staartjes VE, Klukowska AM, Schröder ML. Pedicle screw revision in robot-guided, navigated, and freehand thoracolumbar instrumentation: A systematic review and meta-analysis. World Neurosurgery. 2018; 116:433-43.e8. [DOI:10.1016/j.wneu.2018.05.159] [PMID]
2. Kose KC, Isik C, Altinel L, Ates A, Ozdemir M. Easy retrieval of polyaxial tulip-head pedicle screws by “U” rod technique. European Spine Journal. 2010; 19(1):144-6. [DOI:10.1007/s00586-009-1096-4] [PMID]