A practical method for the retrieval of tulip-head polyaxial pedicle screw by reusing the rod in revision and implants removal surgery: introduction of technique and evaluation of clinical outcomes.

BACKGROUND

The removal of spinal implants is needed in revision surgery or in some cases whose fracture had healed or fusion had occurred. The slip of polyaxial screw or mismatch of instruments would make this simple procedure intractable. Here we introduce a simple and practical method to address this clinical dilemma.

METHODS

This is a retrospective study. The patients underwent new technique for retrieving the implants from July 2019 to July 2022 were labeled as group A, while the patients underwent traditional implants retrieval technique from January 2017 to January 2020 were labeled as group B. Patients in each group were subdivided into revision surgery group (r group) and simple implants removal group (s group) according to the surgery fashion. For the new technique, the retrieved rod was cut off to a proper length which was matched with the size of tulip head, and was replaced into the tulip head. After tightened with nut, a monoaxial screw-rod "construct" was formed. Then the "construct" can be retrieved by a counter torque. The operation duration, intraoperative blood loss, post-operative bacteria culture, hospital stay and costs were analyzed.

RESULTS

A total of 116 polyaxial screws with difficult retrieval (43 screws in group A, 73 screws in group B) in 78 patients were recorded, in which 115 screws were successfully retrieved. Significant differences were found in the mean operation duration, intraoperative blood loss when comparing the r group in group A and B, as well as the s group in group A and B (P < 0.05). There were no significant differences in hospital stay and costs between group A and B. Three patients were found positive bacteria culture of drainage tube/tape in group A (3/30), while 7 patients in group B (7/48). The most prevalent bacteria was Propionibacterium acnes.

CONCLUSION

This technique is practical and safe in retrieving tulip head poly-axial screw. Reduced operation duration and intraoperative bloods loss may potentially alleviate the hospitalization burden of patients. Positive bacterial cultivation results are common after implants removal surgery, but they rarely represent an organized infection. A positive culture with P. acnes or S. epidermidis should be interpreted with caution.