ABSTRACT
STUDY DESIGN: A retrospective study. OBJECTIVES: We report the efficacy of the entry point and approach angle of a working cannula using preoperative prone abdominal computer tomography (PACT). SUMMARY OF LITERATURE REVIEW: To date, there are no reports on the entry point and approach angle of a working cannula when performing transforaminal percutaneous endoscopic lumbar discectomy (TPELD) with consideration of the individual anatomic variations and characteristics of herniated disc and surgical instruments. MATERIALS AND METHODS: Cases of herniated intervertebral discs from L4-5, who have previously undergone PACT before TPELD, were included. A total of 25 patients were observed over a 1 year period. The entry point and approaching angle of the working cannula with PACT were calculated, and the results were applied to the TPELD. The clinical results were assessed 1 month after surgery using the VAS, ODI and MacNab criteria, and were confirmed by a radiology and MRI examination. RESULTS: The preoperative measured data using PACT showed that the mean approaching distance and mean approaching angle of the working cannula were 12.4 cm and 75.4 degree, respectively. The VAS improved from a mean of 8.1 preoperatively to a mean of 2.3 12 months after surgery. The ODI improved from a mean of 59 preoperatively to a mean of 24 at 12 months after surgery. According to the MacNab criteria, all patients were classified as either excellent and good during the follow up periods. The extruded disc of all patients had been well removed according to the MRI scan performed 1 month after surgery. CONCLUSIONS: The scientific approach method using PACT based on the characteristics of patients and surgical instruments can be performed easily and accurately, and access and decompress the extruded disc directly.