Objective
This study aimed to evaluate and compare the structural and functional characteristics of commercially available percutaneous epidural neuroplasty (PEN) catheters. Correlations among catheter properties were also examined to identify potential implications for clinical practice.
Methods
Nine PEN catheter products from different manufacturers were analyzed. Various physical properties were assessed, including catheter diameter, length, lever rotation angle, bending degree, and advancing force. Bending degree was measured at maximal and half-maximal lever rotation angles, with and without the guidewire inserted. Advancing force was determined by measuring pressure generated at the catheter tip upon contact with the electronic scale plate. Wilcoxon signed-rank and Spearman correlation tests were used for statistical analysis.
Results
Catheters exhibited considerable variations in structural and functional properties. The average catheter diameter and length were 2.0±0.6 mm and 287.8±30.3 mm, respectively; the mean lever rotation angle was 57°±21°. When the steering lever was rotated to its maximum allowable angle, proximal bend angle significantly increased in the wire-off state relative to the wire-on state, suggesting a trade-off between flexibility and structural support. Advancing force significantly varied across products; a positive correlation was observed between catheter diameter and advancing force.
Conclusion
This study identified substantial variations in catheter characteristics across different products. Increased catheter flexibility after guidewire removal may lead to positional instability, requiring careful consideration during PEN procedures. Larger catheter diameters were correlated with increased advancing force, which could influence ease of insertion and patient comfort. These findings emphasize the need for standardized PEN catheter specifications to optimize safety and efficacy in clinical practice.

Objective
To investigate the value of Hounsfield units (HUs) as an independent predictor of failed percutaneous drainage of spinal tuberculosis paraspinal abscess under computed tomography (CT) guidance.
Methods
A retrospective analysis was conducted on 61 patients who underwent CT-guided percutaneous drainage for spinal tuberculosis paraspinal abscess between October 2017 and October 2020. Preoperative CT scans were used to measure the HUs of the abscess. Patients were categorized into successful drainage (n = 49) and failed drainage (n = 12) groups. Statistical analysis involved independent sample t-tests and chi-square tests to compare between the 2 groups. Binary logistic regression was performed to identify independent predictive factors for drainage failure. Receiver operating characteristic (ROC) curves were employed to ascertain risk factor thresholds and diagnostic performance.
Results
Among the patients, 49 experienced successful drainage while 12 faced drainage failure. The mean HUs of abscesses in the failed drainage group were significantly higher than those in the successful drainage group (p < 0.001). ROC analysis revealed an area under the curve of 0.897 (95% confidence interval, 0.808–0.986) for predicting drainage failure based on HUs. The optimal HU cutoff value for predicting drainage failure was 22.3, with a sensitivity of 91.7% and specificity of 69.4%.
Conclusion
HUs are an independent predictor of failed percutaneous drainage of spinal tuberculosis paraspinal abscess under CT guidance. The HU value of 22.3 can be used as an initial screening threshold for predicting the success or failure of drainage.