Application of 3D printing technique in percutaneous nephrolithotomy of patients with complicated kidney stones

Objective To investigate the application of 3D printing technique in percutaneous nephrolithotomy (PCNL) of patients with complicated kidney stones. Methods From January 2015 to December 2017, 60 patients with complicated kidney stones were enrolled in the First Affiliated Hospital of Hebei North University for prospective study, and PCNL was proposed.All the patients were randomly divided into 3D print group (30 cases) and conventional image inspection group (30 cases, control group). Before operation, CT urography (CTU) was used in both groups.In 3D printing group, digital imaging and communications in medicine (DICOM) files of CT were extracted for 3D image postprocessing, and thermoplastic materials were used to print 3D model.In the 3D printing group, the digital imaging and communications in medicine (DICOM) files of CT were extracted for 3D image post-processing, and the 3D model was printed with thermoplastic materials.According to the comprehensive planning of 3D kidney model, a virtual safe and reliable percutaneous renal access was established for each patient, and PCNL was executed.The patients in the two groups were compared before, during and after operation.Preoperative: age, sex, body mass index, blood creatinine, stone size and CT value.During the operation: (1) the target renal calices location time; (2) the conformity between the preoperative planning and the actual operation; (3) the operation completion time.After operation: (1) stone removal rate; (2) hemoglobin reduction level; (3) postoperative recovery. Results All the 60 patients successfully completed the operation, 30 patients successfully printed out the 3D model, which can accurately express the relationship between the stone and the adjacent anatomical structure, the internal renal artery and the collecting system.Positioning time of 3D printing group in target renal calices((2.9 ± 1.5) min vs.(5.8 ± 1.7) min, P=0.023), coincidence between simulated and actual puncture calices((89.5 ± 3.5)% vs.(60.2 ± 5.7)%, P=0.005), postoperative stone removal rate ((89.9 ± 4.5)% vs.(75.9 ± 5.2)%, P=0.009), and hemoglobin levels((1.4 ± 0.5) g/L vs.(2.9 ± 1.4) g/L, P=0.032) were superior to the control group, and the difference was statistically significant.But there was no significant difference between the two groups (all P>0.05). Conclusion The 3D printed kidney model truly restores the anatomical details around the kidneys and stones, providing a stereoscopic and intuitive way to perform surgery, so it maybe has a significance guidance for percutaneous nephrolithotomy. Key words: Kidney stones; Percutaneous nephrolithotomy; Kidney model; Surgery simulation