| BackgroundThe past decades have witnessed dramatic development of flexible ureteroscopy(FURS), which provides a new minimally invasive method for upper urinary diseases and has been accepted and applied more and more all over the world. However, some obvious shortcomings and disadvantages do exist in the application of FURS,including high complexity and difficulty of manipulation, long learning curve,fragility or poor durability, unreasonable ergonomic during operations, which limit its further development and popularization.ObjectiveFocusing on combination of medicine and engineering, we utilized robotic technology, computer technology, three-dimension print, and current clinical needs to design and construct a robotic assisted system for FURS, which aimed to ease the manipulation process, enhance the stability, improve the ergonomics, and shorten the learning curve.Methods(1) Analyzing and decomposing the movement of FURS during operations, and measuring the hardware parameters of Storz Flex-X2 which used in the whole study.(2) Designing the robotic assisted system that achieves all kinds of movements of FURS by mechanical control, and designing the laser fibre delivery systems. After validation of design, the engineering prototype was constructed and then evaluated preliminarily.(3) Based on the standard four-phage CT scan data of renal calculi patients, the stone and renal collecting system were segmented and 3D reconstructed using Mimics software. Then the renal stone model that simulated the real anatomic features of patients was produced through 3D print, which was further used in robotic system assessment and other assistance.(4) The performance and effect of the robotic assisted system for FURS was evaluated by experiments on the 3D-printed renal stone models. Four FURS trainees and four experienced surgeons (individual surgical experience with classic FURS)were recruit in this experiment, which were asked to perform robotic assisted FURS on 4 renal stone models separately. The mean examination time per renal model and overall examined calices number were recorded and compared, and all participants fulfilled a questionnaire focusing on ergonomics after performance. Besides, the fibre deliver system was tested whether the fibre could be mechanically advanced towards the stone..(5) The assisting role of 3D print technology for the treatment of renal stone that located in lower calyx with the infundibulopelvic angle (IPA) less than 30°, was also investigated. We also attempted to construct a navigation system for the FURS during operation, and validated its potential effect.Results(1) The movements of FURS during routine surgery consisted of three different motion dimensions, which were front-and-back motion along scope axis, rotation motion around scope axis, and tip deflection controlled by the steering lever respectively. And the hardware parameters of Storz Flex-X2 were measured and record precisely.(2) The robotic assisted system for FURS was designed based on master-slave model, and the engineering prototype was produced successfully. All three dimensions of FURS motion including front-and-back movement, rotation and tip deflection,could be achieved successfully by the robotic system. Additionally, the robotic system was also equipped with mechanical fibre deliver system, steering lever limitation,rapid unloading function and sterile consideration.(3) Using Mimics software, the stone and collecting system were respectively segmented from plain scan and excrete phase CT, and 3D reconstruction was performed and saved as STL file. Then the renal stone model was 3D printed using photosensitive resin. The model was also inspected with FURS, which revealed that the 3D printed renal stone model could simulate the real anatomic features of real collecting system. The low cost and time consumption promoted the potential application of the 3D printed renal stone model.(4) For experienced surgeon, the mean inspection time for each renal using robotic assisted system was 3.05 min, and the overall number of inspected renal calyces was 34/34. For the trainees, by using the robotic assisted system they could inspect most renal calyces (32/34), and the mean inspection time was also similar with the time of experienced surgeons (3.05 min vs 3.37, P>0.05). What's more, there was a significant difference when comparing the ergonomics of robot-assisted and classic FURS (total questionnaire score: 31.3 vs 5.6; p < 0.01), and this was true for all domains of the questionnaire. These results demonstrated that the robotic assisted system could ease the manipulation process and improve the ergonomics during surgery. The fibre deliver system and the system stability were both confirm well.(5) The renal lower calyx stone model with IPA<30° was 3D printed successfully.By validation on this model, the FURS was proved to be able to reach lower calyx via passive deflection, and surgeon could exercise the FURS manipulation on the renal model that simulating the specific patient's collecting system before formal surgery.So the 3D print technology could be used in some difficult cases.The FURS navigation system based on magnetic positioning could display the real time positon of the tip of scope on the reconstructed image of collecting system.This system could assisted trainees to locate the FURS in surgery, and therefore shortened the learning curve.ConclusionThe robotic assisted system for FURS developed in this study provides a suitable and safe platform for manipulating FURS, which eases the manipulation process,enhances the stability, and improves the ergonomics compared with classic FURS.Moreover, the 3D print and navigation techniques are also preliminarily applied in FURS operations, which assist the treatment of lower calyx stone with IPA<30° and location of scope tip during operations respectively. This study is a creative exploration to find an effective method to overcome some difficulties and challenges in FURS by combining endourology and engineering. Further studies should evaluate its impact on the clinical outcome of FURS. |
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