Artificial sphincters: An overview from existing devices to novel technologies

In silico assessment of the reliability and performance of artificial sphincter for urinary incontinence

BACKGROUND

The standard artificial urinary sphincter (AUS) is an implantable device for the treatment of urinary incontinence by applying a pressure loading around the urethra through an inflatable cuff, often inducing no-physiological stimulation up to tissue degenerative phenomena. A novel in silico approach is proposed to fill the gap of the traditional procedures by providing tools to quantitatively assess AUS reliability and performance based on AUS-urethra interaction.

METHODS

The approach requires the development of 3D numerical models of AUS and urethra, and experimental investigations to define their mechanical behaviors. Computational analyses are performed to simulate the urethral lumen occlusion by AUS inflation under different pressures, and the lumen opening by applying an intraluminal pressure progressively increased under the AUS action (Abaqus Explicit solver). The AUS reliability is evaluated in terms of tissue stimulation by the mechanical fields potentially responsible for vasoconstriction and tissue damage, while the performance by the intraluminal pressure that causes the lumen opening for a specific occlusive pressure, showing the maximum urethral pressure for which continence is guaranteed.

RESULTS

The present study implemented the procedure considering the gold standard AMS 800 and a novel patented AUS. Results provided the comparison between two sphincteric devices and the evaluation of the influence of different building materials and geometrical features on the AUS functionality.

CONCLUSIONS

The approach was developed for the AUS, but it could be adapted also to artificial sphincters for the treatment of other anatomical dysfunctions, widening the analyzable device configurations and reducing experimental and ethical efforts.

Urinary Incontinence and Other Pelvic Floor Dysfunctions as Underestimated Problems in People under Forty Years: What Is Their Relationship with Sport?

Urinary incontinence is still an underestimated problem due to its anatomical complexity and social taboo. Most of the time, it is believed to affect predominantly the elderly female population, and the literature still lacks data on its presence in the younger and male populations. Its relationship with other pelvic floor dysfunctions (PFDs) and sport activity remains an open topic. Thus, the present study surveyed 342 subjects of both genders, ranging from 18 to 39 y/o and with different sport activity levels, to understand the prevalence of PFDs (such as haemorrhoids, anal fissures, involuntary urinary/faecal leakage, and urgency). The results also showed a significative prevalence in younger, sporty, and male people. Approximately one third of the population had urinary incontinence mostly during stress activities (sport activity: 17%, cough/sneeze: 13%). The statistical analysis confirmed a higher prevalence in the cases of a light (32%) and intense (41%) sport activity level and a protective role of sport if practiced between 5 and 10 h/week, with bodybuilding/CrossFit and running seeming to be the riskiest sports. The relationship with the other PFDs showed a statistically significant dependence with most of them, confirming that urinary incontinence cannot be considered a separate problem from the other PFDs.

Simulation of artificial anal sphincter motion and interaction with intestinal environment using SOFA

BACKGROUND

Artificial anal sphincter is an implantable medical device for treating fecal incontinence. Reasonable simulation facilitates the advancement of research and reduces experiments on biological tissue. However, the device's clamping motion and sensor interaction with the intestine in the simulation still require further exploration. This article presents a simulation of the artificial anal sphincter's clamping and sensing and its interaction with the intestinal environment using the Simulation Open Framework Architecture (SOFA).

METHODS

Firstly, the proposed simulation algorithm and its principles in SOFA are analyzed. Secondly, the clamping motion and sensor system of the artificial anal sphincter are simulated. Thirdly, a finite element model of intestine is established based on the properties of intestinal soft tissue. Finally, the in vitro experiments are performed.

RESULTS

The simulation results indicate that the sensor system of the artificial anal sphincter has good sensing performance during the clamping motion and fecal accumulation process. Experiments have shown that optimal sensory capabilities can be achieved as the posture of the artificial anal sphincter with a roll angle between 20° and 40°. The comparison demonstrates a mean absolute error of 10%-20% between simulation and in vitro experimental results for sensor forces, which verifies the effectiveness of the simulation.

CONCLUSION

The proposed novel simulation achieves a more comprehensive interaction between the artificial anal sphincter motion and intestinal environment. This study may provide more effective simulation data for guidance in improving the performance of sensor perception of artificial anal sphincter for further research.

Development and future prospects of the artificial urinary sphincter

BACKGROUND

Urinary incontinence is a urinary disorder in which urine leaks out involuntarily. This disorder seriously affects the quality of life of patients. For patients with mild incontinence, conservative treatment and medication may be the ideal treatment modality, but for patients with severe incontinence, an artificial urinary sphincter is currently a better treatment option.

METHODS

In order to design an ideal artificial urinary sphincter, this article first searched and collected literature based on Preferred Reporting Items for Systematic Reviews and Meta-Analyses searched strategy by selecting specific subject terms and reviewed the artificial urinary sphincters that are currently in the research stage based on different activation methods.

RESULTS

In response to the deficiencies of the existing artificial urinary sphincter, this article discusses the future optimization of the artificial urinary sphincter from three aspects: individual improvement of the artificial urinary sphincter, engineering design elements, and optimization of the artificial urinary sphincter manufacturing process.

CONCLUSIONS

The manufacture of an idealized artificial urinary sphincter capable of meeting clinical needs is of great importance to improve the quality of life of patients. However, this approach is a reasonable option to explore and should not be overestimated until further evidence is available.

Magnetically controlled artificial urinary sphincter: An overview from existing devices to future developments

BACKGROUND

Urinary incontinence is a common clinical problem in the world today. Artificial urinary sphincter is a good treatment approach for severe urinary incontinence, which is designed to mimic the action of the human urinary sphincter and assist patients to regain urinary function.

METHODS

There are many control methods based on artificial urinary sphincter, such as hydraulic control, electromechanical control, magnetic control, and shape memory alloy control. In this paper, the literature was first searched and documented based on PRISMA search strategy for selected specific subject terms. Then, a comparison of artificial urethral sphincters based on different control methods was conducted, and the research progress of magnetically controlled artificial urethral sphincters was reviewed, and their advantages and disadvantages were summarized. Finally, the design factors for the clinical application of magnetically controlled artificial urinary sphincter are discussed.

RESULTS

As magnetic control allows for non-contact force transfer and does not generate heat, it is proposed that magnetic control may be one of the more promising control methods. The design of future magnetically controlled artificial urinary sphincters will need a variety of considerations, including the structural design of the device, manufacturing materials, manufacturing costs, and convenience. In addition, validation of the safety and effectiveness of the device and device management are equally important.

CONCLUSIONS

The design of an ideal magnetically controlled artificial urinary sphincter is of great importance to enhance patient treatment outcomes. However, there are still great challenges to be faced for the clinical application of such devices.