Medical Engineering & Physics最新文献

Background: Drape-forming is a cost-effective method used worldwide to manufacture bespoke ankle foot orthoses (AFOs). It involves draping a heated polymer material sheet over a positive cast of the user's limb. Previous research has shown that the manual nature of drape-forming can influence the thickness of the final AFO and even lead to structures that are inadequately rigid to be clinically effective. This study assesses the difference between the prescribed and the final thickness of AFOs meant for use by UK's National Health Service (NHS) and estimates its potential impact on AFO rigidity.

Methods: A clinically relevant method to measure AFO thickness as part of the manufacturing process was developed and validated. This method was used by three major UK manufacturers for all bespoke rigid AFOs they provided to the NHS within a predefined period. A validated finite element model was used to estimate the impact of the observed difference between prescribed and final thickness on AFO stiffness.

Results: 86 AFOs were assessed in total. Final thickness was between 4.0% and 35.5% lower than the prescribed one (median thickness reduction= 17.4%). This discrepancy in thickness led to a relative reduction in AFO stiffness ranging between 7.0% and 80.0% (median stiffness reduction= 30.7%).

Discussion: The adequacy of AFO thickness cannot be judged based on prescription thickness. Measurements of final thickness as part of standard practice should be considered to enhance the provision of bespoke AFOs. Further research is needed to establish thresholds of acceptable manufacturing-induced deviation from the prescribed AFO thickness.

Objectives: Cervical cancer is a serious threat to women's life and health and has a high mortality rate. Colposcopy is an important method for early clinical cervical cancer screening, but the traditional vaginal dilator has problems such as discomfort in use and cumbersome operation. For this reason, this study aims to design an intelligent vaginal dilatation system to automate colposcopy and enhance patient comfort.

Methods: An intelligent vaginal dilatation system combining flexible and rigid dilatation techniques is proposed. A fluid-solid coupled finite element method was used to simulate the dilation process of the system during colposcopy. The smart dilator was inserted into a simulated vaginal model in the simulation, and the fluid domain pressure inlet was set to be 1.5 kPa, and the solid material was a hyperelastic model of medical silicone rubber. Subsequently, the prototype machining was completed and in vitro dilatation displacement and pressure experiments were conducted.

Results: The simulation results showed that the maximum expansion of the system was 32.2 mm, and the average pressure on the simulated vaginal wall was 605.91 kPa. The average maximum expansion of the system in the in-vitro expansion displacement experiment was 30.49 ± 0.05 mm, which was basically the same as the simulation results. The results of the in vitro pressure experiment showed that the intelligent dilatation system had a larger force area on the vaginal wall at the same level of dilatation, and the pressure value was smaller and more uniformly distributed. Compared with the traditional duckbill dilator, it can effectively reduce the local pressure feeling and improve the uniformity of dilation.

Conclusion: The intelligent vaginal dilatation system proposed in this study is superior to traditional dilators in terms of dilatation performance, safety and comfort. The feasibility of its design and potential for clinical application were verified.