A Novel Bespoke Hypertrophic Scar Treatment: Actualizing Hybrid Pressure and Silicone Therapies with 3D Printing and Scanning.

The treatment of hypertrophic scars (HSs) is considered to be the most challenging task in wound rehabilitation. Conventional silicone sheet therapy has a positive effect on the healing process of HSs. However, the dimensions of the silicone sheet are typically larger than those of the HS itself which may negatively impact the healthy skin that surrounds the HS. Furthermore, the debonding and displacement of the silicone sheet from the skin are critical problems that affect treatment compliance. Herein, we propose a bespoke HS treatment design that integrates pressure sleeve with a silicone sheet and use of silicone gel using a workflow of three-dimensional (3D) printing, 3D scanning and computer-aided design, and manufacturing software. A finite element analysis (FEA) is used to optimize the control of the pressure distribution and investigate the effects of the silicone elastomer. The result shows that the silicone elastomer increases the amount of exerted pressure on the HS and minimizes unnecessary pressure to other parts of the wrist. Based on this treatment design, a silicone elastomer that perfectly conforms to an HS is printed and attached onto a customized pressure sleeve. Most importantly, unlimited scar treating gel can be applied as the means to optimize treatment of HSs while the silicone sheet is firmly affixed and secured by the pressure sleeve.

A study of using a simple 2D image analysis method to monitor the surface area of hypertrophic scars on hand during pressure therapy.

Hypertrophic scars are usually evaluated based on scar assessment scales such as Vancouver Scar Scale (VSS) and the Patient and Observer Scar Assessment Scale (POSAS) which are difficult in recording small changes in the scar conditions over time. This study adopts a simple method to quantify the size of hypertrophic scars on hands by using a camera and tripod set-up for image capturing and a free software, ImageJ, for analysis. The ability to record the changes in scars condition and healing progress of this method were investigated. Four hypertrophic scar samples on the hands were captured at 8 time-points during 24-week of pressure therapy. Three operators were trained for 2h to use the software and then carried out image analysis on 32 scar images to obtain the surface areas of the hand and the scars and repeat the entire measurement for 3 times. The results show that the measured scar surface areas have good intra-operator reliability with an intraclass correlation coefficient (ICC) of 0.943 (0.922, 0.96) and moderate inter-operator reliability with an ICC of 0.554 (0.063, 0.795). No significant within-subject effect of the repeat of measurements (p>0.05) and between-subject effect of the three operators (p>0.05) were found on the scar area measurements and the proportion of the scars on hands but significant differences were found between different time-points of the image capturing (p<0.05). The image analysis method is more sensitive to the change of scars conditions over time than the VSS record. This is an economical and relatively easy method to quantify the changes in the hypertrophic scars which could be useful for monitoring the progress of therapy and encourage treatment compliance.

Numerical simulation of pressure therapy glove by using Finite Element Method.

Pressure therapy garments apply pressure to suppress the growth and flatten hypertrophic scars caused by serious burns. The amount of pressure given by the pressure garments is critical to the treatment adherence and outcomes. In the present study, a biomechanical model for simulating the pressure magnitudes and distribution over hand dorsum given by a pressure glove was developed by using finite element method. In this model, the shape geometry of the hand, the mechanical properties of the glove and human body tissues were incorporated in the numerical stress analyses. The geometry of the hand was obtained by a 3D laser scanner. The material properties of two warp knitted fabrics were considered in the glove fabric model that developed from the glove production pattern with 10% size reduction in circumferential dimensions. The glove was regarded an isotropic elastic shell and the hand was assumed to be a homogeneous, isotropic and linearly elastic body. A glove wearing process was carried in the finite element analysis and the surface-to-surface contact pressure between hand and glove fabric was hence obtained. Through validation, the simulated contact pressure showed a good agreement with the experimental interface pressure measurement. The simulation model can be used to predict and visualise the pressure distribution exerted by a pressure therapy glove onto hand dorsum. It can provide information for optimising the material mechanical properties in pressure garment design and development, give a clue to understand the mechanisms of pressure action on hypertrophic scars and ultimately improve the medical functions of pressure garment.