Technical knitting and ergonomical design of 3D seamless compression hosiery and pressure performances in vivo and in vitro

Abstract

The present study was conducted from a new and innovative view to analyze pressure performances of elastic compression hosieries (ECHs) based on a technical knitting and ergonomic design and development methodology. ECHs with pressure classes I and II have been designed and developed. Multiple influencing factors and their dynamic interaction involved in the working mechanisms of ECHs were analyzed and discussed in this study. Yarn properties, material combinations, knitting structural complex, and parameters setting of machinery elements determine the fabric elasticity, stiffness, hosiery configuration, pressure magnitudes and gradient distribution. A good agreement and significant correlation on pressure performances of the developed hosieries are present from positions B1 to D when being tested on the wooden leg model by using Medical stocking tester in vitro and on the studied subjects’ legs in vivo. A reasonable pressure gradient was presented on the leg model (i.e. 70–100 % pressure at B1 and 50–80 % at C compared with the pressure exerted at ankle B), which supported the technical knitting design methodology applied in this study. However, some differences at ankle region B existed between the in vivo and in vitro values due to differences of anatomic structures that existed on the tested ankle areas. The location of testing points and body postures being undertaken by the wearers also significantly influenced the pressure profiles in vivo. More stretch deformations in hosiery fabric are produced, as assessed by static stiffness index evaluation, at the ankle when the body posture changes from standing to supine. The developed ECHs with pressure classes I and II received positive feedback on pressure and comfort perceptions on testing spot. More explorations are needed to elevate the consistency of the in vitro and in vivo pressure values at ankle region and to investigate their long-term pressure performances in practical wear through innovative knitting technical design with considerations of ergonomic factors and conducting larger scale of wear trials in future studies.