Spiky-joint: a bioinspired solution to combine mobility and support

Ali Khaheshi,Hamed Rajabi,Stanislav N. Gorb

doi:10.1007/s00339-021-04310-5

Abstract

Mobility and support are two structural properties that are often mutually exclusive. However, combining them could enhance the performance of mechanical components, and offer novel technical applications. Here through the implementation of a bioinspired interlocking mechanism in the design of a supportive, yet mobile, wrist splint, we tackled the conflicting combination of the two properties. We elaborated our design into a technology readiness level and, using 3D printing, directly converted it into a real-life application. In contrast to the existing splints, our bioinspired splint supports human wrist without impairing its movements. Hence, it can be used to prevent hyperextension injuries without hindering wrist function. By being interlocked at the maximum wrist extension, our splint could be an ideal wrist support for athletes, especially weightlifters. By restricting the wrist mobility, it could also be used as a support device to treat less severe medical issues, such as sprain, strain, or even for the recovery after cast removal, during which full immobilization may result in muscle atrophy. Our design strategy is purely structural; hence, it can be easily modified and implemented in other engineering applications. The simple, yet efficient, solution developed in this study offers a universal paradigm for developing engineering systems that pursuit both mobility and support.Graphic abstract

Highlights

Musculoskeletal injuries refer to the damage of muscular or skeletal system
We introduce the concept of ‘variable mobility’, which is borrowed from elaborated joints of insect wings
Inspired by the interlocking mechanism of vein joints on insect wings, we developed the concept of variable mobility and implemented it into the design of a supportive, yet mobile, wrist splint

Summary

Introduction

Musculoskeletal injuries refer to the damage of muscular or skeletal system. They affect muscles, bones, joints, and thereby locomotion. Around 80% of sport-related injuries are associated with the musculoskeletal system [21]. Conventional plaster casts and splints are still the most common tools that are used to treat musculoskeletal injuries worldwide [13] (Fig. 1a). Regardless of the worldwide use of the conventional casts and splints, there are several issues associated with them. These include high weight, poor ventilation, difficult removal, discomfort, rigidity and non-recyclability [10]. The latter, i.e. non-recyclability, results in an average of 670,000 kg waste per year [15]

Unconventional casts and splints

The concept of ‘variable mobility’

Discussions and future directions

Findings

Compliance with ethical standards