Feasibility study for a controllable orthotic knee joint

Abstract

Purpose. The purpose of this study was to demonstrate the feasibility of producing an orthotic knee joint that could lock and unlock during ambulation for eventual use in a reciprocating gait orthosis (RGO) for severely disabled patients.

Method. Three prototype orthotic knee joints incorporating braking mechanisms were designed and manufactured to demonstrate their ability to withstand a maximum calculated sagittal plane bending moment of 73 Nm. Each was then subjected to bench trials to test their performance against the required specification.

Results. Although all three joints achieved the requirement to sustain the specified externally applied bending moments, the hydraulic disc brake system proved significantly superior and was selected for more comprehensive testing.

Conclusions. The results confirmed the feasibility of utilising a hydraulic braking mechanism within an orthotic knee joint to withstand the knee flexing moments during walking in a lower limb orthosis. This gave the development group confidence to progress to the prototype design phase with the specific aim of eventually incorporating such a joint in an RGO designed for severely disabled patients such as those with complete paraplegia up to level T4 and those with severe neurological dysfunction.

Keywords:

• Orthotic knee joint
• lower limb
• orthosis
• stance control

Acknowledgement

The Health Technology Devices portal is acknowledged for its assistance in producing this work.

Declaration of Interest:

This article was based on work supported and funded by the Health Technology Devices portal (project HTD007) of the UK National Institute for Health Research. The sponsors were not involved in any aspect of the study. A UK patent application has been granted to the lead author for an orthotic knee joint design using a braking mechanism. The authors report no conflicts of interest. The authors alone are responsible for the content and writing of the paper.