A sensorimotor PROsthesis for the upper LIMB - PROLIMB II

Chief Investigator: Prof Joseph Hardwicke

Clinical Delivery: Dawn Davies, Natalie Kenny, Sian McKee

Lead Coordinator: Shivam Joshi

University Hospitals Coventry & Warwickshire NHS Trust

Engineering & Physical Sciences Research Council (EPSRC)

To investigate the feasibility of using a prosthetic fingertip digit with integrated mechanical haptic feedback (PROLIMB II prosthesis) on patients who have had one or more fingers/thumb amputated.

Single centre feasibility pilot study.

Injuries and Accidents / Surgery

The finger and fingertip are the most frequently amputated body parts, due to work-related incidents. Yet because of space, weight and cost constraints, prosthetic fingers and fingertips are heavy and bulky with limited active motion and sensation. Most are basic variations on the hook and claw. Lower limb prostheses have become extremely technologically advanced in their design and materials, and upper limbs lag behind in all of these areas. This is due to the complexity of the anatomy and function of the upper limb compared to the lower. There are no commercially available prostheses that offers direct sensory feedback and as such, rely on visual feedback from the wearer.

The vision of the PROLIMB II project is to develop and combine mechanistic models of hand motion and haptic sensing to deliver novel, affordable body-powered prosthetic fingertip digits with enhanced motion and sensation to address current clinical needs and support the quality of life of amputees. With collaboration from the University of Warwick (UoW) and University College London (UCL), and Naked Prosthetics the PROLIMB II study will aim to model, design, fabricate and validate an affordable body-powered prosthetic fingertip digit with integrated sensory feedback. University Hospitals Coventry & Warwickshire (UHCW) NHS Trust will provide the clinical facility with which to assess the comfort, usability and acceptance of this prosthetic in the daily lives of patients with digit amputations. This project will be a proof of concept study with verification of the prosthetic in motion capture (gait) laboratories as well as the use of simple validation data collection over a longer period.

1st March 2022

36 months

10

The PROLIMB II study was undertaken to see how a novel haptic fingertip (to give the feel of sensation) mounted to a Naked Prosthesis single digit prosthetic was used by patients who had suffered digit loss. The number of patients screened was 14 with five recruited. One participant was withdrawn as they were not eligible for the Naked Prosthesis, so a total of four participants were retained and deemed suitable for using the PROLIMB II prosthesis.

The QuickDASH (QD) questionnaire was used to assess the disability score with or without the prosthesis. QD showed significant improvement in symptoms when using the prosthesis versus no prosthesis (p<0.05). There was no difference between the groups of no prosthesis vs prosthetic or no prosthesis vs haptic prosthetic. It also showed no significant improvement in work or sports/arts function when using the prosthetic (either haptic or not) versus no prosthesis. From this it appears that the haptic tip did not improve nor impair function of the prosthesis. Sensation in the normal fingers was on average 0.2 grams to elicit a sensation, in the prosthetic this required 300+ grams.

The TAPES-R questionnaire is a self-administered questionnaire that comprises psychosocial adjustment, activity restriction, and prosthetic satisfaction domains. It showed no difference in the opinion of the prosthetic with when compared pre- or post-haptic tip addition.

Patients were asked how much they (or the NHS) should pay for the prosthesis. The estimated value was £1,700. All four patients would recommend the prosthesis (with or without haptic) and intended to continue using the PROLIMB II prosthesis after completion (two said “Yes, all the time”, and two said “Yes, some of the time”).

Feedback was also given about the haptic tip such as fragility, leaking, and home-made looking. The unmodified haptic was well accepted but the haptic tip did not really add to the overall product it seems. Overall, the haptic tip caused no harm and appears not to have impaired the Naked Prosthesisä to a point where the prosthesis loses the gains it made over no prosthesis.