Engineering a new wrist joint replacement prosthesis—a multidisciplinary approach

Abstract

The wrist joint is highly complex and there remain unresolved problems to be overcome in designing a successful wrist joint prosthesis. Consequently, the results of total wrist joint replacements have been poor compared to those for hip and knee joint replacements. A multidisciplinary team of orthopaedic surgeons and engineers is working at Bath to tackle some of the key issues in the engineering of a new wrist joint prosthesis. Following a brief background to the work being undertaken by the group, this paper describes two ongoing research activities. Firstly, an assessment is being made of the optimum geometry for a wrist replacement through the use of a geometric constraint modeller. The second activity is the development of a mechanical simulator to assess wrist prosthesis function and loading. A computer algorithm controls articulation of the wrist using cables that mimic normal wrist tendons. This system allows for full movement of the hand and can also simulate external loading. The forces transmitted at the prosthesis/bone interfaces can be monitored using sensors attached adjacent to the prosthesis.

The importance of abductor pollicis longus in wrist motions: A physiological wrist simulator study

“…One of the main advantages of the control strategy was the use of specimen-specific muscle moment arms about the wrist axes as custom inputs. This accounted for the variations in APL observed across specimens, due to the presence of multiple distal tendon slips ( Thwin et al, 2014 ), which is one of the possible reasons for the omission of the APL during in vitro testing on other simulators reported in the literature ( Dimitris et al, 2015 , Erhart et al, 2012 , Farr et al, 2013 , Leonard et al, 2002 ). However, the variations of the APL moment arm about the FE and adduction-abduction axes of the carpometacarpal joint ( Smutz et al, 1998 ) were not considered in this study, since the position of the first metacarpal was not actively controlled.…”

“…Moreover, it also acts as a stabiliser of the wrist during active FE in vivo ( Kauer, 1980 ). Despite this, the APL is often neglected during the simulation of wrist motions using physiological wrist simulators ( Dimitris et al, 2015 , Erhart et al, 2012 , Farr et al, 2013 , Leonard et al, 2002 ). However, results from multiple cyclic planar and complex wrist motions simulated in this study, with and without the APL, showed that its absence resulted in alterations in the force distribution across the wrist muscles.…”

“…Therefore, physiological wrist simulators often recreate the kinematic and kinetic conditions of the natural joint in vitro by applying tensile loads to tendons of these muscles ( Werner et al, 1996 ). However, some in vitro studies employing wrist simulators neglect the APL, and replicate wrist motions with five actively loaded muscles ( Dimitris et al, 2015 , Erhart et al, 2012 , Farr et al, 2013 , Leonard et al, 2002 ).…”

Joint Replacement Implants

“…A test protocol for finger implants has been proposed following the development of a finger joint simulator [68]. Details on the development of a wrist simulator have been described [69].…”

An In Vitro Hand Simulator for Simultaneous Control of Hand and Wrist Movements

“…In active simulators, the tendons are loaded using controllable electromechanical, hydraulic, or pneumatic actuators. Both feed-forward [3] and feedback [1], [2], [7] control architectures have been used for wrist motion creation. The redundancy in the human musculature poses a challenge in calculating muscle forces to move the joint.…”