Engineering a next generation physiological wrist simulator for innovation of rehabilitation protocols and surgical interventions

How would your life change if you could not use your hands effectively? An estimated 2.7 million people in the UK suffer from a debilitating loss of manual dexterity, which has a dramatic effect on their quality of life. The wrist is the most common site of traumatic injury in the human body, but despite this, treating hand and wrist injuries remains a challenge for the hand surgeon and therapist. Methods of treatment often vary from clinician to clinician and the success of their outcomes is difficult to assess. A reason for this is the complexity of the wrist - it is comprised of eight bones that move relative to those in the forearm and the hand.
One method for determining the effects of treatment is to study the forces in the muscles and the motions that result. This can be done using computer models. However, many parameters are needed in order to create a computer model that accurately represents the complex anatomy. An alternative way in which we can evaluate the interactions between the many joints in the hand and wrist, is through the use of joint motion simulators. These simulators replicate joint movement in human specimens by applying forces to the tendons, enabling us to measure the forces in the muscles and joints. This allows us to compare the effects of different surgical and therapeutic procedures in a way that is simply not possible with patient volunteers. In this way we can objectively assess treatment regimens, testing the biomechanical outcomes, before applying them to patients.
My research group has developed and tested a joint motion simulator for the wrist that includes six major muscles. However, it is well known that the function of the muscles that control the fingers is highly linked to those that control the wrist. Therefore, the aim of this project is to use our expertise to create a new custom-made joint motion simulator for the wrist that also includes the finger muscles. This work will create a unique and innovative device that possesses greater realism and functionality by enabling us to replicate the motions of the fingers in addition to the wrist. Motors will be used to create the effects of the muscles. Specialised cameras will be used to monitor and control the motion of the joints in real-time. Testing will be performed in collaboration with colleagues in surgery, who will also ensure the clinical impact of the work.
The result of this research will produce a device that can be used in the design and testing of implants and other orthopaedic devices, the validation of computational models of the musculoskeletal system, the design of prosthetics, and the training of clinicians.

Wrist injuries are particularly prevalent in older people due to traumatic events like falls and chronic conditions like osteoarthritis, the frequency of which is rising with the ageing population. Due to high anatomical variability, it is difficult to compare objectively the efficacy of different treatment regimens. The key area of societal impact of this work is the potential for improved quality of life for those suffering from hand and wrist injuries and pathologies. Using the simulator developed here, the muscle forces that result from treatment may be quantified and compared; therefore, the knowledge gained from using this device in further studies will enable objective decision-making regarding the choice of treatment strategy. Enhanced treatment following wrist injury will have a clear, direct economic and societal impact.
Through the creation of a physiological simulator we obtain a test bed for the development of new implantable devices. Implant dislocation, joint instability, and joint loosening remain a challenge in total wrist arthroplasty. Through my clinical collaborators and attendance at clinical conferences I will make contact with key manufacturers of these devices, and invite them to attend a demonstration of the simulator.
Findings from this project may also be of interest to commercial musculoskeletal modelling enterprises. As such, I will seek out possibilities whereby the control strategies derived through this project can be implemented in commercial packages.
I will engage with the general public using a wide range of methods. I maintain a research group webpage which I regularly update with news about my research group and I am an active user of social media to promote my group's work. I will run a stand at the Imperial Festival, which is attended by thousands of members of the public each year. Finally, I will present this work to secondary school students as part of the summer school programmes here at Imperial College.