Prosthetics and Orthotics

Lower Limb Prostheses

There are over 65,000 amputees and 700,000 wheelchair users in the UK who rely on assistive equipment to ensure their mobility, independence, and quality of lives. Poor equipment fittings can lead to discomfort, pain and further health issues. For example, for lower limb amputees, prosthetic socket fit and its comfort/ compliance to the residual stump is the most important concern of any prosthesis user, yet to date, limited tools and knowledge is available for objective assessment. To address this, a multidisciplinary team encompassing platform technologies in sensor/actuators, engineering materials, tissue health, and computational engineering has been established. With their industrial partners, Blatchfords, they have recently secured MRC Biocatalyst funding to develop an instrumented liner for direct use on the stump tissues of amputees.

An alternative bioengineering approach to examine socket shapes, involves use of a hand-held 3D surface scanner and reverse engineering techniques. These are being used to examine the influence of surface patterning upon shape registration and extraction. Researchers have developed a MATLAB code to post-process scan data and evaluate method accuracy and repeatability. This data will provide a robust platform to establish a statistical model of amputee stump shape. Collected data will have direct uses in soft tissue modelling and research into the influence of surgical techniques, contributing to the creation of a multi-patient dynamic computational model, predicting the biomechanical adaptations to below-knee amputation.

Cervical Collars

Immobilisation of the cervical spine with a cervical collar (c-collar) is routine care for trauma patients until potential fractures or ligamentous injury are ruled out (American College of Surgeons, 2008). Additionally, c-collars are frequently applied for longer durations to provide restrictions in cervical range of motion (ROM) during community rehabilitation (Webber-Jones, 2002). In order to limit cervical mobility, collars are fixed securely to the individual’s neck via strapping and height adjustment, creating points of increased pressure and shear forces at the skin-device interface. Coupled with an altered microclimate, resulting from increased interface temperature and humidity, these devices pose a high risk for pressure ulcers (PU) development. Patients requiring c-collars are vulnerable to skin damage due to their reduced ability to sense and respond to noxious stimuli, including pressure, owing to reduced consciousness or neurological deficit.

Common sites of skin breakdown specifically associated with c-collars include the occiput, mandible, ears, chin, laryngeal prominence, shoulders and sternum (Hewitt, 1994). Many trauma patients, especially critically ill individuals, have increased susceptibility to PUs, potentially resulting from reduced consciousness (Ham et al,. 2014a), response to noxious stimuli (Bader et al., 2005) and reduced intrinsic tolerance to pressure (Buchanan et al,. 1987). Prevalence of c-collar related tissue breakdown has been reported to range from 6.8-38% (Ham et al,. 2014b) and documented as high as 55% when worn for greater than 5 days (Davis et al,. 1995). However, much of the existing literature regarding c-collars consists of observational studies (Davis et al,. 1995; Powers et al,. 2006) concerned with PU incidence.

There is a need to monitor the physiological reaction of the skin during c-collar application. Recent research investigating skin health has identified inflammatory cytokines as suitable biomarkers to monitor the physiological response of skin to pressure and shear. Experimental studies have been conducted to investigate the effects of device strap tension on microclimate, interface pressure and the physiological inflammatory response of the skin tissue (Worsely et al, 2016). However, this experimental approach has not yet been applied to c-collars, despite the unacceptably high incidence of collar-related PUs.

The proposed work package will investigate the effects of varying c-collar design and application technique on tissue interface pressure, microclimate (temperature and humidity) and the physiological response of the skin at the skin-device interface. In particular we will investigate the influence of materials used within the c-collars regarding their compliance with the skin and ability to allow airflow to vulnerable skin tissues.