Evaluation of the effect of different sitting assistive devices in reclining wheelchair on interface pressure

Influence of back support shape in wheelchairs offering pelvic support on asymmetrical sitting posture and pressure points during reaching tasks in stroke patients

Many poststroke hemiplegic patients have an asymmetrical wheelchair-sitting posture. This study aimed to investigate the impact of different back support shapes on asymmetrical sitting posture and pressure points among poststroke hemiplegic patients during an activities of daily living–related reaching task. This study included 23 poststroke hemiplegic patients who performed tasks that involved the movement of objects using the unaffected upper limb to the affected side while sitting in a conventional wheelchair (C-WC) with a flat back support or a wheelchair providing pelvic and thoracic support (P-WC). Body alignment angles from video images and pressure distribution on supporting surfaces were measured using a two-dimensional motion analysis software (Dartfish) and a pressure mapping system (FSA). Regarding movement performance, although postural asymmetry increased in both wheelchair types, the degree of postural variation was smaller with P-WC use than C-WC use (p < 0.05), with partly reduced postural asymmetry. With P-WC, one-sided ischial asymmetrical pressure was significantly less after the movement (p < 0.05). In conclusion, P-WC’s back support shape contributed to a decrease in postural asymmetry for pelvic girdle support both at rest and during movement. This highlights the importance of a wheelchair back support shape and may help to increase the quality of activities of daily living movement in poststroke hemiplegic patients in wheelchairs.

Bioengineering considerations in the prevention of medical device-related pressure ulcers

BACKGROUND

In recent years, it has become increasingly apparent that medical device-related pressure ulcers represent a significant burden to both patients and healthcare providers. Medical devices can cause damage in a variety of patients from neonates to community based adults. To date, devices have typically incorporated generic designs with stiff polymer materials, which impinge on vulnerable soft tissues. As a result, medical devices that interact with the skin and underlying soft tissues can cause significant deformations due to high interface pressures caused by strapping or body weight.

METHODS

This review provides a detailed analysis of the latest bioengineering tools to assess device related skin and soft tissue damage and future perspectives on the prevention of these chronic wounds. This includes measurement at the device-skin interface, imaging deformed tissues, and the early detection of damage through biochemical and biophysical marker detection. In addition, we assess the potential of computational modelling to provide a means for device design optimisation and material selection.

INTERPRETATION

Future collaboration between academics, industrialists and clinicians should provide the basis to improve medical device design and prevent the formation of these potentially life altering wounds. Ensuring clinicians report devices that cause pressure ulcers to regulatory agencies will provide the opportunity to identify and improve devices, which are not fit for purpose.

Biomechanical analysis of different dynamic sitting techniques: an exploratory study

Prolonged static sitting in wheelchairs increases the risk of pressure ulcers. This exploratory study proposed three dynamic sitting techniques in order to reduce the risk of developing pressure ulcer during wheelchair sitting, namely lumbar prominent dynamic sitting, femur upward dynamic sitting, and lumbar prominent with femur upward dynamic sitting. The purpose of this study was to analyze the biomechanical effects of these three techniques on interface pressure. 15 able-bodied people were recruited as subjects to compare the aforementioned sitting techniques in a random order. All parameters, including dynamic contact area, dynamic average pressure, and dynamic peak pressure on backrest and seat were measured and compared. In result, when compared with lumbar prominent dynamic sitting, femur upward dynamic sitting and lumbar prominent with femur upward dynamic sitting appeared to yield significantly lower dynamic average and peak pressure on the back part of seat, and significantly higher dynamic average and peak pressure on the front part of seat. This study can serve as a reference point for clinical physicians or wheelchair users to identify a suitable dynamic sitting technique.