Archived project

Mattress Analysis and the effects on postural alignment, EMG activity and Pressure

Goal: Laurence is currently working alongside Dr Ambreen Chohan and Professor Jim Richards in conjunction with a major bed and mattress manufacturing company. Together, they are completing research into a range of new products that have been developed with the aim of improving spinal alignment during sleep.

Methods: Motion Analysis, Surface EMG, Questionnaire Design, Pressure Measurement

Date: 10 August 2016 - 9 September 2017

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Project log

Ambreen Chohan
added a research item
Bed-time postural management systems may provide pressure relief and reduce the risk of body shape distortion amongst immobile patients as part of a 24-hour postural management plan. Robust evidence investigating their use is not available. This study explored the potential effectiveness of a postural management system considering peak contact pressure and user perceptions. Healthy participants (n=15) were screened using a modified Red Flags Screening tool. Conformat system was used to analyse contact pressure under the shoulder and buttocks and was recorded for ten minutes with/without the postural management system in supine and side lying. Participants were asked questions relating to their comfort/restrictiveness (Numerical Rating Scales). In side lying, peak contact pressure at the greater trochanter was significantly lower with the intervention compared to the control condition. In supine lying, the intervention reported significantly lower peak contact pressures at the shoulder. At the ischial tuberosity peak contact pressure was significantly higher with the intervention compared to the control condition. Perceived comfort did not significantly change between test conditions. Participants reported that they felt significantly more restricted with the intervention. Findings suggest potential benefits of reduced pressure at the shoulders in supine-lying and at the greater trochanter in side lying with a PMS, reducing the risk of pressure injury formation. A postural management system that maintains body shape and reduces risk of pressure injuries could reduce the economic burdens of health implications associated with poor positioning, enhance patient care and reduce risks to carers associated with manual handling techniques used during repositioning.
Ambreen Chohan
added a research item
Background Humans spend around a third of a lifetime in bed[1]. Sleep disturbance is becoming increasingly recognised as a clinically important symptom in people with chronic low back pain[2]. There are a variety of mechanisms that reduce back pain and improve quality of sleep by decreasing spinal muscle activity, improved spinal alignment, and reducing pressure at main contact areas between the body and the sleep surface[3,4,5]; one of which involves mattress comfort layers. Methods Twenty participants volunteered for this study. Ten QualisysTM cameras recorded movement of the spine in 6-degrees of freedom using a multisegment spine model[4] during side-lying on three visually identical mattresses. Internally all mattresses contained an identical zoned 1000-count spring configuration with three different comfort layers of equal depth (Geltex, Latex and Memory Foam). Peak pressure distribution was measured at the hip and shoulder and additional comfort and firmness ratings were recorded. Results A statistically significance difference was seen in the peak pressure of the shoulder between mattresses. A Pairwise comparison showed that the Geltex was significantly different than Latex (2.36kPa) and Memory Foam (2.41kPa). Within mattress peak pressure at the shoulder also changes significantly over time for the Geltex and Latex mattresses but not Memory Foam. Lower peak pressures were shown at the hip for Geltex (2.17kPa) when compared to Latex (2.39kPa) and Memory Foam (2.51kPa). Though Geltex was perceived the most firm, hip peak pressure changes significantly over time in Latex and Memory Foam but not in Geltex. In the coronal plane there was a statistically significant difference between the mattresses at the upper lumbar to lower lumbar segment with differences shown between: Geltex and Latex, Geltex and Memory Foam and Latex and Memory Foam. The lower lumbar to pelvis segment also showed significant difference between: Geltex and Latex against Memory foam. In the sagittal plane the lower thoracic and upper lumbar segment showed statistically significant differences between mattresses shown between Geltex and Latex and Geltex and Memory foam. Discussion Evidence suggests that a Geltex comfort layer will disperse pressure at the hip and shoulder more effectively than either Latex or Memory Foam comfort layers. Geltex showed significantly less deviation from the spinal neutral position in key areas around the lower lumber suggesting a more neutral spinal posture to afford improved relaxation. Acknowledgements Staff time for this project was funded by Silentnight Group Ltd.,UK. References 1. Gordon,S,J., et al., (2011)Physio Canada, 63(2), p183-190. 2. Hurley,D., et al., (2010)J Musc Skel Dis, 11(70). 3. Lahm,R., et al., (2002)Ergon, 45(11) p798-815. 4. Verhaert,V., et al., (2011)Ergon, 54(2), p169-78. 5. Lee,H., et al., (2006)Int. J Ind Erg, 36, p943-49.
Laurence Smith
added a research item
Background A third of our lifetime is spent in bed [1], so to achieve improved quality of sleep it is vital to establish optimal sleeping conditions. A sleep system’s main function is to support the body in such a way that the muscles and intervertebral discs are able to recover from an almost continuous load throughout the day. This allows the pressure to be relieved from the intervertebral discs and surrounding musculature, therefore initiating recovery, rehydration and regeneration of elasticity within soft tissues [2-3]. Failure to achieve a state of recovery can lead to the onset of Lower Back Pain (LBP), which is said to have effected 2/3 adults within the UK, and as many as 2.5 million people on a daily basis. There are a variety of mechanisms said to reduce LBP and subsequently improve the quality of sleep including improved spinal alignment, and the reduction of pressure at main contact areas between the body and the mattress [4-6]. Whilst varying comfort layers and mattress firmness can help to address these mechanisms of LBP, mattress zoning is one of the latest developments in pocket sprung mattress design aiming to improving sleep quality and reducing LBP, and thus this study explored the biomechanical differences between a zoned (Z) and non-zoned (NZ) mattress on humans. Methods Twelve healthy participants (aged 35.9±13.1 years) were recruited and screened using the Red flags screening questionnaire [7]. Ten QualisysTM Oqus7 cameras recorded movement of the spine in 6 degrees of freedom using a multisegment spine model [8] during side lying. Z and NZ 1000-count pocket sprung mattresses, topped with a minimal comfort layer were used. Additional subjective measures of Mattress comfort and firmness taken, whilst pressure distribution was measured at the hip and shoulder (Tekscan, MA, USA). Results A significantly higher peak hip pressure (2.92kPa) was noted for the Z mattress compared to the non-zoned (2.63kPa; p=0.004). No significant differences in peak pressure at the shoulder were noted between the two mattresses. There was no significance relating to perceived mattress firmness or comfort (p=0.524 and p=0.537 correspondingly). Spinal posture was measured in terms of how far posture varied from a neutral position. Within the sagittal plane there were significant differences between the Z and NZ mattresses at the UL-LL region (p=0.046) with the Z mattress deviating the least. Similarly, within the coronal plane the UT-MT (p=0.038) and LT-UL (p=0.024) posture demonstrated statistically significant improvements. The Z mattress demonstrated less rotation within the LL-PEL segment of the spine (p=0.012), however it displayed significantly poorer results within the LT-UL and UL-LL segments (p=0.026 and p=0.016 respectively). Discussion There is evidence to suggest that whilst a zoned mattress does not disperse pressure as effectively at the hip, it is in fact more supportive to compensate as it reduces “hammocking” and improves overall spinal alignment. The zoned mattress outperformed the non-zoned mattress in key areas around the lower lumbar to pelvic region suggesting that it may help to reduce torsional strains, potentially helping individuals with LBP. It is evident from this data that a multi-factoral approach is beneficial in understanding our interaction with sleep surfaces.
Laurence Smith
added a project goal
Laurence is currently working alongside Dr Ambreen Chohan and Professor Jim Richards in conjunction with a major bed and mattress manufacturing company. Together, they are completing research into a range of new products that have been developed with the aim of improving spinal alignment during sleep.