In healthcare and long-term care settings, “positioning” is considered an important approach to help reduce the risk of pressure injuries (pressure ulcers) in people who cannot move independently.
Positioning means keeping the body in an appropriate posture to reduce pressure and shear, thereby maintaining comfort.
Among commonly used methods is the 30° lateral position (30° tilt).
In practice, however, relatively few people apply it correctly.
I myself used to perform it based on a vague understanding.
However, continuing to do so can invite unintended risks.
This article explains the significance and pitfalls of the 30° lateral position, fundamentals of pressure injuries, and a cushion—the Bananafit Small Flow Type—which appears useful for repositioning; my discussion draws on related patent filings.
※This article is based on the author’s personal perspective as a nurse, drawing on experience and publicly available patent information.
It includes personal impressions and may also contain references to the author’s activities (advertisement/PR).
Basics of Pressure Injuries and the 30° Lateral Position
A pressure injury is a skin and soft-tissue injury in which prolonged pressure impedes blood flow and causes necrosis.
Unlike wounds caused by external trauma, the primary cause is internal ischemia; early changes can be subtle and often go unnoticed until the injury has progressed.
They are especially common in bedridden individuals, in older adults with decreased skin barrier function, and in those with low body mass where bony prominences are pronounced.
Sites such as the sacrum, heels, and greater trochanter are prone to high interface pressure and thus frequent locations of injury.
Therefore, regular repositioning to avoid prolonged loading of the same area is fundamental prevention.
A representative method is the 30° lateral position.
This posture tilts the trunk about 30° from supine, offloading bony prominences and distributing body weight over larger muscle masses (e.g., the gluteal region).
Source:https://item.rakuten.co.jp/benkei-wakaba/w641007-400/
With appropriate cushioning, the contact area increases and pressure can be more evenly distributed.
For these reasons, the 30° lateral position is widely recognized as a commonly used positioning approach that may help in pressure-injury prevention.
Current Practice and Issues with the 30° Lateral Position
At home, families often find it difficult to perform regular repositioning for people at high risk of pressure injury, so mattresses with automatic repositioning functions are frequently introduced.
In hospitals and facilities, staff perform repositioning at scheduled intervals.
At facilities I visit, we often ask families to provide a large, inexpensive polyester-filled pillow for repositioning.
We try to keep costs down and use what’s on hand while making the 30° lateral position our standard approach.
However, because these are not purpose-built devices, the following problems arise:
- The angle varies every time depending on how the pillow is inserted.
- The fill packs down with use and no longer supports the body.
- Poor fit allows sliding, and the person drifts back toward supine.
Differences in body habitus and the degree of contracture can also make it difficult to achieve adequate offloading.
In such cases, we often use a triangular positioning wedge that reliably creates the desired angle simply by inserting it.
Many shapes and sizes exist, and long-term care insurance often allows rental with trial use before adoption.
The Risk of “Undermining”
While the 30° lateral position allows offloading of bony prominences, improper positioning can conversely worsen pressure injuries.
In this posture, body weight can be resolved into:
① a force perpendicular to the surface, and
② a force parallel to the surface that tends to make the body slide down.
Compared with supine—where loading is largely perpendicular—the perpendicular component is smaller, reducing interface pressure on the skin.
So far this sounds beneficial.
But the parallel component matters. If the surface were as slick as a slide, the body would simply slip downward.
In reality, friction at the body–cushion interface prevents sliding at about 30°, and the posture appears stable.
However, even when the skin stays in place due to friction, the skeleton tends to shift downward, creating relative displacement between skin and bone—that is, tissue shear.
Shear causes a sense of tightness and, more importantly, is considered one of the contributing factors in pressure-injury formation.
In the 30° lateral position, the skin over the pelvis is pulled while the greater trochanter area concentrates pressure.
Pressure injuries that develop under these conditions may look small at the surface while extending deeply underneath.
The mechanism is as follows.
When a pressure injury forms under shear, returning the skin to its original position releases the pulling force so that, superficially, the injury may appear offset from the bony prominence.
Internally, however, the injury tracks obliquely toward the bony prominence, forming deep undermining.
To prevent such shear-related damage, one must create a support surface that counteracts downward skeletal shift and perform positioning correctly.
Options include supporting with a firm cushion or propping with a rolled towel.
In reality, limited knowledge and staffing often make such meticulous positioning difficult to sustain.
Bananafit Small Flow Type
A product that has been developed to address some of these challenges is the Bananafit Small Flow Type cushion by Paramount Bed.
I would like to try it in practice.
Source:https://www.paramount.co.jp/series/3/3000337
Two patents appear to cover the cushion’s main body structure and its easy-withdrawal mechanism.
Based on the published specifications, the features are as follows.
Publication No. JP 2025-104980 A
Publication Date July 10, 2025
Title Positioning Aid Inserted Under a Mattress and Sheet for the Positioning Aid
Publication No. JP 2025-104967 A
Publication Date July 10, 2025
Title Positioning Aid
Problems the Device Aims to Solve
- Directly supporting the back with a wedge can feel uncomfortable.
- Inserting a wedge under the mattress can excessively change posture and introduce shear, depending on its size/shape.
- Tailored wedges for each individual are costly.
- Repositioning care imposes a high physical burden on caregivers.
- Withdrawing wedges can displace clothing and sheets due to friction, adding caregiver workload and causing discomfort, skin problems, and pain.
How to Use & Key Features
- Use: Primarily inserted under the mattress.
Source:https://www.paramount.co.jp/series/3/3000337
- Thinner profile: Maximum height 20–80 mm, minimizing discomfort while providing offloading; the thinner profile is easier to handle and insert.
- Moderate incline: Support angle 6–9° to achieve effective offloading; head end / foot end inclines are tuned for comfort. The modest angle avoids excessive mattress lift and disturbance during sleep.
- Appropriate firmness: 200–700 N (newtons), balancing pressure redistribution and comfort.
- Repeatable placement: Aligning the cushion edge with the mattress or bed edge helps position it correctly—even for non-professionals. A dedicated sheet is also available to make placement more intuitive.
- Easy withdrawal: A sliding section moves independently from the main body; during withdrawal, the main cushion is removed first. The slide section remains under the mattress and can then be removed with only minimal mattress lift,reducing sheet displacement and helping lower the risk of discomfort or shear-related skin problems.
Source: Adapted in part from JP 2025-104967 A.
- Disinfection-ready cover: Chemical-resistant, cleanable with 1% sodium hypochlorite; water-repellent finish resists soiling and enables easy wipe-down.
Feasibility in Practice
●From my experience, thick wedges under the mattress tilt the whole surface, making it difficult to achieve the intended posture; I rarely see this method used for that reason.
This thinner, flatter cushion seems more likely to allow fine angle adjustments.
●When performing single-caregiver repositioning for heavier patients, we sometimes place a bath towel under the body to lift and turn.
While convenient, towel wrinkles can themselves raise pressure-injury risk.
If this cushion can be inserted with only slight mattress lift, towels may become unnecessary.
●Even with high-performance pressure-redistributing mattresses, using a soft polyester pillow to brace the body can diminish mattress performance.
This approach may preserve mattress function while enabling repositioning.
●That said, some mattresses are heavy and difficult to lift, and thick air mattresses may reduce the effect of an under-mattress wedge.
●Beyond tilting the body, inserting the cushion under the contralateral pelvic area might create a support surface that counters shear over the greater trochanter in the 30° lateral position.
●Because its use is as simple as placing it at a fixed position,it may offer practical support in home care, even for users with limited caregiving experience.
Closing Thoughts
No single positioning cushion fits everyone, because body habitus, degree of paresis/contracture, and mobility vary widely.
I have not yet used this cushion myself, but I would like to refine positioning through iteration and include this as one option to test.
※This article reflects the author’s personal views and experiences, and includes references to published patents and materials.
It also contains information about the author’s activities (advertisement/PR).
Please feel free to contact me for inquiries related to writing, technical overviews, or market-entry support.
References
JP 2025-104980 A, “Positioning Aid Inserted Under a Mattress and Sheet for the Positioning Aid,” published July 10, 2025, Paramount Bed Co., Ltd.
JP 2025-104967 A, “Positioning Aid,” published July 10, 2025, Paramount Bed Co., Ltd.
Yutaka Okaniwa, Byōki ga Mieru vol.14: Dermatology, 1st ed., 2020, Medic Media Co., Ltd.
Kōichi Ogawa, Learning Nursing Ergonomics with Illustrations, 2016, Tokyo Denki University Press.
Japanese Society of Pressure Ulcers (JSPU): https://www.jspu.org/general/prevention
Paramount Bed Co., Ltd.: https://www.paramount.co.jp/series/3/3000337
Waku-Waku Chokkan-dō: https://waku2chokkan.com/websem13-30risk
