Knowledge Base → Questions → Perineal, tailbone or sit bone pain: how can you tell?
Perineal, tailbone or sit bone pain: how can you tell?
The perineum lies between the anus and the genitals; the tailbone (coccyx) is at the bottom of the spine, between the buttocks; the sit bones (ischial tuberosities) are the two bones you sit on. Each area needs something different from your seat. When the sit bones hurt, check that the load stays well distributed around them, without giving up the offloading another area needs.
How can you tell them apart?
| Area | Where | Common signs | What the seat should do |
|---|---|---|---|
| Perineum | Between the anus and the genitals | Burning, shooting pain, heaviness, worse when sitting | Remove contact at the center without removing support |
| Tailbone | Bottom of the spine, between the buttocks | Pain on contact and when getting up | Remove pressure at the back |
| Sit bones | Under the bones of the buttocks | A painful point under load, burning | Keep the most continuous support possible around the painful sit bone |
| Several areas along the midline | From the pubic bone to the tailbone | Symptoms in several areas under pressure | Remove contact along the whole midline if targeted offloading is not enough, provided the sides can carry the load; several pains do not, on their own, justify a continuous channel |
| Several areas | — | Pain that moves depending on position | Decide based on the most restrictive area |
Why does it matter?
Because offloading that relieves one area loads another. Removing the center shifts weight onto the sit bones and the edges; removing the back shifts it forward. If the sit bones are already painful, check that the offloading does not increase the load on them.
What if it hurts in several places?
The choice starts from the areas that must be kept free of contact and those that can still bear pressure. With confirmed sit bone pain, the Aporia framework looks, among the configurations that keep the necessary area free of contact, for the one that keeps the most continuous support around the painful sit bone. This is a rule of our framework, not a universal clinical recommendation. Sit bone pain that only appears after a while may reflect secondary overload: on its own, it is not enough to change configurations.
Which Aporia seat should you consider?
The painful area guides you, but the choice also depends on the areas that can still bear pressure, your seat and how you use it.
- No area to keep free of contact, including with painful sit bones: Aporia Back Pain, continuous support on four supports.
- The perineum must be kept free of contact, sit bones and thighs that tolerate pressure: Aporia Perineal, central cut-out and four supports; the sit bones remain supported on either side of the cut-out; check the dimensions on the product page against the seat of your chair.
- The area behind the anus, up to the tailbone, must be kept free of contact, while the perineum can stay supported: Aporia Coccyx, rear cut-out; same checks.
- Several areas of the midline to keep free of contact at the same time, sides that can carry the load: Aporia Canyon, continuous 6 cm (2.4 in) midline channel; with painful sit bones, check that the edges of the channel do not concentrate the load on them.
- Unsure which areas tolerate pressure, or you do not know: describe your pain, your seat and how you use it to receive guidance (optional questionnaire, no diagnosis).
What other questions do people ask?
Can you have pain in both the perineum and the tailbone? Yes, the two areas are close and are often loaded together when the pelvis tilts backward.
Is a U-shaped cushion suitable for the tailbone? Only if its rear cut-out really clears the tailbone under load; a U open at the front does not.
Publisher: Blue Portance. Written by Gil Ayache, PhD (Mines Paris – PSL). Reviewed: October 19, 2026. Sources: Aporia framework (sit bone rule of the V16 engine); files from our online questionnaire (analysis of October 15, 2026). Aporia® cushions are not medical devices.
Note: this content explains mechanisms related to sitting. It is not a medical diagnosis or prescription, and it does not replace the advice of a healthcare professional.
