Tailbone Pain: Why Sitting Is the Problem

Tailbone pain is often described as an odd, hard-to-explain problem. The anatomy explains it clearly, and the explanation points straight at the treatment.

Here is what the coccyx is, why sitting loads it, and what the conservative options actually do.

What the coccyx is

The coccyx is the small structure at the very bottom of the spine. The StatPearls review of coccyx pain describes it as consisting of 3 to 5 separate vertebral bodies with variable fusion between them, so its exact form differs from one person to the next.

It joins the sacrum at the sacrococcygeal joint through a fibrocartilaginous disc and a pair of facet joints, one on each side. So there is a real joint there, with real movement, rather than a fused stub.

Plenty of soft tissue attaches to it. In front, levator ani, iliococcygeus, coccygeus, and pubococcygeus. Behind, gluteus maximus. On both sides, the sacrotuberous and sacrospinous ligaments. Several of those muscles are part of the pelvic floor, which is why tailbone pain and pelvic floor function are often assessed together.

The tripod that explains everything

Here is the detail that makes the symptom pattern make sense.

During sitting, the coccyx forms a weight-bearing tripod with the two ischial tuberosities. The ischial tuberosities are the sitting bones, the two hard points you can feel underneath you on a firm chair. Three points, carrying your upper body weight between them.

So when the coccyx is painful, sitting is not incidental to the problem. Sitting is a loading position for the injured structure, in the same way that standing on a sore heel loads the heel.

That framework explains the aggravating factors listed in the review: prolonged sitting, cycling, standing up from sitting, prolonged standing, sexual intercourse, and bowel movements. It also explains the specific detail that pain is typically worse in a partly reclined, backward-leaning position. Leaning back rotates the pelvis and shifts weight off the sitting bones and onto the coccyx. A soft, reclined sofa often hurts more than an upright wooden chair for exactly that reason.

Standing up from sitting is its own moment. Moving between loaded and unloaded positions changes the pressure on the joint quickly, and many people describe a sharp catch during that transition rather than while seated.

Who it happens to, and why

The StatPearls review reports that coccydynia is five times more common in females than males. Listed risk factors are female sex, obesity, rapid weight loss, osteoarthritis, and contact sports.

The causes fall into a few groups. Direct trauma, meaning a fall backward onto the tailbone, is the one most people can name. Repetitive microtrauma builds the same problem gradually, and cycling is a common contributor because of where the load sits on the saddle. Childbirth is a recognised cause, since the coccyx moves during delivery and can be injured in the process. Prolonged sitting alone can be enough. Some cases are idiopathic, meaning no cause is identified.

The review is also clear that infection and malignancy have to be excluded. Chordoma, a tumour that can occur in this region, is named specifically. Ordinary tailbone pain rarely turns out to be either of these. It does explain why pain that keeps getting worse, or comes with fever, weight loss, or a lump, needs medical assessment rather than a cushion.

For anyone in the postpartum period, tailbone pain often sits alongside other pelvic changes, and our guide to returning to running after birth covers how the pelvic floor is rebuilt during that time. Pain around the pelvis during pregnancy has its own pattern, covered in our article on pelvic girdle pain in pregnancy.

What imaging can add

Most cases do not need imaging. When it is used, one option is specific to this problem.

Dynamic radiographs compare the position of the coccyx while seated against its position while standing, which measures how much it moves under load. The review gives normal coccygeal mobility as 5 to 20 degrees. Under 5 degrees indicates hypomobility, meaning the coccyx moves less than expected. Over 20 degrees indicates hypermobility, meaning it moves more.

Both findings can be associated with pain, which is a useful reminder that the answer is not simply more movement or less movement. The result gives the clinician information about how the joint is behaving under load, and it feeds into the plan rather than deciding it.

Cushions, and what they are doing

The cushion is usually the first practical change, and its purpose follows directly from the tripod.

The review describes a cushion with a wedge-shaped cut-out beneath the coccyx, which allows the coccyx to be suspended. The cut-out removes the surface underneath the tailbone, so the load that would have gone through it goes through the sitting bones instead. U-shaped and circular donut cushions are also used and work on the same principle.

Which shape suits a particular person often comes down to trying them. What matters is that the tailbone is not in contact with the seat.

Alongside the cushion, the other lever is how long you sit at a time. Breaking up long seated periods reduces the total time the structure spends loaded, and it is often the change that produces the first improvement. Our article on desk ergonomics for neck and back pain covers how to set up a workstation that makes standing breaks realistic rather than aspirational.

The rest of conservative care

The outlook here is genuinely good. Success of conservative treatment has been reported at 90 percent in the StatPearls review, and only a small percentage of cases go on to coccygectomy, the surgical removal of the coccyx.

The conservative options described include NSAIDs for pain relief, physiotherapy, activity modification, and kinesiotaping. Physiotherapy assessment usually looks at the pelvic floor muscles that attach to the coccyx, the hips, and how you load the area through sitting and daily activity.

Where those measures are not enough, injections are described as the next step. Fluoroscopy-guided steroid injections are reported to benefit cases that have been present for under six months. Ganglion impar blocks are used in chronic cases. Both are procedures done by a physician, and both sit after conservative care rather than instead of it.

Recovery timelines vary a lot and depend on the cause. A tailbone bruised in a fall behaves differently from one irritated over months of long sitting, and both differ from a postpartum presentation.

When to get it looked at

Tailbone pain that has lasted more than a few weeks, that is stopping you sitting through work or driving, or that keeps returning is worth having assessed. There is no reason to sit quietly with this one for months, and people often do, because it feels like an awkward area to raise.

Some situations need a physician first. Pain after a significant fall or injury should be assessed for a fracture. Pain that is getting steadily worse instead of settling, fever, unexplained weight loss, night pain that does not change with position, a lump in the area, or new changes in bladder or bowel control all need medical review. Lions Gate Hospital is the emergency department for the North Shore. The reason for taking those signs seriously is that infection and malignancy have to be excluded before this is treated as a mechanical problem.

If sitting has become the hardest part of your day, book an assessment and we will look at how you are loading the area and what changes that. You can see what we treat or reach the clinic here.

This article is general information, not personal medical advice. A regulated practitioner can confirm whether the patterns described apply to you.

Sources

• Coccyx Pain, StatPearls, NCBI Bookshelf
• College of Health and Care Professionals of BC public registry

This article is for general information only and does not constitute medical advice, diagnosis, or treatment. Individual presentations vary, and assessment findings and treatment plans differ from person to person. If you are experiencing severe symptoms, neurological changes (numbness, weakness, bowel or bladder changes), or a significant trauma, contact your physician or emergency services. Care at Medstar Sport Physio & Health is provided by practitioners registered with their respective British Columbia regulatory colleges.