What is an ischial tuberosity?

If you’ve ever been sitting for a long time and noticed a pain in your buttocks, it could be a problem related to the tuberosity in your pelvis. It’s also referred to as your sit bones or seat bones because it absorbs your weight when you sit.

That pain you feel when you’ve been sitting too long may be irritation or inflammation of the ischial bursa, a fluid-filled sac located between the ischial tuberosity and the tendons that connect the hamstring muscle to the bone. Serious inflammation in this area is called ischial bursitis, also known as weaver’s bottom or tailor’s seat.

Ischial tuberosity anatomy

The ischial tuberosity is a rounded bone that extends from the ischium — the curved bone that makes up the bottom of your pelvis. It’s located just below the ischial spine, which is a pointed bone that extends up the backside of your pelvis.

Three tendons connect the hamstring, a muscle in the back of your thigh, to the ischial tuberosity. The gluteus maximus muscle covers the ischial tuberosity when your leg is straight and your thigh is extended. When your knee is bent and your thigh is flexed, the gluteus maximus moves and leaves the ischial tuberosity uncovered. This explains why you don’t have that large gluteus maximum muscle as extra padding for your ischial tuberosity when you sit down.

What is ischial bursitis?

A bursa is a fluid-filled sac that acts as a cushion between tendons and bones in joints. For example, you have bursas in your hips, knees, elbows, and shoulders. Anything that puts pressure on a bursa can cause inflammation, leading to a painful condition called bursitis.

In some cases, repetitive motions can cause bursitis. A baseball pitcher, for example, may get bursitis in the elbow or shoulder of their pitching arm. Similarly, leaning on or pressing against a joint can irritate the bursa inside. Sitting, especially, on a hard surface, can irritate your ischial bursa, causing ischial bursitis.

Ischial bursitis symptoms include:

  • aching or stiffness in your pelvis
  • pain when you sit down
  • trouble sleeping on the affected side
  • redness or swelling around the bursa.

Diagnosing ischial bursitis starts with a physical exam and a review of your symptoms. Your doctor may have you sit, stand, and move your legs and hips, while noting your symptoms. If a physical exam doesn’t suggest any obvious cause of your symptoms, you may need an X-ray to give your doctor a better view of your pelvis. They may also use an MRI scan or ultrasound to check for an inflamed bursa since they’re better at showing soft tissues. In some cases, your doctor might take a small fluid sample from the affected bursa.

How can I relieve ischial tuberosity pain?

Bursitis often resolves on its own with rest. However, ischial bursitis can take longer to heal since it’s hard to completely avoid sitting. As you heal, there are several things you can do to manage ischial tuberosity pain.

Medications

Over-the-counter pain relievers, such as acetaminophen (Tylenol) or a nonsteroidal anti-inflammatory drug, such as naproxen (Aleve) or ibuprofen (Advil), may be enough to ease your symptoms.

If those medications aren’t effective, you may benefit from an injection of a corticosteroid to reduce the inflammation of the bursa.

Exercise

Physical therapy to help strengthen muscles and improve flexibility may be helpful. Simply climbing stairs can also be helpful — just be sure to hold on to a railing in case you feel pain that affects your balance.

You can also do some stretching to increase flexibility in your hamstring and relieve pressure on the ischial bursa. Helpful stretches include:

  • Gluteus stretch. Lie stretched out on your back with your head supported by a cushion. Bend one knee. With both hands around the knee, pull it slowly toward your chest and hold the position for 5 to 10 seconds. Slowly straighten your leg, and do the same with your other knee. Repeat 5 to 10 times.
  • Piriformis stretch. Sit on the floor with both legs straight. Cross one leg over the other, with your foot along the knee. With the opposite hand, gently pull your bent knee across the middle of your body. Hold this position for 10 to 30 seconds. You should feel a stretch in the muscles of your outer thigh. Repeat with the other leg.

The bottom line

Your ischial tuberosity is the lower part of your pelvis that’s sometimes referred to as your sit bones. It helps to absorb your weight when you sit. However, it can also cause pain when a nearby fluid-filled sac, called the ischial bursa, becomes inflamed and causes ischial bursitis. This usually resolves on its own, but over-the-counter pain relievers and gentle stretching can help to ease your pain.