What Is the Periosteum?

Medically Reviewed by Sabrina Felson, MD on May 29, 2023
4 min read

The periosteum is a thin membrane on the outside of your bones. It serves to protect your bones but also has the ability to help them heal. It can even help your body grow new bone when damage occurs.

Scientists sometimes compare the periosteum of bones to the cambium layer of trees. Just as trees repair themselves and grow in harsh environments, so can your bones. The periosteum helps bone growth.

The outer periosteum layer contributes to the blood supply of your bones and the surrounding muscles. It also contains the network of nerve fibers that transmit messages throughout your body.

The inner layer helps to protect your bones and stimulates repair after an injury or fracture. The inner layer of the periosteum is thickest in the womb and through infancy. This layer slowly thins out as you grow into adulthood.

Most of the time, the periosteum is good for your health. However, sometimes it stimulates bone growth in a way that creates benign tumors. These are also called periosteal chondromas. They are made of cartilage and usually appear in the joints where two different bones meet.‌

The good news with periosteal chondromas is that they aren’t attached to your bone. These growths do not pose a danger to your health, although they may impact your ability to move as easily. If left untreated, periosteal chondromas may erode the surrounding bone, leading to permanent damage.

Diagnosing and treating periosteal chondroma. First, your doctor examines the area and asks about your symptoms. They will look for tenderness in the area and any protrusions and reduce your mobility.

An X-ray is the best way to determine the severity of a benign tumor on your bones.  X-rays provide your doctor a clear picture of the:

  • Overall size of the growth
  • Impact on surrounding bones
  • Placement within the joint and connecting bones‌
  • Severity of any damage‌

If the growth is made of soft tissue, your doctor may need an imaging scan like a CT to evaluate the development of the growth. This also offers the opportunity to image cross-sections of the growth for a more complete picture.

The next step is completing a biopsy. While periosteal chondromas are usually benign, other growths may not be. Your doctor determines whether a biopsy is necessary, and a tissue sample is examined under a microscope. If imaging tests are inconclusive, your doctor will perform a biopsy. In a biopsy, a tissue sample of the tumor is taken and examined under a microscope.

If the growth needs to be removed, your doctor completes surgery on the site. This procedure is called an excision, used to remove a growth from your body. During the surgery, your doctor may take steps to repair the surrounding bone if necessary. 

Periostitis is an inflammation of your periosteum. It can be infectious, but usually, it is a chronic condition caused by impact or injury to an area of bone. Your bone may swell or become inflamed if you have periostitis.

The impact of exercise can lead to chronic periostitis. It may be difficult to differentiate between this condition and shin splints or a stress fracture. If you have any pain or inflammation following exercise, talk to your doctor about how you feel. They can help determine what condition causes your symptoms, which may include:

  • Difficulty bearing weight
  • Tenderness in your bones
  • Unusual pain or stiffness in the days following your exercise 
  • Fever or chills
  • Swelling around your bone‌
  • Pus pockets forming around the bone

Diagnosing and treating chronic periostitis. Your doctor may ask about your symptoms and conduct a visual examination of the area. Additional tests like an X-ray may help to rule out a fracture. While there is no cure for periostitis, your doctor may suggest resting, taking pain medication to relieve your symptoms, and rehabilitation.‌

To prevent future cases of periostitis, your doctor may want to:

  • Correct underlying weaknesses in your hips or legs that lead to an irregular gait
  • Improve the mechanics of your exercise, including stride‌
  • Ensure you have the best shoes for your exercise

Acute periostitis. Bacteria and infection lead to this type of periostitis. Instead of a condition of its own, acute periostitis is a symptom that something else is wrong. You may have severe pain and pockets of infected pus surrounding your bone. If it goes untreated, acute periostitis often leads to necrosis.‌

Diagnosing and treating acute periostitis. When it comes to infection, a swift response is key to recovery. Your doctor may complete a bone scan to rule out other bone issues and determine the severity of your infection. Blood work or a bacteria culture can provide more information about which treatment is necessary.

You may need surgery to drain the area so it has a better chance to heal. Antibiotics are often prescribed via medication or IV. This may last several days to a few weeks. Longer treatment is usually advised for bone issues because antibiotics don’t reach your bones as easily as they reach soft tissue.