Blocker's Exostosis

ExitCare ImageBlocker's exostosis is an overgrowth in a portion of the bone in the upper arm (humerus). It is also called arm exostosis. This condition occurs at the site of repeated injury, usually direct blows. Blocker's exostosis is a benign bony reaction to repeated injury.


  • Occasionally, there are no symptoms.

  • Pain and tenderness in the area of the exostosis that is worsened by pressure or minor injury.

  • Physical changes noticed in the contour of the arm, either visibly or by touch.

  • If the exostosis breaks (rare), a feeling of a movable piece within the arm may be felt.

  • Bruising (contusion) and swelling with repeated injury.


  • Repeated injury (contusions, sprains, or strains) that involve the humerus.

  • Chronic irritation to an already damaged bone area.

  • Occasionally a person may be born with the condition, this is known as osteochondroma.


  • Participation in contact sports, especially those that include blocking with the arms (football, rugby, and martial arts).

  • Poor muscle strength or conditioning.


  • Wear proper protective equipment and ensure correct fit for arm pads.

  • Allow for recovery from any arm injury.

  • Maintain strength and flexibility in the arm. Learn and use correct techniques for the sports activities to reduce the likelihood of injury.


Upper arm exostosis usually causes no disability when treated appropriately.


  • Prolonged healing time if activity is resumed before healing is allowed.

  • Proneness to repeated arm injury.

  • Pressure on nearby nerves, blood vessels, muscles, ligaments, tendons, or other soft tissue.

  • Formation of a fluid filled sac (bursa) over the exostosis. This condition has the ability to cause bursitis.

  • Increasing size of exostosis and symptoms due to repeated injury.

  • Risks of surgery, including infection, bleeding, injury to nerves, recurrence of the exostosis, and fracture of the arm.


Treatment depends on the severity of the exostosis. For cases with no symptoms, no treatment is necessary. For cases with symptoms, treatment initially consists of medication and ice to control pain and inflammation. One should modify the activities that cause pain. This may include taking a break form sports to allow for healing. Cold and heat treatments may help resolve symptoms. Stretching and strengthening exercises of the arm muscles may also be helpful. The exercises and heat and cold treatments may be done at home or under the direction of a therapist. Occasionally a cortisone injection is used to reduce inflammation in chronic cases. Padding of the arm is usually recommended, when possible, when returning to sports to prevent recurrence. Rarely, surgery to remove the exostosis is recommended, but only if symptoms persist after 6 or more months of conservative treatment.


  • If pain medication is necessary, nonsteroidal anti-inflammatory medications, such as aspirin and ibuprofen, or other minor pain relievers, such as acetaminophen, are often recommended.

  • Do not take pain medication for 7 days before surgery.

  • Prescription pain relievers are usually only prescribed after surgery. Use only as directed and only as much as you need.

  • For chronic cases, corticosteroid injections may be given to reduce inflammation.


  • Cold treatment (icing) relieves pain and reduces inflammation. Cold treatment should be applied for 10 to 15 minutes every 2 to 3 hours for inflammation and pain and immediately after any activity that aggravates your symptoms. Use ice packs or an ice massage.

  • Heat treatment may be used prior to performing the stretching and strengthening activities prescribed by your caregiver, physical therapist, or athletic trainer. Use a heat pack or a warm soak.


  • Symptoms get worse or do not improve in 2 weeks despite treatment.

  • Any of the following occur after surgery:

  • Pain, numbness, or coldness in the arm and hand.

  • Blue, gray, or dark color in the fingernails.

  • Increased pain, swelling, redness, drainage, or bleeding in the surgical area.

  • Signs of infection, including headache, muscle aches, or a general ill feeling with fever.

  • New, unexplained symptoms develop (drugs used in treatment may produce side effects).