Bob VogelQ. I’m 34 and in my 10th year as a T6 complete paraplegic. About a year ago, I developed a pressure sore on my sacrum, and a couple months into the healing process I noticed my right hip was red and swollen. My doc put me through a bunch of tests, including a bone scan that confirmed I had heterotopic ossification — bone growth in the tissues around my hip. It has grown so much that it is affecting the range of motion in my hip.

I was prescribed a medication called Didronel to stop the growth. My physician said we can discuss surgery to remove the bone growth to try and regain some range of motion, but not until another bone scan shows it has stopped growing. He also said it is a messy surgery.

What causes heterotopic ossification? What are the signs and symptoms? In addition to medication for stopping growth, is there any way to shrink it? How hard is it to remove?

— Scott

A. Heterotopic ossification is a condition where bone grows in muscle, tendons or other soft tissues around joints in the body. The new bone grows three times faster than normal and can cause jagged, painful joints. In some cases, there is so much growth that it restricts joint movement. HO can also develop into areas that protrude and are prone to cause skin breakdown. In nondisabled people HO is caused by some type of trauma, such as dislocation of the hip or tears in a joint — the body “thinks” the trauma is a fracture and tries to heal it by making bone.

HO in people with spinal cord injury is called neurogenic HO, and the cause in acute SCI is not known. There is no way of predicting who will develop it, says Dr. Douglas Garland, a retired orthopedic surgeon and former director of neurotrauma at Rancho Los Amigos Rehab Center, who has written peer-reviewed papers on the subject. When HO occurs in the acute stage of SCI, it most frequently happens within two months of injury. It can also occur years or decades later and manifests in 10 to 20 percent of people with SCI. It oc