Heterotopic ossification

Dr B A Gopal Krishna, Consultant – Orthopaedics and Joint replacement surgeon, Manipal Hospital, Jayanagar

Heterotopic ossification (HO) is a rare and debilitating bone disorder. It is the abnormal growth of bones in soft tissue. These extra bones may rupture the soft tissues and cause friction between the bones leading to complicated medical conditions. It is acquired by people with musculoskeletal trauma, spinal cord injury, or other neurological disorders. It mainly affects elbow, hip, shoulder, and joints. It is more commonly seen in men than in women.

Symptoms of Heterotopic ossification
The symptoms of Heterotopic ossification mimic other inflammatory conditions of bone and joints. Timely diagnosis and treatment at an earlier stage may reduce the severity of this condition. A few common symptoms associated with this disorder are as follows:

• Loss of joint flexibility
• Redness, swelling, and warmth at joints
• Pain and discomfort in the joints
• Muscle spasm
• Fever

Complications of Heterotopic ossification
Heterotopic ossification with Autonomic dysreflexia is an emergency condition. In this case, the pain or discomfort message does not reach the brain due to spinal cord injury. If not treated immediately, it leads to serious complications like organ damage, stroke, brain injury or death may occur.

Patients with a respiratory disorder are prone to develop HO due to being on ventilation for a longer time and exposure to neuromuscular agents. These agents generally cause paralysis of skeletal muscle.

Causes of Heterotopic ossification
The exact cause of Heterotopic ossification is unknown. There are many theories about its development in an injured person. The following may be a few reasons that lead to this condition:

• Trauma or injury
• Severe bleeding
• Loss of oxygen
• Inflammation
• Muscle spasms
• Immobilization or paralysis
• Genetics

Diagnosis of Heterotopic ossification
Heterotopic ossification is an irreversible condition. Early detection leads to better treatment without surgeries. Few tests to diagnose this condition are as follows. Blood tests, CT scan, X-rays, Ultrasound

Treatment and prophylaxis of Heterotopic ossification
The initial stage of treatment includes medication to prevent further growth of bones and physical therapy to prevent loss of joint flexibility. Non-steroidal anti-inflammatory drugs and Biphosphonates are effective for prophylaxis and treatment of this condition. Indomethacin is considered a gold standard to treat this disorder. Combined radiotherapy and Non-steroidal anti-inflammatory drugs such as Indomethacin are found to be effective in preventing abnormal bone formation after hip arthroplasty

Surgery and radiation therapy are performed in severe conditions like joint stiffness, loss of movement, or excruciating pain. Post-surgery, patients are usually advised by the doctor not to lift heavy weight for three to six weeks. It may take around six to nine months to relapse back to work depending on the health of the patient and affected area.

Pandemic has led to many medical complications. HO is a well-known entity in the medical fraternity, but its association with Covid is a cause for concern. Probably hypoxic tissue damage caused by Covid is a trigger point. This is compounded by prolonged immobility as seen with patients on ventilator support. To date, only four to five cases of HO formation are reported in patients with severe Covid illness. This low number may be because of a lack of awareness among the public who, don’t reach medical facilities until it’s too late.