Heterotopic ossification in COVID-19: A series of 4 cases.

Dear Editor, Heterotopic ossification (HO) refers to abnormal formation of mature lamellar bone in soft tissues without connection to the periosteum, around proximal articulations, knees and elbows. The hip joint is affected in 77% of cases and the shoulder in 18%, and HO results in muscular and articular pain, joint ankylosis and loss of independence. HO is usually found in patients with central and peripheral nervous system lesions. [...