Heterotopic Ossification Medication

Updated: Jan 27, 2021
  • Author: John Speed, MBBS; Chief Editor: Elizabeth A Moberg-Wolff, MD  more...
  • Print

Medication Summary

Today, the medical treatment of HO is directed at early HO. In the later stages of the development of mature bone, medical treatment is ineffective. Etidronate (Didronel) is the only available medication for the treatment of HO after SCI. [27, 44] Treatment with NSAIDs may be required initially, until the resolution of inflammation and the normalization of CRP levels. [11]


Nonsteroidal anti-inflammatory agents

Class Summary

Presumed to have direct and indirect effects on the formation of HO. Direct effect refers to the inhibition of the differentiation of mesenchymal cells into osteogenic cells, and indirect effect refers to the inhibition of posttraumatic bone remodeling by suppression of the prostaglandin-mediated inflammatory response.

Indomethacin (Indocin)

Known to inhibit synthesis of prostaglandins.



Class Summary

The bisphosphonate group of compounds has properties similar to naturally occurring pyrophosphate, which may be a regulator of calcification. [3] Etidronate disodium is the most extensively studied of this class of drugs for the treatment of HO. Etidronate acts by (1) inhibiting precipitation of calcium phosphate from unsaturated solutions, (2) delaying aggregation of apatite crystals into layers, and (3) blocking conversion of calcium phosphate into hydroxyapatite. Apparently, predisposition to the inflammatory process and mineralization decreases with time, although it is not understood why. This phenomenon may be why there is no massive rebound bone formation after cessation of etidronate. Thus, the effectiveness of etidronate depends entirely on when and how long it is given, and the drug does not affect HO that has already formed.

Etidronate disodium (Didronel)

Reduces bone formation and does not alter renal tubular reabsorption of calcium. The effects of etidronate increase as the dose increases. Agent does not appear to affect fracture healing.