Acquired and congenital forms of heterotopic ossification: new pathogenic insights and therapeutic opportunities.

Heterotopic ossification (HO) involves the formation and accumulation of extraskeletal bone tissue at the expense of local tissues including muscles and connective tissues. There are common forms of HO that are triggered by extensive trauma, burns and other bodily insults, and there are also rare congenital severe forms of HO that occur in children with Fibrodysplasia Ossificans Progressiva or Progressive Osseous Heteroplasia. Given that HO is often preceded by inflammation, current treatments usually involve anti-inflammatory drugs alone or in combination with local irradiation, but are not very effective. Recent studies have provided novel insights into the pathogenesis of acquired and genetic forms of HO and have used the information to conceive and test new and more specific therapies in animal models. In this review, I provide salient examples of these exciting and promising advances that are undoubtedly paving the way toward resolution of this debilitating and at times fatal disease.