Heterotopic ossification (HO) is perhaps the
single most significant obstacle to independence, functional mobility, and
return to duty for combat-injured veterans of Operation Enduring
Freedom and Operation Iraqi Freedom. Recent research into the cause(s)
of HO has been driven by a markedly higher prevalence seen in these
wounded warriors than encountered in previous wars or following
civilian trauma. To that end, research in both civilian and military
laboratories continues to shed light onto the complex mechanisms
behind HO formation, including systemic and wound specific factors,
cell lineage, and neurogenic
Neurogenic heterotopic ossification (NHO) is
a disorder of aberrant bone formation affecting one in five patients sustaining
a spinal cord injury or traumatic brain injury. Ectopic bone forms
around joints in characteristic patterns, causing pain and limiting
movement especially around the hip and elbow. Clinical sequelae
of neurogenic heterotopic ossification include urinary tract infection,
pressure injuries, pneumonia and poor hygiene, making early diagnosis
and treatment clinically compelling. However, diagnosis remains
difficult with more investigation needed. Our pathophysiological
understanding stems from mechanisms of basic bone formation enhanced
by evidence of systemic influences from circulating humor factors
and perhaps neurological ones. This increasing understanding guides
our implementation of current prophylaxis and treatment including
the use of non-steroidal anti-inflammatory drugs, bisphosphonates,
radiation therapy and surgery and, importantly, should direct future, more
effective ones.
