Abstract
Heterotopic ossification (HO) is a relatively common complication of total hip arthroplasty (THA), but is rather rare after total knee arthroplasty (TKA). In both cases, it is usually asymptomatic and is most commonly identified as an incidental finding on post-operative radiographs. However, in severe cases it can result in decreased range of motion and pain. There are several risk factors that have been shown to be associated with development of HO. These include male gender, ceramic-on-ceramic bearings, prior stroke, and hypertrophic osteoarthritis.
Heterotopic ossification can be treated with physical therapy during the maturation phase (12 to 24 weeks), but surgical intervention is required if the stiffness persists. All heterotopic bone should be excised with careful attention to neurovascular structures. Patients should begin prophylaxis following HO excision and prior to any subsequent surgeries. Heterotopic ossification prophylaxis consists of NSAIDs, radiotherapy, or a combination of both modalities. These therapies are not without complications, therefore, routine administration of prophylaxis for all patients is not indicated. Several new pathways of inhibiting extra-skeletal bone formation in HO are under investigation (retinoid acid receptor agonists, apyrase, and LDN-193189). Future studies should focus on identification of patients at risk for HO as well as better therapeutic options with less side effects.
