Acquired heterotopic ossification in hips and knees following encephalitis: case report and literature review

BACKGROUND: Heterotopic ossification (HO) is a rare and potentially detrimental complication of soft-tissue trauma, amputations, central nervous system injury (traumatic brain injuries, spinal cord lesions, tumors, encephalitis), vasculopathies, arthroplasties and burn injury, characterized by lamellar bone growth in non-osseous tissues such as the muscle and the joint capsule. Heterotopic ossification associated with encephalitis is rare and the occurrence of excessive, symptomatic heterotopic ossification around bilateral hips and bilateral knees is rarely described in the literature. CASE PRESENTATION: We present a 47-year-old man with heterotopic ossification in the bilateral hips and bilateral knees that prevented him from walking after being attacked by encephalitis as the case study. He developed severe pain and significantly impaired range of motion of bilateral hips and bilateral knees. Research so far revealed that the management of heterotopic ossification is controversial. After requiring revision surgery resection of heterotopic ossification, reconstruction of the medial collateral ligament and adjunctive pharmacotherapy of 200 mg Celecoxib for 8 weeks after operation, he regained mobility of his joints. On review of X-ray, there was no recurrence of HO and no loosening of rivets which were used in the reconstruction of medial collateral ligament. CONCLUSION: Heterotopic ossification in the bilateral hip joints and bilateral knee joints associated with encephalitis have never been reported previously. Daily functions of heterotopic ossification patients can be hampered by pain, inflammation, reduced mobility, the loss of normal posture and other complications. Further studies of presumptive root causes, the early diagnosis, preventability and optimal therapeutic measures for heterotopic ossification following encephalitis are required. Different patient should be managed with different appropriated protocol based on the risk of individual patient and the institutional experience.