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

Abstract

BackgroundHeterotopic 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 presentationWe 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.ConclusionHeterotopic 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.

Heterotopic ossification: radiological and pathological review

“…Although the exact cellular origin is debated, it is commonly accepted to be multipotent cells in the local tissue. The requirements necessary for HO formation include having an inducing agent, an osteogenic precursor, and a permissive environment for osteogenesis19,20 which when met leads to proliferation and formation of bone 21. Bidner et al .…”

“…Bidner et al . have proposed that failure to regulate the immune system or inflammatory response lead to the release of inciting agents that lead to HO 19,22. Further investigations by Salisbury et al .…”

Heterotopic ossification following anti-NMDA receptor encephalitis: a case report

“…Although several HO cases after viral encephalitis have been reported [4], our case is the first report of autoimmune encephalitis with HO.…”

“…Neurogenic HO following traumatic brain injury (TBI) and spinal cord injury (SCI) has been widely reported. However, HO associated with encephalitis is rarely reported [3, 4]. …”

Acquired Neurogenic Heterotopic Ossification Following Treatment for ADEM: A Case Report and Literature Review

“…That is to say, none of the available prophylactic measures would affect the outcome of HO once the process begun. Therefore, a urgent need exists to improve the current diagnostic modalities for HO which are inadequate to diagnose and intervene on HO at early time-point (21) Radiological findings X-ray cannot discover HO until 4-6 weeks (21) Brooker et al classified post-traumatic HO according to its radiological findings (Table I) (4) Conventional radiography is commonly utilized at initial evaluation of patients with clinical symptoms suggestive of HO. Typically, a soft tissue mass or swelling is the earliest radiographic finding.…”