Symptomatic heterotopic ossification after very severe traumatic brain injury in 114 patients: Incidence and risk factors
Introduction
Heterotopic ossification (HO) is a localised and progressive formation of pathologic ectopic bone, mainly located in the soft tissue near the big joints.7, 11, 27, 30
HO is primarily observed as a slowly developing complication following trauma to the central nervous system (CNS), traumatic spinal cord lesions (SCI) as well as traumatic brain injury (TBI).8, 10, 12, 13, 14, 16, 18, 21, 25, 26, 29, 33, 34
The reported overall incidence of HO in adults varies from 11 to 73.3% depending on patient population, diagnostic method and research methodology. The clinical importance has been reported to be 10–20%.4, 7, 8, 11, 16, 22, 28, 32, 34
The aetiology and pathogenesis of HO are unknown. Humoural as well as local and/or systemic factors are believed to initiate the formation of bone-forming cells. Several factors have been suggested as aetiological to HO: demographic, trauma-related (various CNS conditions and severity, blunt or penetrating CNS trauma, fractures, surgery), clinical (coma duration, presence of spasticity, immobilisation, coma outcome and duration), genetic (HLA antigens), physiological (infections, local micro-trauma/haemorrhage), and biological (serum alkaline phosphatase and serum calcium).3, 4, 6, 7, 8, 9, 11, 12, 13, 15, 18, 19, 23, 29, 30, 32
The aim of this study was to determine the incidence and potential risk factors of developing symptomatic HO among adult patients with very severe traumatic brain injury.
Section snippets
Patients and methods
The study comprised an approximately complete, consecutive series of 114 adult patients (over 14 years of age) from a well-defined geographical area, and with a posttraumatic amnesia (PTA) period of at least 28 days, i.e. very severe TBI. After neurosurgical treatment, they were transferred on average 17 days post injury to intensive rehabilitation at the Brain Injury Unit (BIU) of the University Hospital at Hvidovre. Demographic and functional data as well as data about trauma severity and
Results
HO was found in 13 (19.1%) of the 68 patients who had undergone radiographic examinations and in 11.4% (13/114) of the total study population. Seven patients had unifocal HO, 5 had bifocal HO and 1 patient had HO in four locations, giving a total of 21 locations with HO. In 16 of 21 locations (76.2%) HO was in association with fractures, mainly in the hip and thigh. HO was not diagnosed in any of the six patients who died during their stay at the BIU.
Nine of the 21 (7.9%) locations with HO were
Discussion
Our finding of HO in 11.4% of 114 patients with PTA of at least 28 days seems low compared to other studies. We may have underestimated the number of patients with HO because X-rays were taken only when symptoms or signs of HO were present, or as a fracture control. It could be assumed that some of the 46 patients, who did not have radiographic examinations of the extremities or pelvic region, have had less or no symptoms of HO. However, it seems less liable that clinically significant HO
Conclusion
In conclusion, we found the incidence of heterotopic ossification among adult patients with very severe traumatic brain injury less than expected from the literature. This could be a result of early intensive rehabilitation.
Conflict of interest
All authors state that they have no conflict of interests.
Acknowledgements
Louise Lau Simonsen and Stig Sonne-Holm contributed to project setup, planning, data collection, data interpretation and presentation in writing. Michael Krasheninnikoff helped with planning and presentation in writing. Aase W. Engberg contributed to planning, data collection and presentation in writing. All authors have contributed to and read the paper, as well as given their permission for their names to be included as co-authors.
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