A 39-year-old man presented to the emergency department with tibial and fibular fractures and a traumatic brain injury (TBI) after a motor vehicle accident.
Imaging studies obtained after the trauma revealed a comminuted wedge fracture of the tibial diaphysis with mild displacement and angulation, along with an overlapping fibular fracture (Figure 1), and multifocal subarachnoid haemorrhage in the right frontoparietal and left parietal regions on brain CT (Figure 2).
Six months after the initial injury, during which the patient remained bedridden without any new trauma history, shoulder X-rays and CT scans were performed due to complaints of shoulder pain (Figures 3a, 3b, and 3c). The imaging revealed extensive bilateral heterotopic ossification in the lower glenohumeral joint, indicating mature ossification.
Background
Heterotopic ossification (HO) is a disorder characterised by new bone formation outside of normal skeletal locations and surrounding paralysed joints [2]. This condition can be categorised into two main types: acquired (the most prevalent type and the primary focus of this presentation), and congenital diseases [4].
HO can result from various causes, such as trauma, surgical interventions, burns, and neurological or rheumatologic diseases, with patients having traumatic brain injury (TBI) and elbow fractures or dislocations being 15 times more likely to develop HO than those without TBI [1,3,4]. 8-20% of TBIs go on to develop neurogenic HO around major joints, with the most frequently affected areas being the hip and thigh [1].
The pathophysiology is not fully understood, but a neurohumoral response is believed to be involved [3].
Clinical Perspective
Clinical findings typically arise 3 to 12 weeks after the triggering event [4] and may include pain, decreased joint mobility, and inflammatory signs [1]. Notably, serum alkaline phosphatase levels significantly increase within the first six to 12 weeks after injury in affected patients [1].
Imaging Perspective
Plain radiographs and computed tomography (CT) are the gold standard methods due to their ability to detect immature bone formation. However, calcifications are only detectable around three to six weeks after symptom onset [1].
In the acute phase of HO, due to inflammation, MRI reveals nonspecific findings, including isointense or hyperintense areas on T1 and T2 sequences. As calcification progresses, signal voids appear at the periphery on all MRI sequences. When mature, more specific signs emerge—such as a hyperintense cancellous fat mass surrounded by hypointense cortical bone—aiding in diagnosis [4].
Three-phase bone scintigraphy is a highly sensitive method that detects early changes, making it an important tool for monitoring and therapeutic planning [4].
Outcome
Non-steroidal anti-inflammatory drugs (NSAIDs), bisphosphonates, and localised low radiation may, prophylactically, benefit high-risk patients, while established HO treatment includes physiotherapy for joint mobility and surgical excision [4,5].
Take Home Message / Teaching Points
Heterotopic ossification (HO) is characterised by the formation of bone in soft tissues, particularly around major joints, with the hip being the most commonly affected joint, often resulting from various causes, the most common being trauma to the central nervous system.
The presentation can vary significantly, ranging from no radiological findings to complete joint ankylosis, and the exact pathogenesis of the disease is still unclear.
Early diagnosis is challenging due to non-specific imaging changes that may be mistaken for other conditions.
All patient data have been completely anonymised throughout the entire manuscript and related files.
Neurogenic heterotopic ossification
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1. Lower Extremity X-ray (Tibia, Fibula): A clear fracture line is visible in the right (or left) tibia and fibula, indicating disruption of bony continuity. The fracture ends show poor alignment, and there is swelling in the surrounding soft tissues.
2. Head CT: Post-traumatic changes are observed in the cranium and brain. There may be contusions or punctate hemorrhagic lesions within the brain parenchyma, suggesting traumatic changes. No significant large intracranial hemorrhage or space-occupying effect is noted.
3. Shoulder (or Upper Limb) X-ray and CT: Irregular high-density lesions are seen in the soft tissues around the shoulder joint, with a relatively clear demarcation from the normal bone cortex, appearing in patchy or lump-like shapes. These findings indicate a possible Heterotopic Ossification (HO). Local soft tissue swelling is present, but there is no clear evidence of infiltration into the bone.
The above differential diagnoses are primarily based on the history of trauma, concomitant neurological injury, imaging findings, and the process of soft tissue ossification.
Considering the patient’s history of trauma (tibiofibular fractures, traumatic brain injury), the appearance of irregular ossification in the periarticular soft tissues, and the typical timeline of several weeks to months after injury for heterotopic bone formation, the most likely diagnosis is “Traumatic Heterotopic Ossification (HO).”
If further confirmation is needed, it can be supplemented by monitoring serum alkaline phosphatase levels, performing a three-phase bone scan, or ongoing observation of the ossified lesion to exclude other forms of soft tissue calcification or bone pathology.
1. Treatment Strategy:
2. Rehabilitation and Exercise Prescription (FITT-VP Principle):
This report is a clinical reference analysis based on the currently available imaging and medical history data. It does not replace in-person consultation or the clinical decision-making of professional physicians. The final plan for diagnosis and treatment should be determined by a specialist after thorough evaluation of the patient’s specific condition.
Neurogenic heterotopic ossification
