Neurogenic heterotopic ossification (NHO) is defined as an ectopic ossification around proximal joints usually seen after traumatic brain injury, spinal cord injury or polytrauma.

NHO causes pain, partial or total joint ankylosis and vascular or nerve complications.

The osteopenia (low bone density) induced by ankylose increases the fracture risk of femoral neck during the hip surgery performed to remove the NHO.

The analyse of femoral head bone mineral density from hip pre-surgical CT scan could anticipate this kind of complication establishing a presurgical prognostic.

If as it turns out the bone density measured from hip pre-surgical CT scan is relevant fracture risk marker, a preventive osteosynthesis or femoral head and neck resection could be performed in the same time of NHO resection.

Inclusion Criteria:

• Patients aged 18 years and over
• Patients having surgery resection of surgery resection of Neurogenic heterotopic ossification of hip.
• Patients with pre-surgery CT-scan and surgery report available

Exclusion criteria:

• Minor patients
• Patients didn't have surgery surgery resection of Neurogenic heterotopic ossification of hip.
• Pre-surgery CT-scan and surgery report not available

Exclusion Criteria:

-

Patients having surgery resection of surgery resection of Neurogenic heterotopic ossification of hip.

Their per-operative CT-scan and surgery report will be collected from the records of Nîmes and Montpellier University Hospital Center

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