Study design: Retrospective study.
Objectives: This study was implemented to detect risk factors for the developing of heterotopic ossifications (HOs) in spinal cord injury (SCI) patients.
Setting: This study was conducted in Murnau, Germany.
Methods: All patients from 2008-2012 with acute SCI were routinely examined by ultrasound of the hips every 2 weeks. The sub group of SCI patients suffering of HO of the hips were extracted and the incidence of developing an HO was calculated. Parameters like age, level of injury, ASIA Impairment Scale (AIS), duration time of accident until diagnosis of HO, Brooker stage, localization of HO (magnetic resonance imaging (MRI)) and symptoms like thrombosis, emboli, decrease of range of motion (ROM), dermal symptoms, swelling, increase in D-Dimere level, were evaluated. Also accompanying injuries of the brain, lung and extremities were recorded.
Results: From January 2008 until January 2012, 575 patients with an acute and traumatic SCI were treated in our Department. During this period 32 HOs were detected in the muscles surrounding the hip. In 10 cases a single side and in 22 cases both sides were affected. A total of 26 patients were detected showing up a Brooker 0, two patients Brooker 1, and five patients a Brooker stage >2. The adductor muscles showed an edema in 19 cases and the quadriceps muscles were affected in 15 cases. 26% of all SCI patients showed AIS A status, but in patients who developed HO, 64% have had an AIS A status. 19% of patients with a HO were AIS B and 9.5% showed an AIS C and D. Regarding the level of injury the distribution of patients suffering of HO was comparable to the distribution of SCI patients without HO. In mean HO were detected 9 weeks after SCI and no new HO were found after the 22nd (n=1) week of injury. Clinical symptoms such as swelling, pain, redness or decrease in ROM or increase in D-Dimere levels were seen in 24 cases. Accompanying injuries like brain injury and lung contusions were found in 83% of patients developing HO. The incidence of thrombosis was comparable to SCI patients without HO. One patient with no accompanying injuries or clinical symptoms was detected by routinely performed ultrasound.
Conclusions: The risk of developing HO in patients with traumatic SCI is 5.5% but increases when accompanying injuries of the brain and lung occur. Patients with a neurological status of AIS A must also be quoted as risk patients. When considering the described risk factors and clinical symptoms, 96% of all HO can be detected.