Femoral nerve palsy following a subperiosteal haematoma

Subperiosteal hematoma of the iliac bone: imaging features of acute and chronic stages with emphasis on pathophysiology

“…Pathophysiology Subperiosteal hematomas forming on flat bones have been reported in the calvarium [9], the orbit [10], and the iliac wing. The vast majority of these lesions occur in children and young adults, with no patient older than 18 years old for the reported cases of iliac hematoma [1][2][3][4][5][6][7][8]. This particular distribution is believed to result from the loose attachment of the periosteum to the underlying bone in young patients, leading to traumatic detachment and nutrient vessel injury and resulting in subperiosteal hemorrhage [11].…”

“…The most common causative activities were gymnastics [3], horse riding [4], and high jump [2]. Interestingly, some of the first reported cases [6][7][8] concerned children hit while driving a bumper car, hence the term "bumper car syndrome" [8].…”

“…In a few cases in the literature, the authors observed a small pseudoaneurysm in the vicinity of these nutrient foramina [4,13,14]. For some authors, the presence of these aneurysms may explain brisk bleeding from the medial and inferior walls of the subperiosteal cavity during surgery [2,8].…”

“…These lesions have been described in a few clinical case reports only [1][2][3][4][5][6][7][8], and no patients have been reported in the radiology literature. Also, to the best of our knowledge, there is no data on the long-term evolution of images for acute subperiosteal iliac hematomas.…”

Incidental finding in a young man

“…Rarely, it can be seen in patients with acetabular fracture [4]. The most widely accepted mechanism, is that of the periosteum of the inner iliac bone surface being avulsed during sudden forceful traction of the iliacus muscle [1,[5][6][7]. This theory is supported by the fact that subperiosteal hematomas develop mainly in children and teenagers, in whom the periosteum is more easily stripped from the bone than in adults [7,8].…”