Maybe it is due to the lack of physical activity during the pandemic, but I have seen way more children presenting to the emergency department with assorted aches and pains. But one of these injuries was a bit more rare and surprising.  

A 15 year-old male presents to the emergency department with inability to walk and leg pain. He was in physical education class where they were performing timed sprints. His initial runs went fine, but he suddenly felt a pop on his right hip and pain. He started to limp afterward and continued to run but the pain worsened. Now he is unable to flex or extend his right leg without significant pain. He did not fall down or sustain any additional trauma.

A radiograph obtained in the emergency department demonstrates the following:

Etiology and Mechanism

Pelvic avulsion fractures usually affect the adolescent athlete population. Our patient sustained an apophyseal avulsion of ischial tuberosity. These injuries are unique to pediatrics because the bones are not fully ossified. Pelvic avulsion fractures usually occur from explosive actions (sprinting, jumping, kicking) where the associated muscle pulls off a part of the bony attachment at the growth plate. 

These are the sites for pelvic avulsion fractures and associated muscles:

Workup and Imaging

It is important to distinguish this type of injury from muscle strain as management is different, and missed diagnosis may result in chronic pain. Patients have pain on palpation, weakness, and limited and/or painful range of motion. Most avulsion fractures can be diagnosed with a plain AP and frog-leg lateral pelvic radiograph. Avulsion fracture of the AIIS may be better visualized on frog leg lateral view. Iliac crest avulsion fractures may be subtle on AP radiograph. MRI or CT may be used to detect more subtle fractures especially with suspicious clinical exam or history.

Management

Most pelvic avulsion fractures are treated conservatively and nonoperatively with rest, analgesia, and rehab with gradual return to activity. Operative intervention remains controversial but is dependent on the degree of displacement (>15 or 20mm) and athletic demands of the patient. Most return to activity in a few months. Operative intervention may result in faster return to normal activity. Complications may include non-union, chronic pain, heterotopic ossifications, and decreased function.

References

1. Keane, Owen . Pelvic avulsion injuries, Don’t Forget the Bubbles, 2019. Available at: https://doi.org/10.31440/DFTB.21307
2. Dixon, A., Saber, M. Apophyseal avulsion fractures of the pelvis and hip. Reference article, Radiopaedia.org. (accessed on 10 Nov 2021) https://doi.org/10.53347/rID-30013
3. Shaath S, Andras L. Pelvis Fractures-Pediatrics. https://www.orthobullets.com/pediatrics/3000/pelvis-fractures–pediatric. (accessed on 10 Nov 2021)
4. Ghanem IB, Rizkallah M. Pediatric avulsion fractures of pelvis: current concepts. Curr Opin Pediatr. 2018;30(1):78-83.
5. Eberbach H, Hohloch L, Feucht MJ, Konstantinidis L, Südkamp NP, Zwingmann J. Operative versus conservative treatment of apophyseal avulsion fractures of the pelvis in the adolescents: a systematical review with meta-analysis of clinical outcome and return to sports. BMC Musculoskelet Disord. 2017;18(1):162.
6. Azar FM, Canale ST, Beaty JH, Campbell WC. Campbell’s Operative Orthopaedics. Frederick M. Azar, S. Terry Canale, James H. Beaty. Fourteenth edition. Elsevier; 2021.
7. Schuett DJ, Bomar JD, Pennock AT. Pelvic apophyseal avulsion fractures: a retrospective review of 228 cases. J Pediatr Orthop. 2015;35(6):617-623.
8. Moeller JL, Galasso L. Pelvic region avulsion fractures in adolescent athletes: a series of 242 cases. Clin J Sport Med. Published online September 15, 2020.