Traumatic Hip Dislocations in Children and Adolescents: Diagnostic Challenges and the Significance of MRI Imaging - A Multi-Center Study
Authors: Braun Mirjam Evi , Fernandez Francisco Fernandez , Riha Lena , Schmal Hagen , Schmittenbecher Peter P. , Schneidmueller Dorin , Strüwind Christoph , Schwerk Philipp , Reineke Sebastian , Traub Frank , Ihle Christoph , Lieber Justus , Wack Christina , Rüther Hauke , Baumann Florian , Marzi Ingo , Busse Lewin-Caspar , Tüshaus Ludger , Adrian Miriam , Bergmann Florian , Graf Alexander , Kaiser Martin M. , Loose Oliver 
Published: May 2024

Background
Traumatic hip dislocations in children and adolescents are rare but associated with significant consequences such as secondary coxarthrosis and avascular necrosis of the femoral head. Delayed reductions are cited in the literature as a primary cause, mainly due to radiologically overlooked dislocations. The heterogeneous symptomatology and primary care in regular emergency departments complicate the diagnosis. This multi-center study aims to evaluate the various diagnostic steps and propose an improved algorithm for diagnosing traumatic hip dislocations in childhood.
Methods
This retrospective multi-center study included 76 patients aged up to 17 years with acute traumatic hip dislocations and open growth plates from 16 German hospitals. Exclusion criteria included insufficient data, positive history of hip dysplasia, and association with syndromal, neurological, or connective tissue disorders predisposing to hip dislocation. Analysis included anthropometric data and imaging (ultrasound, X-ray, MRI, CT) from 1979 to 2022. Examined parameters included gender, age, associated fractures, mechanisms of injury, initial care, time to reduction, associated injuries, and diagnostic modalities. Statistical analysis was performed using SPSS while strictly adhering to ethical guidelines.
Results
76 patients met the inclusion criteria. Primary imaging showed a clear dominance in X-ray diagnostics in one plane 46% (n = 35) and two planes 39% (n = 30). In 87% of the cases (n = 66), dislocations were diagnosed during initial presentation. Dislocations were missed in 12% (n = 9), with seven children under the age of eight years old. Fifty percent of dislocations of those under four years old were not detected. Delayed reduction occurred in 12 children (15.8%), with 8 patients undergoing reduction more than 24 hours after trauma. The reason in 12% of the cases (n = 9) was an undetected dislocation in imaging. Dislocations were particularly commonly overlooked in conventional X-rays, whereas none were missed in MRI. Fifty-four patients (71%) had associated injuries, of which 57.9% (n = 44) were diagnosed only with MRI.
Conclusion
Successful primary diagnosis of traumatic hip dislocations, which are delayed in 15% of cases and carry an increased risk of femoral head necrosis, requires an algorithm, especially for young children where dislocations are often not automatically suspected. MRI plays a crucial role in the secondary diagnostic phase due to the high incidence of associated injuries. MRI provides a more precise depiction, especially of cartilaginous acetabular avulsions and soft tissue interpositions. These findings underscore the indispensable role of MRI diagnostics in traumatic hip dislocations and a unified diagnostic algorithm.
Level of Evidence: IV