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Purpose: Given that pediatric traumatic hip dislocations are relatively rare, the purpose of the current study is twofold: first, to contribute a significant cohort to the existing corpus, and second, to provide evidence toward the role that computed tomography and magnetic resonance imaging could play in identification and management of this type of injury. Methods: A retrospective review was conducted of all patients with traumatic hip dislocation who presented from 2012 to 2022 at a tertiary-level pediatric trauma center. Data regarding demographics, mechanism of injury, imaging, and treatment were tabulated. Outcomes of interest included immobilization length, concomitant injuries, imaging performed and findings, and rates of avascular necrosis, pain, and stiffness. Concomitant injuries were identified using imaging, clinical, and operative notes. Differences between categorical variables were compared using chi-square analysis or Fischer-exact testing, while continuous variables were compared using Student t tests or Wilcoxon rank sum tests when appropriate. Results: Thirty-four patients were identified. Postreduction, 28 patients had a cumulative 17 magnetic resonance imaging, 19 computed tomographies, and 1 intraoperative arthrogram. Of these, 16 patients had 19 injuries identified on advanced imaging that were missed on initial radiographs. Eleven of these patients went on to operative treatment. In eight of these, postreduction advanced imaging helped guide the decision for surgery. In four patients, magnetic resonance imaging was necessary to fully characterize injury to the posterior acetabular rim after initial identification on computed tomography. Magnetic resonance imaging was also used to rule out one computed tomography-diagnosed acetabular fracture. Conclusion: Magnetic resonance imaging is valuable to fully define associated rim and intra-articular injuries following initial treatment of pediatric traumatic hip dislocations. Level of evidence: Level IV diagnostic study.

We study the reaction efficiency of a surficial process in which a diffusing, tumbling dipole A reacts (eventually and irreversibly) with a stationary target dipole B. In contrast to earlier studies of such irreversible diffusion‐reaction events (A+B→C), we consider the situation where at each and every site of the space accessible to the diffusing coreactant A, there is also embedded a fixed dipole. To quantify the influence on the reaction efficiency of (angle‐averaged, dipole–dipole) potential interactions between the tumbling dipole A and the ensemble of stationary dipoles, we design a lattice‐statistical model to describe this problem and use both analytical methods and numerical techniques rooted in the theory of finite Markov processes to work out its consequences. Specifically, we define the reaction space to be an n×n=N square‐planar lattice with the target dipole occupying the centrosymmetric site in that space and determine the mean number of steps required before the irreversible event, A+B→C, occurs. Our results reveal two qualitatively‐distinct regimes of behavior for this diffusion‐reaction process, a low temperature (or strong coupling) regime dominated by nearest‐neighbor excursions only, and a high‐temperature (or weak‐coupling) regime dominated by non‐nearest neighbor excursions of the tumbling dipole A, with the transition between these two regimes occurring over a relatively narrow range of interparticle couplings. This behavior has the character of an ‘‘order–disorder’’ transition and is interpreted here in terms of an ‘‘order parameter’’ W related to a generalized Onsager length. The behavior uncovered is studied as a function of system size and of the boundary conditions imposed.