Imaging the Pediatric Athlete: Acute and Stress Skeletal Injuries.

Sports-related traumatic injuries in children have increased in tandem with participation in higher level activities. The developing musculoskeletal structures in children are susceptible to unique injuries that vary with location and the stage of skeletal maturation. The imaging evaluation of sports injuries in children presents several unique challenges. The purpose of this article is to educate the reader on injuries unique to the skeletally immature athlete with focus on their imaging evaluation and diagnosis.

Combined posterolateral corner and acute anterior cruciate ligament injuries in an adolescent cohort: a magnetic resonance imaging analysis.

PURPOSE: Failure of a reconstructed anterior cruciate ligament (ACL) has significant morbidity in the paediatric and adolescent patient population. Untreated concomitant posterolateral corner (PLC) injury is an identified cause of failed ACL reconstruction; however, the injury pattern has yet to be defined for the paediatric population. METHODS: Magnetic resonance imaging (MRI) studies of the knee performed between 1 January 2009 and 1 January 2013 were retrospectively reviewed. Imaging reports indicating an intra-substance injury of the ACL were reviewed, and all associated injured structures were recorded. Injury patterns were categorised by age, gender, physis status and associated injuries. Logistic regression and chi-square analyses compared ACL disruptions with and without concomitant PLC injuries. RESULTS: One hundred and twenty-eight patients (74 boys and 54 girls, average age 15.27 years) sustained an ACL disruption. Concomitant injury to the PLC was seen in 13.3% of injuries. Associated PLC injuries were significantly associated with lateral meniscus injury and Segond fractures. Lateral meniscus injury was predictive of PLC injury (p = 0.05) upon logistic regression analysis. CONCLUSION: Concomitant PLC injuries were found in 13.3% of all ACL disruptions on MRI analysis. Lateral meniscus injuries associated with an ACL disruption were predictive of concomitant PLC injury. Combined injury of the ACL and lateral meniscus should prompt close scrutiny to PLC structures.

The Effect of Bony Parameters on the Pediatric Knee: Normal versus Anterior Cruciate Ligament Injury versus Tibial Spine Avulsion Fracture.

Purpose Anterior cruciate ligament (ACL) injuries can present as a ligamentous disruption or avulsion fracture of the tibial spine in pediatric patients. Differences in knee morphometric parameters have been investigated between pediatric cohorts with ACL disruptions and tibial spine avulsion fractures. However, no study to date has compared morphometric parameters in patients with tibial spine avulsion fracture against a control population. Methods A retrospective review of pediatric patients undergoing knee magnetic resonance imaging (MRI) studies was performed, identifying 15 patients with tibial spine avulsion fracture between January 1, 2009, and January 1, 2013. Inclusionary criteria consisted of patients who sustained an acute tibial spine avulsion fracture and had MRI examination. The MRI studies were analyzed by a pediatric musculoskeletal radiologist, who measured identified bony parameters, and results were compared with an age-matched control group and a skeletally immature cohort with ligamentous disruption of the ACL. Data were analyzed using unpaired t test and logistic regression. Results Cohorts included 15 patients with a tibial spine avulsion fracture, 39 with an ACL disruption, and 28 in the age-matched control group. The tibial spine group demonstrated no significant differences in bony parameters when compared with the control group, but had significantly wider tibial eminence widths in comparison to the ACL group (2.92 cm [0.4] versus 2.71 cm [0.27]; p = 0.040). Additionally, this finding was predictive of tibial spine avulsion injury when assessed by logistic regression. Conclusions Pediatric patients who sustain a tibial spine avulsion fracture exhibit significantly wider tibial eminences when compared with the cohort with ACL injuries. This indicates a possible biomechanical explanation for differences in ACL injury patterns that should be examined in future, prospective analyses.

Knee morphometric risk factors for acute anterior cruciate ligament injury in skeletally immature patients.

STUDY DESIGN: Retrospective, case-control. PURPOSE: Knee morphometric risk factors for noncontact anterior cruciate ligament (ACL) injury have been a popular topic with skeletally mature patients. Little research has focused on the skeletally immature, with conflicting conclusions. This study performs a comprehensive analysis of identified parameters thought to predispose to ACL injury in a skeletally immature cohort. METHODS: A retrospective review of pediatric patients undergoing knee magnetic resonance imaging (MRI) was performed over a 4-year period. Inclusionary criteria included mid-substance ACL disruption, skeletal immaturity, noncontact injury, without associated ligamentous disruption, and no medical condition associated with ligamentous laxity. MRI studies were analyzed by a pediatric musculoskeletal radiologist, measuring identified bony parameters, and compared with an age-matched control group without ligamentous injury. Data were analyzed using unpaired t-tests and logistic regression. RESULTS: One hundred and twenty-eight patients sustained an ACL disruption, 39 met all inclusionary criteria (66 excluded for associated ligamentous disruption, 23 skeletally mature, three traumatic mechanisms, one with Marfan syndrome). When compared to an age-matched control cohort, the notch width index (NWI) was found to be significantly smaller in the ACL-injured group (p = 0.046). Subgroups analysis demonstrated significant differences in morphometric parameters between subjects with isolated ACL injuries and concomitant medial collateral ligament (MCL) strain. CONCLUSIONS: The NWI was significantly smaller in the ACL injury group. Significant differences were noted between isolated ACL injuries and ACL injuries with an MCL strain. This study further highlights the need for incorporating associated injury patterns when investigating the influence of morphometric factors for ACL injury in the skeletally immature. LEVEL OF EVIDENCE: Level III.

Blunt renal trauma in children with pre-existing renal abnormalities.

The kidneys are the most commonly injured genitourinary organ in children following blunt abdominal trauma. Though the retroperitoneal location affords the kidneys some protection from the forces experienced in blunt abdominal trauma, the kidneys are at greater risk of injury when a disease process exposes them from their normal shielded location. In such cases, the injuries may appear to be disproportionate in relation to the severity of the trauma history, confusing the imaging findings. Recognition of both the underlying disease process as well as the manifestations of acute trauma is important; therefore, we present a pictorial essay of traumatized kidneys in children with pre-existing renal abnormalities.

MRI of displaced meniscal fragments.

A torn meniscus frequently requires surgical fixation or debridement as definitive treatment. Meniscal tears with associated fragment displacement, such as bucket handle and flap tears, can be difficult to recognize and accurately describe on MRI, and displaced fragments can be challenging to identify at surgery. A displaced meniscal fragment can be obscured by synovium or be in a location not usually evaluated at arthroscopy. We present a pictorial essay of meniscal tears with displaced fragments in patients referred to a pediatric hospital in order to increase recognition and accurate interpretation by the radiologist, who in turn can help assist the surgeon in planning appropriate therapy.