Reliability and modality analysis of patellar height measurement in pediatric knee.

Introduction: Various measurement methods and imaging technique are in use to measure patellar height in pediatric patients. However, there is no gold standard as to which measurement method and modality are the most reliable for pediatric patients. Therefore, the aim of this study was to determine the inter-observer reliability, intra-observer reliability, and applicability of various patellar height measurement methods in pediatric knee. Additionaly, we analyzed the reliability across different imaging modalities. Methods: Total 450 pediatric patients (age: 5-18 years) were evaluated using lateral knee radiographs and magnetic resonance imaging (MRI). The patellar height ratios were measured using five methods. Five methods were Insall-Salvati (IS), Koshino-Sugimoto (KS), Blackburne-Peel (BP), modified Insall-Salvati (MIS), and Caton-Deschamps (CD). The patients were categorized into two age groups: P (ages 5-13) and Q (ages 14-18). Each measurement was conducted twice by two raters. The intra-observer reliability, inter-observer reliability and inter-modality reliability were calculated. In addition, applicability was defined as the possibility to apply each measurement method to each age group. Results: The KS method showed the highest inter-observer reliability and intra-observer reliability when using MRI for both age groups. The inter-observer reliability and intra-observer reliability of the IS for lateral knee radiographs was highest among all observers for group Q. The CD method showed the highest inter-observer reliability in group P, while the KS showed the highest intra-observer reliability in group P using lateral radiographs. The KS method showed the highest inter-modality reliability in group P, while the IS showed the highest inter-modality reliability in group Q. The KS method was applicable to all patients when using lateral knee radiography, and the IS method was applicable to all patients when using MRI. Conclusions: Our results show that the reliability of various measurement method and imaging technique differed based on pediatric knee age group when measuring patellar height. Therefore, in the case of pediatric patients, reliability measurement methods and imaging techniques according to the patient's age should be applied.

Evaluating the Clinical Utility of Brachial Plexus Block for Reducing Opioid Exposure in Pediatric Elbow Fracture Surgery: A Retrospective Cohort Study.

Background and Objectives: Reducing opioid exposure in common pediatric surgeries is of paramount importance. This study aimed to assess the efficacy of regional nerve blocks in reducing opioid exposure while preserving high success rates. Materials and Methods: We conducted a retrospective matched cohort study (1:1) including patients with elbow fractures < 12 years old who underwent treatment with percutaneous pinning. Patients were divided into general-anesthesia (GA) and GA-followed-by-supraclavicular-brachial-plexus-block (GA-SCB) groups. The primary outcome was the number of patients administered postoperative rescue opioids. The secondary outcomes included intraoperative and postoperative opioid administration, the time to first request for rescue analgesia, pain scores, block success rate, block performing time, and block-related complications. Results: In a total of 478 patients, 363 underwent percutaneous pinning, and 86 were cohort-matched (GA: n = 43, GA-SCB: n = 43). On the first postoperative day, 34 (79.0%) patients in the GA group were administered postoperative rescue opioids, compared with 12 (27.9%) in the GA-SCB group (p < 0.001). All the patients in the GA-SCB group were opioid-free during the intraoperative period. No SCB-associated complications were observed. Total opioid consumption was significantly lower in the GA-SCB group than in the GA group until the first postoperative day (GA vs. GA-SCB, 3.2 ± 3.0 mg vs. 0.9 ± 1.8 mg, p < 0.001). Conclusions: SCB application in pediatric patients who underwent elbow fracture surgery significantly reduced opioid exposure and had a high success rate when performed using ultrasound guidance by an expert. Furthermore, the complication risk and surgical delay were minimal.

Reconsidering injection volume for caudal epidural block in young pediatric patients: a dynamic flow tracking experimental study.

INTRODUCTION: Caudal epidural block is a commonly used analgesic technique in pediatric patients. Ultrasound could be used to increase the accuracy of the block by visual confirmation of the drug-spreading. Therefore, we aimed to estimate the cephalad spread of injection volume by caudal route using dynamic ultrasound imaging in young pediatric patients. METHODS: Forty patients, aged 6-24 months, undergoing foot surgery were included. After inducing general anesthesia, an angiocatheter was inserted into the sacral canal under ultrasound guidance. Thereafter, the probe was placed in the paramedian sagittal oblique position, and prepared 0.15% ropivacaine was injected, 1 mL at a time, up to 1.0 mL.kg-1. The ultrasound probe was moved cranially following the bulk flow of local anesthetics. Our primary outcome was the required volume of local anesthetics to reach each level of interlaminar space. RESULTS: The dynamic flow tracking was available in 39 patients, and the required volume of the injectate to reach L5-S1, L4-L5, L3-L4, L2-L3, L1-L2, T12-L1, and T11-T12 was 0.125, 0.223, 0.381, 0.591, 0.797, 0.960, and 1.050 mL.kg-1, respectively. The required volume to reach the immediate upper spinal level was inconsistent across various spinal levels. CONCLUSIONS: Local anesthetics of 0.223, 0.591, and 0.797 mL.kg-1 could provide sufficient analgesia for localized foot, knee, and hip surgeries, respectively. However, since the required volume of the local anesthetics could not be calculated linearly, the real-time dynamic flow tracking technique for the caudal epidural block is recommended in young pediatric patients. TRIAL REGISTRATIONS: ClinicalTrials.gov (NCT04039295).

Ogden Type IV Tibial Tuberosity Fractures in Healthy Adolescents: Preoperative Magnetic Resonance Imaging and 2-Year Clinical Follow-up Study.

Background: Ogden type IV tibial tuberosity fractures, defined as a type of fracture with posterior-inferior metaphyseal extension (Salter-Harris type II variant), are uncommon but challenging pediatric fractures. The purpose of this study was to investigate the clinical and radiological presentation and associated surgical outcomes. Methods: Ten previously healthy patients who had been surgically treated at the authors' institution between 2015 and 2018 with at least 2 years of postoperative follow-up were included. Demographic, clinical, and radiological characteristics and treatment/follow-up data were investigated. Results: All included patients were male. All injuries resulted from jump-landings. Unacceptable remaining angular deformity after closed reduction, particularly increased posterior tibial slope angle, was the leading cause of surgery. All preoperative magnetic resonance images (MRIs) showed entrapped periosteum on the anteromedial side of the proximal tibial physis. Surgical removal of the entrapped periosteum achieved successful reduction. Metaphyseal fracture angles between the fracture plane of the metaphyseal beak and the posterior tibial condyle on the axial image of MRI were relatively constant, with an average of 24.3° ± 6.0°. Mean bone age at the time of trauma was older than mean chronological age (16.4 ± 1.0 years vs. 14.6 ± 1.1 years, respectively; p = 0.005). All patients reached skeletal maturity within 2 postoperative years, with little posttraumatic residual height growth (mean, 1.6 ± 0.7 cm from injury to skeletal maturity). At final follow-up, no patients showed significant angular deformity, tibial length discrepancy, or functional deficit. Conclusions: In healthy adolescents, Ogden type IV tibial tuberosity fractures typically occur by jump-landing injuries, when they have little residual growth remaining. Therefore, accurate fracture reduction was required because of limited remodeling potential. Patients with unacceptable reduction should be investigated for entrapped periosteum on the anteromedial side of the physis because it was the primary obstacle in achieving adequate reduction.

[Impact of social distancing on traumatic injury incidence during the COVID-19 pandemic: A study using nationwide data from South Korea from 2018 to 2020.] / Impact de la distanciation sociale sur l'incidence lésions traumatiques pendant la pandémie de COVID-19 : étude utilisant des données nationales de la Corée du Sud de 2018 à 2020.

BACKGROUND: COVID-19 spread rapidly in 2020. To decrease its transmission rate, governments worldwide implemented social distancing. It has transformed people's physical and social activities. Such changes, differently influenced by age, might affect the incidence of traumatic injury. HYPOTHESIS: The impact of social distancing on traumatic injuries can influence differently by age. PATIENTS AND METHODS: Nationwide randomized stratified sampling data (2018 to 2020, 1 million people per year) from Korean National Health Insurance Sharing Service were used. In this period, 364,690 patients with traumatic injuries were analyzed. People were grouped by age into 0 - 4, 5 - 19, 20 - 64, and ≥ 65 years. The incidence of traumatic injuries was compared between periods of social distancing and no social distancing. Social distancing levels, injured body parts, injury types, hospitalization rate, total medical cost per patient, weather, temperature, and holidays were also included for detailed analysis. RESULTS: Only the 5-19 age group showed the significant interaction of social distancing and traumatic injury. In this group, as the social distancing level increased, the injury incidence decreased especially during the spring and autumn semesters. However, the proportion of injuries requiring hospitalization and total medical cost per patient increased. DISCUSSION: Social distancing significantly affects the incidence of traumatic injuries for schooler (5 - 19 years). Considering that the incidence changed during these semesters, the restriction of school attendance, due to social distancing, may have caused the decrease. Reduced trauma in this group seems to be related to decrease of mild trauma, considering the hospitalization rate and total medical costs. LEVEL OF EVIDENCE: III, retrospective cohort study.

Impact of social distancing on traumatic injury incidence during the COVID-19 pandemic: A study using nationwide data from South Korea from 2018 to 2020.

BACKGROUND: COVID-19 spread rapidly in 2020. To decrease its transmission rate, governments worldwide implemented social distancing. It has transformed people's physical and social activities. Such changes, differently influenced by age, might affect the incidence of traumatic injury. HYPOTHESIS: The impact of social distancing on traumatic injuries can influence differently by age. PATIENTS AND METHODS: Nationwide randomized stratified sampling data (2018 to 2020, 1 million people per year) from Korean National Health Insurance Sharing Service were used. In this period, 364,690 patients with traumatic injuries were analyzed. People were grouped by age into 0-4, 5-19, 20-64, and≥65years. The incidence of traumatic injuries was compared between periods of social distancing and no social distancing. Social distancing levels, injured body parts, injury types, hospitalization rate, total medical cost per patient, weather, temperature, and holidays were also included for detailed analysis. RESULTS: Only the 5-19 age group showed the significant interaction of social distancing and traumatic injury. In this group, as the social distancing level increased, the injury incidence decreased especially during the spring and autumn semesters. However, the proportion of injuries requiring hospitalization and total medical cost per patient increased. DISCUSSION: Social distancing significantly affects the incidence of traumatic injuries for schooler (5-19years). Considering that the incidence changed during these semesters, the restriction of school attendance, due to social distancing, may have caused the decrease. Reduced trauma in this group seems to be related to decrease of mild trauma, considering the hospitalization rate and total medical costs. LEVEL OF EVIDENCE: III, retrospective cohort study.

Clinico-radiological factors predicting the failure risk of conservative management in moderate to severe pediatric idiopathic flexible flatfoot.

This study aimed to investigate the clinico-radiological factors of related future surgical treatment in patients with pediatric flexible flatfoot (FFF) who first visited the orthopedic clinic before the age of 10 years. Sixty-five patients diagnosed with moderate/severe idiopathic FFF deformity between the ages of 2-10 years were included. We developed prognostic models for the risk of the surgery during the follow-up period. Twenty (30.8%) patients required surgical treatment, and all of them underwent calcaneal lengthening osteotomy. Among them, 7 (10.8%) patients required concomitant Achilles-lengthening surgery. Unilateral involvement, older age, smaller calcaneal pitch angle, and higher talo-first metatarsal malalignment were considered high-risk factors for pediatric FFF surgery. Prognostic models identified three prognostic risk groups based on those factors, and survival curves revealed significant differences among the groups. Our prognostic models help predict the failure risk of conservative management of pediatric idiopathic FFF. Level of Evidence: Level III, prognostic study.

Evaluation of age group and sex differences in the measurement of patellar height of pediatric knee in a Korean population.

Introduction: Various methods based on bony landmarks are used to determine patellar height. This study analyzed five methods for patellar height measurement on lateral knee radiographs, namely, the Insall-Salvati, Koshino-Sugimoto, Blackburne-Peel, modified Insall-Salvati, and Caton-Deschamps methods. Methods: Overall, 425 pediatric participants (221 males, 204 females; age range 5-18 years) were included and were divided equally into three age groups (A, 5-10 years; B, 11-13 years; and C, 13-18 years). For the comparison of the applicability of each method, the applicable probabilities for each age group and sex-based differences were analyzed using logistic regression techniques. Intra-rater reliability and inter-rater variability were analyzed by two trained raters. Results: The Koshino-Sugimoto method was applicable to all patients. The 80% applicable age of female patients was lower than that of male patients for the Blackburne-Peel (male = 11.9, female = 11) and Caton-Deschamps (male = 11.9, female = 11.1) methods. However, in the Insall-Salvati (male = 12, female = 12.1) and modified Insall-Salvati (male = 12.6, female = 13.1) methods, the 80% applicable age in male patients was lower than that in female patients. The Koshino-Sugimoto method showed the highest variability in group B, while the Insall-Salvati showed the highest variability in group C. In terms of intra-observer reliability, the Caton-Deschamps method showed the same reliability as the Insall-Salvati method, in group C. Conclusions: Our results demonstrated differences in the reliability, variability, and applicability of patellar height measurement methods according to age group. The applicability of patellar height measurement methods also differed according to sex. Therefore, based on age group and sex, different methods should be used for patellar height measurement in pediatric patients.

Analysis of Tertiary Hospital Utilization in Pediatric Orthopaedics: a Study Using Nationwide Sample Data from Korea.

BACKGROUND: In the Korean medical system, the severity classification for a specific disease depends primarily on its nationwide admission rate in tertiary hospitals. Inversely, one of the important designation criteria for a tertiary hospital is the hospital's treatment ratio of patients classified as having a specific severe disease. Most diseases requiring pediatric orthopaedic surgery (POS) are not currently classified as high severity in terms of disease severity. We investigated the admission rates for the representative POS diseases in tertiary hospitals and compared these rates with those for adult orthopaedic surgery (AOS) diseases. METHODS: Seven POS diagnoses and three AOS diagnoses were selected based on frequency of admission. Nationwide sample data were used to investigate the admission rates for these representative diagnoses from 2008 to 2017. RESULTS: Six of the seven frequent POS diagnoses presented high admission rates in tertiary hospitals (62.5-92.3%). In contrast, all frequent AOS diagnoses presented low admission rates in tertiary hospitals. CONCLUSION: The admission rates of frequent POS diagnoses in tertiary hospitals are high. Considering that these rates are the most important factors for the classification of disease severity, POS diseases seem to be underestimated in terms of severity. This may lead to a tendency for tertiary hospitals to intentionally reduce the admission of children with POS diseases. As a result, these children may not receive appropriate professional care. Therefore, for the disease severity, POS diseases should be classified differently from general AOS diseases by using different criteria reflecting the patient's age.

Injury Characteristics and Predisposing Effects of Various Outdoor Traumatic Situations in Children and Adolescents.

BACKGROUD: Many studies have reported injury characteristics of individual traumatic situations. However, a comparative analysis of specific risks is meaningful to better understand injury characteristics and help establish injury-prevention measures. This study was conducted to investigate and compare injury characteristics in children and adolescents by various outdoor traumatic situations. METHODS: Outdoor traumatic situations were determined and classified into physical activity-related injury (n = 3,983) and pedestrian (n = 784) and passenger (n = 1,757) injuries in traffic accidents. Home injury (n = 16,121) was used as the control group. Then, the characteristics of each outdoor trauma were compared with 1:1 matched indoor trauma (among home injuries); each outdoor traumatic situation's predisposing risk for the injured body part, injury type, and injury severity were analyzed; and changes by age of frequency ranking among physical activity-related injuries were investigated. RESULTS: Outdoor trauma showed higher risks for limb injuries (injured body part), fracture and muscle/tendon injuries (injury type), and severe injuries (severity) than indoor trauma. Various outdoor traumatic situations presented different predisposing effects on injury characteristics. Among physical activity-related injuries, bicycle injury was commonest across all ages, and playing activities were common causes for injury for individuals of age < 9 years, whereas sports activities overwhelmed the common causes thereafter. CONCLUSIONS: The findings would help to better understand the specific injury risk of various outdoor traumatic situations and may potentially facilitate the establishment of more effective injury-prevention measures.

Physeal Abnormalities in Children With High-risk Neuroblastoma Intensively Treated With/Without 13-Cis-Retinoic Acid.

BACKGROUND: This study aimed to investigate the presence of physeal abnormality and its effect on growth in children with high-risk neuroblastoma treated by intensive multimodal treatment with/without 13-cis-retinoic acid (13-CRA). METHODS: Fifteen patients diagnosed with high-risk neuroblastomas at the age of 1 to 10 years, who received treatment such as high-dose chemotherapy and autologous stem cell transplantation with/without 13-CRA, and with complete data during their >2-year follow-up were retrospectively reviewed. The physeal abnormalities were investigated by whole-body magnetic resonance imaging, serially performed every 3 to 6 months. The patients' height growth was also investigated and compared with that of age-and-sex-matched patients with brain tumors who also underwent high-dose chemotherapy and autologous stem cell transplantation. RESULTS: Six of 15 patients presented multifocal physeal abnormalities during follow-up, and all lesions occurred in patients with 13-CRA use. The lesions in 3 patients completely resolved spontaneously without any adverse effect on growth, but some lesions in the other 3 patients progressed to disturb the bony growth. Height growth of matched patients with brain tumors were not significantly different, and none of the matched controls showed definite bony deformity during the follow-up. CONCLUSIONS: Some children who were treated for high-risk neuroblastomas experienced multifocal physeal insults, probably due to the use of 13-CRA. Most lesions resolved spontaneously, but some led to bony deformity. If the lesions are not followed by premature physeal closure, there seems to be no further adverse effect of 13-CRA on leg length growth. Routine periodic screening for physeal status is needed for the patients with high-risk neuroblastomas using 13-CRA. LEVEL OF EVIDENCE: Level IV-prognostic study.

Classification of Middle Phalangeal Postaxial Polysyndactyly Based on Intraoperative Arthrography Is Useful for Surgical Decision-making in Children Younger Than 2 Years.

BACKGROUND: The middle phalangeal type of postaxial polysyndactyly (MPPP) of the foot is a common congenital limb anomaly and is usually treated surgically at a young age. Owing to the insufficiency of radiologic evaluation due to largely cartilaginous portions of the pediatric foot, we performed intraoperative arthrography (IOA) for MPPP. This study was aimed at presenting a new classification system for foot MPPP in young children based on IOA findings and investigating its intraoperative decision-making. METHODS: Thirty-seven patients aged below 2 years who underwent IOA and surgical treatment of foot MPPP in our institute between January 2018 and April 2020 were retrospectively reviewed. The mean patient age at operation was 1.31 years (range, 0.91 to 1.99 y). IOA was performed in the common proximal interphalangeal (PIP) joint. The excisional level and side were determined on the basis of the IOA findings and bony alignment between the proximal and distal phalanges for functional and cosmetic purposes. Arthrographic findings and surgical procedures were recorded. RESULTS: A new classification divided MPPP into 2 major types according to the presence (type A) or absence (type B) of longitudinal contrast filling between the fifth and sixth middle phalanges. These 2 major types were further divided into 4 subtypes according to the shape of the PIP joint by contrast filling. There were 19, 15, and 3 cases of type A, B, and indeterminate IOA. Fifth and sixth ray excisions were performed in 26 and 11 cases, respectively. Interobserver reliability of the classification represented excellent agreement (Cohen κ coefficient=0.823). CONCLUSIONS: Our new classification based on IOA helped determine the articular dominance and its detailed morphology, which can help predict postoperative stability and mobility of the remaining toe. IOA is a simple, safe, and useful imaging tool for the surgical treatment of foot MPPP in patients aged below 2 years. LEVEL OF EVIDENCE: Level III.

Prediction of High-Grade Hip Joint Effusion With Simple Radiographs in Children: A Comparative Study With Magnetic Resonance Imaging.

OBJECTIVES: The objective of this study was to investigate the predictive value of asymmetric joint space widening on simple radiographs for the presence of hip joint effusion in children with unilateral hip pain. METHODS: Sixty-eight patients aged 6 to 17 years with both simple radiograph and magnetic resonance imaging of both hips were retrospectively reviewed. We evaluated the predictive effects of radiographic surrogates for joint space widening on the presence of high-grade hip joint effusion. We also sought to investigate a predictive model for the presence of hip joint effusion with the patients' clinical and radiological data. RESULTS: Radiographic values showed high specificity but low sensitivity for the presence of high-grade joint effusion. On multivariate analysis, sex and the difference ratio of medial and superior gaps were independent predictive factors for unilateral high-grade hip joint effusion. CONCLUSIONS: For children 6 years and older with asymmetric hip joint space widening on simple radiographs, further evaluations for the presence of hip joint effusion should be considered because of its high specificity. The predictability can improve if both medial and superior gaps, and sex are included in the evaluation. In girls, hip joint effusion seems to widen the joint space more easily than in boys, which may be owing to the more ligamentous laxity of and less musculature around the hip in girls. However, the risk of joint effusion should not be underestimated even if a child presents symmetry on the simple radiograph because of its low sensitivity and the possibility of bilateral involvements or early stage of diseases.

Initial angular deformity and its recovery of the proximal tibial metaphyseal fracture according to the cause: trampoline-related injury versus other injuries.

PURPOSE: This study investigated the initial angular deformity of proximal tibial metaphyseal fracture in children and its recovery during follow-up according to the cause of injury. METHODS: Prospective data about the patients with a proximal tibial metaphyseal fracture at the age less than six years and available follow-up data at two years post-trauma were retrospectively reviewed. They were grouped into trampoline-related injuries (TRI) and non-TRI groups based on the cause of injury. Proximal tibial valgus and recurvatum angles were measured to assess angular deformity on the coronal and sagittal planes, respectively. RESULTS: A total of 47 patients (33 TRI and 14 non-TRI) were included. Initially, the valgus angles were -1.5° in TRI and 1.6° in non-TRI groups (p < 0.001) and the recurvatum angles were 7.8° in TRI and 4.1° in non-TRI groups (p = 0.048). After two-year follow-up, the valgus angles were 0.2° in TRI and 0.9° in non-TRI groups (p = 0.070), and the recurvatum angles were 6.5° in TRI and 2.3° in non-TRI groups (p = 0.001). CONCLUSION: For children with a proximal tibial metaphyseal fracture, the initial coronal deformity was different according to the injury cause (varus in TRI whereas valgus in non-TRI). Although there was a near complete recovery after approximately two years of follow-up in the coronal deformities, the sagittal deformity (genu recurvatum) seems to recover incompletely or tardily, especially for those caused by TRI. LEVEL OF EVIDENCE: III.

Growth of the capitellar ossification center and its relationship within the lateral condyle of the distal humerus in skeletally immature elbows: a study using MR images.

To more accurately interpret the anterior humeral and radiocapitellar lines on simple radiographs of pediatric elbow, we investigated age-related changes of the capitellar ossific nucleus (CON) by using MRIs. Elbow MRIs from 79 children aged 1-16 years and free from demonstrable lesions in the distal humerus were retrospectively reviewed. On coronal images, the distal cartilaginous vertex of the capitellum, which articulates with the center of the radial head, was situated about 15%p laterally from the center of CON regardless of age. On sagittal images, the anterior humeral line passed the center of CON in older children (>6 years), but passed anteriorly in children with an age ≤6 years. Also on sagittal images, the anterior cartilaginous vertex of the capitellum was positioned within 10% of the level of the center of CON in all age groups. Recognition of the capitellar ossification pattern within the lateral condyle would aid in more accurate assessment of pediatric elbows on simple radiographs. Based on the results of the present MRI study, the following points were identified for the interpretation of simple radiographs: (1) The radiocapitellar line on anteroposterior views intersects the CON by about 15%p laterally regardless of age; (2) The anterior humeral line on lateral views intersects the center of the CON in older children, but passes anteriorly in younger (≤6 years) children; and (3) The radiocapitellar line on lateral radiographs invariably passes the center of CON regardless of the age.

Differential MRI findings of transient synovitis of the hip in children when septic arthritis is suspected according to symptom duration.

We investigated the differential MRI findings in children with transient synovitis of the hip in whom septic arthritis was suspected. Under the hypothesis that disease progression can alter representative MRI findings, we stratified these findings in accordance with symptom duration as this can correlate with disease progression. We analyzed 65 children who underwent MRI for acute hip pain and who were suspected of having a septic condition (i.e. presented with fever or increased inflammatory markers) when the imaging was performed. Symptom duration was defined as the interval from the first presentation of hip pain to the MRI scan. We divided the patients into two subgroups according to symptom duration: patients with short symptom duration (≤2 days, short-term subgroup, n = 30) and those with long symptom duration (≥3 days, long-term subgroup, n = 35). Twenty-eight (43.1%) of the study subjects were diagnosed with septic arthritis. Whereas only a high-grade joint effusion was a significant MRI finding differentiating septic arthritis from transient synovitis in the whole cohort, the presence of contralateral joint effusion in the short-term subgroup (P = 0.024) and the absence of a change/enhancement of the signal intensity of soft tissue in the long-term subgroup (P < 0.001) were significant predictors of transient synovitis. The significances of differential MRI findings for septic arthritis and transient synovitis seem to change according to symptom duration. We suggest that symptom duration, which may correlate with disease progression, should also be considered when interpreting MRIs of children under suspicion of septic arthritis.

Varus shearing force is a main injury mechanism of pediatric trampoline-related injury in addition to compressive axial loading.

BACKGROUND: Many case studies have been published about trampoline-related injury (TRI); however, a comparative study could allow a more specific analysis of the characteristics of TRI, and enable more differentiated approaches to prevent such injuries. We investigated the injury mechanism of TRI in children compared with other pediatric trauma. METHODS: Of 35,653 children (age 0-18 years) who visited the pediatric emergency department after traumatic injuries from January 2011 to June 2017, 372 patients with TRI (TRI group) were retrospectively identified. Among the remaining 35,281 patients with other trauma (non-TRI group), 372 were 1:1 matched to the TRI group according to sex, age, injured body part, and body weight (matched-control group). The patients' data, injured site, and injury patterns were compared between the groups. RESULTS: The most frequently injured body part was the knee/lower leg in the TRI group and the head in the non-TRI group. The most frequent injury types were fractures in the TRI group and open wounds in the non-TRI group. In the comparison between the TRI and matched-control groups, the most common lower-extremity fractures were proximal tibial fractures with varus angulation in the TRI group and tibial shaft spiral fractures in the matched-control group. For the upper extremities, the risk of lateral condylar humeral fracture was higher in the TRI group. The TRI group presented more physeal involvements. CONCLUSIONS: The risks of varus stress injury (proximal tibial fracture with varus angulation in lower extremity and lateral condylar humeral fracture in upper extremity) were higher in the TRI group than in matched-control group. Thus, varus shearing force seems to be an important injury mechanism in TRI in addition to compressive force. This varus force may increase the risk of physeal injury by generating additional shear force on the physis.

Prediction of the Peripheral Rim Instability of the Discoid Lateral Meniscus in Children by Using Preoperative Clinicoradiological Factors.

BACKGROUND: The discoid lateral meniscus (DLM) in children often presents peripheral rim instability (PRI) and is susceptible to tear or subluxation, which manifests symptoms and leads to a poor prognosis. We aimed to investigate the association between preoperative clinical and MRI findings and the intraoperative findings of PRI. METHODS: Children and adolescents aged younger than 16 years who underwent surgical treatment for DLM were retrospectively reviewed. Cases of bucket-handle tear were not included because they would confound the stability of the peripheral rim. Total 60 knees from 47 children were included. PRI was additionally subdivided based on the location, such as anterior, middle, and posterior, during the investigation. RESULTS: In multivariate analyses, both central (inward) (P=0.004) and external (outward) (P=0.029) displacement of lateral meniscal margin, and peripheral tear of the anterior body (P=0.022) were significant predictors of PRI, regardless of the location. The predictive factors for PRI based on each location were female gender (P=0.004), subjective symptom of clicking sound (P=0.023), and central displacement of the anterior meniscal margin (P=0.034) for anterior PRI; flexion contracture >10 degrees (P=0.017) and peripheral tear of the middle body (P<0.001) for middle PRI; and central displacement of the posterior meniscal margin (P=0.036) and peripheral tears of the anterior (P=0.029) and middle bodies (P=0.047) for posterior PRI. CONCLUSIONS: We evaluated the preoperative clinical and MRI findings that predict PRI of pediatric DLM. Displacements of the DLM, not only centrally (inward) but also externally (outward), seem to be significant predictive factors for PRI. Furthermore, some clinical findings were associated with PRI, even predicting the locations. Although the actual surgical procedure should be determined by meticulous probing during arthroscopy, preoperative prediction of the presence and location of PRI would help decrease the risk of oversight during surgery. LEVEL OF EVIDENCE: Level III-Diagnostic Study.

Clinical significance of asymmetric skin folds in the medial thigh for the infantile screening of developmental dysplasia of the hip.

BACKGROUND: The presence of asymmetric skin folds in the medial thigh (ASM) is often used as one of the screening items for developmental dysplasia of the hip (DDH). However, few studies have evaluated the clinical relevance of ASM in DDH. METHODS: We reviewed the data of 584 infants aged 4-12 months who were referred to our institute because of suspicious findings in periodic infantile DDH screenings. The reasons for referral were classified into ASM, gluteal asymmetry, limb-length discrepancy, limitation of hip abduction, and click/clunk of the hip. A simple radiograph and hip examination including stability assessment were evaluated in all the infants by an experienced pediatric orthopedic surgeon. RESULTS: Most of the referred infants presented with ASM only (78.4%, 458/584), but none of them were diagnosed with DDH. On the other hand, about 18.3% of infants referred for other reason(s) were diagnosed with DDH. CONCLUSION: Although the presence of ASM was the most common reason for referral, it had little clinical significance as a screening item for DDH in the infants aged 4-12 months. Therefore, ASM alone is not a clinical indicator of DDH.

Fracture Pattern and Periosteal Entrapment in Adolescent Displaced Distal Tibial Physeal Fractures: A Magnetic Resonance Imaging Study.

OBJECTIVES: To investigate the fracture pattern and periosteal entrapment in adolescent distal tibial physeal fractures. DESIGN: Retrospective case series. SETTING: Level I academic trauma center. PATIENTS/PARTICIPANTS: Fifty patients (10-16 years of age) with displaced Salter-Harris type II, III, or IV distal tibial physeal fractures were retrospectively reviewed. INTERVENTION: Periosteal involvement, fracture pattern. MAIN OUTCOME MEASUREMENTS: We investigated the incidence and location of periosteal entrapment in those fractures and the angle of the fracture plane of metaphyseal fragments on axial plane by using magnetic resonance imaging. RESULTS: Of the 15 type II, 12 type III (4 malleolar and 8 Tillaux), and 23 type IV (2 malleolar and 21 triplane) fractures, 72.0% (36/50) presented with periosteal entrapment. Among all type II and triplane fractures, periosteal entrapment was observed in the anterolateral corner when there was any displacement on that corner. By contrast, only 1 of 8 Tillaux fractures presented with periosteal entrapment. In almost all supinated foot injuries of type II and triplane fractures, the metaphyseal fracture line was parallel to the intermalleolar axis on axial plane. CONCLUSIONS: Salter-Harris type II and triplane fractures have a high risk of periosteal entrapment especially in the anterolateral corner. Therefore, even without preoperative magnetic resonance imaging, surgical repositioning of entrapped periosteum should be considered after failed closed reduction. In cases of supinated foot injuries of type II or triplane fractures requiring surgical fixation, a metaphyseal fracture plane parallel to the oblique coronal plane connecting the medial and lateral malleoli may assist surgeons in achieving appropriate metaphyseal fixation. LEVEL OF EVIDENCE: Diagnostic Level IV. See Instructions for Authors for a complete description of levels of evidence.