MRI Features That Contribute to Decision-Making for Treatment of Capitellar OCD Lesions: An Expert Consensus Using the Delphi Method.

Background: Most healthcare providers utilize magnetic resonance imaging (MRI) to assist in diagnosing and treating osteochondritis dissecans (OCD) of the capitellum. However, consensus on imaging features that portend clinically relevant information in the care of these lesions has not been determined. Purpose: To conduct a survey on the MRI features of a capitellar OCD that are salient for clinical decision-making using a classic Delphi protocol. Study Design: A consensus statement. Methods: Invitations to participate were sent to 33 healthcare providers identified as capitellar OCD experts. A classic 3-round survey method was used to gather agreement and consensus on the level of importance for clinical decision-making on 33 MRI features. A concise list of features that guide decision-making on the stability of an OCD lesion and the ability of an OCD lesion to heal with nonoperative care was also identified. Agreement and consensus were determined a priori as ≥66%. Results: Of the 33 identified experts, 20 agreed to participate, and 17 (52%) completed all 3 rounds. Of the 33 MRI features evaluated, 17 reached agreement as important for clinical decision-making by the experts. Consensus was reached for a concise list of MRI features that were significant to decision-making (94%), suggestive of a stable lesion (100%), had the potential to heal with nonoperative treatment (94%), were suggestive of an unstable lesion (100%), and had low potential to heal with nonoperative treatment (88%). Conclusion: This 3-round Delphi process produced consensus on clinically relevant MRI features that contribute to clinical decision-making for capitellar OCD. The results of this study will be used as the basis for an interrater reliability assessment of the identified salient features, creating the foundation for developing a reliable MRI assessment tool rooted in clinical experiences. The development of a standardized assessment of capitellar OCD is intended to improve clinical practice and patient outcomes.

Patellar osteochondritis dissecans: maturation-dependent patellofemoral joint characteristics.

BACKGROUND: The likelihood of healing of osteochondritis dissecans decreases with skeletal maturity and there are theories that abnormal biomechanical forces contribute to the development and progression of these lesions. OBJECTIVE: To characterize, according to regional skeletal maturity, the morphology and alignment indices of the patellofemoral joint on MRI in patients with patellar osteochondritis dissecans. MATERIALS AND METHODS: MRI examinations of patients with patellar osteochondritis dissecans obtained between January 2008 and May 2023 were retrospectively reviewed to determine regional skeletal maturity, osteochondritis dissecans lesion size and location, patellar and trochlear morphology (Wiberg/Dejour classifications), and to calculate trochlear sulcus angles, trochlear depth index, lateral trochlear inclination, Insall-Salvati index, Caton-Deschamps index, patellar tendon-lateral trochlear ridge, and tibial tubercle-trochlear groove distances. Values were compared between skeletally immature and mature groups. RESULTS: Sixty-eight children (22 girls, 46 boys, age: 14.0 ± 1.7 years) yielded 74 knees with patellar osteochondritis dissecans lesions, 14 (19%) of which were skeletally mature. The most common anatomic location was over the central patella [median ridge (34/74 - 46%) on the axial images and over the middle third (45/74 - 61%) on the sagittal images]. Overall, mean trochlear sulcus angle (high, 151 ± 11°), trochlear depth index (low, 2.8 ± 1.4 mm), and Insall-Salvati index (borderline, 1.3 ± 0.1) were abnormal for the entire sample. Skeletally mature knees were significantly more likely to have higher (more dysplastic) Dejour types when compared to skeletally immature knees (p < 0.01). Knees in the mature group, compared to immature, had significantly more abnormal mean lateral trochlear inclination (15 ± 8° vs. 19 ± 6°, p = 0.03) and patellar tendon-lateral trochlear ridge distance (5.55 ± 4.31 mm vs. 2.89 ± 4.69 mm, p = 0.04). Half of the knees had ≥ 4 abnormal features that predispose to patellofemoral maltracking; mature knees were significantly (p = 0.02) more likely to have a higher number of abnormal features (> 6 features, 7/14, 50.0%) versus immature knees (0-3 features, 33/60, 55.0%). CONCLUSION: In children with patellar osteochondritis dissecans, abnormal patellofemoral morphology and alignment indices were common in all patients and more severe in mature knees.

Pediatric foot fractures on radiographs: distribution and predictors of surgery.

PURPOSE: To examine the distribution and characteristics of pediatric foot fractures on radiographs with respect to age and skeletal maturation, and to identify predictors of surgery. METHODS: This retrospective study included children (≤ 18 years) with foot fractures, who underwent radiographic examinations (2020-2022). Electronic medical records were reviewed to obtain demographic and clinical data. Fracture characteristics, including anatomic location, presence of displacement, angulation, articular involvement, and, if skeletally immature, physeal involvement and Salter-Harris fracture pattern were collected. Logistic regression models were used to identify predictors of surgery. RESULTS: 1,090 (596-boys, 494-girls; mean age, 11.0 ± 4.0 years) patients with 1,325 (59.8% metatarsal, 33.8% phalangeal, and 6.4% tarsal) fractures were included. Fractures of 1st metatarsal were more common among younger children whereas fractures of 2nd-4th and 5th metatarsals were more common among older children (median ages: 5.9 years vs. 10.3 years and 12.4 years, p < 0.001). Intra-articular fractures were more common among maturing and mature than immature bones (25.3% and 20.4% vs. 9.9%, p < 0.001). Physeal involvement was uncommon (162/977, 16.6%) and the most common pattern was Salter-Harris type II (133/162, 82.1%). A minority (47/1090, 4.3%) of patients required surgery and independent predictors of surgery included physeal involvement (OR = 5.12, 95% CI: 2.48-10.39, p < 0.001), multiple fractures (OR = 3.85, 95% CI: 1.67-8.53, p = 0.001), fracture displacement (OR = 9.16, 95% CI:4.43-19.07, p < 0.001), and articular involvement (OR = 2.72, 95% CI:1.27-5.72, p = 0.008). Using these predictors, the likelihood for surgery ranged between 8.0% with 1 and 86.7% with 3 predictors. CONCLUSION: Pediatric foot fracture patterns differed based on age and regional skeletal maturation. Physeal involvement, multiple fractures, fracture displacement, and articular involvement were independent predictors of surgery in our study group.

Return to Play in Youth Athletes: Role of the Radiologist with Focus on the Upper Extremity.

Increase in youth sports participation, longer duration of play, and earlier starting points have increased the prevalence of acute and repetitive overuse musculoskeletal injuries. This rise in injury rates has led to increased efforts to better understand the susceptible sites of injury that are unique to the growing immature skeleton. Upper extremity injuries are currently the best studied, particularly those that occur among pediatric baseball players and gymnasts. The weak link in skeletally immature athletes is the growth plate complex that includes those injuries located at the epiphyseal and apophyseal primary physes and the peripherally located secondary physes. This article reviews the anatomy and function of these growth plate complexes, followed by a discussion of the pathophysiologic mechanisms, spectrum of imaging findings, and existing evidence-based guidelines for injury prevention and return to play.

Youth soccer players: patterns of injury involving the primary growth plates of epiphyses.

Youth soccer (football) is immensely popular internationally. Earlier participation, sport sub-specialization, and year-around practice have led to an increased incidence of injury from both acute trauma and repetitive overuse. The growth plates (physes) of the immature skeleton are particularly vulnerable to injury and delayed diagnosis can lead to future growth disturbance and long-term morbidity. Familiarity with the various components of the growth plate complex necessary for ensuring normal endochondral ossification is fundamental in understanding the various patterns of imaging findings following injury. This review discusses the zonal columnar arrangement of the growth plate proper and the contrasting function of the vasculature within the subjacent epiphysis and metaphysis. This is followed by an evidence-based discussion of the common patterns of injury involving the epiphyseal primary growth plate observed among youth soccer players: subcategorized into physeal fractures (direct injury) and physeal stress injuries (indirect insult to subjacent metaphysis). In this section, the role of imaging and characteristic imaging features will be discussed. While the normal physiologic and pathophysiologic mechanisms can be applied to other growth plates, such as primary growth plates underlying the apophyses and secondary growth plates surrounding the secondary ossificiation centers, which also undergo endochondral ossification, the current review is focused on injuries involving the primary growth plates underlying epiphyses.

Identification of fractures on pediatric foot radiographs: do localization cues improve diagnostic accuracy and reduce interpretation time?

OBJECTIVE: To investigate the diagnostic accuracy and time in the detection of fractures on pediatric foot radiographs marked without and with localization cues. METHOD: One-hundred randomly selected foot radiographic examinations that were performed on children (<18 years old) after injury and with at least 4 weeks of follow-up were included. Blinded to history and diagnosis, 4 readers (one each: medical student, pediatrician, pediatric orthopedic surgeon, and pediatric musculoskeletal radiologist) retrospectively and independently reviewed each examination twice (without and with cue, at least 1 month apart, and after randomization). Each reader recorded the presence or absence of a fracture, fracture location, diagnostic confidence, and the total (interpretation) time spent on each study. Diagnostic accuracy, reader confidence, and interpretation time were compared between examinations without and with cues. RESULTS: Our study included 59 examinations without and 41 with fractures (21 phalangeal, 18 metatarsal, and 2 tarsal fractures). Localization cues improved inter-reader agreement (κ=0.36 to 0.64), overall sensitivity (68 to 72%), specificity (66 to 73%), and diagnostic accuracy (67 to 73%); thus, overcalled and missed rates also improved from 34 to 27% and 32 to 28%, respectively. Reader confidence improved with cue (49 to 61%, p<0.01) with higher incremental improvement with younger children (30% for 1-6 years; 14% for 7-11 years; and 10% for 12-17 years). Interpretation time decreased by 40% per examination (40±22 s without to 24±13 s with cues, p<0.001). CONCLUSION: Localization cues improved diagnostic accuracy and reader confidence, reducing interpretation time in the detection of pediatric foot fractures.

Pediatric thrower's elbow: maturation-dependent MRI findings in symptomatic baseball players.

BACKGROUND: Elbow pain is common among youth baseball players and elbow MRI is increasingly utilized to complement the clinical assessment. OBJECTIVE: To characterize, according to skeletal maturity, findings on elbow MRI from symptomatic youth baseball players. MATERIALS AND METHODS: This IRB-approved, HIPAA-compliant retrospective study included pediatric (<18 years of age) baseball players with elbow pain who underwent MRI examinations between 2010 and 2021. Two radiologists, blinded to the outcome, independently reviewed examinations to categorize skeletal maturity and to identify osseous and soft tissue findings with consensus used to resolve discrepancies. Findings were compared between skeletally immature and mature patients and logistic regression models identified predictors of surgery. RESULTS: This study included 130 children (115 boys, 15 girls): 85 skeletally immature and 45 mature (12.8±2.3 and 16.2±1.0 years, respectively, p<0.01). Kappa coefficient for interobserver agreement on MRI findings ranged from 0.64 to 0.96. Skeletally immature children, when compared to mature children, were more likely to have elbow effusion (27%, 23/85 vs 9%, 4/45; p=0.03), medial epicondyle marrow edema (53%, 45/85 vs 16%, 7/45; p<0.01), avulsion fracture (19%, 16/85 vs 2%, 1/45; p=0.02), and juvenile osteochondritis dissecans (OCD, 22%, 19/85 vs 7%, 3/45; p=0.04), whereas skeletally mature children were more likely to have sublime tubercle marrow edema (49%, 22/45 vs 11%, 9/85; p<0.01) and triceps tendinosis (40%, 18/45 vs 20%, 17/85; p=0.03). Intra-articular body (OR=4.2, 95% CI 1.5-47.8, p=0.02) and osteochondritis dissecans (OR=3.7, 95% CI 1.1-11.9, p=0.03) were independent predictors for surgery. CONCLUSION: Differential patterns of elbow MRI findings were observed among symptomatic pediatric baseball players based on regional skeletal maturity. Intra-articular body and osteochondritis dissecans were independent predictors of surgery.

Patella and Trochlea Osteochondritis Dissecans: Demographics and Treatment Paradigms.

OBJECTIVE: Previous research on patellar and trochlear groove osteochondritis dissecans (OCD) is limited by small sample sizes. This study aims to describe the presentation of patients with OCD lesions of the patella and trochlea and characterize the outcomes of operative and nonoperative treatments. METHODS: This retrospective cohort study identified all patients from a single institution from 2008 to 2021 with patellar and/or trochlear OCD lesions. Patients were excluded from the study if surgical records were unavailable or if the patient had knee surgery for a different injury at index surgery or in the 12 months postoperative. Minimum follow-up was 12 months. Outcomes included a return to sports (RTS), pain resolution, radiographic healing, and treatment "success" (defined as full RTS, complete pain resolution, and full healing on imaging). RESULTS: A total of 68 patients (75 knees) were included-45 (60%) with patellar OCD and 30 (40%) with trochlear. Of the patients, 69% were males. The median age at knee OCD diagnosis was 14 years. At the final follow-up, 62% of knees (n = 44) recovered sufficiently to allow a full RTS and 54% of knees (n = 39) had full pain resolution. Of the 46 knees with radiographic imaging at least 1 year apart, 63% had full healing of the lesion. There was no significant difference in RTS, pain resolution, radiographic healing, or overall success when comparing treatments. CONCLUSIONS: This study provides valuable epidemiologic demographic and outcome data regarding the scarcely reported patellar and trochlear OCD. While over half of patients fully returned to sports and reported full pain resolution, a large proportion continued to experience symptoms over a year after presentation. Future research should aim to better define the treatment algorithms for these OCD subtypes. LEVEL OF EVIDENCE: Level III.

Maturation-dependent patterns of knee injuries among symptomatic pediatric soccer players on MRI.

OBJECTIVE: To systematically investigate the prevalence of knee MRI findings among symptomatic pediatric soccer players with respect to skeletal maturity and to identify predictors of surgery. METHODS: This IRB-approved, HIPAA-compliant retrospective study included soccer players (< 18 years of age) who underwent MRI examinations in the past 5 years (2018-2023). Two radiologists retrospectively and independently reviewed all examinations to categorize skeletal maturity and to identify osseous and soft tissue findings. Findings were compared between maturation groups, and logistic regression models were used to identify predictors of surgery. RESULTS: Ninety-seven players (45 boys, 52 girls) included 39 skeletally immature, 21 maturing, and 37 mature knees. Kappa coefficient for interobserver reliability ranged between 0.65 and 1.00. Osgood-Schlatter disease (OSD) was more common among immature than maturing and mature knees (25% vs 14% and 5%, p = 0.04); anterior cruciate ligament (ACL) injury was more common among maturing and mature than immature knees (59% and 48%, vs 15%, p < 0.01); and meniscal tears were more common among mature than immature and maturing knees (medial, 41% vs 18% and 14%, p = 0.03; lateral, 43% vs 21% and 19%, p = 0.04). Players in the mature group were more likely to undergo surgery (p = 0.01). The presence of an effusion (OR = 19.5, 95% CI 2.8-240.9, p = 0.01), ACL injury (OR = 170.0, 95% CI 1.3-6996.9, p < 0.01), and lateral meniscal tears (OR = 10.8, 95% CI 1.8-106.1, p = 0.02) were independent predictors of surgery. CONCLUSION: Differential patterns of injury were found among symptomatic pediatric soccer players; the presence of an effusion, ACL injury, and lateral meniscal tears were independent predictors of surgery, likely contributing to the higher rates of surgery among skeletally mature players.

Outcomes following Free Fibula Physeal Transfer for Pediatric Proximal Humerus Reconstruction: An International Multi-Institutional Study.

BACKGROUND: Vascularized fibula epiphyseal flap was first described in 1998 for proximal humeral reconstruction in children/infants. The authors aim to review their international, multi-institutional, long-term outcomes. METHODS: An international, multi-institutional review (2004 to 2020) was conducted of patients younger than 18 years undergoing free vascularized fibula epiphyseal transfer for proximal humeral reconstruction. Donor- and recipient-site complications, pain, and final ambulatory status were reviewed. Growth of the transferred bone was assessed under the guidance of a pediatric musculoskeletal radiologist. RESULTS: Twenty-seven patients were included with a median age of 7 years (range, 2 to 13 years). Average follow-up was 120 ± 87.4 months. There were two flap failures (7.4%). Recipient-site complications included fracture [ n = 11 (40.7%)], avascular necrosis of the fibula head [ n = 1 (3.7%)], fibular head avulsion [ n = 1 (3.7%)], infection [ n = 1 (3.7%)], and hardware failure [ n = 1 (3.7%)]. Operative fixation was necessary in one patient with a fracture. The case of infection necessitated fibula explantation 2 years postoperatively, and ultimately, prosthetic reconstruction. Sixteen patients developed peroneal nerve palsy (59.3%): 13 of these cases resolved within 1 year (81% recovery), and three were permanent (11.1%). One patient (3.7%) complained of upper extremity pain. Longitudinal growth was confirmed in all but three cases [ n = 24 (88.9%)] at an average rate of 0.83 ± 0.25 cm/year. CONCLUSIONS: The vascularized fibula epiphysis for proximal humerus reconstruction in children preserves the potential for future growth and an articular surface for motion. Peroneal nerve palsy is common following harvest, although this is often transient. Future efforts should be geared toward reducing postoperative morbidity. CLINICAL QUESTION/LEVEL OF EVIDENCE: Therapeutic, IV.

MRI findings of growth plate fractures of the knee: are there age- and fracture-dependent differences?

OBJECTIVE: To investigate MRI findings in children with physeal fractures of the knee with respect to age, location, and articular involvement. METHODS: Children with physeal fractures who underwent knee MRI between 2008 and 2021 were included. Two radiologists retrospectively reviewed all examinations to determine articular involvement, findings of physeal instability (perichondral disruption, periosteal entrapment), and internal derangement (cruciate ligament injury, meniscal tear, chondromalacia). Independent samples t, Mann-Whitney U, Pearson's chi-square, and Fisher's exact tests were used to compare findings. RESULTS: Fifty-six patients (37 boys, 19 girls; mean age: 12.2 ± 2.5 years; 32 distal femur, 24 proximal tibial fractures) included 24(43%) intraarticular fractures. Fractures were more common in the tibia than the femur (67% versus 25%, p = 0.004) and intraarticular fractures were more common in older than younger children (13.1 ± 2.0 versus 11.5 ± 2.7 years, p = 0.01), to associate with chondromalacia (46% versus 12%, p = 0.02) and undergo surgery (33% versus 10%, p = 0.04) when compared to extraarticular fractures. Perichondral disruption (n = 44, 79%) and periosteal entrapment (n = 13, 23%) did not significantly differ based on location or articular involvement (p > 0.05). At a median follow-up of 17.5 months (interquartile range: 1.25-34), 3 patients (2 intraarticular, 1 extraarticular fractures) developed osteoarthritis, osteochondral lesion, and leg-length discrepancy from growth arrest, which required additional surgery. CONCLUSION: Intraarticular physeal fractures were more common with older children, associate with chondromalacia, and underdo surgical intervention when compared to extraarticular fractures of the knee. While MRI findings of physeal instability were common, no significant differences were found between fractures based on anatomic location or fracture pattern.

Distribution of pediatric hand fractures: age- and bone maturation-dependent differences.

PURPOSE: To investigate the distribution and characteristics of fractures of bones of the hand on radiographs with respect to age and skeletal maturity of the fractured bone, and to identify predictors of surgery. METHODS: This cross-sectional, retrospective study included children (≤ 18 years) with hand fractures who underwent radiographic examinations (2019-2021). Fracture location, presence of displacement (≥ 2 mm), angulation (≥ 10°), articular extension, and if skeletally immature, then physeal involvement and Salter-Harris grade were recorded. Mann-Whitney U, Kruskal-Wallis, Fisher's exact, and chi-square tests as well as logistic regression analyses were used. RESULTS: Study group of 508 (350 boys, 158 girls; median age, 11.9 years) included 575 (63% phalangeal, 37% metacarpal, and 0.3% carpal) fractures. Younger children were more likely to sustain phalangeal and older children carpal and metacarpal fractures (median ages: 10.8 vs 12.3 and 13.8 years, p < 0.001); and fractures of the small finger accounted for 50% of metacarpal and 43% of phalangeal fractures. Fracture displacement (12% vs 22%, p = 0.02) and angulation (25% vs 49%, p < 0.001) were more common with mature than immature bones. A third of immature bones had physeal involvement and the most common pattern was Salter-Harris type II (89%). Surgical intervention was uncommon (11%) and independent predictors were displacement (OR = 3.99, 95% CI 1.95-8.19, p < 0.001) and articular extension (OR = 5.11, 95% CI 2.00-13.07, p < 0.001). CONCLUSION: While younger children were more likely to sustain phalangeal than metacarpal fractures and less likely to have displacement and angulation when compared to older children; only displacement and articular extension were significant independent predictors of surgery.

Pediatric hand fractures detection on radiographs: do localization cues improve diagnostic performance?

OBJECTIVE: To compare the diagnostic accuracy and interpretation time for detection of pediatric fractures on hand radiographs with and without localization cues. MATERIALS AND METHODS: Consecutive children, who underwent radiographic examinations after injury, over 2 years (2019-2021) and with > 2 weeks of follow-up to confirm the presence or absence of a fracture, were included. Four readers, blinded to history and diagnosis, retrospectively reviewed all images twice, without and with cue, at least 1 week apart and after randomization, to determine the presence or absence of a fracture, and if present, anatomic location and diagnostic confidence were recorded. Interpretation time for each study was also recorded and averaged across readers. Inter-reader agreement was calculated using Fleiss' kappa. Diagnostic accuracy and interpretation time were compared between examinations using sensitivity, specificity, and Mann-Whitney U correlation. RESULTS: Study group included 92 children (61 boys, 31 girls; 10.8 ± 3.4 years) with and 40 (31 boys, 9 girls; 10.9 ± 3.7 years) without fractures. Cue improved inter-reader agreement (κ = 0.47 to 0.62). While the specificity decreased (63 to 62%), sensitivity (75 to 78%), diagnostic accuracy (71 to 73%), and confidence improved (78 to 87%, p < 0.01), and interpretation time (median: 40 to 22 s, p < 0.001) reduced with examinations with localization cue. Specifically, examinations with fracture and cue had the shortest interpretation time (median: 16 s), whereas examinations without fracture and without cue had the longest interpretation time (median: 48 s). CONCLUSION: Localization cues increased inter-reader agreement and diagnostic confidence, reduced interpretation time in the detection of fractures on pediatric hand radiographs, while maintaining diagnostic accuracy.

Radiographic Evaluation of Pediatric Patients with Patellofemoral Instability.

PURPOSE OF REVIEW: The purpose of this review is to highlight the radiographic assessments of utility in the evaluation of a pediatric patient with patellofemoral instability to facilitate a thorough work-up. Understanding of these measures is useful in understanding evolving research in this field, providing accurate patient risk assessment, and appropriately directing surgical decision-making. RECENT FINDINGS: Recent literature has broadened the radiographic characterization of the pediatric patellar instability and its anatomic risk factors. Knee MRI can inform the assessment of skeletal maturity and novel axial alignment measurements may enhance our identification of patients at increased risk of recurrent instability. Additional improvements have been made in the objective measurement and classification of trochlear dysplasia. Knee MRI-based skeletal age assessments may obviate the need for hand bone age assessments in growing children with patellofemoral instability. Novel objective measures exist in the evaluation of pediatric patellar instability both in the assessment of axial alignment and trochlear dysplasia. Future work should focus on how these measures can aid in guiding surgical decision-making.

Pediatric Osteosarcoma: Correlation of Imaging Findings with Histopathologic Features, Treatment, and Outcome.

Osteosarcoma is the most common primary bone sarcoma in children. Imaging plays a pivotal role in diagnostic workup, surgical planning, and follow-up monitoring for possible disease relapse. Survival depends on multiple factors, including presence or absence of metastatic disease, chemotherapy response, and surgical margins. At diagnosis, radiography and anatomic MRI are used to characterize the primary site of disease, whereas chest CT and whole-body bone scintigraphy and/or PET are used to identify additional sites of disease. Treatment starts with neoadjuvant chemotherapy, followed by en bloc tumor resection and limb reconstruction, and finally, adjuvant chemotherapy. Preoperative planning requires precise tumor delineation, which traditionally has been based on high-spatial-resolution anatomic MRI to identify tumor margins (medullary and extraosseous), skip lesions, neurovascular involvement, and joint invasion. These findings direct the surgical approach and affect the options for reconstruction. For skeletally immature children, the risk of cumulative limb-length discrepancy and need for superior longevity of the reconstruction have led to the advent and preferential use of several pediatric-specific surgical techniques, including rotationplasty, joint preservation surgery, autograft or allograft reconstruction, and extendible endoprostheses. A better understanding of the clinically impactful imaging features can directly and positively influence patient care. Online supplemental material is available for this article. ©RSNA, 2022.

Diffusion Tensor Imaging of the Knee to Predict Childhood Growth.

Background Accurate and precise methods to predict growth remain lacking. Diffusion tensor imaging (DTI) depicts the columnar structure of the physis and metaphyseal spongiosa and provides measures of tract volume and length that may help predict growth. Purpose To validate physeal DTI metrics as predictors of height velocity (1-year height gain from time of MRI examination) and total height gain (height gain from time of MRI examination until growth stops) and compare the prediction accuracy with bone age-based models. Materials and Methods Femoral DTI studies (b values = 0 and 600 sec/mm2; directions = 20) of healthy children who underwent MRI of the knee between February 2012 and December 2016 were retrospectively analyzed. Children with height measured at MRI and either 1 year later (height velocity) or after growth cessation (total height gain, mean = 34 months from MRI) were included. Physeal DTI tract volume and length were correlated with height velocity and total height gain. Multilinear regression was used to assess the potential of DTI metrics in the prediction of both parameters. Bland-Altman plots were used to compare root mean square error (RMSE) and bias in height prediction using DTI versus bone age methods. Results Eighty-nine children (mean age, 13 years ± 3 [SD]; 47 boys) had height velocity measured, and 70 (mean age, 14 years ± 1; 36 girls) had total height gain measured. Tract volumes correlated with height velocity (r2 = 0.49) and total height gain (r2 = 0.46) (P < .001 for both) after controlling for age and sex. Tract volume was the strongest predictor for height velocity and total height gain. An optimal multilinear model including tract volume improved prediction of height velocity (R2 = 0.63, RMSE = 1.7 cm) and total height gain (R2 = 0.59, RMSE = 1.8 cm) compared with bone age-based methods (height velocity: R2 = 0.32, RMSE = 2.9 cm; total height gain: R2 = 0.42, RMSE = 5.0 cm). Conclusion Models using tract volume derived from diffusion tensor imaging may perform better than bone age-based models in children for the prediction of height velocity and total height gain. © RSNA, 2022.

MRI Predictors of Residual Dysplasia in Developmental Dysplasia of the Hip Following Open and Closed Reduction.

BACKGROUND: Following open or closed reduction for children with developmental dysplasia of the hip, there remains a significant risk of residual acetabular dysplasia which can compromise the long-term health of the hip joint. The purpose of this study was to use postoperative in-spica magnetic resonance imaging (MRI) data to determine factors predictive of residual acetabular dysplasia at short-term follow-up. METHODS: We retrospectively reviewed 63 hips in 48 patients which underwent closed or open reduction and spica casting for developmental dysplasia of the hip. MRI performed in-spica at ∼3-week follow-up were used to assess 11 validated metrics and 2 subjective factors. Acetabular index (AI) was measured on anteroposterior pelvic radiographs at 2-year postoperative follow-up. Binary logistic regression was then used to identify variables predictive of residual dysplasia, defined as an AI greater than the 90th percentile for age based on historic normative data. RESULTS: Average age at surgical reduction was 9.3±3.2 months. 58.7% (37/63) of reductions were open. A total of 43 (68.3%) hips demonstrated residual acetabular dysplasia at 2 years postoperatively based on normative values. In those with persistent dysplasia, patients were on average older at the time of reduction (10.0 mo±3.2 vs. 8.0 mo±2.8, P=0.010) and more likely female (88.4% vs. 60.0%, P=0.010). Patients with residual dysplasia were more likely to have mild subluxation on postoperative MRI (40.0% vs. 10.5%, P=0.022). Hips with a cartilaginous acetabular index (CAI) of >23 degrees were 7.6 times more likely to develop residual dysplasia. Type of reduction (ie, closed vs. open) did not appear to influence the rate of residual dysplasia (P=0.682). CONCLUSION: In this series, the rate of residual dysplasia after surgical reduction was higher than most previous reports, with no appreciable difference between closed and open reductions. Older age, female sex, and a higher CAI were associated with a greater risk of persistent radiographic dysplasia. In particular, hips with a CAI >23 degrees were 7.6 times more likely to be dysplastic at 2-year follow-up. LEVEL OF EVIDENCE: Level III.

Reliability and Validity of an MRI-Based Knee Sagittal Alignment Measure in a Pediatric Cohort.

BACKGROUND: Magnetic resonance imaging (MRI) sagittal alignment is a measure that has been described and validated in the adult population as a means of distinguishing normal knees from those with anterior cruciate ligament (ACL) injury, but this measure has not been formally assessed among pediatric patients. The purpose of this study was to (1) assess the reliability of this MRI-based measure in a pediatric cohort, and (2) validate its ability to distinguish between ACL and non-ACL-injured knees in this population. METHODS: A consecutive series of knee MRI examinations performed at our center were reviewed to identify studies of pediatric patients (1) with ACL injury, and (2) without significant pathology. Patient age, sex, physeal status (open, closing, or closed), knee laterality, and magnet strength (1.5 or 3-Tesla) were collected. The sagittal alignment was measured in both medial and lateral tibiofemoral compartments using a previously described method. Mean anterior tibial translation was then calculated for each study. Inter-rater and intrarater reliability testing was performed on a subset of randomly-selected patients from each cohort by three raters by calculating intraclass correlation coefficients. Sagittal alignment measurements of all patients were then completed by a single author after reliability was confirmed. The medial and lateral compartment translation and mean anterior tibial translation measurements of normal and ACL-injured knees were compared. RESULTS: Inclusion criteria were met by 131 studies: 86 from uninjured knees (normal cohort) and 45 knees with ACL injury (ACL cohort). Studies were performed at a mean age of 13.4 with a near equivalent sex distribution. Inter-rater and intrarater reliability were good to excellent for all measures for patients in both normal and ACL cohorts. Normal and ACL-injured knees demonstrated a significant difference in anterior tibial translation in all measured regions. The mean anterior tibia translation for ACL-injured knees was 2.01 mm (95% confidence interval: 1.03-2.98) versus -0.44 mm (95% confidence interval: -0.89-0.014). CONCLUSION: This study identified good to excellent inter-rater and intrarater reliability of knee sagittal alignment measurements among pediatric patients. It also demonstrated a significant difference in medial compartment, lateral compartment, and mean tibial translation in patients with and without ACL injury, validating previous findings demonstrated in adult cohorts. These findings may be useful in assisting providers in the confirmation of suspected ACL injury and insufficiency and guide operative management in cases of clinical uncertainty. LEVEL OF EVIDENCE: Level III-retrospective comparative study.

MRI evaluation of pediatric tibial eminence fractures: comparison between conventional and "CT-like" ultrashort echo time (UTE) images.

OBJECTIVE: UTE MRI offers a radiation-free alternative to CT for bone depiction, but data on children is lacking. The purpose of this study was to determine whether UTE images improve detection and characterization of pediatric tibial eminence fractures. METHODS: Fifteen MRIs with UTE from 12 children (10 boys, 2 girls; mean age: 12.6 ± 3.3 years) with tibial eminence fractures (2018-2020) and 15 age-matched MRIs without fractures were included. After randomization, 5 readers reviewed images without and with UTE, at least 1 month apart, and recorded the presence of fracture and preferred images. If fracture is present, radiologists also recorded fragment size, number, and displacement; surgeons assigned Meyers-McKeever grade and management. Disagreements on management were resolved through consensus review. Kappa and intra-class correlation (ICC), sensitivity, and specificity were used to compare agreement between readers and fracture detection between images without and with UTE. RESULTS: For fracture detection, inter-reader agreement was almost perfect (κ-range: 0.91-0.93); sensitivity and specificity were equivalent between images without and with UTE (range: 95-100%). For fracture characterization, UTE improved agreement on size (ICC = 0.88 to 0.93), number (ICC = 0.52 to 0.94), displacement (ICC = 0.74 to 0.86), and grade (ICC = 0.92 to 0.93) but reduced agreement on management (κ = 0.68 to 0.61), leading to a change in consensus management in 20% (3/15). Radiologists were more likely to prefer UTE for fracture and conventional images for non-fracture cases (77% and 77%, respectively, p < 0.001). CONCLUSION: While UTE did not improve diagnosis, it improved agreement on characterization of pediatric tibial eminence fractures, ultimately changing the preferred treatment in 20%.