Eccentric Capitellar Ossification Limits the Utility of the Radiocapitellar Line in Young Children

Imaging Assessment of the Pediatric Elbow: Developmental Variants and Common Pathologies

The pediatric elbow is a complex joint that undergoes rapid growth and development. The normal anatomy of the elbow varies depending on the age of the patient, which can be challenging for imaging interpretation. This article reviews developmental variants and common pathologies of the pediatric elbow, with a focus on their radiologic features. Normal anatomy and development of the pediatric elbow are discussed, including the six ossification centers and elbow alignment. Congenital anomalies such as longitudinal deficiencies of the upper extremity are reviewed. Some common injuries that affect the elbow, such as supracondylar fracture, lateral condyle fracture, medial epicondyle avulsion, and radial head dislocation are also described.

Age-dependent Sagittal Plane Remodeling of Pediatric Supracondylar Fractures

BACKGROUND

Current treatment guidelines for pediatric supracondylar fractures have not fully accounted for age-related variations in the remodeling potential. This study aimed to explore age-dependent sagittal plane remodeling in supracondylar fractures by assessing cases with residual deformities after treatment.

METHODS

This study included 62 patients under 16 years of age treated for supracondylar fractures at our institution from 2002 to 2022. The distance between the posterior and anterior aspects of the capitellar ossific nucleus (CON) was defined as the CON size, while the distance from the anterior humeral line to the posterior aspect of CON was termed DAP-CON. The value obtained by subtracting the DAP-CON on the unfractured side from the DAP-CON on the fractured side was divided by the CON size and multiplied by 100 and termed the displacement of CON (d-CON). The absolute value of the difference between d-CON after intervention and d-CON at the last follow-up was denoted as sagittal plane remodeling.

RESULTS

For this patient cohort, the mean age was 5.5 years (range, 1.4 to 14.6 years), and the mean follow-up period was 30.4 months (range, 12.0 to 137.1 months). Sagittal plane remodeling was more pronounced in children younger than 5 years (group I) compared with those older (group II) ( P <0.001). In multiple regression analysis, only age at the time of injury was found to be a significant variable ( P <0.001). The receiver operating characteristic curve analysis identified 4.2 years as the cutoff age for predicting >33% sagittal plane remodeling, with an area under the curve of 0.975.

CONCLUSIONS

Children below the age of 5 years exhibit sagittal plane remodeling, with a cutoff age identified at 4.2 years for achieving >33% of d-CON. This indicates that mild deformities (16.5%

LEVEL OF EVIDENCE

Level IV-retrospective study.

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MESH Headings

• Humans
• Child
• Child, Preschool
• Male
• Adolescent
• Female
• Age Factors
• Humeral Fractures/surgery
• Infant
• Retrospective Studies
• Bone Remodeling
• Follow-Up Studies
• Fracture Fixation, Internal/methods

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Affiliation(s)

Yun Ki Kim Department of Orthopedic Surgery, Regional Rheumatoid and Degenerative Arthritis Center, Chungnam National University Hospital, Chungnam National University School of Medicine, Daejeon, Korea
Seung Hoo Lee Department of Orthopedic Surgery, Chungnam National University Sejong Hospital, Chungnam National University College of Medicine, Sejong, South Korea

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The efficacy of pediatric elbow radiographic guidance in diagnosis of lateral humeral condyle fracture

Although lateral humeral condyle fracture is common, the incidence of missed diagnosis is very high. Delayed and missed diagnosis led to significant morbidities and loss of functions. We designed a pediatric elbow radiographic guidance aiming to improve the accuracy of diagnosis. This study was aimed to evaluate the efficacy of the radiographic guidance for the diagnosis of lateral condyle fracture. A cross-sectional study was conducted after defining the essential parameters as a guidance for assessing the pediatric elbow radiographs. We included medical students, emergency medicine, orthopedic, and radiology residents and fellows into this study. A questionnaire was used to evaluate the efficacy of the guidance. All participants underwent a pretest evaluation, followed by studying the guidance, and then finished a posttest evaluation. Baseline characteristics, diagnostic scores, and parameter evaluation scores were collected. The pretest and posttest scores were analyzed using paired t-test. Association between baseline characteristics and diagnostic scores were analyzed using multiple regression analysis. We included 177 participants. Average diagnostic score was significantly increased after using the guidance, from 12.2 ± 1.9 to 13.0 ± 1.7 (p < 0.0001). Medical students showed the most improvement, from 11.9 ± 1.9 to 13.1 ± 1.3 (p <0.001). All means of essential parameter evaluation scores were significantly improved in overall participants.The pediatric elbow radiographic guidance is useful for evaluation and diagnosis of lateral condyle fracture, especially for young physicians and trainees. Therefore, this should be recommended in routine medical education and general practice.

Comprehensive Analysis of Pediatric Elbow Radiographic Lines and Angles

OBJECTIVES

The study aimed to determine relevant radiographic lines and angles of children's elbow.

METHODS

DESIGN

A retrospective cross-sectional study.

SETTING

Tertiary pediatric trauma center.

PATIENT SELECTION CRITERIA

X-rays of healthy children's elbows 0-18 years of age in whom the radiographic image of the elbow in 2 projections was read without signs of fracture and possible indirect signs of fracture, whereas the exclusion criterion was a clearly visible poor image projection.

OUTCOME MEASURES AND COMPARISONS

Gender, age [patients were divided into 6 groups-group 1 (0-3 years), group 2 (4-6 years), group 3 (7-9 years), group 4 (10-12 years), group 5 (13-15 years), group 6 (16-18 years)], side, intersection of the radiocapitellar line in the anteroposterior (AP) projection, intersection of the radiocapitellar line in the lateral projection, intersection of the anterior humeral line, Baumann angle, carrying angle, lateral capitellohumeral angle, shaft condylar angle, intersection of the coronoid line and radioulnar overlap.

RESULTS

Two hundred elbows were evaluated. The radiocapitellar line in AP and lateral projections passed through the middle third of the capitellum in 74.5% and 93%, respectively. The anterior humeral line passed through the middle third of the capitellum in 88.5% of cases. When observing the proportion of radiocapitellar lines passing through the middle third of the capitellum in the AP, with increasing age an increasing proportion of lines pass through the middle third of the capitellum [from 8.3% in group 1 (0-3 years) to 94.1% in group 6 (16-18 years), P = 0.001] and lateral projection (from 50% in group 1%-100% in group 6, P = 0.023) and anterior humeral line (from 25% in group 1%-100% in group 6, P = 0.0001). The mean Baumman angle, carrying angle, lateral capitellohumeral angle, shaft condylar angle were 71.59 degrees, 10.97 degrees, 50.84 degrees, and 55.31 degrees, respectively. With age, the shaft condylar angle records the greatest increase (from 41.6 degrees in group 1-68.2 degrees in group 6, P = 0.000). A correlation was observed between Baumann angle and carrying angle (r = -0.674) and between Baumann angle and radioulnar overlap (r = 0.542).

CONCLUSIONS

Considering the anatomical variability of children's elbow, radiologic measurements and their interpretation, in the context of timely diagnostics, must be approached with great caution, especially in younger age groups, because it is with them that the largest proportion of lines and angles do not follow established principles.

LEVEL OF EVIDENCE

Diagnostic Level IV. See Instructions for Authors for a complete description of levels of evidence.

Magnetic Resonance Imaging Manifestations of Annular Ligament Injuries in Children With Monteggia Fractures

BACKGROUND

Magnetic resonance imaging (MRI) is commonly performed in children with elbow injuries to visualize soft tissues such as the annular ligament. Herein, we investigated the MRI manifestations of annular ligament injuries in children with Monteggia fractures following attempted closed reduction.

METHODS

The clinical and imaging data of 88 children with acute Monteggia fractures treated at our hospital between 2015 and 2019 were analyzed. Clinically and radiographically, 67 patients achieved radiologic reduction of the radial head at the time of MRI, whereas 21 patients had a failed closed reduction. Annular ligament injury and superior radioulnar joint congruency were analyzed qualitatively, and the maximum superior radioulnar joint gap distance was measured.

RESULTS

MRI manifestations of annular ligament injury were primarily characterized as varying degrees of annular ligament displacement, as follows: I degree (10 patients), the annular ligament encircled the radial head without displacement; II degree (5 patients), the annular ligament was partially displaced but visibly encircled the radial head at the level of the radial notch; and III degree (73 patients), the annular ligament was completely displaced. In 15 patients with I and II degrees annular ligament injuries, the annular ligament encircled the radial head (maximum superior radioulnar joint gap distance, 1.2±0.3 mm), showing good congruency of the superior radioulnar joint. In 73 patients with III degree annular ligament injury, the annular ligament was displaced and did not encircle the radial head (maximum superior radioulnar joint gap distance, 3.3±2.7 mm; P <0.05), showing good congruency of the superior radioulnar joint in 25 of 73 patients, and significantly poor congruency in 48 of 73 patients ( P <0.05).

CONCLUSIONS

Annular ligament injuries in children with Monteggia fractures exhibit different degrees of displacement of the annular ligament. In I and II degree annular ligament injuries, the annular ligament still encircles the radial head. In III degree annular ligament injuries, the annular ligament is displaced away and is no longer around the radial head. Without the annular ligament restraining the radial head, the superior radioulnar joint is more likely to exhibit poor congruency and increased gap distance.

LEVEL OF EVIDENCE

Level II.

Using the radiocoronoid line for diagnosis of elbow dislocation

The radiocapitellar line (RCL) has been widely used to diagnose elbow dislocation. However, there are limitations to the RCL, with the cartilaginous portion of bone making interpretation of radiographs difficult. The study aims to show that the radiocoronoid line, which connects two points on the medial aspect of the radius, proximal to the radial tuberosity, is more suited to diagnose elbow dislocations in the anterior-posterior projection. This study also observes factors affecting accuracy of the radiocapitellar line. The radiographs of 50 normal and 17 laterally dislocated elbows were obtained. An unbiased independent reviewer drew the radiocoronoid and radiocapitellar line (RCL). Four other blinded independent reviewers drew the RCL and the radiocoronoid line for 20 radiographs and repeated the process a week later. The accuracy of the RCL was assessed using distance away from bisection point of capitellum, and ratio (distance from the point where line crosses capitellum to lateral aspect of capitellum over the total width of capitellum). The relationship of the radio-coronoid line and the lateral aspect of coronoid fossa was assessed, with dislocation being the line lateral to it and normal being medial to or on it. The radiocoronoid line had a higher accuracy (95.5%) compared to RCL (32.8%), higher specificity (94%) compared to RCL (10%) as well as higher positive predictive value (85%) compared to RCL (27.4%). There was no intra- or inter-observer variability for the radio-coronoid line. Skeletal age statistically predicted the ratio for the male population ( P < 0.05), however, the independent variables did not statistically predict the dependent variables for the female and total population. The radiocoronoid line serves as an additional method to assess radiocapitellar joint lateral dislocation. It is more accurate and reliable than the radiocapitellar line in the anterior-posterior projection. Sex and skeletal age also influence the accuracy of the radiocapitellar line with the radiocapitellar line nearing the bisection point as skeletal age in males increases.

Ultrasound imaging in diagnostics of Monteggia lesion in children

PURPOSE

The aim of the study is to evaluate the use of ultrasound imaging in diagnostics of Monteggia lesion in children where conventional radiographs and the use of the radiocapitellar line fail to provide an accurate diagnosis.

METHODS

Prospective diagnostic study of 70 patients treated between May 2018 and July 2021 in a pediatric level 1 trauma center. In 20 patients with the confirmed radiographic diagnosis of Monteggia lesion, an ultrasound of the humeroradial joint was performed to determine signs of both normal and dislocated elbow joint. In 36 patients with suspected humeroradial dislocation on plain radiographs, ultrasound imaging was performed to determine the definitive diagnosis. Overall, 14 patients with elbow joint injury other than humeroradial dislocation were excluded from the study.

RESULTS

The "double-hump sign" and the "congruency sign" were determined as normal findings on ultrasound of the humeroradial joint. These signs were applied to patients with unclear findings on radiographs. In three patients, the dislocation of the humeroradial joint was confirmed by ultrasound. In two patients, "defect in congruency sign" was seen during reduction despite normal radiographs, which required re-reduction. In 31 patients, dislocation of the humeroradial joint was refuted. In 34 out of the 36 patients, the diagnosis determined by ultrasound was confirmed in follow-up. Two patients did not attend the follow-up examination.

CONCLUSION

Ultrasound imaging is an accessible, non-invasive, and dynamic point-of-care method that can be applied in children suffering from suspected humeroradial dislocation and/or subluxation.

LEVEL OF EVIDENCE

Level III-diagnostic study.

Is a Right Angle the Right Angle? Normal Coronal Radiographic Alignment in the Pediatric Finger Phalanges

BACKGROUND

Quantifying pediatric phalanx fracture displacement requires understanding the normal radiographic alignment of pediatric phalanges, which has never been assessed in the coronal plane, although prior studies have assumed the articular surfaces and physes to be perpendicular to the diaphyses. This study tests the hypothesis that these relationships are not uniformly perpendicular and instead vary by digit and age.

METHODS

Normal hand bone age radiographs were retrospectively reviewed from 40 males and 40 females 2 to 18 years old. For each finger proximal phalanx (P1) and middle phalanx (P2), 2 raters each measured twice the angle between the diaphysis and distal articular surface (D-DA), diaphysis and physis (D-P, when physis present), and diaphysis and proximal articular surface (D-PA). Intra-rater and inter-rater reliability were calculated with intraclass correlation coefficients. 95% confidence intervals were calculated for each angle for each digit, phalanx, age group, and sex to determine which angles ~90 degrees. Variability among ages and sex was assessed with analysis of variance.

RESULTS

Intra-rater and inter-rater intraclass correlation coefficients were >0.90, except in P2 ∠D-DA in children under 8 years old with unossified P2 condyles. Overall, only 173 (47.8%) of 362 confidence intervals included 90 degrees. Three angles of the small finger (P1 ∠D-DA, P2 ∠D-P, P2 ∠D-PA) never ~90 degrees at any age or sex, with an average 10 degrees ulnar tilt of the small finger proximal interphalangeal joint. Of the 24 angles across digits and phalanges, 10 varied significantly with age, especially in the index and middle finger P1 where initially wedge-shaped epiphyses progressively became more symmetric with age.

CONCLUSIONS

The coronal radiographic angles between the phalangeal diaphyses and articular surfaces or physes differ from 90 degrees more than half the time in pediatric fingers, and nearly half the angles vary by age. These findings demonstrate that the articular surfaces and physes of the pediatric finger phalanges are not uniformly perpendicular to the diaphyses, underscoring the need to consider the variability among digits, phalanges, ages and subjects.

LEVEL OF EVIDENCE

Level IV.

Management of Monteggia Injuries in the Pediatric Patient

Monteggia fracture-dislocations in the pediatric population have unique patterns of injury that require distinct considerations in diagnosis and management. When appropriately diagnosed and treated early, acute pediatric Monteggia injuries have favorable outcomes. Missed or inadequately treated injuries result in chronic Monteggia lesions that require more complex surgical reconstructions and are associated with less predictable outcomes. This article reviews the classification, diagnosis, and treatment of acute and chronic pediatric Monteggia injuries as well as the controversies there in.

A Practical Method for Obtaining True Lateral Elbow X-rays in a Paediatric Age Group: Lateral Elbow X-ray in the Standing Salute Position

INTRODUCTION

Paediatric elbow fractures constitute 10% of all paediatric fractures. Radiological interpretation of the immature elbow is difficult due to its cartilaginous structure. We aimed to describe an X-ray technique in paediatric patients to obtain true lateral elbow X-rays and to prevent the repeat X-ray shots.

MATERIALS AND METHODS

Radiographs of 39 children, with a mean age of 48.17 months (range; 7-84 months), with elbow trauma were included. All elbow lateral radiographs were taken in the 90º flexion position. In the first group, radiographs were taken using the standard technique(lateral radiographs in shoulder internal rotation). In the second group, lateral radiographs of the elbow were taken while the patient was standing and the forearm was elevated passively with 90° shoulder abduction and 90° elbow flexion (standing salute position). Three criteria were examined from the graphs to determine the true lateral elbow graphy.

RESULTS

In group 1 (n = 20) and group 2 (n = 19), lateral elbow radiographs were evaluated. No statistically significant differences were found between the groups, in terms of mean age and distal humeral fractures. In group 2; the presence of humeroulnar joint space, partial coronoid superposition of the radius head and presence of the hourglass formation were significantly higher.

DISCUSSION

It is clear that radiographs taken in appropriate positions decreases diagnostic errors. In our study, the ratio of correct lateral radiographs was significantly higher in the radiograph group in the standing salute position, suggesting this method was safe for accurate lateral radiographs, in accordance with our hypothesis.

Missed Diagnosis and Acute Management of Radial Head Dislocation With Plastic Deformation of Ulna in Children

BACKGROUND

Radial head dislocation with ulnar bowing (Monteggia type I equivalent injury) is a frequently missed injury. If not recognized acutely, these missed injuries can lead to serious long-term complications. The purpose of this study was to evaluate the rate of missed diagnosis and to report on the characteristics and early management of this specific injury pattern.

METHODS

A total of 112 patients with Monteggia fracture-dislocation were identified, of which 18 patients had sustained a Monteggia type I equivalent injury. The total duration between injury, diagnosis, and treatment was noted. Medical records were reviewed to identify cases with the initially missed diagnosis. The radiographic assessment included the direction of radial head dislocation and location/displacement of the apex of the ulnar bow. Clinical outcomes were evaluated using Kim elbow performance score.

RESULTS

Thirteen of 18 cases with Monteggia equivalent injury were missed at the initial presentation. The diagnosis was established when the patients followed up in the orthopaedic clinic. Of these 18 patients, 11 were treated by closed reduction/cast and 7 patients required surgery. Significant differences were found between the closed reduction/cast and operative group for the mean time from injury to treatment (3.2±2.6 vs. 12.7±13.6 d). For each day of delay in treatment, the odds for surgical intervention increased by a factor of 1.126 (12.6%). There were no significant differences between the location and magnitude of the apex of the ulnar deformity between the 2 groups. Kim elbow score was excellent in all cases at the latest follow-up.

CONCLUSIONS

Clinical suspicion and careful radiographic assessment are of utmost importance for every child with forearm and elbow injury without an apparent fracture, as there is a high rate of missed diagnosis for this specific Monteggia injury pattern. Prompt treatment would allow for successful closed reduction while even minor delays would increase the need for surgical intervention.

LEVEL OF EVIDENCE

Therapeutic, level 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.

An Alternative to the Traditional Radiocapitellar Line for Pediatric Forearm Radiograph Assessment in Monteggia Fracture

OBJECTIVE

To find a new reference for assessment of pediatric forearm radiographs besides the traditional RCL.

METHODS

RCLs were drawn on the anteroposterior (AP) and lateral radiographs of 170 normal pediatric forearms. Three lines were drawn on each radiograph: the first was drawn along the longitudinal center of the radial neck (N-line); the second, along the radial shaft (S-line); and the third, through the midpoints of the proximal and distal radial physes (P-line).

RESULTS

The P-line was least likely to miss the capitellum on both AP views and lateral views, and the P-line most frequently passed through the central third of the capitellum on both AP views and lateral views.

CONCLUSIONS

Our proposed radiocapitellar P-line was found to be much more reliable in younger children than traditional RCLs.

Significance of the Lateral Humeral Line for Evaluating Radiocapitellar Alignment in Children

BACKGROUND

The radiocapitellar line (RCL) was originally described for evaluation of the alignment of the RC joint on lateral images of the elbow. Although, many authors have translated the utilization of RCL into coronal imaging, previous studies have not been performed to confirm validity. The purpose of this paper was to identify an accurate way of evaluating pediatric RC alignment in the coronal plane.

METHODS

Thirty-seven anteroposterior (AP) radiographs of 37 children were evaluated to determine the position of the RC joint in the coronal plane. All had acceptable magnetic resonance imaging (MRI) studies available for comparison. The lateral humeral line (LHL), consisting of a line along the lateral edge of the ossified condyle of the distal humerus parallel to the axis of the distal humeral shaft, was studied as it related to the lateral cortex of the radial neck. Three children with a confirmed diagnosis of a Bado III, lateral displaced radius, Monteggia fracture were also evaluated.

RESULTS

The LHL passed along the edge of or lateral to the radial neck on all AP radiographs and all MRI studies. The RCL failed to intersect the capitellum on 2 AP radiographs. On MRI, the RCL also passed lateral to the capitellar ossification center in 3 patients. In addition, the RCL was seen passing through the capitellum at a mean of the lateral 30% (range, 0% to 64%) on AP radiographs and 26% (range, 0% to 48%) on MRI. For all 3 children with a Bado III Monteggia fracture, the LHL crossed the radial neck and the RCL did not intersect the capitellum.

CONCLUSIONS

The RCL can fail to intersect the capitellar ossification center on AP radiographs and MRI in pediatric elbows without injury. The LHL consistently lies lateral to the radial neck in normal elbows and medial to the lateral aspect of the radial neck on all Bado III fracture-dislocations. It, therefore, can be used as an adjunct in evaluating the RC joint on AP imaging. The RCL most commonly intersects the lateral one third of the ossification center on both plain radiographs and MRIs.

LEVEL OF EVIDENCE

Level III-diagnostic.