MR imaging of capitellar ossification: a study in children of different ages

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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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.

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.

Correlation Between Morphometric Measurements and Carrying Angle of Human Elbow

Purpose: This prospective cohort study aims to determine the correlation between morphometric measurements and the carrying angle of human elbow.

Methods: One hundred forty children were enrolled in the study. They were evaluated for age, sex, morphometric measurements, clinical carrying angle (CCA) and radiological carrying angle (RCA). The morphometric measurements included in the study were length of arms and forearms, inter-epicondylar distance of both sides, trans-trochanteric distance, height and body mass index. The mean of carrying angles in unrelated groups (gender and secondary sexual features) was compared using the unpaired t-test. Pearson’s correlation coefficient was calculated to determine the strength and direction of the relationship between carrying angle and continuous variables (age, height, body mass index, forearm length, arm length, inter-epicondylar distance and trans-trochanteric distance).

Results: The mean age was 5.84±4.76 years. Ninety-eight (70%) were males, and forty-two (30%) were females. The means of RCAs of the left side and right side were 9.07±2.13 and 8.85±2.09, respectively. The mean values of CCA on the left side and right side were 8.77±2.03 and 8.55±2.01 each. A significant positive correlation was found between CCA and age, weight, height, arm length, forearm length, inter-epicondylar distance and trans-trochanteric distance. CCA was found to be significantly negatively correlated with body mass index.

Conclusion: CCA is significantly correlated with age, BMI and morphometric measurements.

A Study of Factors Associated With Carrying Angle of the Human Elbow in Pediatric Age Group

Purpose

This prospective cohort study aims to determine the factors that are associated with the carrying angle of the human elbow in the pediatric age group.

Methods

One hundred forty children up to 15 years of age were assessed for age, sex, forearm lengths of both sides, arm length of both sides, trans-trochanteric diameter, height, BMI, the inter-epicondylar distance of both sides, Baumann’s angle of both sides, presence or absence of secondary sexual characteristics, clinical carrying angle (CCA) of both sides, and radiological carrying angle (RCA) of both sides. Unpaired t-test was used to compare the means of carrying angle in the unrelated groups, namely gender and secondary sexual characteristics. The strength and direction of the relationship between carrying angle and continuous variables were tested by calculating Pearson’s correlation. Variables found to be associated with carrying angle at significance level >0.25 on bi-variable analysis were used to design a linear regression model to identify factors associated with carrying angle.

Results

The mean age was 5.84±4.76 years. Ninety-eight (70%) were males, and forty-two (30%) were females. The mean CCA on the right side was 8.55±2.01. The mean CCA on the left side was 8.77±2.03. The mean RCA on the right side was 8.85±2.09. The mean RCA on the left side was 9.07±2.13. On bi-variable analysis, the CCA was found to be associated with age, secondary sexual characteristics, weight, height, arm length, forearm length, inter-epicondylar distance, trans-trochanteric distance, and Baumann’s angle. CCA was found to be significantly negatively correlated with BMI. On multivariate linear regression, the CCA was found to be associated with age and inter-epicondylar distance.

Conclusion

Age and inter-epicondylar distance are the true associations of carrying angle.

Qualitative and quantitative assessments of radiographic healing of osteochondritis dissecans of the humeral capitellum

Background

Little is known about the optimal timing of early return to sports after which the osteochondritis dissecans (OCD) lesion can completely heal. The aims of this study were to investigate the clinical outcomes of nonoperative treatment and elucidate the relationship between the radiographic findings and the timing for the return to sports.

Methods

We performed a retrospective review of 32 patients who presented with stable OCD of the capitellum and were treated nonoperatively for a minimum of 3 months. The mean follow-up period was 22.1 months. OCD lesions were assessed qualitatively and quantitatively on anteroposterior radiographs of the elbow at 45° of flexion every 3 months. The width of the OCD lesion (OCDw) and lateral width of the normal capitellum were measured and were associated with return to sports activities.

Results

In 21 patients (66%), the progression of ossification was seen at a mean period of 4.1 months. Eighteen (56%) had partial union at a mean period of 4.3 months. Twenty-nine cases (91%) returned to sports activities after a mean of 4.6 months. Nine cases (28%) achieved complete union after a mean period of 15.0 months. Fifteen (47%) required surgery after a mean period of 11.8 months. The mean OCDw (%) was 10.2 ± 3.9 mm (56%) at the initial presentation and 8.0 ± 6.0 mm (41%) at the final follow-up examination, and the decrease in OCDw was 2.2 ± 3.1 mm (15%). The mean decrease in OCDw in patients with progression of ossification during the first 3 months was significantly larger than in patients without progression of ossification (4.9 ± 4.7 mm and -0.7 ± 4.5 mm, respectively; P = .002). In patients who had both an OCDw value of <8.0 mm and a lateral width value of >2.0 mm at the time of the return to sports, the rate of successful nonoperative treatment (86%) and complete union (71%) was significantly higher in comparison with other patients (P = .03 and P = .02).

Conclusions

OCD lesions showed difficult healing in the middle one-third of the capitellum. The progression of ossification during the first 3 months was a significant predictor of successful nonoperative treatment and complete union. Surgery should be considered for lesions without the progression of ossification during the first 3 months. We propose both an OCD lesion width of <8.0 mm and a lateral normal width of >2.0 mm as radiographic landmarks of the timing of the return to sports.

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.

Retrospective study of open reduction and internal fixation of lateral humeral condyle fractures with absorbable screws and absorbable sutures in children

BACKGROUND

Lateral humeral condyle fractures are the second most common elbow fracture in children. Displaced and rotated fractures require stabilization and reduction. Kirschner wires (K-wires) are most commonly used in the fixation of these fractures. Here, we introduce a new fixation method that uses an absorbable screw. We aim to determine if it is feasible to treat lateral humeral condyle fractures with an absorbable screw by comparing functional outcomes following absorbable screw fixation vs. K-wire fixation.

METHODS

Between May 2007 and September 2010, 86 patients were treated with absorbable screws (43 patients) or K-wire (43 patients). All patients had been diagnosed with lateral condyle fractures that were classified as either Jacob type II (unstable) or III. One absorbable screw (3.5 mm-diameter) was used for fixation in 1 group, while two 1.6 to 1.8 mm K-wires were used in the other group. Patients were followed 6 months about the elbow function according to Broberg and Morrey standard. On 5-7 years, the patients were followed about the carrying angle (valgus deformities and varus deformities), range of motion (flexion loss and extension loss), prominent lateral condyle, symptomatic implants, and fishtail deformity.

RESULTS

Anatomic reduction was achieved in all patients. Each group had one radial nerve injury that were present preoperatively. Nerve function recovered spontaneously within 3 to 4 weeks of surgery in both patients. No patient developed necrosis of the capitulum in both groups. Nine patients in K-wires group and 2 in absorbable screw group developed symptomatic implants (P = .048). On the sixth month, there was no significant difference on elbow function according to Broberg and Morrey standard. On 5 to 7 years (average, 6.7 ± 1.3 years), valgus deformities was 6.8 ± 1.2 vs 5.7 ± 0.8, varus deformities was 7.2 ± 1.5 vs 5.1 ± 1.9, flexion loss was 12.4 ± 2.2 vs 9.5 ± 3.1, extension loss was 11.1 ± 3.1 vs 10.2 ± 2.7, prominent lateral condyle was 27.9% vs 37.2%, fishtail deformity was 7.3% vs 4.9%, no significant difference between these groups.

CONCLUSIONS

Open reduction with absorbable screw fixation is feasible and safe for the treatment of lateral condyle fractures of the humerus in children.

LEVEL OF EVIDENCE

Therapeutic III.

Nonoperative management of stable pediatric osteochondritis dissecans of the capitellum: predictors of treatment success

BACKGROUND

Osteochondritis dissecans (OCD) of the capitellum is a rare but potentially debilitating condition. We sought to determine the healing potential of stable capitellar OCD treated nonoperatively, as well as factors predictive of successful nonoperative management.

METHODS

We performed a retrospective review of patients younger than 19 years who presented with stable OCD of the capitellum and were treated nonoperatively for a minimum of 2 months. The average clinical and radiographic follow-up period was 12.1 months (range, 3.1-63.7 months). A multivariable logistic regression model was used to determine independent predictors of healing.

RESULTS

The study included 89 patients (93 elbows), including 49 male patients (55%); the mean age was 12.7 years (range, 8.9-18.6 years). Of the 93 elbows, 50 (53.8%) had successfully healed at a mean of 8.3 months. The symptom duration was significantly shorter in the healing group than the nonhealing group (5.3 ± 4.4 months vs 8.8 ± 9.0 months, P = .02). There were no significant differences in age, physeal status, sex, hand dominance, or sport. Hefti stage I lesions had a higher rate of healing (64.3%) than stage II (31.4%, P = .004), as did OCDs without cyst-like lesions (CLLs, 62.0%) compared with those with CLLs (20.8%, P = .001). The normalized lesion area was significantly larger in the nonhealing group (26.9% vs 18.6%, P < .001). A smaller normalized area and the absence of CLLs were independent predictors of healing.

CONCLUSIONS

Over half of stable capitellar OCD lesions have the potential to heal with activity restriction. Smaller lesions without CLLs are more likely to heal with nonoperative treatment.

Transphyseal separation of the distal humerus in newborns

Obstetric traumatic separation of the distal humeral epiphysis is a very uncommon injury, which presents a diagnostic challenge. These case serials reviewed the functional outcomes of 5 patients who had sustained a fracture-separation of the distal humeral epiphysis at birth. The diagnosis was made at a mean time of 40.8 h after delivery. All the patients were treated with gentle close manipulation, reduction under fluoroscopy and above-elbow cast application. After discharge, the patients were followed up for a mean of 30 months. Clinico-radiological results were excellent in four patients. One case necessitated closed reduction and percutaneous K-wire fixation at one week follow-up due to failed reduction. Cubitusvarus deformity was the only complication noted in 1 case. Good functional outcome can be expected in newborns with fracture-separation of the distal humeral epiphysis wherein the physis is anatomically reduced.

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.

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

BACKGROUND

The radiocapitellar line (RCL) has long been used for the radiographic evaluation of elbow alignment. In children, the capitellar ossific nucleus serves as a proxy for the entire capitellum, but this substitution has not been verified. Using magnetic resonance imaging (MRI), we sought to understand how maturation of the ossific nucleus of the capitellum affects the utility of RCL throughout skeletal maturation of the elbow.

METHODS

The RCL was drawn on coronal and sagittal MRIs in 82 children (43 boys, 39 girls; age range, 1 to 13 y) with at least 3 patients in each 1-year interval age group. The perpendicular distance of the RCL from the center of both the cartilaginous capitellum and the capitellar ossific nucleus was measured relative to its total width, and a percent offset for each measurement was calculated. Logarithmic regression analysis was performed to analyze the effect of age and sex on percent offset.

RESULTS

The RCL reliably intersected with the central third of the cartilaginous capitellum at all ages in both planes. Although the RCL intersected with the ossified capitellum in all but 3 measurements, it intersected with the central third of the ossified capitellum less often in younger children in both sagittal (B=0.47, P<0.001) and coronal (B=0.31, P=0.002) planes. Percent offset decreased significantly with age in a logarithmic manner in both sagittal (r=0.57, P<0.001) and coronal (r=-0.47, P<0.001) planes. 95% confidence intervals predict that the sagittal plane RCL will accurately intersect the central third of the ossified capitellum by age 10 years in girls and age 11 years in boys but not in the coronal plane.

CONCLUSIONS

Eccentric ossification of the capitellum explains RCL variability in young children. The RCL does not reliably intersect the central third of the ossified capitellum until ages 10 years in girls and 11 years in boys in the sagittal plane. The RCL should be used within its limitations in skeletally immature children and should be combined with advanced imaging if necessary.