Pediatric Shoulder Girdle

The pediatric shoulder girdle is a complex anatomical structure uniting the upper extremity and trunk. The osseous structures, their articulations, and the surrounding soft tissue support structures (muscles, tendons, and ligaments) allow for a wide range of motion at the shoulder. Growth and maturation of the components at the shoulder girdle vary, particularly the osseous structures. This characteristic renders interpretation of imaging of the pediatric shoulder girdle more challenging because normal or variant anatomy can be confused for pathology. We review the physiologic growth and maturation of the shoulder girdle with special emphasis on the development of the bones and their articulations. The role of various imaging modalities and the common osseous and soft tissue variants in the pediatric shoulder are also discussed.

Demystifying the Radiography of Age Estimation in Criminal Jurisprudence: A Pictorial Review

Skeletal radiographs along with dental examination are frequently used for age estimation in medicolegal cases where documentary evidence pertaining to age is not available. Wrist and hand radiographs are the most common skeletal radiograph considered for age estimation. Other parts imaged are elbow, shoulder, knee, and hip according to suspected age categories. Age estimation by wrist radiographs is usually done by the Tanner-Whitehouse method where the maturity level of each bone is categorized into stages and a final total score is calculated that is then transformed into the bone age. Careful assessment and interpretation at multiple joints are needed to minimize the error and categorize into age-group. In this article, we aimed to summarize a suitable radiographic examination and interpretation for bone age estimation in living children, adolescents, young adults, and adults for medicolegal purposes.

Defining shoulder function and dysplasia in patients with longitudinal deficiencies of the upper limb

BACKGROUND

Phenotypic differences and functional limitations in children with congenital radial and ulnar longitudinal deficiencies (RLD/ULD) are well understood for the forearm and hand. However, anatomical features of shoulder elements in these pathologies have only been scarcely reported. Moreover, shoulder function has not been assessed in this patient population. Therefore, we aimed to define radiologic features and shoulder function of these patients at a large tertiary referral center.

METHODS

We prospectively enrolled all patients with RLD and ULD (minimum age: 7 years) for this study. Eighteen patients (12 RLD, 6 ULD) with a mean age of 17.9 years (range, 8.5-32.5) were evaluated using clinical examination (shoulder motion and stability), patient-reported outcome measures (Visual Analog Scale, Pediatric/Adolescent Shoulder Survey, Pediatric Outcomes Data Collection Instrument), and radiologic grading of shoulder dysplasia (including length and width discrepancy of the humerus, glenoid dysplasia in the anteroposterior and axial view [Waters classification], and scapular and acromioclavicular dysplasia assessment). Descriptive statistics and Spearman correlation analyses were performed.

RESULTS

Despite five (28%) cases having anterioposterior shoulder instability and five (28%) cases with decreased motion, outcome scores indicated an overall excellent function of the shoulder girdle, with mean Visual Analog Scale of 0.3 (range, 0-5), mean Pediatric/Adolescent Shoulder Survey of 97 (range, 75-100), and mean Pediatric Outcomes Data Collection Instrument Global Functioning Scale of 93 (range, 76-100). The humerus was, on average, 15 mm shorter (range, 0-75), and metaphyseal and diaphyseal diameters both reached 94% of the contralateral side. Glenoid dysplasia was detected in nine (50%) cases, with increased retroversion evident in 10 (56%) cases. However, scapular (n = 2) and acromioclavicular (n = 1) dysplasia were rare. Based on radiographic findings, a radiologic classification system for dysplasia types IA, IB, and II was developed.

CONCLUSIONS

Adolescent and adult patients with longitudinal deficiencies exhibit various mild-to-severe radiologic abnormalities around the shoulder girdle. Nevertheless, these findings did not seem to negatively affect shoulder function as the overall outcome scores were excellent.

Nonunion of the so-called acromion: a systematic review with consideration of the terminology

INTRODUCTION

There is no widely accepted standard for the classification and treatment of traumatic acromion/scapular spine fracture nonunion due to the scarcity of this condition and the confusion of terminology.

MATERIALS AND METHODS

PubMed and Scopus were searched using "scapular fracture" and "acromion fracture" or "scapular spine fracture" as search terms. The inclusion criteria were English full-text articles concerning acromion/scapular spine fracture nonunion that described patient characteristics and presented appropriate images. The exclusion criteria were cases without appropriate images. Citation tracking was conducted to find additional articles and notable full-text articles written in other languages. Fractures were classified using our newly proposed classification system.

RESULTS

Twenty-nine patients (19 men, 10 women) with 29 nonunions were identified. There were four type I, 15 type II, and 10 type III fracture nonunions. Only 11 fractures were isolated. The mean period from initial injury to final diagnosis was 35.2 ± 73.2 months (range 3-360 months) (n = 25). The most frequent cause of delayed diagnosis was conservative treatment for fracture in 11 patients, followed by oversight by the physician in 8. The most common reason for seeking medical advice was shoulder pain. Six patients received conservative therapy, and 23 received operative treatment. Fixation materials included various plates in 15 patients, and tension band wiring in 5. Bone grafting was performed in 16 patients (73%, 16/22). Of the 19 surgically treated patients with adequate follow-up, the outcome was rated excellent in 79%.

CONCLUSIONS

Isolated acromion/scapular spine fracture nonunion is rare. Fracture type II and III, arising in the anatomical scapular spine, accounted for 86% of the fractures. Computed tomography is required to prevent fracture oversight. Surgical therapy produces good stable results. However, it is important to select the appropriate surgical fixation method and material after considering the anatomical characteristics of the fracture and stress on the fractured portion.

LEVEL OF EVIDENCE

V.

Normal ossification of the glenoid mimicking a glenoid fracture in an adolescent patient: a case report

A 13-year-old male was diagnosed with a glenoid fracture following direct shoulder trauma, for which surgical treatment was considered. After referral to a center for pediatric orthopedic care, physical examination, contralateral shoulder X-ray, and detailed computed tomography examination ruled out the presence of fracture; these findings were later confirmed by magnetic resonance imaging. Normal ossification patterns in the adolescent shoulder may simulate a fracture in traumatic settings. To accurately diagnose and manage pediatric shoulder pathology, orthopedic surgeons must be aware of the normal anatomy of the growing shoulder, its secondary ossification centers, and growth plates.

Metaphyseal and Diaphyseal Contours: Variants and Pitfalls

We discuss several variants of the metaphyseal and diaphyseal bone surfaces that may be misleading in clinical practice. They include metaphyseal stripes, spiculated metaphyseal cortex, cortical desmoid, laminated lateral supracondylar ridge, cortical vascular canals, variations in shape or lucency of normal tuberosities, cortical thickening of normal ridges, and well-organized undulated hyperostosis at the proximal phalanges.

MR Imaging of the Developing Pediatric Marrow: An Overview of Pearls and Pitfalls

The dynamic and developing pediatric skeleton is a well-elucidated process that occurs in a stepwise faction. Normal development has been reliably tracked and described with Magnetic Resonance (MR) imaging. The recognition of the normal patterns of skeletal development is essential, as normal development may mimic pathology and vice versa. The authors review normal skeleton maturation and the corollary imaging findings while highlighting common marrow imaging pitfalls and pathology.

Does reverse total shoulder arthroplasty with allograft-prosthesis composite (APC) have surgical benefits over hemiarthroplasty with APC in patients with tumors of the proximal humerus?

Background

The research on surgical outcomes of hemiarthroplasty and reverse total shoulder arthroplasty using allograft-prosthesis composites for the proximal humeral oncologic condition is still scarce. Therefore, this study aimed to compare surgical outcomes of shoulder joint reconstruction with hemiarthroplasty and reverse total shoulder arthroplasty using allograft-prosthesis composites for tumors of the proximal humerus.

Methods

Eleven patients underwent hemiarthroplasty or reverse total shoulder arthroplasty using allograft-prosthesis composites for tumors of the proximal humerus between July 2011 and April 2018 were reviewed. Radiographic analysis for bone union of allograft-host bone junction, implant loosening, stress shielding and shoulder dislocation or subluxation was performed. Functional outcomes were evaluated using visual analog scales for pain, range of motion, Simple Shoulder Test score and Musculoskeletal Tumor Society score. Furthermore, oncologic outcome and complications were also assessed, respectively.

Results

There were five patients with hemiarthroplasty (mean age, 23.2 years) and six patients with reverse total shoulder arthroplasty (mean age, 46.8 years, P = 0.05). Radiographically, there were no events associated with implant loosening, stress shielding and shoulder dislocation or subluxation in the two groups. There were no differences in functional outcomes between the two groups. There was no local recurrence in entire cohort. In the hemiarthroplasty group, one patient was required revision surgery to reverse total shoulder arthroplasty at postoperative 6 years due to rotator cuff dysfunction. In the reverse total shoulder arthroplasty group, one patient showed the fracture occurred at allograft-host bone junction at postoperative 6 months.

Conclusions

Surgical outcomes of hemiarthroplasty with allograft-prosthesis composites were not inferior to reverse total shoulder arthroplasty when applied in properly selected patients. The authors recommended that hemiarthroplasty with allograft-prosthesis composites could be used for young age patients without glenoid metastasis involvement, and reverse total shoulder arthroplasty with allograft-prosthesis composites could be used for patients with old age or metastatic bone tumors.

Imaging Review of Normal and Abnormal Skeletal Maturation

The growing skeleton undergoes well-described and predictable normal developmental changes, which may be misinterpreted a as pathologic condition at imaging. Primary and secondary ossification centers (SOCs), which form the diaphysis and the epiphysis of long bones, respectively, are formed by endochondral and intramembranous ossification processes. During skeletal maturation, the SOCs may appear irregular and fragmented, which should not be confused with fractures, osteochondritis dissecans, and osteochondrosis. These normal irregularities are generally symmetric with a smooth, round, and sclerotic appearance, which are aspects that help in the differentiation. The metaphysis, epiphysis, and growth plates or physes are common sites of injuries and normal variants in the pediatric skeleton. The metaphysis contains the newly formed bone from endochondral ossification and is highly vascularized. It is predisposed to easy spread of infections and bone tumors. The physis is the weakest structure of the immature skeleton. Injuries to this location may disrupt endochondral ossification and lead to growth disturbances. Pathologic conditions of the epiphyses may extend into the articular surface and lead to articular damage. At MRI, small and localized foci of bone marrow changes within the epiphysis and metaphysis are also a common finding. These can be related to residual red marrow (especially in the metaphysis of long bones and hindfoot), focal periphyseal edema (associated with the process of physeal closure), and ultimately to a normal ossification process. The authors review the imaging appearance of normal skeletal maturation and discuss common maturation disorders on the basis of developmental stage and location. ^©RSNA, 2022.

An anatomical study for the location of suprascapular and spinoglenoid notches using three-dimensional computed tomography images of scapula

Background

The optimal position for creating portals for arthroscopic suprascapular nerve decompression has not been sufficiently verified. Therefore, this study aimed to investigate the anatomical characteristics of the scapula for optimal portal creation using 3-dimensional computed tomography images. The posterolateral corner of the acromion was designated as the starting point for measurements because there is no secondary ossification center present.

Methods

This study included 223 patients (females, 129; males, 94) who underwent computed tomography of the shoulder joint. Three-dimensional images of the scapula were created, and the distance from the posterolateral corner of the acromion to the suprascapular and spinoglenoid notches was measured. Additionally, the correlation coefficient with height and the differences between the female and male groups were investigated.

Results

The distances from the posterolateral corner of the acromion to the suprascapular and spinoglenoid notches were 42.9 ± 4.6 and 31.5 ± 3.6 mm, respectively, and their correlation coefficients with height were 0.12 and 0.067, respectively. There was no significant difference in the distance from the posterolateral corner of the acromion to the suprascapular (42.5 ± 4.1 vs. 43.9 ± 5.1 mm, P = .098) and to the spinoglenoid (31.4 ± 3.3 mm vs. 32.0 ± 3.9 mm, P = .12) notches between the female and male groups.

Conclusion

Regardless of height and sex, the distances from the posterolateral corner of the acromion to the suprascapular and spinoglenoid notches were approximately 43 and 32 mm, respectively. Therefore, creating portals at these locations may be effective for arthroscopic suprascapular nerve decompression.

Diagnosis and Treatment of Scapular Fractures in Children and Adolescents: A Critical Analysis Review

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Fractures of the growing scapula account for about 0.1% of all pediatric fractures, with the majority occurring at an age of ≥10 years.

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Radiographic diagnosis requires a detailed knowledge of the ossification sequence of the growing scapula. Computed tomography examination is indicated for displaced fractures of the glenoid fossa, the scapular neck, and complex fractures; magnetic resonance imaging should be performed in cases of suspected injury to the physis and with stress fractures, depending on patient age and the potential need for general anesthesia during the scanning process.

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Separation of the base of the coracoid process is often associated with acromioclavicular dislocation. Clavicular fractures rarely occur in combination with injuries to the growing scapula.

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The majority of scapular fractures can be treated nonoperatively. Indications for surgery are displaced intra-articular fractures, scapular neck fractures with a displacement of >2 cm, coracoid base separation associated with acromioclavicular dislocation, and scapulothoracic dissociation.

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Displaced intra-articular fractures of the glenoid fossa should be followed after healing until skeletal maturity. Complications are rare and occur most frequently with scapulothoracic dissociation.

Open Reduction and Internal Fixation of Pediatric Scapula Fractures: A Report of 2 Cases

CASE

Two pediatric patients with displaced, extra-articular scapula fractures who underwent surgery because of concerns for persistent deformity and decreased function with continued nonoperative management.

CONCLUSION

We advocate careful consideration of all patient factors and treatment options when addressing pediatric scapula fractures. Specific fracture patterns with altered shoulder girdle mechanics may warrant surgical intervention to restore anatomic alignment and stability.

Normal Humeral Head Ossification in Pediatric and Adolescent Shoulders Can Mimic Hill-Sachs Lesions: A Magnetic Resonance Imaging-based Study

BACKGROUND

The sequential maturation of the humeral head (HH) as viewed on magnetic resonance imaging (MRI) has not been described to date. Proper assessment may be complicated by the presence of physeal tissue in pediatric patients. Past studies suggest that skeletally immature patients may also have a higher risk of a false-positive diagnosis of Hill-Sachs lesion on MRI. The purpose of this study was to define pediatric HH developmental patterns using MRI and to investigate for any associations with findings of known false-positive Hill-Sachs.

METHODS

Picture Archiving and Communication System (PACS) records at an urban academic tertiary care musculoskeletal facility from 2014 to 2020 were queried for shoulder MRI in patients aged 0 to 15 years. Patients were excluded if they had a history of glenohumeral instability, fracture, growth arrest, brachial plexus injury, surgery, or infection. All images were independently evaluated by a musculoskeletal fellowship-trained radiologist. Each HH was staged based on skeletal maturity.

RESULTS

For both sexes, HHs matured in a predictable manner with increasing chronological age associated with a higher ossification stage. False Hill-Sachs lesions were observed in girls aged 4 to 7 and boys aged 5 to 14, exclusively during stage I to II ossification.

CONCLUSIONS

False Hill-Sachs lesions were visualized on MRI in stage I to II proximal humerus ossification. Due to differential timing of skeletal maturation, males present with false Hill-Sachs lesions at a later age than females on average. When interpreting shoulder MRI for glenohumeral instability, clinicians should be cautious of false Hill-Sachs lesions, especially in younger patients with distinct greater tuberosity and HH ossification centers (stage I to II ossification).

LEVEL OF EVIDENCE

Level III.

Association of the Posterior Acromion Extension with Glenoid Retroversion: A CT Study in Normal and Osteoarthritic Shoulders

Posterior eccentric glenoid wear is associated with higher complication rates after shoulder arthroplasty. The recently reported association between the acromion shape and glenoid retroversion in both normal and osteoarthritic shoulders remains controversial. The three-dimensional coordinates of the angulus acromialis (AA) and acromioclavicular joint were examined in the scapular coordinate system. Four acromion angles were defined from these two acromion landmarks: the acromion posterior angle (APA), acromion tilt angle (ATA), acromion length angle (ALA), and acromion axial tilt angle (AXA). Shoulder computed tomography scans of 112 normal scapulae and 125 patients with primary glenohumeral osteoarthritis were analyzed with simple and stepwise multiple linear regressions between all morphological acromion parameters and glenoid retroversion. In normal scapulae, the glenoid retroversion angle was most strongly correlated with the posterior extension of the AA (R² = 0.48, p < 0.0001), which can be conveniently characterized by the APA. Combining the APA with the ALA and ATA helped slightly improve the correlation (R² = 0.55, p < 0.0001), but adding the AXA did not. In osteoarthritic scapulae, a critical APA > 15 degrees was found to best identify glenoids with a critical retroversion angle > 8 degrees. The APA is more strongly associated with the glenoid retroversion angle in normal than primary osteoarthritic scapulae.

Proximal Humerus Fractures in the Pediatric Population

PURPOSE OF REVIEW

The purpose of this review is to review recent literature focusing on proximal humerus anatomy, epidemiology of these fractures, diagnosis and treatment options, and clinical outcomes.

RECENT FINDINGS

Non- or minimally displaced proximal humerus fractures treated nonoperatively do not lead to short- or long-term complication and do not cross over to operative treatment. There is a higher rate of operative management with older age, increased injury severity score, treatment at an adult hospital, and private insurance. Operative management is preferred with closed or open reduction and percutaneous pinning, but elastic nailing and plate fixation are other options with good postoperative outcomes. Pediatric proximal humerus fractures occur after fall onto the affected shoulder or arm. Diagnosis is usually made with radiographs. Understanding the proximal humerus anatomy is critical to the proper management of these injuries to aid reduction and predict remodeling potential. There is considerable debate around the management of proximal humerus fractures in the pediatric population. Treatment is based on patient age, fracture displacement, and remodeling capacity. Nonoperative management is successful in younger patients or less displaced fractures, and operative management is usually considered in older patients with more displaced fractures.

REPRODUCIBILITY OF THE CLASSIFICATION OF PROXIMAL HUMERAL OSSIFICATION IN IDIOPATHIC SCOLIOSIS

ABSTRACT Objective To evaluate the intra- and interobserver reproducibility of the classification of proximal humeral ossification in patients with idiopathic scoliosis. Methods Observational, descriptive, cross-sectional study. Radiographs (anteroposterior) of 29 patients diagnosed with idiopathic scoliosis were chosen and investigated at the Spine Surgery Outpatient Clinic of the Department of Orthopedics and Traumatology of the Hospital Getúlio Vargas, Recife, Pernambuco. These radiographs were evaluated and classified by 9 spinal orthopedic surgeons at two moments, with a minimum interval of 30 days, for analysis of the intraobserver and interobserver reproducibility of the classification of proximal humeral ossification used as a predictor of peak growth velocity. Results Intraobserver reproducibility achieved moderate to substantial concordance with the kappa index. In the analysis of interobserver reproducibility using the Fleiss’ kappa method, a reasonable to moderate concordance was observed, except for in stage 5, in which concordance ranged from substantial to almost perfect. Conclusion In this study, the reproducibility of the Li classification in most of the stages was reasonable to moderate for the interobserver assessment and moderate to substantial for the intraobserver assessment, which differs from the current literature. Level of evidence III; Diagnostic studies – Investigation of a diagnostic test.

Humeral lesser tuberosity avulsion fractures - magnetic resonance imaging characteristics in the pediatric population

BACKGROUND

Avulsion fractures of the humeral lesser tuberosity are rare injuries in skeletally immature patients and can pose a diagnostic challenge that often leads to delayed identification.

OBJECTIVE

To describe the demographics, mechanism of injury and magnetic resonance imaging (MRI) findings of lesser tuberosity avulsion fractures in children.

MATERIALS AND METHODS

A retrospective search of children with lesser tuberosity avulsion fractures on MRI was done. Available radiographs were evaluated. Demographics, mechanism of injury, MRI characteristics and treatment were recorded.

RESULTS

Thirteen children, all male, were included (median age: 13.8 years, range: 12.5-16.8 years). The most common mechanism was blunt, overhead or hyperextension traumatic injury related to sports. All patients were skeletally immature and 10/13 demonstrated isolated avulsion fractures at the footprint. Only one patient had associated osteochondral injury to the humeral head and labral tear. Two children demonstrated medial dislocation/subluxation of the biceps tendon. The median size of the avulsed fragment was 15 mm (range: 5-29 mm), median anteroposterior displacement was 3 mm (range: 0-6 mm) and medial displacement was 1 mm (range: 0-20 mm). There was no correlation between age and the size of the avulsed fragment (P=0.29). Common injury patterns were complete avulsion of the subscapularis footprint (6/13) and partial avulsion of inferior footprint (6/13). Two-thirds of the radiographs were initially reported as normal, but retrospectively showed two missed fractures. One of the initial radiographs raised concern for bone tumor. The best view for identifying an avulsion fragment was the axillary view. Seven patients of the 13 patients underwent internal fixation.

CONCLUSION

Avulsion fractures of the lesser tuberosity are rare, challenging to diagnose and often radiographically occult. MRI can identify the injury at the subscapularis tendon footprint with variable size and displacement. The long head of the biceps tendon is usually normal in location. Although this entity is rare, radiologists should be aware of it to allow for correct and prompt diagnosis and prevent unnecessary biopsy or contrast administration.

Pediatric Musculoskeletal Trauma: Upper Limb

Pediatric upper extremity injuries, acute and chronic due to overuse, are commonly encountered in the clinical setting. However, interpretation of imaging studies is often challenging in pediatric patients because of changing postnatal skeletal development and the broad spectrum of pathology that can potentially occur. This article discusses normal skeletal development and the pathomechanics of skeletal injuries in pediatric patients. It also outlines a framework for imaging as it pertains to the pediatric upper extremity, with specific emphasis on acute and chronic injuries to the shoulder, elbow, forearm, and wrist.

Effect of Younger Starting Pitching Age on Humeral Retrotorsion in Baseball Pitchers With an Ulnar Collateral Ligament Injury

BACKGROUND

Increased humeral retrotorsion (HRT) has been found to be a risk factor for ulnar collateral ligament (UCL) tears in baseball players. Recent work has demonstrated the age of 11 years as a potential watershed age for HRT development.

HYPOTHESIS

In a group of baseball pitchers with UCL injuries, athletes who started pitching before the age of 10 years will demonstrate significantly more dominant limb humeral retrotorsion (DHRT) when compared with a group of baseball pitchers who reported starting pitching at 10 years or older.

STUDY DESIGN

Cohort study; Level of evidence, 3.

METHODS

A total of 84 baseball pitchers with a diagnosed UCL injury were divided into 2 groups based upon the age at which participants began pitching: 33 players reporting a starting pitching age of 10 years or older (group 1) were compared with 51 baseball pitchers reporting a starting pitching age under 10 years (group 2). Participants' DHRT and nondominant limb humeral retrotorsion (NDHRT) were measured using diagnostic ultrasound. Independent t tests were run to compare mean group differences of all patient data, starting pitching age, age at time of injury, DHRT, NDHRT, and humeral retrotorsion difference (HRTdiff).

RESULTS

There were no significant differences between groups with regard to age at time of injury, height, weight, or playing years' experience. There was a statistically significant difference in the participant-reported starting pitching age. Significant differences between groups were noted for DHRT (group 1: 20.0°± 9.4°, group 2: 14.5°± 10.3°, P = .015) and for NDHRT (group 1: 38.6°± 8.8°, group 2: 32.9°± 9.5°, P = .007). No significant differences between groups were found for HRTdiff (P = .940).

CONCLUSION

Baseball pitchers with a UCL injury who reported a starting pitching age younger than 10 years demonstrated significantly greater DHRT and NDHRT when compared with UCL-injured baseball pitchers who reported a starting pitching age at 10 years or later. The results of this study demonstrate that a younger starting pitching age results in increased HRT in players with UCL injuries.

Contemporary imaging of the pediatric shoulder: pearls and pitfalls

In skeletally immature patients, the presence of growth plates and articular cartilage of the shoulder can create a predisposition for unique injuries not observed in adults. Furthermore, increasing participation in sports by children and adolescents appears to be leading to a corresponding increase in the number of sports-related injuries. The importance of radiologists being familiar with pediatric shoulder imaging and its associated injuries is therefore growing. In this article, we review the normal development and maturation pattern of ossification centers of the shoulder from the early gestational period through adolescence. Brachial plexus birth palsy, physeal injuries, shoulder dislocation, and internal impingement are discussed within the context of the child's age and the mechanism of injury to guide radiologists to a correct diagnosis.

Physeal Injuries of the Coracoid Process Are Closely Associated With Sports Activities: A Systematic Review

Background:

Physeal injuries of the coracoid process are rare but may be increasing because of increased participation of youth in year-round sports.

Purpose:

To analyze reported physeal and apophyseal injuries of the coracoid process.

Study Design:

Systematic review; Level of evidence, 4.

Methods:

PubMed and Scopus were searched using the terms scapula fracture and coracoid fracture. The inclusion criteria were English full-text articles describing coracoid fracture as well as articles that described patient characteristics and presented appropriate images. The exclusion criteria were descriptive cases without images as well as those lacking appropriate images. Citation tracking was conducted to find additional articles and full-text articles written in other languages. Articles were included if they reported physeal injury or judged to involve physeal injury based on the provided images.

Results:

Overall, 22 studies including 32 patients (29 males, 3 females) were identified. All but 2 patients were younger than 18 years of age, and 66% (21/32) had sustained injuries during or as a result of participation in sporting activities. The affected site was the physis at the base in 18 patients, an intra-articular fracture in the primary coracoid ossification center combined with the subcoracoid ossification center to form an intra-articular fracture in 5, the apophysis of the tip in 3, the apophysis of the angle in 5, and uncertain in 1. Eleven patients had concurrent acromioclavicular injuries. The injury was acute in 23 patients, chronic in 6, and traumatic nonunion in 3. Among 21 cases in which treatment methods and outcomes were described, 21% of the acute cases (4/19), and 2 of the 3 nonunions were surgically treated. Only 1 study used a widely accepted evaluation method. Follow-up periods ranged from 6 weeks to 2 years. Outcomes were generally excellent for nonoperative and operative treatment and without any serious complications.

Conclusion:

Coracoid physeal injuries occurred most commonly in patients aged 13 to 15 years of age (71%) and were usually sustained during or as a result of sports activities (66%). The most common injury site was the physis at its base. The cause of these injuries is probably severe or repeated traction of the attached muscles and ligaments. The majority of these injuries can be successfully treated nonoperatively.

Evaluation of proximal humeral epiphysis ossification in 3.0 T MR images according to the Dedouit staging method: Is it be used for age of majority?

Magnetic resonance imaging (MRI) for forensic age estimation is among the research issues since it does not lead to radiation exposure. In this study, the ossification stage of the proximal humeral epiphysis was determined retrospectively in 178 male and 109 female individuals in the 12 to 30-year age group using 3.0 T MRI. All images were evaluated with the proton density fat saturated turbo spin echo (PD TSE FS) sequence and the T2 TSE FS sequence. A five-stage scoring system was used following the method of Dedouit et al. The relevant statistics were defined as minimum, maximum, mean ± standard deviation, 95% confidence interval of mean and median and the intra- and interobserver agreement levels were very good (κ > 0.80). There were no significant age differences between males and females in any of the stages (all p-values>0.05). According to the present study, stage 5 was initially observed at age 22 years for both genders. According to our results, it is possible to determine the completion of the 18th year of life in either gender on the shoulder joint. Proximal humeral epiphysis ossification may be used as an additional method for forensic age estimation through MRI.

Pitfalls in MRI of the Developing Pediatric Ankle

Normal skeletal development in the pediatric ankle is dynamic and often produces variable imaging appearances that are subject to misinterpretation. Radiologists must understand the underlying developmental phenomena, such as endochondral and membranous ossification and physeal fusion, and be familiar with their common and uncommon imaging manifestations unique to the pediatric ankle. This is especially true as the use of MRI in the evaluation of musculoskeletal trauma expands among younger populations. The authors focus on MRI evaluation of the skeletally maturing pediatric ankle and present pearls for accurately distinguishing normal findings and imaging pitfalls from true pathologic findings. The normal but often variable imaging findings of preossification, secondary ossification, and multiple ossification centers, as well as the range of bone marrow signal intensities that can be visualized within ossification centers, are described, along with tips to help differentiate these from true pathologic findings such as contusion, fracture, or tumor. The authors also review dynamic periosteal and physeal contributions to bone growth to highlight helpful distinguishing features and avoid misdiagnosis of common subperiosteal and periphyseal abnormalities. For example, the normal trilaminar appearance of the immature cortex and periosteum should not be mistaken for periosteal reaction, traumatic stripping, or subperiosteal hematoma. In addition, the physis can have several confusing but normal appearances, including normal physeal undulations (eg, Kump bump) or focal periphyseal edema, which should not be mistaken for pathologic findings such as physeal fracture, infection, or bar. ^©RSNA, 2020.

Imaging of the Acromioclavicular Joint: Anatomy, Function, Pathologic Features, and Treatment

The acromioclavicular joint is an important component of the shoulder girdle; it links the axial skeleton with the upper limb. This joint, a planar diarthrodial articulation between the clavicle and the acromion, contains a meniscus-like fibrous disk that is prone to degeneration. The acromioclavicular capsule and ligaments stabilize the joint in the horizontal direction, while the coracoclavicular ligament complex provides vertical stability. Dynamic stability is afforded by the deltoid and trapezius muscles during clavicular and scapular motion. The acromioclavicular joint is susceptible to a broad spectrum of pathologic entities, traumatic and degenerative disorders being the most common. Acromioclavicular joint injury typically affects young adult males and can be categorized by using the Rockwood classification system as one of six types on the basis of the direction and degree of osseous displacement seen on conventional radiographs. MRI enables the radiologist to more accurately assess the regional soft-tissue structures in the setting of high-grade acromioclavicular separation, helping to guide the surgeon's selection of the appropriate management. Involvement of the acromioclavicular joint and its stabilizing ligaments is also important for understanding and classifying distal clavicle fractures. Other pathologic processes encountered at this joint include degenerative disorders; overuse syndromes; and, less commonly, inflammatory arthritides, infection, metabolic disorders, and developmental malformations. Treatment options for acromioclavicular dysfunction include conservative measures, resection arthroplasty for recalcitrant symptoms, and surgical reconstruction techniques for stabilization after major trauma.

Clinical and radiographic outcomes of the open Latarjet procedure in skeletally immature patients

INTRODUCTION

Recurrent anterior glenohumeral instability has been studied in the young population and limited evidence is available for adolescent patients. Our study is a retrospective review of patients aged <17 years who underwent open Latarjet procedure.

METHODS

Forty-five patients were available for review. Clinical outcomes were assessed by range of movements, stability, Walch-Duplay score (WDS), Rowe score (RS), Constant-Murley score (CMS), Subjective Shoulder Value (SSV), and return to sport. Radiographs were reviewed for osteoarthritis and complications.

RESULTS

The median age of patients was 15.7 years (13-17), and 56% had hyperlaxity. The median follow-up time was 6.6 years (3-26). The median postoperative movements showed recovered elevation (175°), external rotation (60°), and internal rotation (T9 level). Seventy-five percent of patients returned to the same level of sport, and 98% were satisfied. Clinical outcomes showed WDS, RS, and CMS scores of 85, 95, and 84 points, respectively, and an SSV of 95%. Twenty percent of patients described mild postoperative pain, and 1 had persistent stiffness. Other complications included 24% subjective apprehension, 4% redislocation, 4% wound problems, and 2% infection. Nine percent of cases had postoperative arthritis. The overall reoperation rate was 11%: 1 open washout for infection and 4 arthroscopic screw removal due to persistent pain. We found that hyperlaxity, female sex, and large or deep Hill-Sachs lesions were frequently associated with persistent apprehension at the last follow-up.

CONCLUSIONS

The open Latarjet procedure provides a low rate of recurrent instability with acceptable complication rates in the long term for skeletally immature patients. It is an effective, safe treatment option without any significant glenoid growth disturbance.

Influence of coracoid anatomy on the location of glenoid rim defects in anterior shoulder instability: 3D CT-scan evaluation of 51 patients

PURPOSE

Glenoid bony lesions play a role in approximately half of anterior shoulder instability cases. The purpose of this study is to see if the anatomy of the coracoid affects the location of glenoid rim defects. We hypothesized that a prominent coracoid (lower and lateral) would be more likely to cause an anterior-inferior glenoid lesion, and a less prominent coracoid more prone to cause an anterior lesion. The null hypothesis being the absence of correlation.

METHODS

Fifty-one shoulder CT-scans from a prospective database, with 3D reconstruction, were analyzed. The position of glenoid lesions was identified using the validated clock method, identifying the beginning and end time. The size of bony glenoid defects was calculated using the validated glenoid ratio method. The position of the coracoid tip was measured in three orthogonal planes.

RESULTS

Analysis included 25 right shoulders and 26 left shoulders in seven females and 41 males. The vertical position of the coracoid tip relative to the top of the glenoid was highly correlated to the location of the glenoid defect on the profile view (r = -0.625; 95% CI 0.423-0.768; p = 0.001). Thus, higher coracoids were associated with anterior lesions, while lower coracoids were associated with anterior-inferior lesions. A more laterally prominent coracoid was also correlated with anterior-inferior lesions (r = 0.433; 95% CI 0.179-0.633; p = 0.002).

CONCLUSION

This study shows that coracoid anatomy affects the location of bony Bankart defects in anterior shoulder instability. Lower and laterally prominent coracoids are associated with anterior-inferior lesions. This variation in anatomy should be considered during pre-op planning for surgeries involving bone graft.

LEVEL OF EVIDENCE

Level 4 basic science.

Os acromiale: systematic review of surgical outcomes

BACKGROUND

The literature is unclear as to the optimal surgical management of a symptomatic os acromiale that has failed nonoperative treatment. Surgical options include excision, acromioplasty, and open reduction and internal fixation. The purpose of this study is to summarize the described methods and compare their reported outcomes with the goal to provide direction on how to surgically manage os acromiale.

METHODS

We performed a systematic review of the current medical literature. Fifteen studies met all the inclusion criteria. Two hundred eleven total subjects (220 shoulders) underwent surgical treatment for a symptomatic os acromiale. There were 140 men and 71 women with a mean age of 49.6 ± 9.1 years. The mean follow-up duration was 40 ± 11.6 months. Surgical techniques used in the included studies were excision, acromioplasty, and open reduction with internal fixation. Concurrent surgical procedures performed were also included.

RESULTS

Meso-os acromiale was the most common type (167 cases, 94.4%). The most common surgical technique was internal fixation (135 cases, 60.8%), with screw fixation being the majority (76 cases, 56.3%). Excision (65 cases, 29.3%) was the second most used technique. The most common concurrent surgical procedure performed was rotator cuff repair (125 cases, 56.3%), followed by distal clavicle excision (31 cases, 14%).

CONCLUSIONS

All surgical techniques employed resulted in improvement in postsurgical clinical outcomes without any technique demonstrating superior results. Operative management of a symptomatic os acromiale that has failed initial nonoperative treatment leads to decreased symptoms and improvement in clinical outcomes.

Normal Glenoid Ossification in Pediatric and Adolescent Shoulders Mimics Bankart Lesions: A Magnetic Resonance Imaging-Based Study

PURPOSE

The purpose of this descriptive study was to define patterns of ossification and fusion of growth centers around the pediatric and adolescent glenoid as a function of age using 3-dimensional, frequency-selective, fat-suppressed spoiled gradient recalled echo magnetic resonance (MR) imaging sequences, with a particular focus on the anterior glenoid rim because of its clinical relevance as a potential confounder of glenohumeral instability.

METHODS

Picture Archiving and Communication System records at an urban academic tertiary care orthopaedic facility from October 2005 to December 2018 were queried for shoulder MRI in patients aged 9 to 17 years. Patients were excluded if they had any diagnoses that could alter glenoid development. All images were independently evaluated by a musculoskeletal fellowship-trained radiologist. Secondary ossification centers were characterized as cartilage anlage, ossified, or fused at 3 anatomic sites: the anterior glenoid rim, coracoid, and superior glenoid rim.

RESULTS

A total of 250 MR examinations (143 males, 107 females) were assessed in this study. The glenoid develops in a predictably sequential manner with ossification at the anterior glenoid rim lagging behind the coracoid and superior glenoid rim. The earliest age of anterior glenoid rim ossification was 11 years for both males (range 11-17) and females (range 11-12). Anterior glenoid rim ossification peaked at age 16 among males (34.8%, 8/23) and age 11 among females (27.3%, 3/11).

CONCLUSIONS

Glenoid ossification and fusion progress in a predictable and chronological manner. This pattern should be used as a guideline when interpreting pediatric shoulder MRI examinations. In particular, an anterior glenoid ossification center should not be confused with an anterior glenoid injury (e.g., Bankart lesion), particularly in males 11 to 17 years old and females 11 to 12 years old.

LEVEL OF EVIDENCE

IV (case series).

Normal development imaging pitfalls and injuries in the pediatric shoulder

The skeletal maturation of the shoulder has been well documented on radiographic and cadaveric studies. Recent increased use of MRI has provided increased understanding of the soft-tissue and osseous changes that occur during development. Thus recognizing normal maturation, imaging manifestations and pitfalls is crucial when evaluating the pediatric shoulder joint. At birth, the humeral diaphysis, midportion of the clavicle, and the body of the scapula are ossified, while the remainder of the bones of the shoulder are composed of non-ossified cartilaginous precursors. During growth, cartilaginous apophyses and epiphyses of the shoulder develop numerous secondary ossification centers, which fuse with the primary ossification centers to form the complete bony components of the shoulder. Additionally changes in the morphology of the growth plates as well as marrow signal occur in an organized manner. This paper affords the reader with an understanding of the normal development of three major components of skeletal maturation in the shoulder: ossification centers, growth plates and marrow signal. These topics are further subdivided into the glenoid, proximal humerus and acromioclavicular joint. We also provide a focus on distinguishing normal anatomy from imaging pitfalls related to skeletal maturation.

Tissue-specific changes in size and shape of the ligaments and tendons of the porcine knee during post-natal growth

Prior studies have analyzed growth of musculoskeletal tissues between species or across body segments; however, little research has assessed the differences in similar tissues within a single joint. Here we studied changes in the length and cross-sectional area of four ligaments and tendons, (anterior cruciate ligament, patellar tendon, medial collateral ligament, lateral collateral ligament) in the tibiofemoral joint of female Yorkshire pigs through high-field magnetic resonance imaging throughout growth. Tissue lengths increased by 4- to 5-fold from birth to late adolescence across the tissues while tissue cross-sectional area increased by 10–20-fold. The anterior cruciate ligament and lateral collateral ligament showed allometric growth favoring change in length over change in cross-sectional area while the patellar tendon and medial collateral ligament grow in an isometric manner. Additionally, changes in the length and cross-sectional area of the anterior cruciate ligament did not increase as much as in the other ligaments and tendon of interest. Overall, these findings suggest that musculoskeletal soft tissue morphometry can vary within tissues of similar structure and within a single joint during post-natal growth.

Pitfalls in Pediatric Trauma and Microtrauma

Fractures are common in children, although accurate diagnosis is confounded by mimics of fractures some of which are unique to the pediatric population. Such fracture mimics include developmental variations of the growth plates, normal anatomic structures that simulate fracture lines, and/or metabolic disorders that alter the pattern of ossification. Although subtle clues on plain radiographs may help to discriminate between a true fracture or injury and a fracture mimic, MR imaging may be helpful to eliminate uncertainty or expedite diagnosis.

Os Acromiale: Reviews and Current Perspectives

Os acromiale is a developmental defect which results from the lack of an osseous union between the ossification centers of the acromion, leading to the fibrocartilaginous tissue connection. The prevalence of os acromiale is 1% to 15%, and is quite common in the African American population. Os acromiale in adults is easily diagnosed by symptoms and X-ray, particularly on the axillary view; however, the differential diagnosis of adolescents may require MRI or SPECT-CT. Generally, nonoperative therapy for symptomatic os acromiale should be started, including physiotherapy, nonsteroidal anti-inflammatory drugs, and injections. Surgical treatment is indicated after failed conservative treatment. In symptomatic patients with fixable acromiale, the tension band technique should be used to make the anterior aspect of the acromion elevated from the humerus head. In patients with small fragments which are unsuitable for reattachment, excision might be the best therapeutic option and lead to good outcomes. Whether using internal fixation or resection, the arthroscopic technique results in a better outcome and fewer complications, especially in older patients or athletes with overhead movement, because of the high incidence of shoulder impingement or rotator cuff tears which can be treated concurrently.

Non-metric traits and anatomical variants that can mimic trauma in the human skeleton

This paper presents some of the more commonly encountered non-metric traits and minor anatomical variants in the adult human skeleton that can mimic or be mistaken for trauma. Distinguishing non-metric traits is contingent upon both a knowledge of potential non-metric traits as well as the normal developmental timing, location, and anatomy of maturational markers in the human skeleton. Distinguishing non-metric traits from trauma in dry bone is an essential component in establishing an accurate and thorough forensic analysis of human remains, especially as it deals with antemortem and perimortem trauma, and postmortem damage.

Management of symptomatic os acromiale: a survey of the American shoulder and elbow surgeons

BACKGROUND

The purpose of this paper was to survey members of the American Shoulder and Elbow Surgeons (ASES) to assess their opinion on management options, help highlight important clinical factors, and elucidate surgical preferences for the treatment of a symptomatic meso-os.

METHODS

An online questionnaire was distributed to the active members of the ASES. The survey queried surgeon demographics and perioperative management preferences, and presented multiple clinical case scenarios of patients with a presumed symptomatic, unstable os acromiale.

RESULTS

There were 116 ASES members who responded to the survey, and 26% (n = 30) who stated they do not operatively manage a symptomatic os. We identified two main clusters of respondents. Cluster 1 (n = 67) (as compared to cluster 2, n = 19) was comprised of surgeons with significantly more experience treating a symptomatic os acromiale (p < 0.05). These surgeons regarded gender, age, BMI, and hand dominance as important clinical factors when deciding when to proceed to surgery. Overall, arthroscopic management of the os was preferred, but those surgeons more experienced in treating os acromiale preferred open reduction and internal fixation (ORIF) in specific clinical cases.

CONCLUSION

The survey findings reflect the current lack of consensus in the treatment of a unstable, symptomatic os acromiale. Overall, arthroscopic management was preferred by most surgeons, though ORIF was preferred in certain clinical scenarios by those more experienced with os acromiale. The overall preference for arthroscopy suggests a possible shift in the treatment paradigm for patients with symptomatic meso-acromions, but higher level studies are needed to substantiate these findings.

Symptomatic, Unstable Os Acromiale

Management of a persistently symptomatic, unstable os acromiale remains controversial. An unstable os acromiale is an easy diagnosis to miss and should be specifically evaluated for in patients with shoulder pain and a high degree of clinical suspicion. Surgical options include open or arthroscopic excision and open reduction and internal fixation. Open excision of large fragments has had poor results. Arthroscopic treatment is commonly used for small fragments (preacromion), and the technique has also been used in larger fragments (meso-os), but concerns persist over postoperative weakness secondary to shortening of the deltoid lever arm. Open reduction and internal fixation through a transacromial approach has been shown to have predictable union rates but can be complicated by symptomatic implant. Recent biomechanical studies have expanded our understanding of optimal fixation constructs, which may also decrease implant-related issues. Ultimately, the choice of which procedure to use will be dictated by patient factors such as age, activity level, and the nature of rotator cuff pathology. LEVEL OF EVIDENCE:: Level V.

Forensic age diagnostics by magnetic resonance imaging of the proximal humeral epiphysis

The most commonly used radiological method for age estimation of living individuals is X-ray. Computed tomography is not commonly used due to high radiation exposure, which raises ethical concerns. This problem can be solved with the use of magnetic resonance imaging (MRI), which avoids the use of ionizing radiation. The purpose of the present study was to evaluate the utility of MRI analysis of the proximal humeral epiphyses for forensic age estimations of living individuals. In this study, 395 left proximal humeral epiphyses (patient age 12-30 years) were evaluated with fast-spin-echo proton density-weighted image (FSE PD) sequences in a coronal oblique orientation on shoulder MRI images. A five-stage scoring system was used following the method of Dedouit et al. The intra- and interobserver reliabilities assessed using Cohen's kappa statistic were κ = 0.818 and κ = 0.798, respectively. According to this study, stage five first appeared at 20 and 21 years of age in males and females, respectively. These results are not directly comparable to any other published study due to the lack of MRI data on proximal humeral head development. These findings may provide valuable information for legally important age thresholds using shoulder MRI. The current study demonstrates that MRI of the proximal humerus can support forensic age estimation. Further research is needed to establish a standardized protocol that can be applied worldwide.

The embryonic and evolutionary boundaries between notochord and cartilage: a new look at nucleus pulposus-specific markers

The adult nucleus pulposus (NP) and articular cartilage are similar in terms of their histocytological components and biomechanical functionalities, requiring a deep understanding of NP-specific markers to better evaluate stem-cell-based NP regeneration. Here, we seek to distinguish NP cells from articular chondrocytes (ACs), focusing on differences in their embryonic formation and evolutionary origin. Embryonically, NP cells are conservatively derived from the axial notochord, whereas ACs originate in a diversified manner from paraxial mesoderm and neural crest cells. Evolutionarily, although the origins of vertebrate NP and AC cells can be traced to similar structures within protostomia-like bilaterian ancestors, the distant phylogenetic relationship between the two groups of animals and the differences in the bodily origins of the tissues suggest that the tissues may in fact have undergone parallel evolution within the protostomia and deuterostomia. The numbers of supposedly NP-specific markers are increasing gradually as microarray studies proceed, but no final consensus has been attained on the specificity and physiology of "exclusive" NP markers because of innate variations among species; intrinsic expression of genes that destabilize the circadian clock; and cooperation by, and crosstalk among, different genes in terms of physiology-related phenotypes. We highlight the embryonic and evolutionary boundaries between NP and AC cells, to aid in recognition of the challenges associated with evaluation of the role played by nucleopulpogenic differentiation during stem-cell-based intervertebral disc regeneration.

Recurrence After Arthroscopic Labral Repair for Traumatic Anterior Instability in Adolescent Rugby and Contact Athletes

BACKGROUND

Traumatic glenohumeral dislocation of the shoulder is one of the most common shoulder injuries, especially among adolescent athletes. The treatment of instability for young athletes continues to be controversial owing to high recurrence rates.

PURPOSE

To investigate the recurrence rate of shoulder instability after arthroscopic capsulolabral repair for adolescent contact and collision athletes.

STUDY DESIGN

Case series; Level of evidence, 4.

METHODS

Sixty-seven patients aged <18 years underwent an arthroscopic labral repair over a 5-year period. The mean ± SD age of the cohort was 16.3 ± 0.9 years (range, 14-17 years) and consisted of 1 female and 66 males. All patients were contact athletes, with 62 of 67 playing rugby. Demographic, clinical, and intraoperative data for all patients with shoulder instability were recorded in our database. Recurrence rates were recorded and relative risks calculated.

RESULTS

At a follow-up of 33 ± 20 months, 34 of 67 patients had recurrent instability for an overall recurrence rate of 51% among adolescent contact athletes after arthroscopic labral repair surgery. The mean time to recurrence was 68.1 ± 45.3 weeks. All recurrences occurred as a result of a further sporting injury. Relative risk analysis demonstrated that athletes aged <16 years had 2.2 (95% CI, 1.2-2.1) times the risk of developing a further instability episode as compared with athletes aged ≥16 years at the time of index surgery ( P = .0002). The recurrence rate among adolescent athletes after bony Bankart repairs was 57.9% versus 47.9% for soft tissue labral repairs ( P = .4698). The incidence of Hill-Sachs lesions ( P = .0002) and bony Bankart lesions ( P = .009) among adolescent athletes was significantly higher than among adult controls ( P = .002). The presence of bone loss did not lead to a significant increase in recurrence rate over and above the effect of age.

CONCLUSION

Adolescent contact athletes undergoing arthroscopic labral repair have an overall recurrence rate of 51%. Rugby players who undergo primary arthroscopic shoulder stabilization aged <16 years have 2.2 times the risk of developing a further instability episode when compared with athletes aged ≥16 years at the time of index surgery, with a recurrence rate of 93%.

Applicability of T1-weighted MRI in the assessment of forensic age based on the epiphyseal closure of the humeral head

This work investigates the value of magnetic resonance imaging analysis of proximal epiphyseal fusion in research examining the growth and development of the humerus and its potential utility in establishing forensic age estimation. In this study, 428 proximal humeral epiphyses (patient age, 12-30 years) were evaluated with T1-weighted turbo spin echo (T1 TSE) sequences in coronal oblique orientation on shoulder MRI images. A scoring system was created following a combination of the Schmeling and Kellinghaus methods. Spearman's rank correlation analysis revealed a significant positive relationship between age and ossification stage of the proximal humeral epiphysis (all subjects: rho = 0.664, p < 0.001; males: 0.631, p < 0.001; females: rho = 0.651, p < 0.001). The intra- and inter-observer reliability assessed using Cohen's kappa statistic was κ = 0.898 and κ = 0.828, respectively. The earliest age of epiphysis closure was 17 years for females and 18 years for males. MRI of the proximal humeral epiphysis can be considered advantageous for forensic age estimation of living individuals in a variety of situations, ranging from monitoring public health to estimating the age of illegal immigrants/asylum seekers, minors engaged in criminal activities, and illegal participants in competitive sports, without the danger of radiation exposure.

Imaging features of glenoid bare spot in a pediatric population

OBJECTIVE

The bare spot (BaS) is a central, well-circumscribed focal defect in the glenoid articular surface, with reported adult incidence of 1-2%. We aimed to reassess MRI features of BaS in the pediatric population and determine its etiology.

MATERIALS AND METHODS

A retrospective search of our database from June 2014 to October 2015 was performed for shoulder MRI in patients between 5 and 25 years and then subdivided into four groups: group 1, 5-10 years; group 2, 10-15 years; group 3, 15-18 years; group 4, 20-25 years. BaS was defined as a well-marginated, central defect of increased signal in the articular surface of the glenoid, seen on at least two planes, without evidence of underlying glenoid pathology. Presence, location and size along with clinical indications were documented.

RESULTS

A final cohort of 253 patients revealed 23 BaS, 3.5% in group 1, 20% in group 2, 5% in group 3 and 4% in group 4. There was a significantly higher incidence in group 2 (p = 0.007) compared to group 3 and p = 0.002 compared to group 4. Location was mainly central. Mean size was significantly bigger in group 2 compared to group 3 and 4. Distribution showed the highest number at 14-15 years of age. Instability was higher in groups 3 and 4.

CONCLUSION

Incidence of BaS in group 2 was significantly higher than in other age groups and higher than in adults. BaS was also larger compared to other populations. These findings support a developmental theory, explained by the centripetal ossification of the glenoid.