Maturation-dependent findings in the shoulders of pediatric baseball players on magnetic resonance imaging.

PURPOSE: To compare the prevalence and characteristics of shoulder osseous and soft tissue findings on magnetic resonance imaging (MRI) with respect to skeletal maturation in symptomatic pediatric baseball players without a history of acute trauma. METHODS: The IRB-approved, HIPAA-compliant retrospective study analyzed 87 consecutive pediatric baseball players (86 boys and 1 girl; mean age, 15.4 ± 2.1 years) with shoulder MRI performed between March 1, 2012 and September 30, 2017. In consensus, two radiologists assessed the MRI studies for findings involving the humerus, the glenoid, the labrum, the rotator cuff, and the acromioclavicular joint. Exact Cochran-Armitage trend and Mantel-Haenszel Chi-square tests were used to investigate the association between these findings and skeletal maturation. RESULTS: The mean ages between players who are skeletally immature (37 shoulders), maturing (26 shoulders), and matured (24 shoulders) were significantly different (p < 0.001). Bone marrow edema (p < 0.001) and sclerosis (p < 0.001) within the proximal humeral metaphysis decreased with skeletal maturation. Glenoid remodeling (p = 0.038) was more severe in the skeletally immature players and the prevalence of Bennett lesions (p = 0.048) increased with skeletal maturation. The prevalence of labral tears, rotator cuff tendinosis, and acromioclavicular joint separation did not significantly change with skeletal maturation. CONCLUSIONS: The change in the prevalence of findings within the proximal humerus and glenoid with skeletal maturation suggest differences in the distribution of stress within the shoulders of pediatric baseball players during development.

Normal Skeletal Maturation and Imaging Pitfalls in the Pediatric Shoulder.

A growing number of magnetic resonance (MR) imaging studies of the shoulder are being performed as a result of greater and earlier participation of children and adolescents in competitive sports such as softball and baseball. However, scant information is available regarding the MR imaging features of the normal sequential development of the shoulder. The authors discuss the radiographic and MR imaging appearances of the normal musculoskeletal maturation patterns of the shoulder, with emphasis on (a) development of secondary ossification centers of the glenoid (including the subcoracoid and peripheral glenoid ossification centers); (b) development of preossification and secondary ossification centers of the humeral head and the variable appearance and number of the secondary ossification centers of the distal acromion, with emphasis on the formation of the os acromiale; (c) development of the growth plates, glenoid bone plates, glenoid bare area, and proximal humeral metaphyseal stripe; and (d) marrow signal alterations in the distal humerus, acromion, and clavicle. In addition, the authors discuss various imaging interpretation pitfalls inherent to the normal skeletal maturation of the shoulder, examining clues that may help distinguish normal development from true disease (eg, osteochondral lesions, labral tears, abscesses, fractures, infection, tendon disease, acromioclavicular widening, and os acromiale). Familiarity with the timing, location, and appearance of maturation patterns in the pediatric shoulder is crucial for correct image interpretation.

What role do plain radiographs have in assessing the skeletally immature acromioclavicular joint?

BACKGROUND: Because of incomplete ossification of the coracoid process and acromion, acromioclavicular joint configuration in the skeletally immature patient differs from that of adults. Although comparison to radiographic standards for this joint is critical in the evaluation of acromioclavicular joint injuries, these standards are not well defined for children or adolescents. QUESTIONS/PURPOSES: We therefore sought to determine (1) the reliability of numerous radiographic measurements of the skeletally immature acromioclavicular joint, including the vertical and shortest coracoclavicular interval, and the acromioclavicular joint offset; (2) the timing of ossification of the acromion and coracoid in males and females; and (3) the differences in the values of these radiographic measurements based on age and sex. METHODS: This study was based on a total of 485 subjects, 8 to 18 years old, who underwent conventional AP view radiographs of both shoulders. The 485 subjects were included to assess normal configuration around the acromioclavicular joint and 466 of these subjects were evaluated for comparison between both sides. The vertical and shortest coracoclavicular interval, coracoclavicular clavicle width ratio, acromioclavicular joint offset, and difference of the coracoclavicular interval of both sides were measured. A reliability test was conducted before obtaining the main measurements. The relationship of measurements with sex, age, and stage of ossification was evaluated. RESULTS: The vertical and shortest coracoclavicular interval showed excellent reliability (intraclass correlation coefficient ([ICC], 0.918 and 0.934). The acromioclavicular joint offset showed low reliability (ICC, 0.543). The ossification centers of the acromion and the coracoid processes appeared and fused earlier in females than in males. The vertical coracoclavicular interval, which was not affected by partial ossification of the coracoid process, was less than 11 mm in the 90% quantile of total subjects in males and 10 mm in the 90% quantile in females. The difference of the vertical coracoclavicular interval of both sides was less than 50% in 436 of 466 (93.4%) patients. CONCLUSIONS: The vertical coracoclavicular interval was the best parameter to assess acromioclavicular joint dislocation in skeletally immature patients. Comparison of both sides of the acromioclavicular joint could help to inform physicians in predicting the need for additional evaluations.

Anatomy and biomechanics of the acromioclavicular and sternoclavicular joints.

The acromioclavicular and sternoclavicular joints have important soft-tissue static constraints that, based on biomechanical studies, imply a great deal of stability. The infrequency of significant symptoms following dislocations of these joints certainly highlights the fact that the dynamic muscle support is also very important. In performing resections of these joints for degenerative disease, our goal should be to preserve these important ligamentous supports by minimizing the amount of bone excised, as this seems to optimize results [84]. Precise isometric reconstruction of these complex, three-dimensional ligamentous structures merits further investigation in the laboratory and clinical settings.

[Age-related characteristics of the human acromioclavicular joint]. / Vozrastnye osobennosti akromial'no-kliuchichnogo sustava cheloveka.

By birth in the acromioclavicular joint the acromial end of the clavicle is osseous, and the acromion of the scapula is cartilaginous. The most intensive formation of the relief and configuration of the articular surfaces of the joint occurs from 1 to 3 years of age. In mature persons the form of the articular surface of the acromial end of the clavicle is often oval and that of the acromion of the scapula--ellipsoid. In newborns the areas of the articular surfaces are nearly equal. The area of the articular surface of the acromial end of the clavicle is significantly more than that of the acromion of the scapula during the periods from 1 to 3, from 13 to 17 and from 21 to 30 years of age. The articular cleft is revealed in the roentgenograms by 17 years of age, when synostosis process of the acromion of the scapula is completed. The thickness of the articular cartilage at different poles of the articular surfaces from birth up to 70 years of age is not equal and therefore it is possible to judge about nonequivalent functional loading on different areas of the articular cartilage. The articular cartilage of the acromial end of the clavicle from birth to 16 years of age is hyaline, after 17 years of age, they acquire the structure of the fibrous cartilage. In the articular cartilage of the acromion of the scapula, this rearrangement is realized more slowly: its fibrous structure is revealed after 23-24 years of age. Involutional changes in the joint are revealed during the fourth decade.(ABSTRACT TRUNCATED AT 250 WORDS)