MRI of internal impingement of the shoulder

Spectrum and patterns of shoulder pathology on MRI in symptomatic elite wheelchair basketball athletes

BACKGROUND

Wheelchair basketball (WCB) is a popular para-sport adapted for athletes with physical disabilities. Shoulder injuries are commonly reported among WCB athletes. However, the understanding of the specific patterns and characteristics of shoulder injuries in WCB players is currently limited, and there is a lack of comprehensive literature available on this subject.

OBJECTIVES

To investigate the spectrum of pathologies observed in elite wheelchair basketball (WCB) athletes referred for MRI evaluation of symptomatic injuries of the shoulder.

METHODS

Retrospective review of consecutive elite WCB athletes referred for MRI evaluation of symptomatic shoulder injury. Demographic, clinical, and functional data including international wheelchair basketball federation (IWBF) classification of each athlete were collected. A total of 28 MRI studies were reviewed. Excluding MRI examinations of the same shoulder, 18 study cases were assessed for pathology of the rotator cuff (RC), labrum, long-head of biceps tendon, glenohumeral and acromioclavicular joints, and osseous lesions of the humerus or glenoid. Correlations between clinical-demographic features and MRI findings were statistically evaluated.

RESULTS

Supraspinatus tears were observed in 72.2%, infraspinatus tears in 50%, and subscapularis tears in 38.9% shoulders. Articular-sided partial tears frequently involved posterior supraspinatus (88.9%) and anterior infraspinatus (100%). Labral tears were seen in 38.9%, with involvement of the posterosuperior labrum in all tears. Hill-Sachs and osseous Bankart lesions (5.6%), and anterior-inferior labral tears (11.1%), were uncommon findings. Statistically significant correlations were observed of low IWBF point class and non-ambulatory athletes with subscapularis tendinosis (p = 0.015, p = 0.001) and tearing (p = 0.050, p = 0.013), and athletes with limited trunk control with subscapularis tendinosis (p = 0.013).

CONCLUSIONS

RC tears are common in elite WCB athletes with pattern of RC and labral tearing suggesting internal (superior-posterior) impingement as a contributory pathoetiologic mechanism. Non-ambulatory, low IWBF point class athletes, as well as those with limited trunk control have a statistically significant increase in subscapularis tendon pathology on MRI.

Is Workload Associated With Internal Impingement in Professional Baseball Pitchers? An Analysis of Days of Rest, Innings Pitched, and Batters Faced

Background

Internal impingement is a common cause of shoulder pain and dysfunction in baseball pitchers.

Purpose/Hypothesis

The purpose of this study was to determine if the amount of rest days between outings, the number of innings pitched in each outing, and the number of batters faced in each outing are risk factors for internal impingement in professional baseball pitchers. It was hypothesized that a higher workload would significantly increase a pitcher's risk of developing internal impingement.

Study Design

Case-control study; Level of evidence, 3.

Methods

All professional (Major and Minor League) baseball pitchers who were diagnosed with internal impingement between 2011 and 2017 were identified using the Major League Baseball's Health and Injury Tracking System. A separate player usage data set was used to determine workload. The authors compared workload variables (days of rest, innings pitched, and batters faced per game) between each of 4 injury-exposure groups (pitchers with documented internal impingement <2, <6, <12, and >12 weeks after a game) and a control group of pitchers with no internal impingement using Student t tests or Mann-Whitney U tests. In a within-pitcher paired analysis of the injury groups, the workload variables during 3 acute periods (<2, <6, and <12 weeks preinjury) were compared with the baseline values (>12 weeks preinjury).

Results

Overall, there were 624 professional baseball pitchers diagnosed with internal impingement during the study period. Compared with pitcher games (n = 213,964), pitchers in all 4 injury-exposure groups had significantly more innings pitched per game (P ≤ .003 for all) and faced significantly more batters per game (P < .001 for all). There were significantly more starting pitchers in each of the injury-exposure groups when compared with the controls (P < .001 for all). However, when comparing acute and baseline workloads in the pitchers diagnosed with internal impingement, there were no significant differences in the number of innings pitched, batters faced, or days of rest.

Conclusion

This analysis revealed significantly greater pitcher workload and percentage of starting pitchers in professional baseball players diagnosed with internal impingement when compared with healthy controls. However, this injury did not seem to be associated with an acute increase in workload.

Shoulder Impingement Syndrome

Shoulder impingement is the most common diagnosis for shoulder pain. Shoulder impingement syndrome has been scrutinized as a misleading "umbrella" term, due to its vague and nonspecific context. It is better subcategorized into subacromial, internal, and subcoracoid impingement. The evaluation and treatment algorithm for each is grossly similar. A thorough history, focused physical examination, and standard radiographs are the first steps. Advanced imaging with MRI or ultrasound may be useful. The mainstay of treatment includes physical therapy, anti-inflammatory medications, and injections. Surgical treatment is reserved for refractory cases, and includes decompression, debridement, and/or repair of injured structures.

Cystic lesions of the humeral head on magnetic resonance imaging: a pictorial review

Cystic lesions of the humeral head are commonly encountered on routine shoulder magnetic resonance imaging (MRI). Differential diagnoses include degenerative lesions, calcific tendinitis with osseous involvement, perianchor cysts, abscesses and less often, tumours. Degenerative lesions, including subcortical and subchondral cysts, are the most commonly encountered. These may be associated with rotator cuff disease and degenerative joint diseases or considered part of ageing depending on the location of the cystic lesions. For instance, cysts of the bare area of the humeral head are considered benign age-related entities, whereas cysts of the greater or lesser tuberosity may herald rotator cuff disease. Infectious lesions, particularly osteomyelitis and intraosseous (Brodie’s) abscesses, are intramedullary in location and should be suspected in the context of clinical features such as fever and radiological features such as the penumbra sign. Perianchor cysts are postoperative lesions associated with the use of suture anchors in surgeries such as rotator cuff tear repairs. They generally self-resolve over 18 to 24 months. On MRI, the distribution, morphology, and signal characteristics can help point towards a specific diagnosis. The patient’s demographic, clinical presentation, and past surgical history can be discriminatory. Knowledge of different cystic lesions in the humeral head and underlying aetiology can be useful in helping the radiologist develop a more thorough search pattern for associated conditions. Determining the underlying cause of cysts can have important implications on management, such as when differentiating perianchor cysts from infection. This pictorial review outlines the differential diagnoses of humeral head cysts on MRI and provides a diagnostic approach for the radiologist.

Mimickers of Hill-Sachs Lesions

The purpose of this article is to describe the imaging appearance, etiology, clinical features, and treatment of rare presentations of common bone and joint diseases known to mimic Hill-Sachs lesions. Knowledge of uncommonly encountered manifestations of ankylosing spondylitis, rheumatoid arthritis, septic joint, hyperparathyroidism, hydroxyapatite deposition disease, malignant bone tumors, and benign bone cysts which mimic traumatic Hill-Sachs lesions is important for radiologists to guide the clinical care of patients who present with shoulder symptoms.

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.

Bennett lesions in overhead athletes and associated shoulder abnormalities on MRI

OBJECTIVE

To determine if a Bennett lesion and its size are associated with additional MRI shoulder abnormalities in an overhead athlete.

MATERIALS AND METHODS

An IRB-approved retrospective review of our database from 1 January 2012 to 1 April 2018 identified 35 overhead athletes with a Bennett lesion on MRI. A control group consisting of 35 overhead athletes without a Bennett lesion were matched for age, level of play (professional vs non-professional), and type of study (arthrogram vs non-arthrogram). Each study was assessed independently by two MSK fellowship trained radiologists. The sizes of the Bennett lesions were measured. Each MRI was assessed for the presence of a labral tear, posterior glenoid cartilage abnormality, humeral head notching or cysts, and fraying or tear of the supraspinatus or infraspinatus tendons. Statistical analyses were performed using Student's t test, Fisher's exact test, and Chi-squared test.

RESULTS

There was an increased incidence of posterior glenoid cartilage abnormalities in athletes with Bennett lesions vs those without (23% vs 3%, p value = 0.01). There was no difference in any other MRI abnormalities, including labral tears and findings of internal impingement between these two groups (p value range = 0.09-0.46). There was no association between the size of a Bennett lesion and the presence of glenoid cartilage lesions, labral tears, internal impingement, age, professional status, or need for surgery (p value range = 0.08-0.96).

CONCLUSION

Symptomatic overhead athletes with Bennett lesions have an increased frequency of posterior glenoid cartilage abnormalities, but not labral tears or findings of internal impingement compared to those without Bennett lesions.

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.

Overuse Injuries of the Shoulder

This article discusses the most common and important overuse injuries of the shoulder with attention to MR imaging and ultrasound findings. Pathologic conditions occurring in athletes and nonathletes are included, with review of relevant anatomy, predisposing factors, and treatment considerations. Specific overuse injuries involving the rotator cuff, long head of the biceps tendon, and subacromial-subdeltoid bursa are reviewed. Impingement syndromes of the shoulder, Little Leaguer's shoulder, and stress-induced distal clavicular osteolysis are also discussed.

Shoulder Injuries in the Overhead-Throwing Athlete: Epidemiology, Mechanisms of Injury, and Imaging Findings

The unparalleled velocity achieved by overhead throwers subjects the shoulder to extreme forces, resulting in both adaptive changes and pathologic findings that can be detected at imaging. A key biomechanical principle of throwing is achieving maximum external rotation, which initially leads to adaptive changes that may result in a pathologic cascade of injuries. In addition to the well-established concepts of glenohumeral internal rotation deficit and internal impingement, osseous and soft-tissue injuries of the shoulder unique to overhead athletes are illustrated. The epidemiology and biomechanics of throwing injuries are reviewed, and examples from the authors' institutional experience with competitive, collegiate, and professional baseball players are provided to demonstrate the constellation of unique imaging findings seen in overhead throwing athletes. Given the widespread popularity of baseball, and other sports relying on overhead throwing motions at all playing levels from recreational to professional, it is important for radiologists in various practice settings to be familiar with the special mechanisms, locations, and types of shoulder injuries seen in the overhead throwing population. ^© RSNA, 2018.

Pathologies of the shoulder and elbow affecting the overhead throwing athlete

The overhead-throwing athlete is susceptible to a variety of predictable disease entities affecting the shoulder and elbow. While the pathophysiology and nomenclature of these diseases are ubiquitous throughout the clinical literature, this information is sparse within the radiology domain. We provide a comprehensive review of these unique injuries with accompanying imaging features in an effort to enhance the role of the radiologist during the management of the overhead thrower. When appropriately recognized and described, the imaging features aid in establishing a diagnosis and ultimately the implementation of appropriate clinical management.

Evaluation and treatment of internal impingement of the shoulder in overhead athletes

One of the most common pathologic processes seen in overhead throwing athletes is posterior shoulder pain resulting from internal impingement. “Internal impingement” is a term used to describe a constellation of symptoms which result from the greater tuberosity of the humerus and the articular surface of the rotator cuff abutting the posterosuperior glenoid when the shoulder is in an abducted and externally rotated position. The pathophysiology in symptomatic internal impingement is multifactorial, involving physiologic shoulder remodeling, posterior capsular contracture, and scapular dyskinesis. Throwers with internal impingement may complain of shoulder stiffness or the need for a prolonged warm-up, decline in performance, or posterior shoulder pain. On physical examination, patients will demonstrate limited internal rotation and posterior shoulder pain with a posterior impingement test. Common imaging findings include the classic “Bennett lesion” on radiographs, as well as articular-sided partial rotator cuff tears and concomitant SLAP lesions. Mainstays of treatment include intense non-operative management focusing on rest and stretching protocols focusing on the posterior capsule. Operative management is variable depending on the exact pathology, but largely consists of rotator cuff debridement. Outcomes of operative treatment have been mixed, therefore intense non-operative treatment should remain the focus of treatment.

Beyond the Cuff: MR Imaging of Labroligamentous Injuries in the Athletic Shoulder

Shoulder disease is common in the athletic population and may arise as a consequence of a single traumatic episode or multiple repeated events. Associated labroligamentous injuries can result in substantial disability. Specific athletic and occupational activities result in predictable injury patterns. Imaging in general and magnetic resonance (MR) imaging, in particular, are vital in establishing the correct diagnosis and excluding common mimicking conditions, to ensure timely and appropriate management. In this review, the utility of MR imaging and MR arthrography will be explored in evaluation of shoulder disease, taking into account normal variants of the labroligamentous complex. Subsequently, broad categories of labral lesions and instability, external and internal impingement, as well as nerve entrapment syndromes, will be discussed, while emphasizing their imaging findings in the clinical context and illustrating key features. More recent concepts of internal impingement and secondary subacromial impingement will also be clarified.

The primer for sports medicine professionals on imaging: the shoulder

Because of its inherent superior soft tissue contrast and lack of ionizing radiation, magnetic resonance imaging (MRI) is highly suited to study the complex anatomy of the shoulder joint, particularly when assessing the relatively high incidence of shoulder injuries in young, athletic patients. This review aims to serve as a primer for understanding shoulder MRI in an algorithmical approach, including MRI protocol and technique, normal anatomy and anatomical variations of the shoulder, pathologic conditions of the rotator cuff tendons and muscles, the long head of the biceps tendon, shoulder impingement, labral and glenohumeral ligament pathology, MR findings in shoulder instability, adhesive capsulitis, and osteoarthritis.

Microinstability and internal impingement in overhead athletes

A complex interplay exists between the static and dynamic stabilizers in the glenohumeral joint, especially in overheard athletes who need a shoulder hypermobile enough to perform overhead activity yet stable enough to prevent joint subluxation. Concomitant shoulder pathologies commonly occur in the setting of microinstability and internal impingement. Before any surgical intervention, a 3- to 6-month course of conservative measures should first be attempted, with exercises focused on rotator cuff and scapular stabilizer strengthening combined with posterior capsule stretching. If surgery is needed, arthroscopic suture plication with treatment of concomitant lesions has been shown to provide the best clinical outcomes.

Isolation of infraspinatus in clinical test positions

OBJECTIVES

Existing clinical tests for infraspinatus lack accuracy and differentiation from supraspinatus is difficult. We aimed to find a position that isolated infraspinatus contraction from supraspinatus and to analyse the contraction characteristics of lower (oblique) and upper (transverse) parts of infraspinatus.

DESIGN

Within-participant, repeated measures experimental study.

METHODS

Intramuscular electromyography was used to measure the level of activation (electromyographic amplitude as a percentage of maximal voluntary contraction) of infraspinatus and supraspinatus on 15 healthy participants. Participants produced an isometric external rotation force at the shoulder, against manual resistance in shoulder positions of neutral, flexion, abduction and extension. Longitudinal force along the humeral axis was also applied.

RESULTS

The two parts of infraspinatus demonstrated different patterns of electromyographic activation. The oblique part of infraspinatus was "markedly active" in all positions while the transverse part was mostly "moderately active". Comparing supraspinatus with infraspinatus, it was found that infraspinatus was significantly more active than supraspinatus from the positions of shoulder flexion and neutral with the highest ratios observed in the position of shoulder flexion. Longitudinal humeral force was not an important factor.

CONCLUSIONS

If isometric external rotation of the shoulder is performed against resistance, the oblique part of infraspinatus will be working harder than the transverse part, irrespective of shoulder position. If differentiation of infraspinatus contraction from supraspinatus is desired, external rotation should be performed from a position of shoulder flexion or neutral. Resisted external rotation in shoulder flexion may form the basis of the development of a more accurate clinical test for infraspinatus.

Ultrasonography of the shoulder with arthroscopic correlation

Ultrasonography is a well-established and widely accepted modality for the evaluation of rotator cuff tears and injury to the biceps brachii tendon. Ultrasonography and magnetic resonance imaging have comparable sensitivity and specificity for diagnosing both full-thickness and partial-thickness rotator cuff tears. This article addresses the ultrasonographic diagnosis of abnormalities of the rotator cuff, rotator interval, and biceps brachii, with magnetic resonance imaging and arthroscopic correlation. Characteristic ultrasonographic findings as well as imaging pitfalls are reviewed.

Shoulder impingement revisited: evolution of diagnostic understanding in orthopedic surgery and physical therapy

"Impingement syndrome" is a common diagnostic label for patients presenting with shoulder pain. Historically, it was believed to be due to compression of the rotator cuff tendons beneath the acromion. It has become evident that "impingement syndrome" is not likely an isolated condition that can be easily diagnosed with clinical tests or most successfully treated surgically. Rather, it is likely a complex of conditions involving a combination of intrinsic and extrinsic factors. A mechanical impingement phenomenon as an etiologic mechanism of rotator cuff disease may be distinct from the broad diagnostic label of "impingement syndrome". Acknowledging the concepts of mechanical impingement and movement-related impairments may better suit the diagnostic and interventional continuum as they support the existence of potentially modifiable impairments within the conservative treatment paradigm. Therefore, it is advocated that the clinical diagnosis of "impingement syndrome" be eliminated as it is no more informative than the diagnosis of "anterior shoulder pain". While both terms are ambiguous, the latter is less likely to presume an anatomical tissue pathology that may be difficult to isolate either with a clinical examination or with diagnostic imaging and may prevent potentially inappropriate surgical interventions. We further recommend investigation of mechanical impingement and movement patterns as potential mechanisms for the development of shoulder pain, but clearly distinguished from a clinical diagnostic label of "impingement syndrome". For shoulder researchers, we recommend investigations of homogenous patient groups with accurately defined specific pathologies, or with subgrouping or classification based on specific movement deviations. Diagnostic labels based on the movement system may allow more effective subgrouping of patients to guide treatment strategies.

MR arthrography of the shoulder: tolerance evaluation of four different injection techniques

OBJECTIVE

We sought to prospectively evaluate patients' pain perception and technical success of four different arthrographic techniques for shoulder MR arthrography.

MATERIALS AND METHODS

A total of 125 consecutive patients were referred for shoulder MR arthrography. The patients were randomly injected under fluoroscopic guidance (n(1) = 37), with CT guidance using an anterior (n(2) = 29) or a posterior approach (n(3) = 32) and with ultrasound guidance (n(4) = 27). For each patient, absolute periprocedural pain on a numerical rating pain scale (0 = "no pain", 10 = "intolerable pain"), technical success of the method used, and reason for referral were recorded.

RESULTS

The technical success rate was 100% for all injection methods. The results regarding absolute periprocedural pain were as follows: fluoroscopic guidance showed a mean pain of 4.05 ± 1.24, CT anterior guidance demonstrated a mean pain of 3.87 ± 0.95, CT posterior guidance showed a mean pain of 1.59 ± 0.81, and ultrasound guidance a mean pain of 3.63 ± 1.12. A significant difference (p < .05) was observed for the posterior route under CT guidance. The mean pain level was significantly higher for older (> 51 year) female patients.

CONCLUSIONS

No differences were found for the technical success rate of the aforementioned techniques. A CT-guided posterior approach seems to be a more comfortable method for the patient.

Throwing injuries of the upper extremity

The overhead throwing motion is a complex sequence of maneuvers that requires coordinated muscle activity in the upper and lower extremities. The shoulder and elbow are subject to multidirectional forces and are particularly vulnerable to injury during specific phases of the overhead throwing motion. Ligamentous, tendinous, neural, and osseous pathology that may occur in the shoulder or elbow of an overhead-throwing athlete will be discussed, with an emphasis on the role of MR imaging and MR arthrography.

Imaging evaluation of the rotator cuff

The rotator cuff is a complex network of interwoven tendons that plays a key role in glenohumeral movement and stability. Cuff abnormality is a common source of shoulder pain, but the clinical presentation is often nonspecific and, as a result, diagnostic imaging, especially magnetic resonance imaging, plays a key role in evaluating these patients. This article reviews imaging modalities available for evaluating the cuff, normal cuff anatomy, and common pathologic conditions that affect it.

The use of ultrasound in the assessment of the glenoid labrum of the glenohumeral joint. Part II: Examples of labral pathologies

Labral pathologies of the glenohumeral joint are most commonly caused by trauma. The majority of lesions affect the anterior part of labrum, resulting from much higher frequency of anterior shoulder dislocations over posterior ones. Another subgroup of labral lesions, not directly related to joint instability, are SLAP tears. Other findings include degenerative changes of labrum and paralabral cysts. Diagnostic imaging is crucial for making a decision regarding operative treatment. Apart from a standard X-ray examination, the imaging mainly relies on magnetic resonance or computed tomography arthrography. Based on their own experience, the authors propose the use of ultrasound in the assessment of labral tears of the glenohumeral joint. Different signs indicating labral pathology may be discovered and assessed during ultrasound examination. They include permanent displacement of the labrum onto the glenoid, labral instability during dynamic examination, lack of the labrum in the anatomical position, hypoechoic zone at the base of the labrum >2 mm in width, residual or swollen labrum as well as paralabral cyst(s). The most frequent appearance of labral pathology is displacement of the anteroinferior labrum onto the external aspect of the glenoid typically seen after anterior shoulder dislocation. The another most important US feature is labral instability while dynamically examined. The swelling or reduced size of the labrum usually indicates degeneration. This article presents sonographic images of selected labral pathologies.

Internal impingement syndromes

Internal causes of impingement are secondary to rotator cuff and capsular dysfunction and are categorized by the location of the impingement and the underlying pathophysiological or mechanical cause of the impingement. These include posterosuperior impingement, anterosuperior impingement, anterior impingement, and entrapment of the long head of the biceps tendon. The objective of this article is to review magnetic resonance imaging findings of each of the 4 types of internal impingement syndromes and discuss the pathophysiology behind the impingement.

Lesions of the biceps pulley as cause of anterosuperior impingement of the shoulder in the athlete: potentials and limits of MR arthrography compared with arthroscopy

PURPOSE

This study aimed to evaluate the diagnostic possibilities of MR arthrography in the correct identification of complex tears of the biceps pulley and their possible correlation with anterosuperior impingement (ASI) development.

MATERIALS AND METHODS

MR arthrography examinations of 23 athletes with clinical suspicion of ASI were reviewed. All examinations were obtained with a 1.5-T unit (Signa Horizon, GE Healthcare). The shoulders were studied with a dedicated surface coil with the patient's arm in the neutral position and in internal and external rotation. In five patients, images in abduction-external rotation (ABER) were obtained. Within 2 month after MR arthrography, the athletes underwent arthroscopic surgery.

RESULTS

MR arthrography images showed a spectrum of tears that, according to the Habermeyer classification, were subdivided into four groups: type 1 in three patients; type 2 in five; type 3 in seven; type 4 in eight. At arthroscopic evaluation, one patient presented type 1 lesion, five type 2, five type 3 and ten type 4. During arthroscopic dynamic manoeuvres, ASI signs were observed in three patients with type 3 lesion and in ten with type 4 lesion.

CONCLUSIONS

MR arthrography is the imaging modality of choice for evaluating lesions of the rotator interval structures, and only complex lesions of the biceps pulley are related to the development of ASI.

Superior labral anteroposterior lesions of the shoulder: part 2, mechanisms and classification

OBJECTIVE

The objectives of this article are to discuss the 10 distinct patterns of superior labral anteroposterior (SLAP) tears to facilitate adequate diagnosis and treatment. Correlations with clinical presentation, mechanism of injury, and treatment will enhance understanding.

CONCLUSION

Imaging plays an important role in the diagnosis of SLAP tears. Knowledge of glenolabral anatomy, related structures and variants, proper imaging techniques, and a systematic approach to MRI interpretation is important in the diagnosis and treatment planning of the 10 types of SLAP lesions. Arthroscopy offers a means for definitive diagnosis.

Posterosuperior and anterosuperior impingement of the shoulder in overhead athletes-evolving concepts

During throwing motion the athlete puts enormous stress on both the dynamic and the static stabilisers of the shoulder. Repetitive forces cause adaptive soft tissue and bone changes that initially improve performance but ultimately may lead to shoulder pathologies. Although a broad range of theories have been suggested for the pathophysiology of internal impingement, the reasons are obviously multifactorial. This review aims to critically analyse the current literature and to summarise clinically important information. The cardinal lesions of internal impingement, articular-sided rotator cuff tears and posterosuperior labral lesions, have been shown to occur in association with a number of other findings, most importantly glenohumeral internal rotation deficit and SICK scapula syndrome, but also with posterior humeral head lesions, posterior glenoid bony injury and, rarely, with Bankart and inferior glenohumeral ligament lesions. Extensive biomechanical and clinical research is necessary before a complete understanding and reconciliation of the varying theories of the pathomechanisms of injury can be developed.

[Shoulder injuries in overhead sports]

Overhead sport places great demands on the shoulder joint. Shoulder pain in overhead athletes and throwers can in the majority of cases be attributed to lesions resulting from chronic overuse of tendons and capsuloligamentous structures or to sequels of microinstability and secondary impingement. Due to its great impact on therapeutic decisions, imaging in athletes with unclear shoulder pain is a challenge. In this connection, magnetic resonance (MR) arthrography represents the cross-sectional imaging modality of first choice, as it allows depiction and exclusion of pathologic alterations of all relevant joint structures with sufficient confidence.This article reviews the biomechanical and clinical aspects and MR arthrographic features of the most common shoulder pathologies in overhead athletes, including biceps tendinopathy, superior labral anterior-posterior (SLAP) lesions, rotator cuff lesions, as well as extrinsic and intrinsic impingement syndromes.

Internal impingement of the shoulder in the overhead athlete

Internal impingement of the shoulder refers to a constellation of pathologic conditions, including, but not limited to, articular-sided rotator cuff tears, labral tears, biceps tendinitis, anterior instability, internal rotation deficit, and scapular dysfunction. Physiologic adaptations to throwing include increased external rotation, increased humeral and glenoid retroversion, and anterior laxity, all of which may predispose an individual to internal impingement. Nonoperative treatment should always be attempted first, with a focus on increasing the range of motion and improving scapular function. When an operative intervention is chosen, it is important to address microinstability in order to have a good outcome and prevent failure.

MR imaging in congenital and acquired disorders of the pediatric upper extremity

Various congenital and acquired disorders can affect the upper extremity in pediatric and adolescent patients. MR imaging can provide unique anatomic and diagnostic information in the evaluation of many of these disorders, including inflammatory, infectious, neoplastic, and arthritic conditions. This article rounds out the issue on pediatric musculoskeletal MR imaging. It focuses on the evaluation of more common congenital disorders, and mainly sports-related injuries of the shoulder, elbow, and wrist in children. MR imaging can be more challenging in diagnosis of some of these disorders. Features of overuse injuries in skeletally immature athletes are a unifying theme throughout the article.