Advanced imaging of glenohumeral instability: the role of MRI and MDCT in providing what clinicians need to know

The inherently unstable anatomy of glenohumeral (GH) joint predisposes it to shoulder dislocation. Shoulder dislocation can occur either due to acute trauma or due to chronic microtraumas in the setting of underlying morphological abnormality. A plain radiograph is the initial imaging modality for diagnosis and management of shoulder dislocation and its associated osseous abnormalities such as Hill-Sachs deformity or osseous Bankart lesion. However, advanced imaging techniques such as multidetector CT (MDCT) with three-dimensional (3D) volume rendering and MRI can be helpful in further characterization of osseous abnormalities and detection of associated soft tissue injuries, respectively. These additional findings may be useful for optimal surgical repair for GH joint stabilization. In this pictorial essay, we present the clinically relevant osseous and soft tissue pathologies in various types of shoulder dislocation, with emphasis on pathologies that can be demonstrated using advanced imaging examinations. Discussed pathologies include glenoid fractures, labral tears, Bankart lesion, Hill-Sachs defect, Perthes lesion, anterior labral posterior sleeve avulsion (ALPSA), glenolabral articular disruption (GLAD), humeral avulsion of the glenohumeral ligament (HAGL), Kim lesion, and other associated soft tissue and nerve injuries.     

MR imaging of recurrent anterior dislocation of the shoulder: comparison with CT arthrography

Posttrauma damage due to anterior glenohumeral joint dislocation may result in recurrent dislocation. Currently CT arthrography is the method of choice to evaluate the extent of osseous and soft-tissue changes before reconstructive surgery. This study was undertaken to determine if MR was able to depict postdislocation abnormalities and if MR is a possible replacement for CT arthrography. Thirteen patients with recurrent anterior shoulder dislocation were evaluated with conventional radiography and MR; CT arthrography was performed in 10. Twelve patients underwent surgery, and the findings of MR and CT arthrography were verified. MR and CT arthrography showed the integrity of the glenoid labrum equally well. All humeral head defects, detected in nine patients with plain film radiography and CT, were easily identified with MR. Information about anterior joint capsule abnormalities is difficult to obtain with MR. However, separation of the capsule from the bony glenoid can be detected if a joint effusion is present to adequately distend the joint. Preliminary results of this study indicate that MR is useful in the assessment of postdislocation abnormalities and may possibly replace CT arthrography in the evaluation of patients with recurrent shoulder dislocation.     

Radiographic evaluation of anterior dislocation of the shoulder

PURPOSE: To establish radiographic criteria to choose the most appropriate technique of reduction for each type of anterior glenohumeral dislocation, and to determine the type of dislocation which requires general anesthesia. MATERIAL AND METHODS: Radiography in two different projections was performed in 67 patients with antero-inferior shoulder dislocations before a reduction attempt. The method proposed by BOss-HOLZACH-MATTER was used as the primary technique for all shoulder dislocations. RESULTS: Most subcoracoid dislocations (84.4%) could be reduced by the BOss-HOLZACH-MATTER method while only a few subglenoid dislocations (15.8%) were reducible by this technique. Displaced associated fractures significantly reduced the success rate of the reduction attempts. CONCLUSION: Anterior dislocations of the shoulder require different methods of reduction depending upon the type (sub-group) of dislocation. Reduction of subglenoid dislocations with associated greater tuberosity fracture should be performed under general anesthesia to avoid head-splitting fracture.     

Intra-articular volume assessment in glenohumeral instability

It is commonly claimed that instability of the shoulder is associated with an enlarged joint volume. The purpose of our study was to assess the intra-articular volume in acute and chronic glenohumeral dislocation. Sixty-seven patients were examined by intra-articular infusion of saline solution. Three groups could be formed. Group 1 (n = 51) consisted of patients with first time traumatic dislocation, group 2 (n = 8) of cases with recurrent post-traumatic dislocation. The patients of group 3 (n = 8) suffered from impingement syndrome and served as the control group. The joint volume was correlated to the body surface area (BSA). We found a strong correlation between height, sex and intra-articular joint volume. There was no statistically significant difference in joint volume correlated to BSA between the three groups. There is no statistically significant difference in joint volume correlated to BSA in patients with traumatic anterior instability, chronic instability and individuals without glenohumeral instability.     

A case study of an axillary artery pseudoaneurysm following anterior dislocation of the glenohumeral joint: A rare presentation on plain film radiographs

Axillary pseudoaneurysm is a rare but important complication of anterior glenohumeral joint dislocation. Diagnosis of axillary pseudoaneurysm is predominantly undertaken following clinical examination but where diagnosis is uncertain, Doppler ultrasound is the imaging examination of choice to confirm diagnosis. In this case study, the initial clinical signs of axillary pseudoaneurysm were masked by the presenting trauma and, although findings indicative of pseudoaneurysm were present on late plain film images, they were not immediately recognised.Misdiagnosis or delayed diagnosis of axillary pseudoaneurysm may result in upper limb morbidity or patient mortality. Consequently, the prompt and accurate identification of an axillary pseudoaneurysm on plain film radiographs, although rare, is essential. Yet for inexperienced film readers, correctly identifying an axillary pseudoaneurysm can be difficult due to its apparent similarity to other pathologies. This article will highlight the differences in radiological appearances between a pseudoaneurysm and a gleno-humeral joint effusion to raise radiographer awareness of the risks and clinical signs of an axillary pseudoaneurysm post gleno-humeral joint dislocation and discuss the difficulties encountered in its diagnosis. Finally, this review will evaluate current diagnostic practices in comparison with best practice, as identified in the literature [Fitzgerald JF, Keates J. False aneurysm as a late complication of anterior shoulder dislocation. Ann Surg 1975;6:785–6; Drury JK, Scullion JE. Vascular complications of anterior dislocation of the shoulder. Br J Surg 1980;67(8):579–81. Waxman DL, France MP, Douglas T, Harryman I. Late lateral displacement of the humeral head after closed reduction of dislocation: a sign of vascular injury. J Bone Joint Surg 1996;78(6):907–10].     

Voluntary glenohumeral dislocation.

Voluntary dislocation of the shoulder is a rare condition with radiographic findings similar to traumatic dislocation. Although these dislocations may be anterior, the majority are posterior. Three cases of spontaneous dislocation are described. While two of these cases had previous trauma to the joint, it is possible that there is no causal relationship. Voluntary dislocations are usually elicited in abduction and extension; frontal and axillary views are most helpful in demonstrating glenohumeral subluxations.     

Sonographic stress measurement of glenohumeral joint laxity in collegiate swimmers and age-matched controls

BACKGROUND: Glenohumeral laxity that is greater than normal has been implicated as a causal factor in the development of shoulder pain and dysfunction in elite swimmers; however, quantitative evidence demonstrating greater-than-normal glenohumeral joint laxity in swimmers is lacking. OBJECTIVE: To quantify glenohumeral joint laxity in elite swimmers and nonswimming controls using stress sonography. STUDY DESIGN: Controlled laboratory study. METHODS: Force-displacement measures were performed bilaterally in 42 National Collegiate Athletic Association Division I swimmers and 44 age-matched controls. Of the 42 swimmers, 27 (64%) reported a history of unilateral or bilateral shoulder pain resulting from swimming. Ultrasound imaging was used to measure glenohumeral joint displacement under stressed and non-stressed conditions. RESULTS: An analysis of variance revealed no significant difference in glenohumeral joint displacement between swimmers (anterior, 2.82 +/- 1.7 mm; posterior, 5.30 +/- 2.4 mm) and age-matched controls (anterior, 2.74 +/- 1.7 mm; posterior, 4.90 +/- 2.7 mm). No significant difference in glenohumeral joint displacement was found between swimmers with a history of shoulder pain (anterior, 2.90 +/- 1.6 mm; posterior, 5.42 +/- 2.3 mm) versus swimmers without a history of shoulder pain (anterior, 2.74 +/- 1.8 mm; posterior, 5.14 +/- 2.6 mm). Shoulders displayed significantly more glenohumeral joint displacement in the posterior direction compared to the anterior direction (P < .001). CONCLUSIONS: Our instrumented technique was unable to identify significantly greater glenohumeral joint displacement in elite swimmers compared to nonswimming controls, and elite swimmers with a history of shoulder pain were not found to have significantly more glenohumeral joint displacement compared to swimmers without a history of shoulder pain. CLINICAL RELEVANCE: Objective assessment of glenohumeral joint displacement in athletes participating in overhead-motion sports may be important for injury prevention and management.     

Arthroscopic lavage speeds reduction in effusion in the glenohumeral joint after primary anterior shoulder dislocation: a controlled randomized ultrasound study

Recent studies have shown that arthroscopic lavage of the glenohumeral joint within 10 days following a primary anterior dislocation significantly lowers the recurrence rate when compared with a nonoperative regime. We hypothesize that the lavage reduces distension in the joint and thereby facilitates adaptation and healing of the soft tissue lesion. Using ultrasound, we assessed the hemarthrosis in the glenohumeral joint weekly in 16 consecutive patients after traumatic primary anterior shoulder dislocation. The patients were randomized into two groups for treatment with either arthroscopic lavage or a nonoperative regime. Except for the lavage the two groups followed an identical rehabilitation program. Transversal dorsal ultrasound of the glenohumeral joint was performed, in which the joint effusion was assessed as the distance between the humeral head and the glenoid. Prior to the lavage the two groups had a similar amount of excessive joint effusion. The effusion declined to a steady state level within 3–7 weeks. The joint effusion decreased more rapidly (33%) in the group treated with arthroscopic lavage (P = 0.02) than in the nonoperated group. Received: 10 December 1998 /Accepted: 2 July 1999     

Quantitative assessment of glenohumeral translation after anterior shoulder dislocation and subsequent arthroscopic bankart repair

BACKGROUND: During the past decade, developments in arthroscopic technology have made arthroscopic repair of labral lesions feasible. However, results with the use of the transglenoid suture technique, or with the use of bioabsorbable tacks, have remained variable in the literature, and the recurrence rates are still inferior to those of open Bankart repair. HYPOTHESIS: Arthroscopic Bankart repair with suture anchors can re-create translational and rotational range of motion of the intact glenohumeral joint, and the number of preoperative dislocations has an influence on the result. STUDY DESIGN: Controlled laboratory study. MATERIALS: Twelve cadaveric shoulders were tested in a robot-assisted shoulder simulator. Anterior and posterior translation and external rotation were measured for intact, dislocated (shoulders were randomly selected to 1 of 3 groups, which were dislocated 1, 3, or 7 times), and repaired conditions at 0 degrees and 90 degrees of glenohumeral elevation. RESULTS: After shoulder dislocation, a significant increase was found in translation and rotation, confirming the creation of a traumatic shoulder instability model. Further testing of the specimen revealed that translational and rotational ranges of motion were reduced by arthroscopic Bankart repair at both testing positions. External rotation was decreased significantly at 0 degrees and 90 degrees of abduction. No significant differences were found between the 3 dislocation groups. CONCLUSION: The results demonstrate a sufficient biomechanical performance of arthroscopic Bankart repair using suture anchors in a traumatic anterior shoulder instability model. With the numbers available, no relationship was found between the number of dislocations and the postoperative result concerning translational or rotational motion. CLINICAL RELEVANCE: Glenohumeral translation and rotation after arthroscopic Bankart repair with use of suture anchors approached near normal values, confirming the clinical success of this technique.     

Glenohumeral instability and rotator cuff tear

The prevalence of rotator cuff tears after traumatic dislocation increases with advancing age, a likely consequence of the age-associated deterioration of the structure and mechanical properties of the tendons of the rotator cuff. These are the effective stabilizers of the glenohumeral joint, compressing the humeral head in the 3-dimensional concavity of the glenohumeral joint. It is impossible to establish whether a lesion of the capsular-labrum complex or of the rotator cuff causes or follows a dislocation, regardless of whether it is anterior or posterior. A peripheral nerve or a brachial plexus injury can be associated with tendon lesion and instability, developing the "terrible triad" of the shoulder. Both conservative and surgical management are possible, and surgeons must choose the most appropriate management modality according to the biologic age, functional demands, and type of lesion.     

Septic arthritis: a rare cause of drooping shoulder

Drooping shoulder, or inferior subluxation of the glenohumeral joint, must be differentiated from true dislocation of the humeral head. In some instances, widening of the glenohumeral joint can be attributed to a large volume of intra-articular fluid. Three patients with septic arthritis leading to drooping shoulder are described, representing the largest series with this development reported to date.     

The prevention and treatment of injuries to the shoulder in swimming

The biomechanics of swimming cause considerable stress on the shoulder joint which may be accentuated by improper stretching or training techniques. The rotator cuff, and particularly the supraspinatus tendon, is at risk in repetitive overhead stroke activity. Arthritis in the shoulder is primarily centered at the acromioclavicular joint; degeneration may occur as a result of overuse or leverage of the scapuloclavicular mechanism, or from motion related to upward pressure at the undersurface of the acromion due to subluxation or instability of the glenohumeral joint. Instability of the glenohumeral joint is a major problem which may occur in itself or in combination with rotator cuff tendinitis. The glenohumeral joint is stabilised superiorly by a posterior superior sling consisting of the long biceps tendon, the superior joint capsule, and the coracoacromial and coracohumeral ligaments. An anterior inferior sling mechanism consisting of the inferior glenohumeral ligament and subscapularis musculotendinous unit provides significant stability if uninjured. Fragments of labral tissue may mechanically wedge into the joint also leading to symptoms of subluxation. If the humeral head is wedged or allowed to slip out of joint due to capsular incompetency, secondary rotator cuff 'impingement' may occur; this is particularly difficult to manage. Prevention of injury is best accomplished through a programme of flexibility and strengthening avoiding overuse.     

Posterior shoulder labrocapsular structures in all aspects; 3D volumetric MR arthrography study

Pathologies of the posterior labrocapsular structures of the shoulder joint are far less common than anterior labrocapsuloligamentous lesions. Most of these pathologies have been associated with traumatic posterior dislocation. A smaller portion of the lesions include posterior extension of superior labral anteroposterior lesions, posterior superior internal impingement, and damage to the posterior band of the inferior glenohumeral ligament. Labrocapsular anatomic variations of the posterior shoulder joint can mimic labral pathology on conventional MR and occasionally on MR arthrographic images. Knowledge of this variant anatomy is key to interpreting MR images and studying MR arthrography of the posterior labrocapsular structure to avoid misdiagnosis and unnecessary surgical procedures. In this article, we review normal and variant anatomy of the posterior labrocapsular structure of the shoulder joint based on MR arthrography and discuss how to discriminate normal anatomic variants from labrocapsular damage.     

Functional shoulder radiography with use of a dynamic flat panel detector

Our purpose in this study was to develop a functional form of radiography and to perform a quantitative analysis for the shoulder joint using a dynamic flat panel detector (FPD) system. We obtained dynamic images at a rate of 3.75 frames per second (fps) using an FPD system. Three patients and 5 healthy controls were studied with a clinically established frontal projection, with abduction of the arms. The arm angle, glenohumeral angle (G-angle), and scapulothoracic angle (S-angle) were measured on dynamic images. The ratio of the G-angle to the S-angle (GSR) was also evaluated quantitatively. In normal subjects, the G-angle and S-angle changed gradually along with the arm angle. The G-angle was approximately twice as large as the S-angle, resulting in a GSR of 2 throughout the abduction of the shoulder. Changes in G-angle and S-angle tended to be irregular in patients with shoulder disorders. The GSR of the thoracic outlet syndrome, recurrent dislocation of the shoulder joint, and anterior serratus muscle paralysis were 3–7.5, 4–9.5, and 3.5–7.5, respectively. The GSR of the anterior serratus muscle paralysis improved to approximately 2 after orthopedic treatment. Our preliminary results indicated that functional radiography by FPD and computer-aided quantitative analysis is useful for diagnosis of some shoulder disorders, such as the thoracic outlet syndrome, recurrent dislocation of the shoulder joint, and anterior serratus muscle paralysis. The technique and procedures described comprise a simple, functional shoulder radiographic method for evaluation of the therapeutic effects of surgery and/or rehabilitation.     

Anatomy of the capsulolabral complex and rotator interval related to glenohumeral instability

The glenohumeral joint with instability is a common diagnosis that often requires surgery. The aim of this review was to present an overview of the anatomy of the glenohumeral joint with emphasis on instability based on the current literature and to describe the detailed anatomy and anatomical variants of the glenohumeral joint associated with anterior and posterior shoulder instability. A review was performed using PubMed/MEDLINE using key words: Search terms were “glenohumeral”, “shoulder instability”, “cadaver”, “rotator interval”, “anatomy”, and “anatomical study”. During the last decade, the interest in both arthroscopic repair techniques and surgical anatomy of the glenohumeral ligament (superior, middle, and inferior), labrum, and rotator interval has increased. Understanding of the rotator interval and attachment of the inferior glenohumeral ligament on the glenoid or humeral head have evolved significantly. The knowledge of the detailed anatomy and anatomical variations is essential for the surgeon in order to understand the pathology, make a correct diagnosis of instability, and select proper treatment options. Proper understanding of anatomical variants can help us avoid misdiagnosis. Level of evidence V.     

Occult Interpositional Rotator Cuff - an Extremely Rare Case of Traumatic Rotator Cuff Tear

Traumatic interposition of a rotator cuff tendon in the glenohumeral joint without recognizable glenohumeral dislocation is an unusual complication after shoulder trauma. Here we report the clinical and imaging presentations of a 17-year-old man with trapped rotator cuff tendons in the glenohumeral joint after a bicycle accident. The possible trauma mechanism is also discussed.     

Treatment of glenohumeral instabilityin the pediatric athlete

Shoulder instability in the skeletally immature athlete is an uncommon but challenging clinical problem. Theclassification of shoulder instability in the pediatric athlete is similar to that in the adult athlete, but may also include the voluntary and habitual dislocator. The natural history of such instability depends on the classification of instability type. Traumatic anterior dislocation has an exceedingly high recurrence, and posterior dislocation is less well known. A natural history of voluntary instability is also uncertain. As in the adult athlete, clinical evaluation is made by history and physical exam. An understanding of the bony development of the glenohumeral joint is crucial in interpreting radiographs of the skeletally immature athlete with glenohumeral instability. The treatment of glenohumeral instability will depend on the classification of the instability type. Surgical treatment, when indicated, should emphasize an anatomic approach aimed at correcting the underlying glenohumeral pathology. This article is intended to provide an overview of the approach to diagnosis and treatment of glenohumeral instability in the pediatric athlete.     

Loose body within the glenohumeral joint in recurrent anterior dislocation: CT demonstration

A loose body within the glenohumeral joint in a patient with chronic anterior dislocation and recent trauma that prevented successful reduction of the dislocated shoulder was demonstrated by CT. Although the use of CT with arthrography has been reported in patients with recurrent dislocations and unstable shoulders, this is the first such reported demonstration using CT without contrast medium of a loose body preventing reduction.     

Arthroscopic assessment of the unstable shoulder

The purpose of this study was to evaluate prospectively the findings during shoulder arthroscopy in patients with recurrent anterior instability of the gleno-humeral joint. One hundred and seventy-eight patietns who fulfilled the criteria of having had at least one documented shoulder dislocation were included in the study. The pathological findings most frequently noted at arthroscopy were: anterior glenoid labral tears (85%), ventral capsule insufficiency (80%), Hill-Sachs compression fractures (67%), glenohumeral ligament insufficiency (55%), rotator cuff tears (20%), posterior glenoid labral tears (8%), and SLAP lesions (5%). Abnormalities were noted more frequently than expected, and there were significant differences between preoperative and postoperative diagnoses. Our study has taught us that a mulitplicity of morphological changes are associated with instability of the glenohumeral joint, and that there is no single cause. The labrum and rim of the anterior inferior glenoid, for instance, showed typical abnormalities corresponding to different entities of anterior instability. In practice, this is very important, as the abnormalities visualized by imaging methods determine the surgical treatment.