Unilateral glenoid hypoplasia: unusual findings on MR arthrography

Magnetic resonance imaging assessment of the discoid glenoid labrum

BACKGROUND

The glenoid labrum varies in size and shape, sometimes resembling the knee's meniscus with a free inner edge projecting into the joint. This incomplete discoid-shaped or meniscoid glenoid labrum is a seldom recognized rare variant.

PURPOSE

To determine the prevalence and magnetic resonance imaging [MRI] characteristics of discoid glenoid labrum.

MATERIAL AND METHODS

Retrospective review of the MRI shoulder joints of 201 patients. The MR images were evaluated for the presence of a discoid labrum, and various characteristics were assessed using predefined criteria.

RESULTS

Among the 201 patients, a discoid glenoid labrum was identified in 27 cases; incidence rate of 13.4 %. The mean age of these patients was 41.85 years [range 15-73 years, SD ± 16.9]. The most common position was anterior or antero-inferior [n = 25; 92.6 %], with the apices of almost all discoid folds found between 3-6o'clock position. Twenty-one [77.8 %] of the discoid folds were small, and 6 [22.2 %] were large. Tears or degeneration were observed in 9 [33.3 %]. A statistically significant difference between genders was found in age [p = 0.026] and width [p = 0.044], with discoid labrum appearing in younger men and covering a larger part of the glenoid fossa. The labra were widest at the 3o'clock position [p = 0.008]. Additionally, we discovered a novel radiological finding termed the 'reversed Oreo cookie sign' in discoid glenoid labra.

CONCLUSION

The discoid glenoid labrum is a shoulder variant that is often overlooked. Recognizing this condition is crucial to avoid misdiagnosing labral pathology and to understand its potential susceptibility to labral tears, degeneration, and shoulder pain.

Discoid Labral Meniscus Covering Two-Thirds of a Type C Glenoid: A Case Report

Background

Glenoid morphology and dysplasia have been extensively described in conjunction with shoulder arthritis. Dysplastic glenoids have a substantial inherent retroversion, a deficient posteroinferior rim, a short scapular neck, and an inferior inclination of the joint surface. The effect of dysplasia on fracture surgery has not been reported to the same extent.

Case presentation

A 65‐year‐old man presented with a proximal humeral fracture. The patient was scheduled for osteosynthesis. The head was deemed unrepairable at the time of surgery and the operative plan changed to replace the proximal humerus. A discoid meniscus‐like labral extension covering two‐thirds of the glenoid was encountered. This finding covered a dysplastic glenoid. The combination of a fracture and a dysplastic glenoid had not been accounted for and made the reconstruction more difficult. The patient received a reverse total shoulder arthroplasty after perioperative considerations regarding reconstruction. At the 2‐month follow up, the patient had a satisfactory clinical outcome, with 90° of flexion and minimal residual pain.

Conclusion

This case illustrates that elective disorders with dysplasia also present to the fracture team. Careful analysis of preoperative imaging should result in an operative plan taking unexpected findings into account.

Posterior Shoulder Instability: What to Look for

Posterior shoulder instability is often hard to diagnose with clinical examination. Patients generally present with vague pain, weakness, and/or joint clicking but less frequently complaining of frank sensation of instability. Imaging examinations, especially MR imaging and magnetic resonance arthrography, have a pivotal role in the identification and management of this condition. This review describes the pathologic micro/macrotraumatic magnetic resonance features of posterior shoulder instability as well as the underlying joint abnormalities predisposing to this condition, including developmental anomalies of the glenoid fossa, humeral head, posterior labrum, and capsular and ligamentous structures.

Glenoid hypoplasia

Glenoid hypoplasia, also known as glenoid dysplasia and dysplasia of the scapular neck, is a failure of ossification of the posteroinferior two-thirds of the glenoid. Once thought to be a rare condition, more recent studies have shown that the incidence of glenoid hypoplasia ranges from 18% to 35%. This case report and literature review highlights the typical clinical presentation, the radiologic findings, and the management options for patients with glenoid hypoplasia.

Glenoid Dysplasia: Pathophysiology, Diagnosis, and Management

➤Subtle forms of glenoid dysplasia may be more common than previously thought and likely predispose some patients to symptomatic posterior shoulder instability. Severe glenoid dysplasia is a rare condition with characteristic radiographic findings involving the posteroinferior aspect of the glenoid that often remains asymptomatic.➤Instability symptoms related to glenoid dysplasia may develop over time with increased activities or trauma. Physical therapy focusing on rotator cuff strengthening and proprioceptive control should be the initial management.➤Magnetic resonance imaging and computed tomographic arthrograms are useful for detecting subtle glenoid dysplasia by revealing the presence of an abnormally thickened or hypertrophic posterior part of the labrum, increased capsular volume, glenoid retroversion, and posteroinferior glenoid deficiency.➤Open and arthroscopic labral repair and capsulorrhaphy procedures have been described for symptomatic posterior shoulder instability. Glenoid retroversion of >10° may be a risk factor for failure following soft-tissue-only procedures for symptomatic glenoid dysplasia.➤Osseous procedures are categorized as either glenoid reorientation (osteotomy) or glenoid augmentation (bone graft), and no predictable results have been demonstrated for any surgical strategy. Glenoid osteotomies have been described for increased retroversion, with successful results, although others have noted substantial complications and poor outcomes.➤In severe glenoid dysplasia, the combination of bone deficiency and retroversion makes glenoid osteotomy extremely challenging. Bone grafts placed in a lateralized position to create a blocking effect may increase the risk of the development of arthritis, while newer techniques that place the graft in a congruent position may decrease this risk.

Glenoid Dysplasia

Glenoid dysplasia is a developmental anomaly of the scapula that is characterized by a bony deficiency of the posteroinferior glenoid and the adjacent scapular neck. Glenoid dysplasia may occur as a primary isolated condition or in association with various syndromes. It is thought to be related to defective ossification of the inferior glenoid precartilage. Radiographs typically demonstrate bilateral, symmetric dysplasia of the scapular neck with a range of associated bony changes. Glenoid dysplasia has been associated with instability and premature glenohumeral arthritis, although the clinical presentation is highly variable. Symptoms are delayed or mitigated as a result of compensatory glenoid labral hyperplasia. The treatment of glenoid dysplasia remains challenging. Nonsurgical treatment is reasonably successful in younger patients, but premature degenerative changes frequently occur. Although favorable results can be obtained with the use of anatomic arthroplasty, continued subluxation and glenoid component failure can lead to unacceptable outcomes.

Unilateral glenoid hypoplasia: a case report and review of the literature

Glenoid hypoplasia is a relatively rare alteration that in most cases involves the pectoral girdle in a bilateral and symmetrical manner. In general, glenoid hypoplasia is associated with skeletal changes such as hypoplasia of the humeral head or changes in the morphology of the acromion and of the coracoid. We describe a rare case of unilateral glenoid hypoplasia without instability and not involving humeral head. The patient was managed effectively with nonoperative measures that featured specific rehabilitation exercises for the shoulder.

Imaging findings in posterior instability of the shoulder

Posterior shoulder instability refers to the symptoms and signs resulting from excessive posterior translation of the humerus. Magnetic resonance (MR) imaging is the radiological modality of choice in the diagnostic assessment of posterior instability. Computed tomography (CT) is useful in the evaluation of osseous abnormalities associated with posterior instability. A detailed description of the posterior osseous and labroligamentous abnormalities has evolved recently, and many variant lesions of the posteroinferior labrum and/or capsular structures have been described. As the recommended surgical management of lesions associated with posterior instability is a lesion-specific approach, awareness of the specific lesions that have been described in association with posterior instability helps in pre-surgical planning. The purpose of this article is to review the classification of, and injury mechanisms leading to, posterior shoulder instability and to describe imaging findings associated with posterior instability, with emphasis on MR imaging.

Hypoplasia of the Glenoid Neck of the Scapula

OBJECTIVE

Our purpose was to describe the primary and associated imaging findings in patients with glenoid hypoplasia required for an accurate diagnostic appraisal of this uncommon abnormality.

METHODS

The medical records and imaging studies of 16 patients with glenoid hypoplasia were retrospectively reviewed. Plain films were available in all patients, arthrography in 2, computed tomography (CT) in 5, CT arthrotomography in 3, magnetic resonance (MR) imaging in 9, and MR arthrography in 3 patients. The imaging studies were reviewed with special attention to the primary and secondary findings associated with glenoid hypoplasia.

RESULTS

On radiographs, the 21 abnormal shoulders documented in the 16 patients with glenoid hypoplasia had an irregular (n=15) or shallow and smooth (n=6) articular surface of the glenoid. Computed tomography findings showed subluxation of the humeral head in 5 cases. On MR images, the hypoplastic bony glenoid and scapular neck were replaced by abnormal tissue of inhomogeneous signal intensity, showing the signal intensity characteristics of fibrocartilage (n=6) or fat (n=5). Widening of the inferior glenohumeral joint space was seen in all cases. Magnetic resonance imaging or MR arthrography revealed variable abnormalities of the labrum, including enlargement (10 shoulders), detachment of labrum from the bony glenoid (6 shoulders), intrasubstance tear (4 shoulders), and perilabral cyst (2 shoulders). The posterior labrum was absent (n=1) or torn (n=1) in one patient with bilateral deformity. Other findings included partial tear of the subscapularis tendon (n=1) and rotator cuff atrophy (n=1) and tear (n=2).

CONCLUSION

Glenoid hypoplasia is a developmental skeletal anomaly comprising a spectrum of associated osseous and cartilaginous changes of the articular cartilage and glenoid labrum. Cross-sectional imaging studies, with or without arthrography, may help further characterize associated derangements of the shoulder, some of which are indicative of shoulder instability.

Glenoid Dysplasia: Radiographic, Direct MR Arthrographic and Arthroscopic Appearances

Glenoid dysplasia is an uncommon developmental abnormality of the scapula that is frequently overlooked. We report a case of severe glenoid dysplasia in a 55 year old man and demonstrate its radiographic, direct MR arthrographic and arthroscopic appearances.

Glenoid Dysplasia: Incidence and Association with Posterior Labral Tears as Evaluated on MRI

OBJECTIVE

Glenoid dysplasia is known to predispose affected patients to accelerated degenerative joint disease. We have observed that there is often an association between glenoid dysplasia and posterior labral tears. Our goal was to assess glenoid dysplasia as seen on MRI and to assess its association with posterior labral tears.

CONCLUSION

In our study population, we found that moderate to severe glenoid dysplasia is not a rare entity as seen on MRI, with an incidence of 14.3%. Furthermore, we found that there is a statistically significant increase in the incidence of posterior labral tears associated with shoulders with moderate or severe glenoid dysplasia compared with those shoulders with no dysplasia or mild dysplasia as evaluated on MRI. Even when the mild cases were included, the incidence of posterior labral tears was significantly increased versus healthy subjects, indicating that even mild cases of glenoid dysplasia may be clinically relevant.

Clinically significant skeletal variations of the shoulder and the wrist: role of MR imaging

Several skeletal variations of the upper extremity may cause painful conditions or precipitate early degenerative changes, either spontaneously or in response to overuse and trauma. Magnetic resonance imaging has proved particularly useful for accurate interpretation of many of these clinically significant skeletal variations; however, the widespread use of MR imaging may have contributed to over-emphasizing their clinical importance, which is still controversial in many cases. We review, illustrate, and discuss clinically significant skeletal variations of the upper extremity as seen on MR images, particularly those involving the shoulder and the wrist. In the shoulder region, we evaluate variations of acromial and coracoid processes as well as variations and minor dysplastic deformities of the glenoid fossa. We also review different skeletal variations of the carpal region, including ulnar variance, ulnar styloid, lunate morphology, carpal coalition, and carpal accessory ossicles. The role of MR imaging in assessing the clinical importance of such conditions, whether potential, controversial, or well established, is emphasized in this review.