Magnetic Resonance Imaging of the Glenoid Labrum

Influence of body mass index on severity of rotator cuff tears

BACKGROUND

Research on the relationship between obesity and rotator cuff tears (RCTs) has been limited to the impact of obesity on the results of arthroscopic repair of RCTs; thus, a need for rigorous research controlling for other factors affecting RCTs is warranted, especially to better understand the impact of body mass index (BMI) on RCT severity.

METHODS

A retrospective study of admission records contained in electronic medical records pertaining to patients who were admitted for RCT repair on 1 shoulder between January 2018 and July 2022 was conducted. In total, 386 patients were included. In accordance with guidance regarding obesity from Taiwan's Ministry of Health and Welfare, patients were divided into three groups: underweight or normal weight (BMI <24.0 kg/m2), overweight (BMI 24.0-26.9 kg/m2), or obese (BMI ≥27.0 kg/m2). Magnetic resonance imaging was used to assess RCT severity in terms of four parameters: Patte stage (PS), fatty infiltration (FI), anteroposterior tear size (AP), and retraction size. Multinomial logistic regression analysis was performed on PS and FI grade data, and multiple linear regression analysis was performed on AP tear size and retraction size in order to analyze impact.

RESULTS

Our results revealed that the average age of the 386 patients was 63.41 years (SD = 9.29) and the mean BMI was 25.88 (SD = 3.72) kg/m2. We found significant differences in PS (P = .003), FI (P < .001), retraction size (P = .001), and AP tear size (P = .001) among patients who were underweight or normal weight, overweight, and obese. After controlling for other risk factors, including age, gender, RCT-prone occupation, duration of shoulder pain prior to surgery, history of shoulder injury, and tobacco use, we found that obese patients had higher severity levels in PS (B = 1.21, OR = 3.36, P = .029), FI (B = 1.38, OR = 3.96, P < .001), retraction size (β = 0.18, P = .001), and AP tear size (β = 0.18, P = .001) compared to underweight or normal weight patients.

CONCLUSIONS

Our study demonstrates that a correlation exists between BMI-measured obesity and RCT severity. We therefore suggest that adults control their weight given that maintaining a healthy weight is highly associated with better shoulder health.

Superior labrum anterior to posterior lesions: Part 2 - Classification with arthroscopic correlation

The glenoid labrum deepens the glenoid fossa and allows for the attachment of the long head of the biceps tendon and glenohumeral ligaments, contributing to the stability of the glenohumeral joint. The superior labrum is a common site of labral injury. The acronym SLAP (superior labrum anterior to posterior or anteroposterior) lesion was introduced by Snyder and colleagues in 1990 to describe superior labral tears based on arthroscopic evaluation. This original classification has since been expanded, and there are currently 10 types of SLAP lesions. The article will describe and illustrate the 10 types of SLAP lesions by means of colour illustrations, MRI images and correlative arthroscopy images. A practical approach to the assessment of SLAP lesions will be recommended.

Contribution

The illustrated review functions as a crucial radiological guide for both radiologists and orthopaedic surgeons. The combination of illustrations, MR and correlative arthroscopic images enhances the comprehensive understanding of labral pathology. The value of the review lies in the presentation of imaging findings and classification, coupled with findings on arthroscopy. This understanding is vital in guiding orthopaedic management for patients, ensuring appropriate treatment strategies.

Superior labrum anterior to posterior lesions: Part 1 - Imaging and anatomy with arthroscopic classification

The glenoid labrum deepens the glenoid fossa and allows for the attachment of the long head of the biceps tendon and the glenohumeral ligaments, contributing to the stability of the glenohumeral joint. The superior labrum is a common site of labral injury, especially in athletic activities involving overhead activity. The acronym SLAP (superior labrum anterior to posterior or anteroposterior) lesion was introduced by Snyder and colleagues in 1990 to describe superior labral tears. The article will review the optimal technique to image the glenoid labrum, covering normal labral anatomy with special emphasis on the anatomic variants of the labrum that can be mistaken for SLAP tears by means of colour illustrations, magnetic resonance imaging and correlative arthroscopy images.

Contribution

The illustrated review functions as a crucial radiological guide for both radiologists and orthopaedic surgeons. The combination of illustrations, MR and correlative arthroscopic images enhances the comprehension of normal labral anatomy and its variants. The review underscores the significance of understanding anatomic variations that may be misinterpreted as pathology. This understanding is vital in guiding orthopaedic management for patients, ensuring appropriate treatment strategies.

Imaging of shoulder instability

The shoulder enjoys the widest range of motion of all the joints in the human body, therefore requires a delicate balance between stability and motility. The glenohumeral joint is inclined to fall into two main instability categories: macro and micro. Macroinstability can be traumatic or atraumatic, with anterior or posterior dislocation of the humeral head. Microinstability falls within the broader section of acquired instability in overstressed shoulder caused by repeated joint stress. Anterior traumatic instability is the most frequent entity and a relatively common injury in young and athletic population. While shoulder instability is a clinical diagnosis, imaging impacts the patient management by detailing the extent of injury, such as capsulo-labral-ligamentous tears, fracture, and/or dislocation, describing the predisposing anatomic conditions and guide the therapetic choice. The aim of this comprehensive review is to cover the imaging findings of shoulder instability by different imaging techniques.

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.

Imaging the Glenoid Labrum and Labral Tears

The shoulder joint is the most unstable articulation in the entire human body. While this certainly introduces vulnerability to injury, it also confers the advantage of broad range of motion. There are many elements that work in combination to offset the inherent instability of the glenohumeral joint, but the glenoid labrum is perhaps related most often. Broadly, clinical unidirectional instability can be subdivided into anterior and posterior instability, which usually raise concern for anteroinferior and posteroinferior labral lesions, respectively. In the special case of superior labral damage, potential dislocation is blocked by structures that include the acromion; hence, while damage elsewhere commonly manifests as clinical instability, damage to the superior labrum is often described by the term microinstability. In this particular case, one of the radiologist's main concerns should be classic superior labral anteroposterior lesions. The glenoid labrum is also subject to a wide range of normal variants that can mimic labral tears. Knowledge of these variants is central to interpreting an imaging study of the labrum because misdiagnosis of labral variants as tears can lead to superfluous surgical procedures and decreased shoulder mobility. This article reviews labral anatomy and normal labral variants, describes their imaging features, and discusses how to discriminate normal variants from labral tears. Specific labral pathologic lesions are described per labral quadrant (anteroinferior, posteroinferior, and superior), and imaging features are described in detail. Online supplemental material is available for this article. ^©RSNA, 2016.

Magnetic resonance imaging and clinical features of glenoid labral flap tears

OBJECTIVE

Displaced flaps of glenoid labral tissue are an uncommonly encountered finding on MRI of the shoulder, and are of unclear clinical significance. The purpose of this study is to describe the imaging characteristics of displaced glenoid labral flaps, evaluate for any common concomitant injuries, and identify the typical clinical presentation and management of patients with this lesion.

MATERIALS AND METHODS

This retrospective, observational study was approved by the institutional review board. Nineteen patients with flap-type tears of the labrum on preoperative MRI were identified. Each examination was retrospectively reviewed by two radiologists for size, location, and signal intensity of the displaced flap of tissue, in addition to any co-existing labrum or cartilage pathological conditions and clinical information.

RESULTS

All displaced flaps extended from the inferior margin of the glenoid into the axillary recess. The average size of the visualized flap was 10.9 by 6.0 by 2.6 mm. Seventy percent of the flaps had signal intensity isointense to labrum and hypointense to hyaline cartilage on T2-weighted images. All 19 patients had concomitant labral pathological conditions and 63% had cartilage defects, visualized on MRI. Clinical evidence of shoulder instability was seen in 83% of patients, and 67% were managed surgically.

CONCLUSION

Glenoid labral flap tears have distinct imaging characteristics that may aid in their identification. Their presence should prompt careful evaluation of the glenoid articular cartilage. Recognition of a labral flap tear may have clinical importance, as 83% of patients with this finding demonstrated clinical evidence of shoulder instability, often requiring surgical intervention.