Image-Based Numerical Analysis for Isolated Type II SLAP Lesions in Shoulder Abduction and External Rotation

The glenohumeral joint (GHJ) is one of the most critical structures in the shoulder complex. Lesions of the superior labral anterior to posterior (SLAP) cause instability at the joint. Isolated Type II of this lesion is the most common, and its treatment is still under debate. Therefore, this study aimed to determine the biomechanical behavior of soft tissues on the anterior bands of the glenohumeral joint with an Isolated Type II SLAP lesion. Segmentation tools were used to build a 3D model of the shoulder joint from CT-scan and MRI images. The healthy model was studied using finite element analysis. Validation was conducted with a numerical model using ANOVA, and no significant differences were shown (p = 0.47). Then, an Isolated Type II SLAP lesion was produced in the model, and the joint was subjected to 30 degrees of external rotation. A comparison was made for maximum principal strains in the healthy and the injured models. Results revealed that the strain distribution of the anterior bands of the synovial capsule is similar between a healthy and an injured shoulder (p = 0.17). These results demonstrated that GHJ does not significantly deform for an Isolated Type II SLAP lesion subjected to 30-degree external rotation in abduction.

Shoulder Magnetic Resonance Arthrography with the Internal and External Rotation Positions of the Humeral Head in the Evaluation of SLAP Lesions

We aimed to evaluate the diagnostic performance of shoulder MR arthrography (MRA) acquired in the neutral (N), internal rotation (IR), and external rotation (ER) positions of the shoulder to detect SLAP lesions. Three observers evaluated 130 MRAs to detect SLAP lesions and to calculate labral diastasis in this triple-blinded study. Sensitivity was much higher in the ER (92.5–97.5%) than in the N (60–72.5%) and IR (42.5–52.5%) positions, and the specificity of all the reviewers was 100% in all the positions. The diagnostic accuracy was higher in the ER too (97.7–99.2%). The diastasis length was significantly higher in the ER (median = 2.5–2.8 mm) than in the N (1 mm) and IR (0 mm) positions and was also significantly higher in those patients requiring surgery (p = 0.001). The highest inter-rater agreement values were observed in the ER both in SLAP detection (k = 0.982) and the diastasis length evaluation (ICC = 0.962). The diastasis length threshold in the ER that best separated the patients who did and did not require surgery was 3.1 mm (AUC = 0.833). In 14.6% of the cases, ER enabled the detection of SLAP lesions not identified in the N position. MRA with the ER improves the diagnosis of SLAP lesions and, together with the IR position, provides additional dynamic information about the diastasis of the lesions. It is recommended to perform additional ER and IR scans in the shoulder MRA protocol.

Magnetic resonance-guided direct shoulder arthrography for the detection of superior labrum anterior-posterior lesions using an open 1.0-T MRI scanner

Purpose

Direct magnetic resonance arthrography (MRA) offers increased diagnostic accuracy compared to conventional magnetic resonance imaging (MRI) in the detection of superior labrum anterior-posterior (SLAP) lesions. The aim of the present study was to present the technique of magnetic resonance-guided direct shoulder arthrography (MDSA), to evaluate the diagnostic value of this novel MRA procedure to detect SLAP lesions in comparison to the currently practiced MRI, and to correlate the radiological findings to the respective arthroscopic findings.

Material and methods

Fifty-six patients with clinical signs of a SLAP lesion underwent both MRI examination and MDSA prior to arthroscopic surgery. The MRI of both interventions were compared with the arthroscopic findings. Statistical analysis was performed using the McNemar test.

Results

Sensitivity, specificity, and accuracy for detecting SLAP lesions were 23%, 88%, and 54% on MRI and 80%, 81%, and 80% on MDSA, respectively. Sensitivity (p < 0.001) and accuracy (p = 0.001) in detection of SLAP lesions were significantly higher by MDSA whereas accuracy showed no significant differences (p = 0.625).

Conclusions

The MDSA can be performed in an open 1.0-T MRI scanner with a high level of technical success and a reasonable methodical effort. The modification of MRA provides the requirements as a practicable routine shoulder magnetic resonance examination including arthrography to detect SLAP lesions. The diagnostic value is significantly better than MRI examinations without included arthrography, which currently predominates the clinical practice to investigate shoulder pathology.

What can the Radiologist do to Help the Surgeon Manage Shoulder Instability?

Imaging of the shoulder forms an important adjunct in clinical decision making in patients with shoulder instability. The typical lesions related with classic anterior and anteroinferior shoulder dislocation are an anteroinferior labral avulsion with or without bony fragment of bone loss – a (bony) Bankart lesion – and a posterolateral humeral head impaction fracture – the Hill-Sachs lesions. These are relatively straightforward to identify on imaging, although normal variants of the inferior labrum and variants of labral damage may cause confusion. Other capsuloligamentous lesions, often associated with less typical types of instability, are much more difficult to identify correctly on imaging, as they occur in the anterosuperior part of the glenohumeral joint with its many normal variants or because they result in more subtle, and therefore easily overlooked, changes in morphology or signal intensity. This paper aims at describing the appearance of the normal and pathologic glenohumeral joint related to shoulder instability. Ample reference will be given as to why identification of abnormalities, whether normal or pathologic, is important to the surgeon facing a treatment decision.

Magnetic resonance imaging evaluation of meniscoid superior labrum: normal variant or superior labral tear

Objective

The objective of this study was to determine the incidence of a "meniscoid" superior labrum.

Materials and Methods

This was a retrospective analysis of 582 magnetic resonance imaging examinations of shoulders. Of those 582 examinations, 110 were excluded, for a variety of reasons, and the final analysis therefore included 472 cases. Consensus readings were performed by three musculoskeletal radiologists using specific criteria to diagnose meniscoid labra.

Results

A meniscoid superior labrum was identified in 48 (10.2%) of the 472 cases evaluated. Arthroscopic proof was available in 21 cases (43.8%). In 10 (47.6%) of those 21 cases, the operative report did not include the mention a superior labral tear, thus suggesting the presence of a meniscoid labrum. In only one of those cases were there specific comments about a mobile superior labrum (i.e., meniscoid labrum). In the remaining 11 (52.4%), surgical correlation demonstrated superior labral tears.

Conclusion

A meniscoid superior labrum is not an infrequent finding. Depending upon assumptions and the requirement of surgical proof, the prevalence of a meniscoid superior labrum in this study was between 2.1% (surgically proven) and 4.8% (projected). However, superior labral tears are just as common and are often confused with meniscoid labra.

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.

Pitfalls in shoulder MRI: part 1--normal anatomy and anatomic variants

OBJECTIVE

The purpose of this article is to review frequently encountered pitfalls as they pertain to normal and variant anatomy of the shoulder, including the rotator cuff and rotator cable, blood vessels, glenoid labrum, and the glenohumeral ligaments.

CONCLUSION

MRI is the preferred method for evaluating internal derangement of the shoulder. Radiologists interpreting MR images should have a detailed understanding of pertinent anatomy and knowledge of common and uncommon pitfalls to avoid during image interpretation.

Diagnostic performance of magnetic resonance arthrography of the shoulder in children

BACKGROUND

No reported data demonstrate the usefulness of magnetic resonance arthrography of the shoulder in children.

OBJECTIVE

To evaluate the sensitivity, specificity and accuracy of MR arthrography in the assessment of superior labral anteroposterior (SLAP) tears of the shoulder, Bankart-type injuries and Hill-Sachs lesions in children as compared to arthroscopy.

MATERIALS AND METHODS

We retrospectively interpreted 66 MR arthrograms of the shoulder and compared them with surgical findings. Assessment included evaluation of the osseous structures, labral-ligamentous complex and determination of skeletal maturity. We calculated sensitivity, specificity and accuracy and compared sensitivity and specificity between skeletally mature and immature children.

RESULTS

MR arthrography demonstrated a sensitivity, specificity and accuracy of 88%, 98% and 94%, respectively, for depiction of SLAP tears; 94%, 92% and 94% for detection of Bankart-type injuries; and 100%, 94% and 97% for diagnosing Hill-Sachs lesions. There was no statistical difference between the skeletally immature and skeletally mature groups.

CONCLUSION

There is no significant difference in the diagnostic accuracy of MR arthrography in skeletally immature versus skeletally mature children. MR shoulder arthrography is an effective method for the detection of labral and bone pathology.

Arthroscopic reconstruction of shoulder's labrum with extensive tears

BACKGROUND

With the continuous development of arthroscopic techniques, the majority of superior labrum anterior-posterior (SLAP) lesions can be treated with minimally invasive endoscopic repair. The aim of this study was to determine the efficacy of arthroscopic capsulolabral reconstruction of SLAP lesions with extensive tears.

METHODS

Eighteen patients with SLAP lesions with extensive tears (median age, 27.50 years) were included in this study. Twelve patients had type-V SLAP lesions, 4 patients had type-VIII SLAP lesions, and 2 patients had deeply located SLAP lesions. The average duration of follow-up was 15.83 months (range, 11-22 months). Outcome measures included shoulder range of motion (ROM), American Shoulder and Elbow Surgeons (ASES) and Constant-Murley scores, and visual analogue scale (VAS) pain score.

RESULTS

After arthroscopic surgery, shoulder forward flexion, shoulder external rotation, and external rotation in 90° of abduction were significantly greater than before surgery (169.5° vs. 165.5°, P = 0.001), (90° vs. 63.5°, P < 0.001), and (90° vs. 81.5°, P = 0.004), respectively. Median ASES and Constant-Murley scores after surgery were both 94 as compared to 77.0 and 77.5, respectively, before surgery (both, P < 0.001). The median VAS score decreased to 1.5 after surgery as compared to 6 before surgery (P < 0.001).

CONCLUSIONS

Arthroscopic repair of SLAP lesions with extensive tears can achieve good outcomes.

Sublabral clefts and recesses in the anterior, inferior, and posterior glenoid labrum at MR arthrography

PURPOSE

To determine the prevalence of a normal variant cleft/recess at the labral-chondral junction in the anterior, inferior, and posterior portions of the shoulder joint.

MATERIALS AND METHODS

One hundred and three consecutive patients (106 shoulders) who had a direct MR arthrogram followed by arthroscopic surgery were enrolled in this IRB-approved study. Scans were carried out on a 1.5-T scanner with an eight-channel shoulder coil. The glenoid rim was divided into eight segments and the labrum in all but the superior and anterosuperior segments was evaluated by two radiologists for the presence of contrast between the labrum and articular cartilage. We measured the depth of any cleft/recess and correlated the MR findings with surgical results. Generalized estimating equation models were used to correlate patient age and gender with the presence and depth of a cleft/recess, and Cohen's kappa values were calculated for interobserver variability.

RESULTS

For segments that were normal at surgery, a cleft/recess was present within a segment on MR arthrogram images in as few as 7 % of patients (within the posteroinferior segment by observer 1), and in up to 61 % of patients (within the posterosuperior segment by observer 1). 55-83 % of these were only 1 mm deep. A 2- to 3-mm recess was seen within 0-37 % of the labral segments, most commonly in the anterior, anteroinferior, and posterosuperior segments. Age and gender did not correlate with the presence of a cleft/recess, although there was an association between males and a 2- to 3-mm deep recess (p = 0.03). The interobserver variability for each segment ranged between 0.15 and 0.49, indicating slight to moderate agreement.

CONCLUSION

One-mm labral-chondral clefts are not uncommon throughout the labrum. A 2- to 3-mm deep smooth, medially curved recess in the anterior, anteroinferior or posterosuperior labrum can rarely be seen, typically as a continuation of a superior recess or anterosuperior labral variant.

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.