Supraspinatus outlet view in the diagnosis of stages II and III impingement syndrome

Automated detection and classification of the rotator cuff tear on plain shoulder radiograph using deep learning

BACKGROUND

The diagnosis of rotator cuff tears (RCTs) using radiographs alone is clinically challenging; thus, the utility of deep learning algorithms based on convolutional neural networks has been remarkable in the field of medical imaging recognition. We aimed to evaluate the diagnostic performance of artificial intelligence (a deep learning algorithm; a convolutional neural network) to detect and classify RCTs using shoulder radiographs, and compare its diagnostic performance with that of orthopedic surgeons.

METHODS

A total of 1169 plain shoulder anteroposterior radiographs (1 image per shoulder) were included in the total dataset and divided into four groups: intact, small, medium, and large to massive tear groups. The sensitivity, specificity, positive predictive value, negative predictive value, accuracy, and area under the receiver operating curve were measured for the detection of RCTs through binary classification. The average accuracy, recall, precision, and F1-score were divided into four groups by cuff tear size for multiclass classification.

RESULTS

The convolutional neural network demonstrated a high performance, with 92% sensitivity, 69% specificity, 86% accuracy, and an area under the receiver operating curve of 0.88 for the detection of RCTs. The average accuracy, recall, precision, and F1-score of the convolutional neural network for classification were 60%, 0.42, 0.49, and 0.45, respectively. The accuracy of the convolutional neural network for the detection and classification of RCTs was significantly better than that of orthopedic surgeons.

CONCLUSION

The convolutional neural network demonstrated the diagnostic ability to detect and classify RCTs using plain shoulder radiographs, and the diagnostic performance exhibited equal to superior accuracy when compared with those of shoulder experts.

Viewing perspective malrotation influences angular measurements on lateral radiographs of the scapula

BACKGROUND

Accurate and reliable assessment of acromial tilt (ATA) and slope (ASA) angles have been important in the clinical evaluation of degenerative and traumatic rotator cuff tears. This study analyzed the influence of radiographic viewing perspective on the ATA and ASA and developed criteria to identify true lateral (TL) view radiographs.

METHODS

Three-dimensional computed tomographic (CT) reconstructions of 52 scapulae without rotator cuff tears or osteoarthritis were studied. Digitally reconstructed radiographs (DRRs) were aligned to obtain a TL view. In 10 random scapulae, incremental ante- and retroversion and up- and downward rotation views were generated (10° increments, ±30°), and ATA and ASA were measured by 2 observers. Clinically applicable criteria were developed and validated to identify TL views.

RESULTS

The mean ATA and ASA on TL views were 33°±4° (range 23°-42°) and 22°±7° (8°-43°), respectively. Mixed effect models showed that DRRs malpositioned in 20° and 30° anteversion and downward rotation decreased the ATA (P ≤ .030). DRRs malpositioned in anteversion and >10° of up- and downward rotation demonstrated a significantly decreased ASA (P ≤ .047). Intra- and interobserver reliability was excellent for TL views (intraclass correlation coefficient ≥ 0.95) but decreased with increasing viewing angle. Anatomic landmark criteria were capable of identifying TL-view radiographs with sensitivity of 81% and specificity of 82%.

CONCLUSION

Both ATA and ASA were significantly affected by malposition in anteversion and downward rotation of the scapula. Reliable ASA measurement was more susceptible in up- and downward rotation than the ATA. New visual criteria can identify TL-view radiographs and should be used in future studies to ensure consistency in ATA and ASA measurement.

The correlation of supraspinatus outlet view with computed tomography for visualization of the anterior acromial undersurface

INTRODUCTION

Understanding the real shape of the undersurface of the acromion prior to acromioplasty is indispensable. Today, Supraspinatus outlet view (SSOV) is a standard view used to determine the shape of the anterior acromion. Three types of acromial undersurface were described by Bigliani and Morrison. The purpose of this study was to find out whether the real acromial type can be visualized on X-ray SSOV and compare the shape of the anterior undersurface of the acromion visualized on SSOV, with the shape revealed on 2D CT reconstructions.

METHODS

The SSOV X-rays and CT scans of 30 consecutive patients suffering from rotator cuff dysfunction were retrospectively analyzed. The shape of the acromion visualized on plain X-rays was classified according to Bigliani and Morrison classification system. Two-dimensional CT reconstructions were performed, reproducing the lateral, middle, and medial sections of the acromion. The acromial type that was visualized on each of those reconstructions was separately classified according to the Bigliani and Morrison system. A complete profile of the acromial undersurface was constructed from the integration of acromial types seen on each CT section. The acromial morphology seen on X-rays and CTs was compared.

RESULTS

A total of 30 patients comprised the study cohort; mean age was 57 (STD = 8.5) years. Three Type I, 22 Type II, and 5 Type III acromions were visualized on the SSOV X-rays. CT reconstructions revealed seven different morphological acromial profiles (I,I,I; I,II,II; I,II,III, etc.), which we divided into 3 groups: (1) Uniform (30%), (2) Internally curved (20%), and (3) Internally hooked (50%). The acromial type visualized on X-ray correlated with the acromial type on at least one CT section in all of the cases. In the case of uniform acromial profile, there is a full correlation between the acromial type visualized on X-rays and the type visualized on CT. In non-uniform profiles, there was an incomplete correlation between the types of the acromion visualized on SSOV and CT. SSOV X-rays correlated with or underestimated, but never overestimated, the acromial morphological type.

DISCUSSION

The curved or hooked portion of the acromial undersurface is not always visualized on the SSOV. On X-rays, the middle and lateral sections are seen more accurate than the medial section.

CONCLUSION

Surgeons should be aware that SSOV X-rays may underestimate the true type of the acromial undersurface.

Differences in acromial morphology of shoulders in patients with degenerative and traumatic supraspinatus tendon tears

PURPOSE

Distinct characteristics of acromial morphology seem to be one factor for the development of degenerative supraspinatus tendon tears. Thus, it is questionable whether patients with traumatic tendon tears also present these parameters. The hypothesis of the present study was that the acromial morphology of patients with degenerative supraspinatus tendon tears differs from patients with traumatic tears.

METHODS

One hundred and thirty-six patients that were treated by arthroscopic rotator cuff repair from 2010 to 2013 were included in this study. Seventy-two patients had degenerative (group 1), and 64 had traumatic (group 2) supraspinatus tendon tears. On preoperative radiographs the Bigliani type, acromial slope, acromiohumeral (AH) distance, lateral acromial angle (LAA), acromion index (AI), and critical shoulder angle (CSA) were measured. Medians of these parameters as well as of age of both groups were compared using the t test.

RESULTS

The percentaged distribution of the Bigliani type differed (group 1 vs. 2: type 1: 18/38, type 2: 56/55, type 3: 26/8). All parameters showed significant differences between degenerative and traumatic tears. Slope: 21.2° (SD 7.6°) versus 19.2° (SD 7.9°, p = 0.026), AH distance: 8.4 mm (SD 2.3 mm) versus 9.9 mm (SD 1.9 mm, p = 0.0006), LAA: 77.0° (SD 4.0°) versus 82.5° (SD 4.7°, p < 0.0001), AI: 0.77 (SD 0.07) versus 0.73 (0.06, p = 0.0239), and CSA: 36.8° (SD 3.6°) versus 35.3° (SD 2.9°, p = 0.007). An LAA <70° or an AH distance of <5 mm only occurred in degenerative tears. Patients with degenerative tears were significantly older (60 vs. 54 years).

CONCLUSIONS

The hypothesis that the acromial morphology of patients with degenerative supraspinatus tendon tears differs from patients with traumatic tears was confirmed. Shoulders with degenerative tears show a narrower subacromial space and a larger lateral extension as well as a steeper angulation of the acromion than with traumatic tears. Thus, the results of this study support the theory of external impingement as a cause for degenerative rotator cuff tears.

LEVEL OF EVIDENCE

IV.

Analysis on the acromial curvature and its relationships with the subacromial space and types of acromion

Objective

To correlate the acromial curvature, using the angles proposed, with the subacromial space and types of acromion.

Methods

Ninety scapulas were studied. The acromia were classified as types I, II or III. The acromial curvature was analyzed by means of the alpha, beta and theta angles. We also measured the distance between the anteroinferior extremity of the acromion and the supraglenoid tubercle (DA). The scapulas were grouped in relation to sex and age. The angles proposed were analyzed in relation to each type of acromion and also in relation to the measurements of the distance DA.

Results

Out of the total number of acromia, 39 (43.3%) were type I, 43 (47.7%) type II and eight (9%) type III. The mean ages for each type of acromion (I–III) were 45.6, 55.2 and 51.1 years, respectively. The proportions of the different types of acromion varied in relation to sex and age. The evaluations on the mean beta angle (p = 0.008) and theta angle (p = 0.028), with comparisons in relation to each type of acromion and measurements of the distance DA (p = 0.037), were shown to be statistically significant.

Conclusion

The angles proposed in our study can be used for morphometric analysis on the acromion, especially regarding its curvature, and can contribute towards studies on diseases of the shoulder and aid in surgical planning and analysis of the acromial slope, by means of radiography or magnetic resonance.

New light on old shoulders: palaeopathological patterns of arthropathy and enthesopathy in the shoulder complex

Rotator cuff disease represents the most common cause of modern shoulder pain and disability. Much of the clinical literature on rotator cuff disease focuses on subacromial impingement and supraspinatus tendinopathy, although other patterns of lesions are also recognised. Rotator cuff disease has received relatively little attention in palaeopathological literature, but signs relating to subacromial impingement have been reported. Given the variety and patterns of lesions that are recognized clinically as rotator cuff disease, this study aimed to investigate whether a similarly wide range of lesions could be identified in human skeletal remains. Degenerative changes in surfaces around the shoulder were recorded in a sample of 86 skeletons. The resultant data were assessed using both simple descriptive statistics and exploratory factor analysis. Degenerative changes characteristic of modern subacromial impingement formed a minor underlying pattern in the data. The predominant underlying variable in the data represented an association between lesser tuberosity, bicipital sulcus and glenohumeral degenerative changes. This pattern reflects recent reports in the clinical literature highlighting the prevalence of subscapularis tendinopathy, and also supports a pathoaetiological model of progression from subscapularis to long head of biceps to glenohumeral involvement. The degenerative changes seen at the non-articular, fibrocartilaginous entheses on the humeral tuberosities were similar to those seen in subchondral bone in osteoarthritis.

Local pressures in the subacromial space

We recorded pressures in the subacromial space with various degrees of humeral abduction. The recordings were made during open surgery and under general anaesthesia using a 2-mm-thick piezo-electric pressure transducer. The pressures were recorded in 14 patients with shoulder impingement syndrome (Neer's stage II) and in eight patients with acromioclavicular dislocation serving as controls. The pressures were higher in the impingement group than in the control group. In both groups the highest pressures were recorded antero-laterally under acromion. In patients with impingement syndrome, the pressures increased significantly with abduction.