Comparison of measurements of the glenopolar angle in 3D CT reconstructions of the scapula and 2D plain radiographic views

The Critical Shoulder Angle Can be Accurately and Reliably Determined from Three-Dimensional Computed Tomography Images

OBJECTIVE

Anteroposterior (AP) radiographs do not necessarily offer the optimal approach to measuring the critical shoulder angle (CSA) due to the malposition of the scapula. Three-dimensional computed tomography (3D-CT) may offer some advantages, including the ability to rotate the scapula for position alignment and pre-operative planning for reducing CSA. This study aimed to investigate the accuracy and reliability of CSA measurement in 3D-CT and to determine whether there is an association between CSA and rotator cuff tears (RCTs).

METHODS

In this retrospective study we identified 200 patients who received shoulder arthroscopy from 2019 to 2021, including 142 patients (81 females, 61 males) with RCTs and 58 patients (14 females, 44 males) with non-RCTs. For each participant, CSA was measured from standard shoulder AP radiographs and anterior views of 3D-CT of the scapula by two independent assessors. Inter- and intra-observer agreements were assessed by the intraclass correlation coefficient (ICC). The relationship between the two measurement methodologies was determined by Spearman's correlation coefficient and Bland-Altman plots. Discriminative capacity was calculated by using receiver operating curve (ROC) analyses in the whole cohort and age sub-groups above and below 45 years.

RESULTS

We found perfect inter-observer (ICC >0.96) and intra-observer (ICC >0.97) reliabilities for CSA measurements obtained from the standard AP radiographs and the 3D-CT. There was a strong correlation between the two methods (r = 0.960, P < 0.001). The mean CSA was 31.7° ± 4.2° in the standard AP radiographs and 31.8° ± 4.4° in the 3D-CT (mean difference 0.02°, P = 0.940; bias 0.02°, limits of agreement -2.29° to +2.33°). ROC analysis of the whole cohort showed that the CSA measured in the standard AP radiographs (area under the ROC curve [AUC] = 0.812, P < 0.001) and the 3D-CT (AUC = 0.815, P < 0.001) predicted RCT with high confidence. ROC analysis of patients aged ≥45 years showed that the CSA measured from the standard AP radiographs (AUC = 0.869, P < 0.001) and the 3D-CT (AUC = 0.870, P < 0.001) were very good at predicting RCTs.

CONCLUSION

CSA measured from standard AP radiographs and 3D-CT showed high consistency, and the CSA could be accurately and reliably measured using 3D-CT. CSAs measured from standard AP radiographs and 3D-CT could predict RCTs, especially in patients aged ≥45 years.

Impact of aberrant beam paths on antero-posterior shoulder radiographs in proximal humeral fractures

INTRODUCTION

Accurate radiographic assessment of proximal humeral fractures (PHF) is important as it influences clinical decision-making and predicts clinical outcome. Since aberrant radiographic views might influence the assessment of fracture displacement, it was the goal of this study to investigate the impact of aberrant beam paths on radiographic assessment of PHF.

MATERIALS AND METHODS

Ten consecutive patients with a displaced PHF, bilateral computed tomography (CT) scan, and a true clinical AP radiograph were included. Digitally reconstructed radiographs (DRRs) were generated and aberrant beam paths were simulated by rotation of ± 30° around the horizontal (flexion and extension) and vertical axis (internal and external rotation) by increments of 10°. Measurement of the neck-shaft-angle (NSA) and eccentric head index (EHI) addressed humeral angulation and offset, respectively. Paired comparisons determined the influence of aberrant beam paths on both measurements between incremental altered views, and between clinical and digital true AP views. Descriptive statistics assessed the change in Neer classification and recommended treatment.

RESULTS

True AP DRRs approximated the clinical true AP view by a mean difference of 2° for NSA, and a mean difference of 0.12 for EHI. NSA in injured shoulders was most susceptible to malrotation around the vertical axis (p < 0.03), with largest differences seen for internal rotation. Aberrant projections in extension had no influence on NSA (p > 0.70), whereas flexion of ≥ 20° and 30° demonstrated differences in injured and uninjured shoulders, respectively (p < 0.05). EHI was only influenced by malrotation in internal rotation in uninjured shoulders (p < 0.03). Alterations in Neer type occurred at 30° of malrotation in 5 cases, with a change in recommended treatment in 2.

CONCLUSIONS

Humeral angulation and offset measurements on AP radiographs are more susceptible to aberrant beam paths in fractured humeri. Altered radiographic beam paths around the vertical axis showed the most substantial influence on the assessment of PHF, with angular measurements demonstrating larger differences then offset measurements. Beam path alterations of 30° can influence the Neer classification, and might influence fracture displacement-based decisions.

Deep-Learning-Based Segmentation of the Shoulder from MRI with Inference Accuracy Prediction

Three-dimensional (3D)-image-based anatomical analysis of rotator cuff tear patients has been proposed as a way to improve repair prognosis analysis to reduce the incidence of postoperative retear. However, for application in clinics, an efficient and robust method for the segmentation of anatomy from MRI is required. We present the use of a deep learning network for automatic segmentation of the humerus, scapula, and rotator cuff muscles with integrated automatic result verification. Trained on N = 111 and tested on N = 60 diagnostic T1-weighted MRI of 76 rotator cuff tear patients acquired from 19 centers, a nnU-Net segmented the anatomy with an average Dice coefficient of 0.91 ± 0.06. For the automatic identification of inaccurate segmentations during the inference procedure, the nnU-Net framework was adapted to allow for the estimation of label-specific network uncertainty directly from its subnetworks. The average Dice coefficient of segmentation results from the subnetworks identified labels requiring segmentation correction with an average sensitivity of 1.0 and a specificity of 0.94. The presented automatic methods facilitate the use of 3D diagnosis in clinical routine by eliminating the need for time-consuming manual segmentation and slice-by-slice segmentation verification.

Scapular fractures osteosynthesis via Judet's posterior approach: clinical and radiographic results

PURPOSE

Scapular fractures are uncommon and mainly treated nonoperatively. Judet's posterior approach allows access to the fracture site through the infraspinatus fossa and may be a technical option when ORIF is decided. The aims of this study were to determine clinical and radiographic outcomes of patients who underwent scapular body and/or glenoid fractures fixation via Judet's posterior approach.

METHODS

We conducted a retrospective single-centre study, and all patients admitted for scapular fracture who underwent osteosynthesis via Judet's approach between January 2014 and September 2021 were included. At a minimum follow-up of one year, clinical outcomes were analyzed through subjective shoulder value (SSV) and Constant-Murley score (CMS). Strength in external rotation was measured in adduction and in 90° abduction and compared to healthy side. Radiographic analysis evaluated postoperative fracture reduction on CT scan and glenohumeral osteoarthritis according to Samilson's classification at last follow-up.

RESULTS

Twenty-one patients were included with a mean follow-up of 44.9 months. Mean SSV, CMS, and adjusted CMS were 73.8% ± 21.0, 65.8 points ± 19.5, and 72.8% ± 20.8, respectively. Strength in external rotation in adduction of the affected shoulder showed significant impairment when compared with the contralateral side (respectively 7.79 kg ± 4.29 and 12.0 kg ± 3.84, p = 0.02). All fractures healed uneventfully, but five patients (23.8%) required early revision surgery for intra-articular screws in three. Intra-articular gap measure decreased from 3.75 mm ± 1.93 in preoperative to 0.59 mm ± 0.97 after ORIF. The rate of arthritis was 15% at last follow-up.

CONCLUSION

Patients who underwent scapular fracture osteosynthesis via Judet's posterior approach exhibited satisfactory but incomplete recovery of the affected shoulder as evidenced by functional scores and external rotation strength measurements at a mean follow-up of 44.9 months. Because of the risk of intra-articular screws, postoperative CT scan is mandatory.

Computer Image-Guided Precise Acromioplasty for Reducing the Critical Shoulder Angle

The shoulders with critical shoulder angle (CSA) of greater than 33-35° are associated with rotator cuff tears, whereas a CSA of less than 30° is likely to be osteoarthritic. However, anterior acromioplasty or lateral acromioplasty could not reduce high CSAs to the desired range (30-33°), with satisfactory accuracy and efficacy. Thus, we introduce a computer image-guided precise acromioplasty (CIG-PAP) technique, an individualized treatment based on three-dimensional planning. We believe that the introduction of this technique will provide an alternative approach to reduce a large CSA to the desired range (30-33°).

Optimization of the Grashey View Radiograph for Critical Shoulder Angle Measurement: A Reliability Assessment With Zero Echo Time MRI

Background:

Suboptimal positioning on Grashey view radiographs may limit the prognosticating potential of the critical shoulder angle (CSA) for shoulder disorders.

Purpose:

To investigate whether radiography optimized according to the latest research is reliable for measuring CSA in comparison with magnetic resonance imaging (MRI) featuring 3-dimensional (3D) zero echo time (ZTE) sequencing, which accentuates the contrast between cortical bone and surrounding soft tissue with high fidelity.

Study Design:

Cohort study (diagnosis); Level of evidence, 2.

Methods:

Patients with shoulder pain were prospectively and consecutively enrolled. All patients had Grashey view radiographs as well as 3.0-T MRI scans with isotropic 3D ZTE sequencing. Acceptable positioning on the radiographs was determined using the ratio of the transverse to longitudinal (RTL) diameter of the lateral glenoid outline; radiographs with an RTL ≥0.25 were repeated. Two observers independently measured the CSA on the radiographs and the coronal oblique reformatted ZTE images, the latter including verification of measurement points by cross-referencing against images from other planes. Reliability of measurements between observers and modalities was analyzed with the intraclass correlation coefficient (ICC). The paired-samples t test was used to compare the differences between imaging modalities.

Results:

Enrolled were 65 patients (35 female and 30 male; mean age, 40.2 years; range, 25-49 years). Radiographs with optimal positioning (RTL < 0.25) were attained after a mean of 1.6 exposures (range, 1-4); the mean RTL was 0.09 (range, 0-0.20). Interobserver agreement of CSA was excellent for radiographs (ICC = 0.91; 95% CI, 0.84-0.94) and good for ZTE MRI scans (ICC = 0.85; 95% CI, 0.71-0.92). Intermodality agreement of CSA between radiographs and ZTE MRI scans was moderate (ICC = 0.66; 95% CI, 0.48-0.73). The CSA was significantly different between an optimal radiograph (30.7° ± 4.3°) and ZTE MRI scan (31.8° ± 3.8) (P = .005). Subgroup analysis revealed no significant differences in CSA measurement between ZTE MRI scans and Grashey view radiographs with an RTL of <0.1 (P = .08).

Conclusion:

CSA measurement on ZTE MRI scans with anatomic point cross-referencing was significantly different from that on Grashey view radiographs, even with optimal positioning, and radiography may necessitate more than 1 exposure. An RTL of <0.1 ensured reliability of radiographs when other standards of sufficient x-ray exposure were met.

Editorial Commentary: Is Your Critical Shoulder Angle Accurate? Only If You Can Verify That You Have the Correct Images

The critical shoulder angle (CSA) has been the focus of significant research related to the etiology and prognosis of rotator cuff tears in recent years, but the accuracy of CSA measurements on plain anteroposterior (Grashey) radiographs has been questioned. Research to better understand what qualifies as a "tolerable" radiograph for reliable measurement of the CSA can inform best practices for obtaining plain radiographs. Optimal measurements rely on optimal images, and knowing how much room for error there is regarding malrotation provides surgeons with unbiased criteria to rule out inadequate images.

The Ratio of the Transverse to Longitudinal Diameter of the Glenoid Projection Is of Good Predictive Value for Defining the Reliability of Critical Shoulder Angle in Nonstandard Anteroposterior Radiographs

PURPOSE

To investigate (1) whether measurement of the critical shoulder angle (CSA) is still reliable in some nonstandard anteroposterior radiographs; and (2) whether the ratio of the transverse to longitudinal diameter of the glenoid projection (RTL) could be used to determine the reliability of the CSA in nonstandard anteroposterior radiographs.

METHODS

The authors analyzed radiology records from 2017 to 2019 for patients with computed tomography (CT) scans of the shoulder. According to the Suter-Henninger classification system, each CT scan underwent 3-dimensional (3D) reconstructions to obtain 8 digitally reconstructed radiographs (DRRs), including 1 type A1 film and 7 type D1 films with different rotation angles. CSA and RTL were measured on all films, and 2 blinded reviewers evaluated DRRs. The relationship between RTL and CSA was determined by Pearson correlation test. The threshold value was determined by receiver operating characteristic (ROC) analyses using RTL as predictors and defined reliable CSA as criterion in the logistic regression. Intra- and inter-rater reliability were assessed by the intraclass correlation coefficient (ICC). Discriminative capacity was calculated with ROC analyses and area under the curve (AUC). An optimal measurement cutoff with resultant sensitivity and specificity was calculated.

RESULTS

A total of 86 patients were included, mean age 40.70 ± 18.25 years, 19 of whom had rotator cuff tears (RCTs) and 67 without RCTs. Spearman's correlation test revealed that the deviation of CSA was positively correlated with RTL, correlation coefficient 0.544 (P < .001) in all patients and 0.686 (P < .001) only in patients with RCTs. ROC analysis of all patients showed that the AUC of the RTL was 0.90, and the optimal cutoff point was 0.25 (sensitivity 88%, specificity 87%). ROC analysis only of patients with RCTs showed that the AUC of the RTL was 0.95, and the optimal cutoff point was 0.22 (sensitivity 95%, specificity 92%).

CONCLUSION

The ratio of the transverse to longitudinal diameter of the glenoid projection (RTL) is of good predictive value in defining the reliability of the CSA in malposition films. Based on the results, the CSA can be considered reliable if its RTL is <0.25.

LEVEL OF EVIDENCE

III, retrospective cohort study investigating a diagnostic test.

Effect of arthroscopic acromioplasty on reducing critical shoulder angle: a protocol for a prospective randomized clinical trial

Background

The critical shoulder angle (CSA), which helps to predict patients who are at risk of rotator cuff tears (RCTs) with large degree and who are susceptible to osteoarthritis with low angle, has been identified as one of the most vital acromial parameters; anterolateral and lateral acromioplasties have been proven to be valid ways to reduce CSA. However, no study has compared the effect of different acromioplasties on the reduction of the large CSA (≥33°) clinically. Additionally, either anterolateral or lateral acromioplasty could not precisely correct large CSAs to a favorable range (30–33°) in each patient. Thus, we will propose a novel precise acromioplasty technique for the purpose of reducing CSA accurately and effectively, and compare the effectiveness of different acromioplasties on the reduction of the CSA.

Methods

A total of 60 RCT patients who have indications for arthroscopic rotator cuff repair and with pre-operative CSA ≥33° will be recruited in outpatient center of Sun Yat-sen Memorial Hospital. Eligible participants will be randomly allocated to Group A (anterolateral acromioplasty), Group B (lateral acromioplasty) or Group C (precise acromioplasty) via a random, computer-generated number system. Three surgical plans will be made for each participant respectively by one professional surgeon according to the results of randomization allocation. The post-operative CSA will be measured 2 days post-operation. Follow-up will be maintained at 3, 6, and 12 months after surgery including the visual analog scale score, the University of California at Los Angeles score, the Constant Shoulder Score and the American Shoulder and Elbow Surgeon Shoulder Assessment Form. Finally, all outcomes will be assessed by two researchers who are blinded to the recruitment and allocation.

Discussion

This is the first clinical trial to evaluate the impact of different acromioplasties on the reduction of the CSA. Additionally, this study will provide a new precise acromioplasty technique, which is a novel precision and individualized treatment to prevent degenerative RCTs by reducing the CSA.

Trial registration

ChiCTR2000032343. Registered on April 26th, 2020.

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.

[Comparative study of surgical treatments of scapula fracture through the muscle space of rotator cuff approach and Judet approach]

Objective

To study the surgical treatments of scapula fracture through the muscle space of rotator cuff approach and the Judet approach, and to evaluate and compare the clinical results.

Methods

Between January 2014 and December 2015, 50 patients with scapula fractures were treated with open reduction and internal fixation of reconstruction plate. Twenty-four patients were treated through the muscle space of rotator cuff approach (group A), and 26 patients were treated through the Judet approach (group B). There was no significant difference in gender, age, cause of injury, type of fracture, and the interval between injury and operation ( P>0.05). The operation time, intraoperative blood loss, and incision length were recorded, and the shoulder functions after fracture healing confirmed by X-ray films were evaluated according to the Hardegger's scoring system.

Results

The operation time, intraoperative blood loss, and incision length in group A were significantly lower than those in group B ( P < 0.05). The incisions of the two groups healed by first intention. All patients were followed up 6-13 months (mean, 11.6 months) in group A and 7-15 months (mean, 12.1 months) in group B. According to Hardegger standard, the effectiveness was rated as excellent in 19 cases, good in 4 cases, and fair in 1 case, with the excellent and good rate of 95.8% in group A, and as excellent in 15 cases, good in 4 cases, fair in 5 cases, and poor in 2 cases with the excellent and good rate of 73.1% in group B. The difference in effectiveness between 2 groups was significant (χ ²=4.81， P=0.03). X-ray films showed that the reduction and internal fixation were satisfied and the fractures healed in 2 groups. The fracture healing time were (29.86±8.38) weeks in group A and (30.05±7.99) weeks in group B, showing no significant difference between 2 groups ( t=0.16, P=0.87).

Conclusion

Compared with the Judet approach, the muscle space of rotator cuff approach has advantages of clearly exposure, less muscular dissection, less intraoperative blood loss, less operation time, easier operation, and satisfied shoulder function can be obtained.

The Effectiveness of Using the Critical Shoulder Angle and Acromion Index for Predicting Rotator Cuff Tears: Accurate Diagnosis Based on Standard and Nonstandard Anteroposterior Radiographs

PURPOSE

To explore whether the critical shoulder angle (CSA) and acromion index (AI) on nonstandard anteroposterior (AP) radiographs could be used as parameters for rotator cuff tear (RCT) diagnosis and to determine the optimized parameters.

METHODS

This study included 174 patients with RCTs or intact rotator cuffs in whom AP radiographs were obtained at our hospital. The radiographs were assessed by 2 independent radiologists and were grouped according to the Suter-Henninger criteria. The CSA and AI were measured on all films. We performed receiver operating characteristic curve analysis by calculating the area under the curve (AUC) to compare the sensitivity and accuracy of both parameters.

RESULTS

Of the 174 enrolled patients, only 47 (27%) met the requirements for standard AP films (types A1 and C1). On standard AP films, both the CSA and AI were significantly different between the RCT and control groups (P < .001 for CSA and P < .001 for AI), with AUCs of 0.86 and 0.80 for the CSA and AI, respectively. On nonstandard AP films (other radiograph types), the mean CSA value was not significantly different between the RCT and control groups (P = .536) whereas the AI showed a significant difference (P = .024). The AUCs were 0.57 for the CSA and 0.64 for the AI.

CONCLUSIONS

On standard AP films, both the CSA and AI could predict rotator cuff disorders, and the CSA had a higher diagnostic accuracy than the AI. In contrast, on nonstandard AP films, the diagnostic efficacy of the AI was better than that of the CSA. On the basis of this study, we suggest an evaluation of the AP films of patients before diagnosis to confirm whether the AP films meet the criteria for standard AP films.

LEVEL OF EVIDENCE

Level I, diagnostic study.

Guidelines for humeral subluxation cutoff values: a comparative study between conventional, reoriented, and three-dimensional computed tomography scans of healthy shoulders

BACKGROUND

The humeral subluxation index (HSI) is frequently assessed on computed tomography (CT) scans in conditions of the shoulder characterized by humeral displacement. An arbitrarily set HSI cutoff value of 45% for anterior subluxation and 55% for posterior subluxation has been widely accepted. We studied whether mean values and thresholds of humeral subluxation, in relation to the glenoid and scapula, were influenced by different imaging modalities.

METHODS

The HSIs referenced to the scapula (SHSI) and glenoid (GHSI) were compared between conventional CT scans, CT scans reoriented into the corresponding reference plane (ie, scapular plane for the SHSI and glenoid center plane for the GHSI), and 3-dimensional (3D) CT reconstructions of 120 healthy shoulders. The 95% normal range determined the cutoff values of humeral subluxation.

RESULTS

The SHSI thresholds for conventional, reoriented, and 3D CT scans were 33%-61%, 44%-68%, and 49%-61%, respectively. A different mean SHSI was found for each imaging modality (conventional, 47%; reoriented, 56%; 3D, 55%; P ≤ .014), with the conventional SHSI showing an underestimation in 89% of the cases. GHSI thresholds for conventional, reoriented, and 3D CT scans were 40%-61%, 44%-56%, and 46%-54%, respectively. The mean GHSI did not differ between each imaging modality (conventional, 51%; reoriented, 50%; 3D, 50%; P = .146).

CONCLUSIONS

The SHSI and GHSI are susceptible to different imaging modalities with consequently different cutoff values. The redefined HSI cutoff values guide physicians in the evaluation of humeral subluxation in conditions characterized by humeral displacement, depending on the available image data.

How to deal with a glenoid fracture

The glenoid fossa is involved in approximately 10% of all scapular fractures.Glenoid fossa incongruity is surprisingly well tolerated.Surgery is recommended when 20% or more of the anterior glenoid fossa is involved.Glenoid rim fractures often lead to chronic shoulder instability.Unstable glenoid neck fractures need surgical treatment and stable fractures can be treated conservatively.CT examination with 3D reformations of the glenoid fossa has improved insight into fracture morphology and fracture patterns and is very helpful for clinical decision makers. Cite this article: EFORT Open Rev 2017;2. DOI: 10.1302/2058-5241.2.160082. Originally published online at www.efortopenreviews.org.