Evaluation of three-dimensional acromiohumeral distance in the standing position and comparison with its conventional measuring methods

Are acromiohumeral distance measurements on conventional radiographs reliable? A prospective study of inter-method agreement with ultrasonography, and assessment of observer variability

OBJECTIVES

This study aims to investigate the reliability of acromiohumeral distance (AHD) measurements using conventional radiographs and to compare non-standardized and standardized radiographs with intra-/interobserver reliability measurements.

PATIENTS AND METHODS

Between February 2021 and January 2022, a total of 110 shoulders of 55 patients (25 males, 30 females; mean age: 49.7±12.6 years; range, 25 to 77 years) were included. Radiographs were taken in four different positions: primarily shoulder anteroposterior (AP), true AP, standardized true AP, and standardized outlet views. The AHD was measured by three orthopedists. A prospective ultrasonography (US) evaluation was performed by an experienced physiatrist, and the relationship between US and radiographic measurements was evaluated. The intra- and interobserver reliability of radiographic measurements was assessed.

RESULTS

On the standardized true AP view measurements, all observers showed a moderate to good agreement with US measurements (intraclass correlation coefficients [ICC]: 0.68-0.75). There was no significant difference between the AHD measurements of the senior orthopedist on standardized true AP and outlet views, and the US measurements. The intraobserver agreement of US measurements was excellent (ICC: 0.98, 95% confidence interval [CI]: 0.98-0.99), and the intraobserver agreement level of measurements on radiographs were good to excellent with a wide range of ICC values (ICC: 0.79-0.97). Interobserver reliability was the highest on the standardized outlet view, with an ICC of 0.91 and 0.88 in two measurement times. Interobserver reliability of other measurements were good with ICC values ranging from 0.82 to 0.88.

CONCLUSION

The AHD measurements on radiographs are compatible with US measurements within up to 2 mm difference if standardization is ensured. Also, measurements on standardized views have a superior consistency with lower standard error of measurement and minimal detectable change values. Therefore, we recommend using standardized true shoulder AP and standardized outlet radiographs in clinical practice and studies, as these are the most accurate in demonstrating true AHD.

Deep learning for automated measurement of CSA related acromion morphological parameters on anteroposterior radiographs

BACKGROUND

The Critical Shoulder Angle Related Acromion Morphological Parameter (CSA- RAMP) is a valuable tool in the analyzing the etiology of the rotator cuff tears (RCTs). However, its clinical application has been limited by the time-consuming and prone to inter- and intra-user variability of the measurement process.

OBJECTIVES

To develop and validate a deep learning algorithm for fully automated assessment of shoulder anteroposterior radiographs associated with RCTs and calculation of CSA-RAMP.

METHODS

Retrospective analysis was conducted on radiographs obtained from computed tomography (CT) scans and X-rays performed between 2018 and 2020 at our institution. The development of the system involved the utilization of digitally reconstructed radiographs (DRRs) generated from each CT scan. The system's performance was evaluated by comparing it with manual and semiautomated measurements on two separate test datasets: dataset I (DRRs) and dataset II (X-rays). Standard metrics, including mean average precision (AP), were utilized to assess the segmentation performance. Additionally, the consistency among fully automated, semiautomated, and manual measurements was comprehensively evaluated using the Pearson correlation coefficient and Bland-Altman analysis.

RESULTS

A total of 1080 DRRs generated from 120 consecutive CT scans and 159 X-ray films were included in the study. The algorithm demonstrated excellent segmentation performance, with a mean AP of 57.67 and an AP50 of 94.31. Strong inter-group correlations were observed for all CSA-RAMP measurements in both test datasets I (automated versus manual, automated versus semiautomated, and semiautomated versus manual; r = [0.990---0.997], P < 0.001) and dataset II (r = [0.984---0.995], P < 0.001). Bland-Altman analysis revealed low bias for all CSA-RAMP measurements in both test datasets I and II, except for CD (with a maximum bias of 2.49%).

CONCLUSIONS

We have successfully developed a fully automated algorithm capable of rapidly and accurately measuring CSA-RAMP on shoulder anteroposterior radiographs. A consistent automated CSA- RAMP measurement system may accelerate powerful and precise studies of disease biology in future large cohorts of RCTs patients.

Incongruity of the scapulohumeral arch: an indirect sign of posterior subluxation of the humeral head in primary glenohumeral osteoarthritis

BACKGROUND

In symptomatic glenohumeral osteoarthritis, arthroplasty is the gold standard to restore a mobile and painless shoulder. The kind of arthroplasty chosen is mainly based on the evaluation of the rotator cuff and the type of glenoid. The aim of this study was to analyze the scapulohumeral arch in primary glenohumeral osteoarthritis (PGHOA) with an uninjured cuff and to determine whether posterior humeral subluxation influences the Moloney line, which corresponds to an intact scapulohumeral arch.

MATERIALS AND METHODS

Between 2017 and 2020, 58 anatomic total shoulder arthroplasties were implanted in the same center. We included all patients with complete preoperative imaging (radiographs and magnetic resonance imaging or arthro-computed tomography scans) assessing an intact rotator cuff. A total of 55 shoulders that had undergone surgery with a total anatomic shoulder prosthesis were analyzed after determination of the type of glenoid in the frontal plane according to the Favard classification on an anteroposterior radiograph and in the axial plane according to the Walch classification on computed tomography scans. The grade of osteoarthritis was evaluated according to the Samilson classification. We analyzed whether there was a rupture of the Moloney line on the frontal radiograph and assessed the acromiohumeral distance.

RESULTS

After preoperative analysis of 55 shoulders, 24 shoulders had type A glenoids and 31 had type B glenoids. Scapulohumeral arch rupture was observed in 22 shoulders, and posterior subluxation of the humeral head was found in 31 shoulders, of which 25 had type B1 glenoids and 6 had type B2 glenoids according to the Walch classification. Most glenoids were type E0 (n = 47.85%). Incongruity of the Moloney line was more frequent in shoulders with type B glenoids (20 of 31 [65%]) than those with type A glenoids (2 of 24 [8%], P < .001). No patient with a type A1 glenoid (0 of 15) had a rupture of the Moloney line, and only 2 patients with a type A2 glenoid (2 of 9) had incongruity of the scapulohumeral arch.

CONCLUSION

In PGHOA, rupture of the scapulohumeral arch seen on anteroposterior radiographs, also known as the Moloney line, may be an indirect sign of posterior humeral subluxation, corresponding to a type B glenoid per the Walch classification. Incongruity of the Moloney line may indicate a rotator cuff injury or posterior glenohumeral subluxation with an intact cuff in PGHOA.

Dynamic evaluation of the sternoclavicular and acromioclavicular joints using an upright four-dimensional computed tomography

In the analysis of the shoulder complex, the sequential changes occurring in the sternoclavicular and acromioclavicular joints during active shoulder motion are challenging to track. This study aimed to investigate the in vivo sternoclavicular and acromioclavicular joint motions during active elevation, including the sequential changes in these joint spaces using upright four-dimensional computed tomography (4DCT). Bilateral shoulders of 12 healthy volunteers upright 4DCT were obtained during active elevation similar to a "hands up" motion. The sternoclavicular and acromioclavicular rotation angles, joint distances, and closest points on the clavicle relative to the thorax and scapula were evaluated during 10°-140° of humerothoracic elevation. During humerothoracic elevation, the clavicle elevated, retracted, and rotated posteriorly relative to the thorax, whereas the scapula rotated upwardly, internally, and posteriorly relative to the clavicle. All the sternoclavicular and acromioclavicular joint rotation angles were significantly different at ≥ 30°-50° of humerothoracic elevation compared with 10° of humerothoracic elevation. The mean sternoclavicular and acromioclavicular joint distances were 2.2 ± 1.1 mm and 1.6 ± 0.9 mm, respectively. The closest points were located on the anteroinferior part of the medial and lateral clavicle in the sternoclavicular and acromioclavicular joints, respectively. Significant differences were observed in the acromioclavicular joint distance and anterior/posterior movements of the closest points in the sternoclavicular and acromioclavicular joints compared with 10° of humerothoracic elevation. Our sternoclavicular and acromioclavicular closest point results indicate that the impingement tends to occur at the anteroinferior part of the medial and lateral aspects of the clavicle and may be related to osteoarthritis.

The Effects of Body Positions and Abduction Angles on Shoulder Muscle Activity Patterns during External Rotation Exercises

BACKGROUND

Excess and repetitive glenohumeral external rotation (ER) is at a higher risk for shoulder injuries, which occurs frequently in professional sports and specific occupations. Current rehabilitation programs emphasize selective targeting of muscle activity, which can help restore dysfunctional muscle imbalances or prevent injuries. However, the impact of different body postures on GH muscle activity during ER exercises has not been fully understood. Therefore, the purpose of this study was to investigate shoulder EMG activity for different body positions and humeral abduction angles during ER exercises.

METHOD

Twenty-three healthy young men (age: 22.3 ± 2.3, height: 175.75 ± 4.02, mass: 75.37 ± 9.14) participated in this study. Surface Electromyography was recorded from seven shoulder muscles: upper trapezius, lower trapezius, serratus anterior, infraspinatus, and deltoid. Six ER exercises: three postures (sitting, supine lying, and prone lying) and two abduction angles (ABD; 45° and 90°) were tested using an isokinetic dynamometer.

RESULTS

During a sitting position, the lower trapezius/upper trapezius muscle activity ratios were significantly increased for sitting compared to supine lying and prone lying (p < 0.001, p = 0.004). Serratus anterior/upper trapezius co-contraction indices were significantly increased for 90° than 45° ABD (p < 0.001).

CONCLUSION

These findings can provide insight into new training programs aimed at restoring GH muscle imbalances.

Three-dimensional shoulder kinematics: Upright four-dimensional computed tomography in comparison with an optical three-dimensional motion capture system

Although shoulder kinematics have been analyzed by various methods, dynamic shoulder motion is difficult to track. This study aimed to validate the shoulder kinematic analysis using upright four-dimensional computed tomography (4DCT) and to compare the results with optical three-dimensional motion capture. During active elevation, bilateral shoulders of 10 healthy volunteers were tracked using 4DCT and motion capture. The scapulothoracic and glenohumeral rotations and the scapulohumeral rhythm (SHR) at each position were calculated, and the differences between 4DCT and motion capture were compared. During 10-140° of humerothoracic elevation, the scapulothoracic joint showed upward rotation, internal rotation, and posterior tilting, and the glenohumeral joint showed elevation, external rotation, and anterior plane of elevation in both analyses. In scapulothoracic rotations, the mean differences between the two analyses were -2.6° in upward rotation, 13.9° in internal rotation, and 6.4° in posterior tilting, and became significant with humerothoracic elevation ≥110° in upward rotation, ≥50° in internal rotation, and ≥100° in posterior tilting. In glenohumeral rotations, the mean differences were 3.7° in elevation, 9.1° in internal rotation, and -8.8° in anterior plane of elevation, and became significant with humerothoracic elevation ≥110° in elevation, ≥90° in internal rotation, and ≥100° in anterior plane of elevation. The mean overall SHRs were 1.8 in 4DCT and 2.4 in motion capture, and the differences became significant with humerothoracic elevation ≥100°. The 4DCT analysis of in vivo shoulder kinematics using upright computed tomography scanner is feasible, but the values were different from those by skin-based analysis at the elevated arm positions.

The robustness of glenohumeral centering measurements in dependence of shoulder rotation and their predictive value in shoulders with rotator cuff tears

OBJECTIVE

De-centering of the shoulder joint on radiographs is used as indicator for severity of rotator cuff tears and as predictor for clinical outcome after surgery. The objective of the study was to assess the effect of malrotation on glenohumeral centering on radiographs and to identify the most reliable parameter for its quantification.

SUBJECTS AND METHODS

In this retrospective study (2014-2018), 249 shoulders were included: 92 with imaging-confirmed supra- and infraspinatus tears (rupture; 65.2 ± 9.9 years) and 157 without tears (control; 41.1 ± 13.0 years). On radiographs in neutral position and external rotation, we assessed three radiographic parameters to quantify glenohumeral centering: acromiohumeral distance (ACHD), craniocaudal distance of the humeral head and glenoid center (Deutsch), and scapulohumeral arch congruity (Moloney). Non-parametric statistics was performed.

RESULTS

In both positions, only the distance parameters ACHD (< 0.5 mm) and Deutsch (< 1 mm) were comparable in the two study groups rupture and control. Comparing the parameters between the study groups revealed only ACHD to be significantly different with a reduction of more than 2 mm in the rupture group. Among the parameters, ACHD ≤ 6 mm was the only cut-off discriminating rupture (12-21% of the shoulders with ACHD ≤ 6 mm) and control (none of the shoulders with ACHD ≤ 6 mm). Ninety percent of shoulders with ACHD ≤ 6 mm presented with a massive rotator cuff tear (defined as ≥ 67% of the greater tuberosity exposed).

CONCLUSION

Glenohumeral centering assessed by ACHD and Deutsch is not affected by rotation in shoulders with and without rotator cuff tear. An ACHD ≤ 6 mm has a positive predictive value of 90% for a massive rotator cuff tear.

In Vivo Anatomical Research by 3D CT Reconstruction Determines Minimum Acromiohumeral, Coracohumeral, and Glenohumeral Distances in the Human Shoulder: Evaluation of Age and Sex Association in a Sample of the Chinese Population

Accurate measurement of the minimum distance between bony structures of the humeral head and the acromion or coracoid helps advance a better understanding of the shoulder anatomical features. Our goal was to precisely determine the minimum acromiohumeral distance (AHD), coracohumeral distance (CHD), and glenohumeral distance (GHD) in a sample of the Chinese population as an in vivo anatomical analysis. We retrospectively included 146 patients who underwent supine computed tomography (CT) examination of the shoulder joint. The minimum AHD, CHD, and GHD values were quantitatively measured using three-dimensional (3D) CT reconstruction techniques. The correlation between minimum AHD, CHD, and GHD value and age with different sexes was evaluated using Pearson Correlation Coefficient. The mean value of minimum AHD in males was greater than that in females (male 7.62 ± 0.98 mm versus female 7.27 ± 0.86 mm, p = 0.046). The CHD among different sexes differed significantly (male 10.75 ± 2.40 mm versus female 8.76 ± 1.38 mm, p < 0.001). However, we found no statistical differences in GHD with different sexes (male 2.00 ± 0.31 mm versus female 1.96 ± 0.36 mm, p > 0.05). In terms of age correlation, a negative curve correlation existed between age and AHD among the different sexes (male R2 = 0.124, p = 0.030, female R2 = 0.112, p = 0.005). A negative linear correlation was found in CHD among the different sexes (male R2 = 0.164, p < 0.001, female R2 = 0.122, p = 0.005). There were no differences between age and minimum GHD in both sexes. The 3D CT reconstruction model can accurately measure the minimum AHD, CHD, and GHD value in vivo and is worthy of further investigation for standard clinical anatomical assessment. Aging may correlate with AHD and CHD narrowing for both sexes.

Three-Dimensional Quantitative Evaluation of the Scapular Skin Marker Movements in the Upright Posture

Motion capture systems using skin markers are widely used to evaluate scapular kinematics. However, soft-tissue artifact (STA) is a major limitation, and there is insufficient knowledge of the marker movements from the original locations. This study explores a scapular STA, including marker movements with shoulder elevation using upright computed tomography (CT). Ten healthy males (twenty shoulders in total) had markers attached to scapular bony landmarks and underwent upright CT in the reference and elevated positions. Marker movements were calculated and compared between markers. The bone-based and marker-based scapulothoracic rotation angles were also compared in both positions. The median marker movement distances were 30.4 mm for the acromial angle, 53.1 mm for the root of the scapular spine, and 70.0 mm for the inferior angle. Marker movements were significantly smaller on the superolateral aspect of the scapula, and superior movement was largest in the directional movement. Scapulothoracic rotation angles were significantly smaller in the marker-based rotation angles than in the bone-based rotation angles of the elevated position. We noted that the markers especially did not track the inferior movement of the scapular motion with shoulder elevation, resulting in an underestimation of the marker-based rotation angles.

[Comparison of the effectiveness of the long head of the biceps tendon with or without proximal amputation after arthroscopic repair of the rotator cuff]

OBJECTIVE

To compare the effectiveness of the long head of the biceps tendon (LHBT) with or without proximal amputation after arthroscopic rotator cuff repair in the treatment of repairable rotator cuff tear with LHBT injury.

METHODS

The clinical data of 68 patients with LHBT injury combined with supraspinatus tendon tear who met the selection criteria between January 2016 and June 2020 were retrospectively analyzed. According to whether the proximal end of LHBT was cut off or not after arthroscopic rotator cuff repair, they were divided into LHBT fixation without cutting group (group A, 32 cases) and LHBT fixation with cutting group (group B, 36 cases). There was no significant difference in gender, age, operating side, preoperative supraspinatus tear width, Constant-Murley shoulder function scale, University of California Los Angeles (UCLA) score, and visual analogue scale (VAS) score between the two groups ( P>0.05). The operation time, elbow flexion muscle strength, and postoperative complications were compared between the two groups. The Constant-Murley shoulder function scale, UCLA score, and VAS score were used to evaluate the recovery of shoulder function before operation and at 3, 6, 12 months after operation. The acromion-humeral distance (AHD) was measured by Y-view X-ray film of the shoulder joint immediately after operation and at last follow-up. AHD and acromion-greater tubercle distance (AGT) were measured by musculoskeletal ultrasound at 0°, 30°, 60°, and 90° of abduction.

RESULTS

There was no significant difference in operation time between the two groups ( t=-0.740, P=0.463). Patients in both groups were followed up (13.0±0.7) months in group A and (13.1±0.8) months in group B, with no significant difference ( t=0.127, P=0.899). At last follow-up, the elbow flexor muscle strength of the two groups reached grade Ⅴ. Complications (including shoulder pain, deltoid atrophy, and rotator cuff re-tear) occurred in 6 patients (18.75%) in group A and 9 patients (25.00%) in group B, without neurovascular injury, surgical site infection, joint stiffness, LHBT spasmodic pain, and Popeye deformity. There was no significant difference in the incidence of complications between the two groups ( χ ²=0.385, P=0.535). The Constant-Murley shoulder function scale, UCLA score, and VAS score significantly improved in both groups at 3, 6, and 12 months after operation ( P>0.05). The above scores in group B were significantly better than those in group A at 3 and 6 months after operation ( P<0.05), and there was no significant difference between the two groups at 12 months after operation ( P>0.05). Y-view X-ray film measurement of the shoulder joint showed that the AHD of the two groups at last follow-up was less than that at immediate after operation, but the difference was not significant ( Z=-1.247, P=0.212); the AHD of group A was significantly greater than that of group B at last follow-up ( t=-2.291, P=0.025). During musculoskeletal ultrasound detection of abduction and shoulder lift, there was no significant difference in the reduction degree of AHD and AGT in group A with abduction of 0°-30° compared with group B ( P>0.05). The reduction degree of AHD and AGT in group A with abduction of 30°-60°, and the reduction degree of AGT in group A with abduction of 60°-90° were significantly smaller than those in group B ( P<0.05).

CONCLUSION

In arthroscopic rotator cuff repair, whether the proximal structure of LHBT is cut off or not after LHBT fixation can effectively improve the symptoms of patients and promote the recovery of shoulder joint function. Compared with preserving the proximal structure of LHBT, cutting the proximal structure of LHBT after LHBT fixation has more obvious pain relief within 6 months, and the latter had better stability above the shoulder joint.

Three-dimensional alignment of the upper extremity in the standing neutral position in healthy subjects

Background

Though alignment of the spine and lower extremities in the standing neutral position has been evaluated, a few studies evaluating the alignment of the upper extremities have also been made. This study assessed the normal alignment of the upper extremities in the standing neutral position and clarified the three-dimensional angular rotations of the upper extremity joints.

Methods

Computed tomography (CT) images of 158 upper extremities from 79 healthy volunteers were prospectively acquired in the standing neutral position using an upright CT scanner. Three-dimensional coordinate systems of the thorax, scapula, humerus, and forearm were designated, and three-dimensional angular rotations of the scapulothoracic, glenohumeral, and elbow joints were calculated.

Results

The median angle of the scapulothoracic joint was 9.2° (interquartile range [IQR], 5.2°–12.5°) of upward rotation, 29.0° (IQR, 24.9°–33.3°) of internal rotation, and 7.9° (IQR, 4.3°–11.8°) of anterior tilt. The median angle of the glenohumeral joint was 4.5° (IQR, 0.9°–7.8°) of abduction, 9.0° (IQR, 2.2°–19.0°) of internal rotation, and 0.3° (IQR, − 2.6°–3.1°) of extension. The median angle of the elbow joint was 9.8° (IQR, 6.9°–12.4°) of valgus, 90.2° (IQR, 79.6°–99.4°) of pronation, and 15.5° (IQR, 13.2°–18.1°) of flexion. Correlations in angular rotation values were found between the right and left upper extremities and between joints.

Conclusions

This study clarified the three-dimensional angular rotation of upper extremity joints in the standing neutral position using an upright CT scanner. Our results may provide important insights for the functional evaluation of upper extremity alignment.