Shoulder Angle Research Articles

Influence of Critical Shoulder Angle and Rotator Cuff Tear Type on Load‐Induced Glenohumeral Biomechanics: A Sawbone Simulator Study

Glenohumeral (GH) biomechanics after rotator cuff (RC) tears are not fully understood. The purpose of our study was to determine if the critical shoulder angle (CSA), type of RC tears, and level of weight bearing increase GH translation, instability based on the instability ratio, muscle forces and joint reaction force (JRF), and shifts the center of force (CoF) superiorly. A GH simulator with muscle‐mimicking cable systems was used to simulate 30° abduction in the scapular plane. A Sawbone humerus and five specimen‐specific scapular anthropometries were used to test six types of RC tears, three weight‐bearing loads, and the native and adjusted (to different CSAs) deltoid origin sites. Linear mixed effects models (CSA, RC tear type, and weight bearing) with random effects (specimen and sex) were used to assess differences in GH biomechanics. With increasing CSA, GH translation increased, JRF decreased, and the CoF position was more inferior. RC tears did not significantly alter GH translation but shifted the CoF position superiorly, close to where glenoid erosion occurs in patients with RC tears with secondary osteoarthritis. Weight bearing significantly increased GH translation and JRF. RC and deltoid muscle forces increased with the presence of RC tears and increased weight bearing. The remaining RC muscles of intact tendons compensated for the torn RC tendons but not for the altered CoF position. GH translation remained comparable to shoulders with intact RC. These findings highlight the importance of early detection, clinical management, and targeted rehabilitation strategies for patients with RC tears.

Relation between critical shoulder angle and degenerative rotator cuff tear: A cross sectional MRI study

Relation between critical shoulder angle and degenerative rotator cuff tear: A cross sectional MRI study

Biomechanics Analysis of Basketball Shooting Via OpenPose Motion Capture System

In basketball, it is crucial to understand the optimal shooting pattern for each individual in terms of gender and shooting distances from the basket. However, incorporating biomechanics shooting analysis quantitatively into the learning process is not preferable. Hence, the purpose of this study is to determine the quantitative aspect of basketball shooting for biomechanics analysis using the OpenPose motion capture system. This marker-less motion capture system generated the biomechanical parameter data subjected to a significant difference test for shooting performance. A total of four players – two males and two females, divided into two levels (intermediate and novice) performed ten continuous jump shots from two different shooting distances (4.57 m and 6.40 m) from the basket. Each individual’s biomechanical parameters were tested in a statistical or independent t test to determine which significant parameter has a measurable difference in shooting performance. When the effects of different body angles on missed to scored baskets were compared, only the right elbow angle (intermediate female player), the right shoulder angle (novice male player) and the left hip angle (intermediate female player and novice male player) showed a significant difference (p < 0.05) towards shooting performance. In the comparison of the velocity of right upper limb key points, only the velocity of the right shoulder (intermediate male player) showed a significant difference (p < 0.05) toward shooting performance. In conclusion, the findings of this study suggest that shooting analysis should be done quantitatively to demonstrate a more profound and clear understanding of biomechanics when considering an improvement in shooting performance.

Anatomic factors associated with degeneration and fraying of the coracoacromial ligament.

The coracoacromial ligament (CAL) is frequently observed to be damaged during arthroscopy and it is unclear how demographic, anatomic, and radiographic factors are related to CAL degeneration in full-thickness rotator cuff tears. A prospective study was conducted of patients at a single institution undergoing shoulder arthroscopy for first-time, full-thickness rotator cuff tears. We evaluated preoperative anteroposterior radiographs to obtain critical shoulder angle, glenoid inclination, acromial index, acromiohumeral distance, lateral acromial angle, and acromial morphology. We documented CAL quality, rotator cuff tear size and pattern during arthroscopy. Multiple logistic regression was used to identify predictive factors for encountering severe CAL fraying during arthroscopy. Shoulders had mild CAL degeneration in 58.1% of cases, whereas severe CAL degeneration was present in 41.9% of shoulders. Patients with severe CAL attrition were significantly older (62.0 years vs. 58.0 years, P=0.042). Shoulders with severe CAL attrition had large rotator cuff tears in 54.1% of cases (P<0.001), and tears involving the infraspinatus (63.2% vs. 29.6%, P=0.003). The severe degeneration group was more likely to have a larger critical shoulder angle measurement on preoperative radiographs than those in the mild attrition group (36.1°±3.6° [range, 30°-45°] vs. 34.1°±3.8° [range, 26°-45°], P=0.037). While the clinical impact of CAL degeneration remains uncertain, increased severity of CAL degeneration is associated with older age, larger rotator cuff tear size, presence of infraspinatus tearing, and increased preoperative critical shoulder angle. Level of evidence: III.

Three-Dimensional Magnetic Resonance Imaging Fast Field Echo Resembling a Computed Tomography Using Restricted Echo-Spacing Sequence Is Equivalent to 3-Dimensional Computed Tomography in Quantifying Bone Loss and Measuring Shoulder Morphology in Patients With Shoulder Dislocation

PurposeTo evaluate the equivalence of 3D-MRI (Fast field echo Resembling A CT Using Restricted Echo-spacing,FRACTURE) and 3D-CT in quantifying bone loss in patients with shoulder dislocation and measuring morphological parameters of the shoulder. MethodsFrom July 2022 to June 2023,patients with anterior shoulder dislocation who were over 18 years of age and underwent both MRI and CT within 1 week were included in the study.The MRI protocol included an additional FRACTURE sequence.3D reconstructions of MRI(FRACTURE) and CT were completed by two independent observers using Mimics 21.0 software through simple threshold-based segmentation.For bone defect cases, two independent observers evaluated glenoid defect, percentage of glenoid defect,glenoid track(GT), Hill-Sachs Interval (HSI), and "on-track/off-track".For all cases,glenoid width, glenoid height,humeral head fitting sphere radius,Critical Shoulder Angle(CSA),glenoid version,vault depth, and post-processing time were assessed.Paired t-test was utilized to assess the difference between 3D-CT and 3D-MRI (FRACTURE).Bland-Altman plot was constructed to evaluate the consistency between 3D-CT and 3D-MRI (FRACTURE). Inter- and intra-observer agreement was evaluated by Interclass Correlation Coefficient (ICC). Paired chi-square test and Cohen’s kappa statistic were used for binary variable("on-track/off-track"). ResultsA total of 56 patients(16 bipolar bone defect, 5 only Hill-Sachs lesion,35 without bone defect) were eventually enrolled in the study.The measurements of 21 bone defect cases showed no statistical difference between 3D-CT and 3D-MRI.Glenoid defect,3D-CT(4.05±1.44mm) vs 3D-MRI(4.16±1.39mm,P=0.208);Percentage of glenoid defect,3D-CT(16.21±5.95%) vs 3D-MRI(16.61±5.66%, P=0.199);Glenoid Track,3D-CT (18.02±2.97mm) vs 3D-MRI(18.08±2.98mm, P=0.659);Hill-Sachs Interval,3D-CT (14.29±1.93mm) vs 3D-MRI(14.35±2.07mm, P=0.668).No significant difference was found between 3D-CT and 3D-MRI in the diagnosis of "on-track/off-track"(P=1.000), and the diagnostic agreement was perfect (Kappa=1.00,P=0.000). There was no statistical difference between two examination methods in the measurements of all 56 cases,except that the post-processing time of 3D-MRI was obviously longer than that of 3D-CT.Glenoid height,3D-CT(34.56±1.98mm) vs 3D-MRI (34.67±2.01mm, P=0.139).Glenoid width,3D-CT(25.32±1.48mm) vs 3D-MRI(25.45±1.47mm, P=0.113).Humeral head fitting sphere radius,3D-CT(22.91±1.70mm) vs 3D-MRI(23.00±1.76mm, P=0.211).Critical Shoulder Angle,3D-CT(33.49°±2.55°) vs 3D-MRI (33.57°±2.51°, P=0.328). Glenoid version, 3D-CT(-3.25°±2.57°) vs 3D-MRI (-3.18°±2.57°, P=0.322).Vault depth,3D-CT(37.43±1.68mm) vs 3D-MRI(37.58±1.75mm, P=0.164).Post-processing time,3D-CT(89.66±10.20s) vs 3D-MRI (360.93±26.76s, P=0.000).For all assessments, the Bland-Altman plots demonstrated excellent consistency between two examination methods,and the ICCs revealed excellent inter-observer and intra-observer agreement. Conclusions3D-MRI (FRACTURE) is equivalent to 3D-CT in quantifying bone loss in patients with shoulder dislocation and measuring shoulder morphological parameters.

Designing an early selection morphological traits index for reproductive efficiency in Pura Raza Española mares.

The low rate of reproductive efficiency in horses may be linked to the equine industry's practice of maintaining breeding stock that stands out for its athletic or morphological performance but exhibits poor reproductive efficiency. In this study, the age at first foaling, age at last foaling, interval between first and second foaling, average interval between foaling, foaling number and reproductive efficiency, and their relationship with the morphological records in 19,758 Pura Raza Española (PRE) mares were analyzed. After a partial least squares analysis height at withers, lateral hock angle, dorsal-sternal diameter, perimeter of anterior cannon bone, angle of shoulder, thoracic perimeter, hip-stifle distance, and angle of croup were the most important traits related with reproductive traits in PRE mares. A multivariate animal model with both morphological and reproductive traits was applied, including age, geographical area, coat color, and average stud size in the decade of the mare's first foaling. The results indicate that reproductive selection is feasible, and is enhanced by the use of morphological traits, given the moderate to high magnitudes of heritability values in both types of traits, which oscillated between 0.1 (interval between first and second foaling) and 0.95 (height at withers). The resulting genetic parameters were used to develop a series of selection indexes based on morphological or morphological and reproductive combination traits to improve reproductive efficiency traits in PRE mares and thus compute the expected genetic response (EGR) for the different strategies. The increase in EGR, when comparing EGR using only reproductive traits as selection criteria vs. using a combined index of both morphological and reproductive traits, oscillated between 4.0% for the age at first foaling to 46.8% for the interval between first and second foaling. In addition, two precocity indexes showed positive EGR when the age at last foaling and the interval between first and second foaling, both with and without morphological traits, were used as selection criteria. Therefore, this analysis reveals that the preselection of reproductive traits based on morphological traits is possible in PRE mares. Ultimately, this knowledge will help breeders achieve genetic progress in reproductive traits, leading to healthier and more successful breeding outcomes in horses.

Rotation sequences for the calculation of shoulder kinematics of the volleyball attack

Calculating upper extremity kinematics during overhead movements presents with problems typically not seen for the lower extremity due to the large range of motion. Due to these unique issues, different rotation sequences have been suggested to circumvent challenges due to gimbal lock (GL) and angle coherence (AC). The purpose of this study is to determine the most appropriate rotation sequence for shoulder angle calculation during a volleyball attack. METHODS: 15 healthy experienced volleyball players (women = 8) performed 5 attacks off a stationary ball. A 12-camera 3D motion capture system was utilized to record trunk and arm kinematics to compare joint angles calculated using the YXY, ZXY, XZY, YXZ, ZYX, and XYZ rotation sequences. Instances of GL and AC inconsistences were marked for each trial. The last 3 trials were used for analysis. RESULTS: The YXY and XYZ sequences presented with the least total number of errors (12 and 5, respectively). 5 instances of GL were present in the XYZ sequence while none were recorded for the YXY sequence. All other sequences returned incoherent angles that greatly exceeded known ranges of motion. CONCLUSION: When performing kinematic analyses during a volleyball attack, researchers should adhere to ISB recommendations and employ the Eulerian YXY sequence for calculations. If greater anatomical understanding is desired, the XYZ sequence may be utilized for most subjects.

The Comparison of Fatigue and Trunk and Neck Postures during Working in Tailors with and Without Nonspecific Chronic Neck Pain

Objectives: Work-induced musculoskeletal pain disorders are among the most common problems among workers. This study aimed to compare fatigue and trunk and neck postures during work in tailors with and without nonspecific chronic neck pain.&#x0D; Methods: In this cross-sectional study, 30 sewing machine operators participated voluntarily and were divided in two groups of people with (15 persons) and without (15 persons) chronic nonspecific neck pain. The craniovertebral, cranial, and shoulder angles were calculated three intervals (at the start of work, after 2 hours of continuous work, after 4 hours of continuous work) using the photogrammetric method. Borg scale was used to examine work-induced fatigue. A one-way repeated measure analysis of variance at the significance level of 0.05 was used for data analysis.&#x0D; Results: There were significant differences in craniovertebral, cranial, and shoulder angle changes (P &lt; 0.001) between the two groups while working. Postural trunk and neck changes were more evident in the nonspecific chronic neck pain group. However, there were no significant differences in terms of fatigue levels between the two groups (P = 0.639).&#x0D; Conclusion: The upper trunk related posture among workers with nonspecific chronic neck pain may be more negatively affected during work. So it is suggested that maintaining proper posture should be more emphasized among these workers.

Influence of Lateralization and Distalization on Joint Function after Primary Reverse Total Shoulder Arthroplasty.

The purpose of this study was to investigate how lateralization shoulder angle (LSA) and distalization shoulder angle (DSA) are related to clinical and kinematic outcomes after reverse total shoulder arthroplasty. Thirty-three patients were evaluated at least six months postoperatively. The Single Assessment Numeric Evaluation (SANE), Constant Murley Score (CMS), Simple Shoulder Test (SST), and Visual Analogue Scale (VAS) were used. Shoulder kinematics was evaluated with a stereophotogrammetric system. LSA and DSA inter-rater reliability was analysed through the interclass correlation coefficient (ICC). Stepwise forward linear regression analysis was conducted between LSA and DSA with clinical scales and kinematic measures, between which a correlation analysis was conducted. The inter-rater reliability for LSA (mean ICC = 0.93) and DSA (mean ICC = 0.97) results were good to excellent. Greater LSA values were associated with higher peaks of internal rotation (p = 0.012, R2 = 0.188) and range of motion (ROM) (p = 0.037, R2 = 0.133). SANE (p = 0.009), CMS (p = 0.031), and SST (0.026) were positively correlated to external rotation, while VAS (p = 0.020) was negatively related. Abduction peaks were positively related to CMS (p = 0.011) and SANE (p = 0.037), as well as abduction ROM (SANE, p = 0.031; CMS, p = 0.014).

A study of concave shoulder angle on the mechanical properties and fractography of friction stir welded AA6061-T651 joints

AA6061-T651 material joints produced by friction stir welding (FSW) were analysed in this study. The analysis was conducted to determine the effect of the concave shoulder angle (CSA) of the tool on mechanical and fractographic properties. The mechanical properties studied included impact strength (IS) and hardness (HS), while the fractography included impact fracture and microstructure. The experiments used a Taguchi L16 (44) orthogonal array and were done thrice. The best parameters were then used four times for confirmation. The research findings confirmed that the change in CSA significantly impacts the IS of welded joints. Combining both artificial neural network (ANN) and genetic algorithm (GA), it was found that 9° is the best CSA for IS. The mechanical properties test results showed an IS of 0.806 J/mm2. The HS of the weld nugget zone (WNZ) decreased by 25.49 % compared to the parent material zone (PMZ). This decrease in HS is due to the phase change of magnesium silicide (Mg2Si), resulting in finer grains in the WNZ than in the PMZ. Meanwhile, the fracture angle of the impact test specimens was 81.7°, indicating moderate toughness characteristics.

Analysis of the concurrent validity and reliability of five common clinical goniometric devices

Measurement errors play an important role in the development of goniometric equipment, devices used to measure range of motion. Reasonable validity and reliability are critical for both the device and examiner before and after to testing in human subjects. The objective is to evaluate the concurrent validity and reliability of five different clinical goniometric devices for the purpose of establishing an acceptable measurement error margin for a novel device. We explored the validity and inter- and intrarater reliability scores of five goniometric devices namely (i) the universal goniometer (UG), a two-armed hand-held goniometer, (ii) the inclinometer (IC), featuring a single base, fluid level, and gravity-weighted inclinometer, (iii) the digital inclinometer (DI), functioning as both a DI and dynamometer, (iv) the smartphone application (SA), employing gyroscope-based technology within a smartphone platform application and (v) the modified inclinometer (MI), a gravity pendulum-based inclinometer equipped with a specialized fixing apparatus. Measurements were obtained at 12 standard angles and 8 human shoulder flexion angles ranging from 0° to 180°. Over two testing sessions, 120 standardized angle measurements and 160 shoulder angle measurements from 20 shoulders were repetitively taken by three examiners for each device. The intraclass correlation coefficient (ICC), standard error of measurement (SEM), and minimal detectable change (MDC) were calculated to assess reliability and validity. Concurrent validity was also evaluated through the execution of the 95% limit of agreement (95% LOA) and Bland–Altman plots, with comparisons made to the UG. The concurrent validity for all device pairs was excellent in both study phases (ICC > 0.99, 95% LOA − 4.11° to 4.04° for standard angles, and − 10.98° to 11.36° for human joint angles). Inter- and intrarater reliability scores for standard angles were excellent across all devices (ICC > 0.98, SEM 0.59°–1.75°, MDC 1°–4°), with DI showing superior reliability. For human joint angles, device reliability ranged from moderate to excellent (ICC 0.697–0.975, SEM 1.93°–4.64°, MDC 5°–11° for inter-rater reliability; ICC 0.660–0.996, SEM 0.77°–4.06°, MDC 2°–9° for intra-rater reliability), with SA demonstrating superior reliability. Wider angle measurement however resulted in reduced device reliability. In conclusion, our study demonstrates that it is essential to assess measurement errors independently for standard and human joint angles. The DI is the preferred reference for standard angle testing, while the SA is recommended for human joint angle testing. Separate evaluations across the complete 0°–180° range offer valuable insights.

Glenohumeral joint osteoarthritis is not associated with clavicle fractures in a large arthroplasty cohort

IntroductionA recent study based on a large osteological collection reported an association between clavicle fractures and osteoarthritis of the glenohumeral joint. No clinical study has yet addressed this potential association. Other radiographic parameters such as the critical shoulder angle have been associated with the risk of glenohumeral joint osteoarthritis. The primary outcome of this study was to determine if there is an association between glenohumeral joint arthritis and clavicle fractures. The secondary outcome was to determine the association between critical shoulder angle and glenohumeral joint arthritis in our patient cohort. MethodsWe retrospectively analysed 572 consecutive shoulder arthroplasty surgeries. Osteoarthritis was the indication for 343 shoulder arthroplasties. 229 shoulder arthroplasties were performed due to another diagnosis such as trauma or fracture, cuff arthropathy, or revision surgery. Three fellowship trained consultant shoulder surgeons assessed the pre- and post-operative radiographs of all patients. ResultsA clavicle fracture was suspected in 5/343 (1.5 %) shoulder arthroplasties performed due to osteoarthritis and 5/229 (2.1 %) shoulder arthroplasties performed for another diagnosis. Interobserver variability was assessed using a Fisher Exact test and showed no significant relationship between osteoarthritis and a fracture of the clavicle (p = 0.531). Critical shoulder angle results correlated with the previously published literature regarding critical shoulder angle and osteoarthritis and rotator cuff arthropathy. ConclusionClavicle fractures were not associated with glenohumeral osteoarthritis in our patient cohort of shoulder arthroplasty patients. Critical shoulder angle results were consistent with published literature. Further research in the form of prospective long term studies are needed to establish if any association exists between clavicle fractures and osteoarthritis of the glenohumeral joint. Level of evidenceLevel III. Retrospective analysis.

The role of bone morphology of the greater tuberosity and lateral acromion on subacromial space during scaption: a three-dimensional dynamic simulation analysis

BackgroundThe bone morphology of the greater tuberosity and lateral acromion plays a central role in subacromial impingement syndrome. The critical shoulder angle (CSA) and greater tuberosity angle (GTA) are two-dimensional measurement parameters that have been validated to evaluate it radiologically. These markers are, however, static and don’t consider the dynamic effect of glenohumeral motion.ObjectivesThis study aimed to better understand the biomechanics in subacromial impingement with a dynamic simulation based on a validated 3D biomechanical model coupling joint kinematics and 3D reconstructed computed tomography.Study design & methodsSixty-one patients were included in this study: a case group of 44 patients with degenerative rotator cuff tears involving only the supraspinatus, and a control group of 17 without a rotator cuff tear. Patients with previous surgeries, traumatic cuff tears, and cuff tear arthropathy were excluded. CSA, GTA, and impingement-free range of motion (IF-ROM) of the glenohumeral joint in scaption were calculated. Correlation tests were used to determine the relationship between ROM and CSA, GTA, and combined CSA and GTA values.ResultsCSA and GTA were significantly higher in the rotator cuff tear group (p = 0.001 and < 0.001), while IF-ROM was significantly higher in the control group (p = 0.001). There was no overall correlation between CSA and GTA (R = 0.02, p = 0.8). Individual correlation between both angles with IF-ROM was negatively weak for CSA (R = -0.4, p < 0.001) and negatively moderate for GTA and IF-ROM (R = -0.5, p < 0.001). However, combining both angles resulted in a negatively high correlation with IF-ROM (R = -0.7, p < 0.001).ConclusionSubacromial space narrowing during scaption is highly correlated to the cumulative values of GTA and CSA. These findings suggest that the combined bony morphology of the lateral acromion and greater tuberosity plays an important role in subacromial impingement.Level of evidenceIII

Monocular camera-based online sensor-to-segment calibration for upper body pose estimation

Robot-assisted rehabilitation training usually requires body pose estimation for either evaluation or robot control. Wearable sensors such as inertial measurement units (IMUs) have been extensively studied as affordable solutions. However, a prerequisite is to calibrate the relative transform between the sensor frame and segment anatomical frame, which is usually complex and time-consuming. In this paper, a visual-inertial fusion approach is proposed where a monocular camera is employed to overcome the drawbacks of IMUs and simplify the calibration process. The locations of IMUs are detected from vision using ArUco markers attached to them and the sensor-to-segment calibration is achieved using additional skeletal keypoint locations detected using the MediaPipe framework during arbitrary movements. Experiments were conducted to evaluate the accuracy of the proposed calibration method and the root mean square error of the shoulder and elbow joint angles are 5.13–7.86° with correlation coefficients above 0.96 in comparison to ground truth joint angles from the optical motion capture system. The proposed method achieves similar accuracy to traditional predefined poses-based calibration methods but simplifies the procedure, making it suitable for patients who cannot perform poses accurately in rehabilitation.

Is prenatal testosterone-estrogen balance related to critical shoulder angle?

BackgroundThe 2D:4D ratio (an indicator of prenatal testosterone-estrogen balance) is the ratio of the second finger length to the fourth finger length. We hypothesized that low 2D:4D values indicating high prenatal testosterone exposure may be associated with increased critical shoulder angle (CSA). AimsThe aim of this study was to evaluate the relationship between CSA and 2D:4D ratio. MethodsMeeting the study criteria, 252 patients were included in the study. We measured CSA on true anterior-posterior radiographs, glenoid version(GV) and glenoid inclination(GI) on MRI images and the lengths of the second and fourth fingers on both hands of the patients. Additionally, we compared 2D:4D ratios and CSA, GV, GI measurements. ResultsWe found a significant negative correlation between CSA and the 2D:4D ratio in both hands (p < 0.001). Patients with CSA > 35° had a significantly lower 2D:4D ratio than patients with CSA < 35° (p < 0.001). When the patients were grouped according to CSA35°, the cut-off value for the left-hand 2D:4D ratio was 0.96, which showed 84.8 % sensitivity and 83.3 % specificity(AUC:0.911). Patients were compared in terms of CSA by categorizing as 2D:4D > 1 and 2D:4D < 1. Accordingly, the CSA value was significantly lower in patients with 2D:4D > 1. In the classification made according to this length classification of the left hand, the cut-off value was 30.25°. This value showed 92.2 % sensitivity and 85 % specificity(AUC:0.956). ConclusionThe 2D:4D ratio is related to CSA. A low 2D:4D ratio(<0.96), indicating high intrauterine testosterone exposure, is associated with CSA > 35°, while a high 2D:4D ratio (>1), indicating low intrauterine testosterone exposure, is associated with a low CSA(<30.25°).

Why is female gender associated with poorer clinical outcomes after reverse total shoulder arthroplasty?

There is a lack of gender-specific research after reverse total shoulder arthroplasty (RTSA). Although previous studies have documented worse outcomes in women, a more thorough understanding of why outcomes may differ is needed. We therefore asked: (1) Are there gender-specific differences in preoperative and postoperative clinical scores, complications, surgery-related parameters, and demographics? (2) Is female gender an independent risk factor for poorer clinical outcomes after RTSA? (3) If so, why is female gender associated with poorer outcomes after RTSA? Between 2005 and 2019, 987 primary RTSAs were performed in our institution. After exclusion criteria were applied, data of 422 female and 271 male patients were analyzed. Clinical outcomes (absolute/relative Constant Score [a/rCS] and Subjective Shoulder Value [SSV]), complications (intra- and/or postoperative fracture, loosening), surgery-related parameters (indication, implant-related characteristics), and demographics (age, gender, body mass index, and number of previous surgeries) were evaluated. Preoperative and postoperative radiographs were analyzed (critical shoulder angle, deltoid-tuberosity index, reverse shoulder angle, lateralization shoulder angle, and distalization shoulder angle). Preoperative clinical scores (aCS, rCS, SSV, and pain level) and postoperative clinical outcomes (aCS and rCS) were significantly worse in women. However, the improvement between preoperative and postoperative outcomes was significantly higher in female patients for rCS (P=.037), internal rotation (P<.001), and regarding pain (P<.001). Female patients had a significantly higher number of intraoperative and postoperative fractures (24.9% vs. 11.4%, P<.001). The proportion of female patients with a deltoid-tuberosity index <1.4 was significantly higher than males (P=.01). Female gender was an independent negative predictor for postoperative rCS (P=.047, coefficient -0.084) and pain (P=.017, coefficient -0.574). In addition to female sex per se being a predictive factor of worse outcomes, females were significantly more likely to meet 2 of the 3 most significant predictive factors: (1) significantly worse preoperative clinical scores and (2) higher rate of intra- and/or postoperative fractures. Female sex is a very weak, but isolated, negative predictive factor that negatively affects the objective clinical outcome (rCS) after RTSA. However, differences did not reach the minimal clinically important difference, and it is not a predictor for the subjective outcome (SSV). The main reason for the worse outcome in female patients seems to be a combination of higher preoperative disability and higher incidence of fractures. To improve the outcome of women, all measures that contribute to the reduction of perioperative fracture risk should be used.

Can we separately measure glenoid vs. humeral lateralization and distalization in reverse shoulder arthroplasty?

Lateralization and distalization in reverse shoulder arthroplasty (RSA) can be measured on anteroposterior (AP) radiographs using 2 previously described angles: lateralization shoulder angle (LSA) and distalization shoulder angle (DSA). However, these 2 angles measure global lateralization and distalization but do not allow to differentiate how much lateralization or distalization are attributable to the glenoid and the humerus. We hypothesized that new angles could allow us to separately measure glenoid vs. humeral lateralization and distalization. A more precise understanding of independent glenoid and humeral contributions to lateralization and distalization may be beneficial in subsequent clinical research. Retrospective analysis of postoperative AP radiographs of 100 patients who underwent primary RSA for cuff-tear arthropathy, massive cuff tear, or glenohumeral osteoarthritis were analyzed. The new angles that we proposed use well-known bony landmarks (the acromion, glenoid, and humerus) and the most lateral point of the glenosphere, which we termed the "glenoid pivot point" (GPP). For lateralization, we used the GPP to split LSA into 2 new angles: glenoid lateralization angle (GLA) and humeral lateralization angle (HLA). For distalization, we introduced the modified distalization shoulder angle (mDSA) that can also be split into 2 new angles: glenoid distalization angle (GDA) and humeral distalization angle (HDA). Three orthopedic surgeons measured the new angles, using the online tool Tyche. Mean values with overall and individual standard deviations as well as intraclass correlation coefficients (ICCs) were calculated. Because the angles form a triangle, the following equations can be made: LSA=GLA+HLA, and mDSA=GDA+HDA. All angles showed excellent inter- and intraobserver reliability (ICC=0.92-0.97) with low means of individual standard deviations that indicate a precision of 2° for each angle. Use of the most lateral part of the glenosphere (termed glenoid pivot point) allows us to separately measure glenoid vs. humeral lateralization and distalization. The 4 new angles (HLA, GLA, GDA, HDA) described in the present study can be used on true AP radiographs, routinely obtained after shoulder replacement, and the measured angles may be used with all types of reverse prostheses available.

Investigating the multifactorial etiology of supraspinatus tendon tears.

The purpose of this study was to develop a multivariable model to determine the extent to which a combination of etiological factors is associated with supraspinatus tendon tears. Fifty-four asymptomatic individuals (55 ± 4 years) underwent testing of their dominant shoulder. Diagnostic ultrasound was used to assess for a supraspinatus tendon tear. The etiological factors investigated includeddemographics (age and sex), tendon impingement during shoulder motion (via biplane videoradiography), glenohumeral morphology (via computed tomography imaging), family history of a tear (via self-report), occupational shoulder exposure (via shoulder job exposure matrix), and athletic exposure (via self-report). Univariate relationships between etiological predictors and supraspinatus tears were assessed using logistic regression and odds ratios (ORs), while multivariable relationships were assessed using classification and regression tree analysis. Thirteen participants (24.1%) had evidence of a supraspinatus tear. Individuals with a tear had a higher critical shoulder angle (OR 1.2, p = 0.028) and acromial index (OR 1.2, p = 0.016) than individuals without a tear. The multivariable model suggested that a tear in this cohort can be explained with acceptable accuracy (AUROC = 0.731) by the interaction between acromial index and shoulder occupational exposure: a tear is more likely in individuals with a high acromial index (p < 0.001), and in individuals with a low acromial index and high occupational exposure (p < 0.001). The combination of an individual's glenohumeral morphology (acromial index) and occupational shoulder exposure may be important in the development of supraspinatus tears.

The Effect of TMJ Intervention on Instant Postural Changes and Dystonic Contractions in Patients Diagnosed with Dystonia: A Pilot Study.

(1) Background: The aim of the present study is to analyze the instant postural changes and changes in the dystonic contractions among patients with dystonia following the use of an intraoral device called a key integrative dynamic TMJ treatment appliance (KIDTA). (2) Methods: Twelve subjects, previously diagnosed with dystonia were enrolled. Their existing records were utilized to assess the changes in their posture and dystonic contractions. The posture analysis was conducted using a mobile application (APECS). The initial records (T0) and records acquired after the delivery of the KIDTA (T1) were utilized in the analysis. The Wilcoxon signed-rank test was performed to compare parameters between T0 and T1, with a significance level set at p < 0.05. (3) Results: Based on the Wilcoxon signed-rank test, statistically significant differences in T1 compared to T0 were observed in the severity of dystonic spasms, body alignment, head shift, head tilt, shoulder alignment, shoulder angle, axillae alignment, ribcage tilt, pelvic tilt, knee angle, and tibia angle (p < 0.05). (4) Conclusions: Within the limitations of the present pilot study, an intervention to the TMJ through a KIDTA appliance seems to mitigate the severity of dystonic contractions and improve the posture with respect to certain postural parameters.

Nerve Distribution Method is Superior to the Conventional Method in BoNT-A Treatment of Trapezius Hypertrophy: A Randomized Controlled Trial.

The contour of the neck and shoulder is defined by the trapezius muscle (TM). Beyond facial procedures, botulinum toxin A (BoNT-A) injections has been increasingly adopted to create a smooth shoulder line. Several studies described the intramuscular nerve branching and the pattern of perforating branch of the accessory nerve in the trapezius muscle, providing essential information for botulinum neurotoxin injection. To this date, research groups seldom perform clinical investigations, especially randomized controlled trials, that demonstrates whether BoNT-A injections using the nerve distribution method for aesthetic purposes is more effective. Patients met the criteria for inclusion were randomized to either the Nerve Distribution group (ND group) or control group. Control group patients received injection using the conventional method while ND group patients received the nerve distribution method. Photographic and ultrasonographic evaluations were carried out at baseline, one month, three months, and six months after the procedure. Patients were also required to complete a questionnaire to evaluate their feedbacks to the injection. After screening, 30 healthy young Chinese women were included. At one-month follow-up, no statistically significant difference was observed between the two methods. At the three-month follow-up, the reduction of the TM thickness for the ND group (0.21 ± 0.09 cm) was more than that for the control group (0.27 ± 0.08 cm), with p = 0.047*. Similar differences were observed for the reduction of the shoulder area proportion (p = 0.031*) and the shoulder angle (p = 0.035*). At the six-month follow-up, the reduction in TM thickness in the ND group (0.2 ± 0.09 cm) was more than that of the control group (0.28 ± 0.06 cm), with p = 0.041*. The global aesthetic improvement scale feedbacks of the two methods showed no significant difference (3.4 ± 0.71 vs 3.8 ± 0.91, p = 0.207). The patients did not experience severe side effects. Compared to the conventional injection method, the nerve distribution method is more effective in reducing the trapezius muscle thickness, shoulder area proportion, and shoulder angle at three months, and shows longer lasting effects. The results of this study introduce unique insights into the design and tailoring of treatment protocols for shoulder-line contouring using BoNT-A.Level of Evidence I This journal requires that authors assign a level of evidence to each article. For a full description of these Evidence-Based Medicine ratings, please refer to the Table of Contents or the online Instructions to Authors www.springer.com/00266 .