Pediatric Shoulder Girdle.

The pediatric shoulder girdle is a complex anatomical structure uniting the upper extremity and trunk. The osseous structures, their articulations, and the surrounding soft tissue support structures (muscles, tendons, and ligaments) allow for a wide range of motion at the shoulder. Growth and maturation of the components at the shoulder girdle vary, particularly the osseous structures. This characteristic renders interpretation of imaging of the pediatric shoulder girdle more challenging because normal or variant anatomy can be confused for pathology. We review the physiologic growth and maturation of the shoulder girdle with special emphasis on the development of the bones and their articulations. The role of various imaging modalities and the common osseous and soft tissue variants in the pediatric shoulder are also discussed.

How anatomic should anatomic total shoulder arthroplasty be? Evaluation of humeral head reconstruction with the best-fit circle.

BACKGROUND: Humeral implant designs for anatomic total shoulder arthroplasty (aTSA) focus on anatomic reconstruction of the articular segment. Likewise, the pathoanatomy of advanced glenohumeral osteoarthritis often results in humeral head deformity. We hypothesized the anatomic reconstruction of the humeral head in aTSA risks overstuffing the glenohumeral joint. METHODS: Ninety-seven cases (52 females) of primary glenohumeral osteoarthritis in patients treated with aTSA were evaluated. Preoperative computed tomography scans were used to classify glenoid morphology according to the Walch classification. Coronal plane images in the plane of the humerus were used to determine the anatomic best-fit circle as described by Youderian et al. Humeral head thinning was determined as the distance from the center of rotation of the best-fit circle to the nearest point along the humeral articular surface. aTSA was modeled with a predicted anatomic humeral head and a simulated 4-mm polyethylene glenoid component. The change in the position of the native humerus was determined. Wilcoxon Rank Sum tests were used to evaluate differences in humeral head thinning and humeral lateralization between monoconcave and biconcave glenoid morphologies. Spearman's rank correlation coefficients were used to assess the relationship between humeral head thinning with preoperative active forward elevation and external rotation. RESULTS: The mean radius of the best-fit circle was 25.0 ± 2.1 mm. There was a mean thinning of 2.4 ± 2.0 mm (range -1.7 to 8.3). The mean percent thinning of the humeral head was 9.4% ± 7.7%. The mean humeral lateralization was 6.4 ± 2.0 mm. Humeral head thinning was not significantly associated with active forward elevation (r = -0.15, P = .14) or active external rotation (r = -0.12, P = .25). There were no significant differences in the percentage of humeral head thinning (P = .324) or humeral lateralization (P = .350) between concentric and eccentric glenoid wear patterns. CONCLUSIONS: Utilization of the best-fit circle as a guide in aTSA may risk excessive lateralization of the humerus and overstuffing the glenohumeral joint. This may have implications for subscapularis repair and healing, as well as glenoid implant and rotator cuff longevity. These findings call into question whether recreation of normal glenohumeral anatomy in aTSA is appropriate for all patients. Humeral head reconstruction in aTSA should account for glenohumeral joint volume and soft tissue contracture.

Statistical shape models that predict native glenoid width based on glenoid height are inaccurate in their current form: a cross-sectional study.

BACKGROUND: The extent of measurement errors of statistical shape models that predict native glenoid width based on glenoid height to subsequently determine the amount of anterior glenoid bone loss is unclear. Therefore, the aim of this study was to (1) create a statistical shape model based on glenoid height and width measured on 3-dimensional computed tomography (3D-CT) and determine the accuracy through measurement errors and (2) determine measurement errors of existing 3D-CT statistical shape models. MATERIALS AND METHODS: A retrospective cross-sectional study included all consecutive patients who underwent CT imaging before undergoing primary surgical treatment of traumatic anterior shoulder dislocation between 2007 and 2022 at the Tohoku University Hospital and affiliated hospitals. Patients were included when instability was unilateral and CT scans of both the injured and contralateral uninjured shoulder were available. 3D segmentations were created and glenoid height and width of the injured and contralateral uninjured side (gold standard) were measured. Accuracy was determined through measurement errors, which were defined as a percentage error deviation from native glenoid width (contralateral uninjured glenoid), calculated as follows: measurement error = [(estimated glenoid width with a statistical shape model - native glenoid width) / native glenoid width] × 100%. A linear regression analysis was performed to create a statistical shape model based on glenoid height according to the formula: native glenoid width = a × glenoid height + b. RESULTS: The diagnosis and procedure codes identified 105 patients, of which 69 (66%) were eligible for inclusion. Glenoid height demonstrated a very strong correlation (r = 0.80) with native glenoid width. The linear regression formula based on this cohort was as follows: native glenoid width = 0.75 × glenoid height - 0.61, and it demonstrated an absolute average measurement error of 5% ± 4%. The formulas by Giles et al, Chen et al and Rayes et al demonstrated absolute average measurement errors of 10% ± 7%, 6% ± 5%, and 9% ± 6%, respectively. CONCLUSION: Statistical shape models that estimate native glenoid width based on glenoid height demonstrate unacceptable measurement errors, despite a high correlation. Therefore, great caution is advised when using these models to determine glenoid bone loss percentage. To minimize errors caused by morphologic differences, preference goes to methods that use the contralateral side as reference.

Effects of Shoulder Corrective Training Program on Pitching Loads and Sonographic Morphology in Elbow Joint in Youth Baseball Players.

ABSTRACT: Chen, P-T, Lin, Y-C, Chang, H-Y, Chiu, C-H, Chen, C-Y, Chen, P, and Lin, Y-H. Effects of shoulder corrective training program on pitching loads and sonographic morphology in elbow joint in youth baseball players. J Strength Cond Res 38(8): e440-e447, 2024-We assessed the effects of a 12-week shoulder corrective training program for shoulder flexibility and strengthening on pitching loads and sonographic morphology of the elbow joints in youth baseball players. Seventeen subjects were recruited and underwent evaluations before and after the training program. We found that following training, subjects demonstrated significantly increased ranges of shoulder internal rotation (38.9 ± 12.9° vs. 69.2 ± 10.8°, p < 0.001), external rotation (91.2 ± 14.6° vs. 107.3 ± 9.5°, p = 0.004), and horizontal adduction (21.5 ± 8.0° vs. 32.7 ± 7.3°, p = 0.002); improved strength in the shoulder internal rotators (8.7 ± 1.6 kg vs. 9.8 ± 2.1 kg, p = 0.04), external rotators (6.5 ± 1.9 kg vs. 7.5 ± 2.8 kg, p = 0.04), middle trapezius (12.7 ± 2.1 kg vs. 14.3 ± 2.4 kg, p = 0.04), and middle deltoid muscles (10.8 ± 3.3 kg vs. 14.8 ± 3.2 kg, p = 0.001); and decreased thickness of the ulnar collateral ligament (6.1 ± 0.6 mm vs. 4.8 ± 0.7 mm, p = 0.002). Although there was no substantial change in elbow torque and arm speed, significantly increased ball speed (51.2 ± 4.6 mph vs. 54.1 ± 4.5 mph, p < 0.001) and decreased arm slot (63.8 ± 11.9° vs. 53.0 ± 12.7°, p = 0.02) were observed. We suggest that adequate corrective training should be performed regularly to minimize or mitigate adverse soft tissue changes at the elbow in youth baseball players. Balanced shoulder strength and flexibility may decrease medial elbow stress during pitching. Future studies should consider the kinetic and kinematic effects of other corrective training programs on the shoulder or elbow joint during pitching.

Dependence of Rotator Cuff Muscle Thickness and Stiffness on Low-Level Contractions: Metrology of the Contraction Level Using Shear-Wave Imaging.

OBJECTIVE: The study aimed to investigate the effects of the level of contraction during isometric shoulder abduction at different abduction angles on muscle thickness and stiffness of the shoulder girdle in asymptomatic individuals. DESIGN: Measurement properties study. SETTING: Biomechanics and motion analysis lab. PARTICIPANTS: Twenty individuals volunteered to participate in this study. MAIN OUTCOME MEASURE: The subjects were tested for morphological and mechanical properties, expressed by thickness and stiffness of the supraspinatus tendon and muscle, and upper trapezius muscle. Moreover, acromiohumeral distance was also evaluated using B-mode ultrasound and shear-wave elastography. INTERVENTION: The thickness and stiffness of the supraspinatus and upper trapezius muscle were assessed at 3 angles of abduction (0°, 60°, and 90°) and 3 levels of contraction (0%, 10%, and 20% of the maximal voluntary isometric contraction) using ultrasonography with shear-wave imaging. Moreover, the acromiohumeral distance was measured to establish the occupation ratio during passive movement. RESULTS: The supraspinatus and upper trapezius muscle thickness and stiffness were significantly greater at 60° shoulder abduction compared with 0°, and 90° compared with 60°, as well as significantly greater at 20% maximal voluntary isometric contraction compared with 0% and 10% maximal voluntary isometric contraction. Thickness and stiffness were significantly greater in the supraspinatus compared with the upper trapezius muscle at all 3 angles of shoulder abduction for all 3 level of contractions. The acromiohumeral distance decreased significantly from 0° to 60° and from 60° to 90°. CONCLUSION: Morphological and mechanical properties of the supraspinatus and upper trapezius muscles depended on the relative level of muscle contraction and the angle of shoulder abduction.

Tension Distribution in Articular Surfaces of the Rotator Cable and Crescent: A Cadaveric Study.

BACKGROUND: The rotator cable functions as a stress and/or load transfer structure. Some studies suggested that a disruption of the cable negatively affects shoulder function and tendon integrity in patients with rotator cuff tears, while others found no functional impairment regardless of rotator cable tear severity. Although anatomical studies have identified distinct regions within the rotator cuff muscles, the strain distribution within the articular sides of the rotator cuff tendons that results from the tension in each region remains unknown. We hypothesized that the posterior region of the supraspinatus (SSP) muscle and the middle region of the infraspinatus (ISP) muscle, with their firm capsular attachments to the cable, transmit 3D strains, and thus tension, to the whole cable, leading to differences in tension within the cable. METHODS: The 3D strain distributions in the articular sides of the SSP and ISP tendons of 8 fresh-frozen cadaveric intact shoulders were determined when tension was applied to the various SSP and ISP muscle regions. RESULTS: Loading the anterior SSP muscle region yielded significantly higher strains in the anterior third of the cable compared with the posterior third (p < 0.05). Loading the posterior SSP muscle region yielded no significant differences among the cable and crescent regions. Loading the middle ISP muscle region yielded higher strains in the anterior and posterior thirds of the cable compared with the middle third (p < 0.01). Loading the superior ISP muscle region yielded no significant differences among the cable and crescent regions (p > 0.05). CONCLUSIONS: Tension generated from the posterior region of the SSP muscle and middle region of the ISP muscle was evenly distributed to the anterior and posterior attachments of the rotator cable, while the tension generated from other SSP and ISP muscle regions was locally transmitted to the respective attachment area. CLINICAL RELEVANCE: The rotator cable and crescent serve pivotal roles in transmitting tension generated from the deep regions of the rotator cuff muscles, i.e., the posterior SSP and middle ISP. These findings indicate that both the rotator cable and the rotator crescent play crucial roles as tension transmitters for the deep regions of the rotator cuff muscles. This information could have important implications for developing anatomically relevant repair techniques and enhancing rehabilitation protocols.

Scapular morphology variation affects reverse total shoulder arthroplasty biomechanics. A predictive simulation study using statistical and musculoskeletal shoulder models.

Reverse total shoulder arthroplasty (RTSA) accounts for over half of shoulder replacement surgeries. At present, the optimal position of RTSA components is unknown. Previous biomechanical studies have investigated the effect of construct placement to quantify mobility, stability and functionality postoperatively. While studies have provided valuable information on construct design and surgical placement, they have not systematically evaluated the importance of scapular morphology on biomechanical outcomes. The aim of this study was to assess the influence of scapular morphology variation on RTSA biomechanics using statistical models, musculoskeletal modeling and predictive simulation. The scapular geometry of a musculoskeletal model was altered across six modes of variation at four levels (±1 and ±3 SD) from a clinically derived statistical shape model. For each model, a standardized virtual surgery was performed to place RTSA components in the same relative position on each model then implemented in 50 predictive simulations of upward and lateral reaching tasks. Results showed morphology affected functional changes in the deltoid moment arms and recruitment for the two tasks. Variation of the anatomy that reduced the efficiency of the deltoids showed increased levels of muscle force production, joint load magnitude and shear. These findings suggest that scapular morphology plays an important role in postoperative biomechanical function of the shoulder with an implanted RTSA. Furthermore a "one-size-fits-all" approach for construct surgical placement may lead to suboptimal patient outcomes across a clinical population. Patient glenoid as well as scapular anatomy may need to be carefully considered when planning RTSA to optimize postoperative success.

Functional anatomy of shoulder muscles in the Pacific white-sided dolphin (Lagenorhynchus obliquidens).

Most intrinsic muscles of the forelimb in dolphins are either degenerated or lost; however, the muscles around the shoulder joint are well preserved. We dissected the forelimbs of Pacific white-sided dolphins and constructed a full-scale model of the flipper to compare and examine their movements following dissection. The humerus was oriented at approximately 45° ventrally from the horizontal plane of the dolphin and 45° caudally from the frontal plane. This maintains the neutral position of the flipper. The deltoideus and pectoralis major muscles were inserted into the body of the humerus, and the flipper was moved in the dorsal and ventral directions, respectively. A large tubercle, known as the common tubercle, was observed at the medial end of the humerus. Four muscles were inserted into the common tubercle: the brachiocephalicus, supraspinatus, and cranial part of the subscapularis, which laterally rotated the common tubercle. Subsequently, the flipper swung forward, and its radial edge was lifted. Conversely, the medial rotation of the common tubercle caused by the coracobrachialis and the caudal part of the subscapularis was accompanied by backward swinging of the flipper and lowering of the radial edge. These findings suggest the function of the flipper as a stabilizer or rudder is caused by the rotation of the humerus's common tubercle.

Artificial Intelligence Machine Learning Algorithms Versus Standard Linear Demographic Analysis in Predicting Implant Size of Anatomic and Reverse Total Shoulder Arthroplasty.

BACKGROUND: Accurate and precise templating is paramount for anatomic total shoulder arthroplasty (TSA) and reverse total shoulder arthroplasty (RSA) to enhance preoperative planning, streamline surgery, and improve implant positioning. We aimed to evaluate the predictive potential of readily available patient demographic data in TSA and RSA implant sizing, independent of implant design. METHODS: A total of 578 consecutive, primary, noncemented shoulder arthroplasty cases were retrospectively reviewed. Demographic variables and implant characteristics were recorded. Multivariate linear regressions were conducted to predict implant sizes using patient demographic variables. RESULTS: Linear models accurately predict TSA implant sizes within 2 millimeters of humerus stem sizes 75.3% of the time, head diameter 82.1%, head height 82.1%, and RSA glenosphere diameter 77.6% of the time. Linear models predict glenoid implant sizes accurately 68.2% and polyethylene thickness 76.6% of the time and within one size 100% and 95.7% of the time, respectively. CONCLUSION: Linear models accurately predict shoulder arthroplasty implant sizes from demographic data. No significant statistical differences were observed between linear models and machine learning algorithms, although the analysis was underpowered. Future sufficiently powered studies are required for more robust assessment of machine learning models in predicting primary shoulder arthroplasty implant sizes based on patient demographics.

[Anatomical study of the limited osteotomy suture button fixation Latarjet procedure with coracoacromial ligament preservation].

Objective: To investigate the morphological characteristics of the glenohumeral joint (including the glenoid and coracoid) in the Chinese population and determine the feasibility of designing coracoid osteotomy based on the preoperative glenoid defect arc length by constructing glenoid defect models and simulating suture button fixation Latarjet procedure. Methods: Twelve shoulder joint specimens from 6 adult cadavers donated voluntarily were harvested. First, whether the coracoacromial ligament and conjoint tendon connected was anatomically observed and their intersection point was identified. The vertical distance from the intersection point to the coracoid, the maximum allowable osteotomy length starting from the intersection point, and the maximum osteotomy angle were measured. Next, the anteroinferior glenoid defect models of different degrees were randomly constructed. The arc length and area of the glenoid defect were measured. Based on the arc length of the glenoid defect of the model, the size of coracoid oblique osteotomy was designed and the actual length and angle of the coracoid osteotomy were measured. A limited osteotomy suture button fixation Latarjet procedure with the coracoacromial ligament and pectoralis minor preservation was performed and the position of coracoid block was observed. Results: All shoulder joint specimens exhibited crossing fibers between the coracoacromial ligament and the conjoint tendon. The vertical distance from the tip of the coracoid to the coracoid return point was 24.8-32.2 mm (mean, 28.5 mm). The maximum allowable osteotomy length starting from the intersection point was 26.7-36.9 mm (mean, 32.0 mm). The maximum osteotomy angle was 58.8°-71.9° (mean, 63.5°). Based on the anteroinferior glenoid defect model, the arc length of the glenoid defect was 22.6-29.4 mm (mean, 26.0 mm); the ratio of glenoid defect was 20.8%-26.2% (mean, 23.7%). Based on the coracoid block, the length of the coracoid osteotomy was 23.5-31.4 mm (mean, 26.4 mm); the osteotomy angle was 51.3°-69.2° (mean, 57.1°). There was no significant difference between the arc length of the glenoid defect and the length of the coracoid osteotomy ( P>0.05). After simulating the suture button fixation Latarjet procedure, the highest points of the coracoid block (suture loop fixation position) in all models located below the optimal center point, with the bone block concentrated in the anteroinferior glenoid defect position. Conclusion: The size of the coracoid is generally sufficient to meet the needs of repairing larger glenoid defects. The oblique osteotomy with preserving the coracoacromial ligament may potentially replace the traditional Latarjet osteotomy method.

Development of a musculoskeletal shoulder model considering anatomic joint structures and soft-tissue deformation for dynamic simulation.

The shoulder joint has a high degree of freedom and an extremely complex and unstable kinematic mechanism. Coordinated contraction of the rotator cuff muscles that stop around the humeral head and the deltoid muscles and the extensibility of soft tissues, such as the joint capsule, labrum, and ligaments, contribute to shoulder-joint stability. Understanding the mechanics of shoulder-joint movement, including soft-tissue characteristics, is important for disease prevention and the development of a device for disease treatment. This study aimed to create a musculoskeletal shoulder model to represent the realistic behavior of joint movement and soft-tissue deformation as a dynamic simulation using a rigid-body model for bones and a soft-body model for soft tissues via a spring-damper-mass system. To reproduce the muscle-contraction properties of organisms, we used a muscle-expansion representation and Hill's mechanical muscle model. Shoulder motion, including the movement of the center of rotation in joints, was reproduced, and the strain in the joint capsule during dynamic shoulder movement was quantified. Furthermore, we investigated narrowing of the acromiohumeral distance in several situations to induce tissue damage due to rotator cuff impingement at the anterior-subacromial border during shoulder abduction. Given that the model can analyze exercises under disease conditions, such as muscle and tendon injuries and impingement syndrome, the proposed model is expected to help elucidate disease mechanisms and develop treatment guidelines.

Evolutionary anatomical and functional characteristics of the intrinsic shoulder and brachial muscles in the northern anteater (Tamandua mexicana).

Tamandua mexicana is an anteater species native from Mexico to Peru. This species is of great evolutionary interest because it belongs to one of the oldest clades of placental mammals in the American continent. This study aimed to describe the origin, insertion, and arterial supply of the intrinsic shoulder and brachial muscles of T. mexicana. We also compared the masses of the functional groups. Gross dissections were performed on both thoracic limbs of 13 cadavers. ANOVA followed by Tukey's test was used for statistical analyses. The subscapularis muscle presents a hiatus to the common tendon of the caput breve of the biceps brachii and coracobrachialis muscles. A variant accessory muscle, the m. articularis humeri lateralis, was found on the lateral surface of the shoulder joint. M. deltoideus pars acromialis has two bellies. The teres major muscle is perforated by the aponeurotic origin of the m. tensor fasciae antebrachii. The triceps brachii has two capita longi. The caput mediale is fused with the m. anconeus medialis. The caput laterale can have an accessory belly as an anatomical variant. Among the functional groups, a significant difference was found between the elbow extensors and flexors, with the latter having the lowest mass. In conclusion, the intrinsic muscles of T. mexicana presented unique features for the species, as well as arrangements in mass distribution that evidence a possible evolutionary convergence among species of the Superorder Xenarthra.

High accuracy of intra-articular needle position during anterior landmark guided glenohumeral injections.

OBJECTIVES: Image-guided ultrasound or fluoroscopic glenohumeral injections have high accuracy rates but require training, equipment, cost, and radiation exposure (fluoroscopy). In contrast, landmark-guided glenohumeral injections do not require additional subspecialist referrals or equipment. An optimal technique would be safe and accurate and have few barriers to implementation. The purpose of this study was to define the accuracy of glenohumeral needle placement via an anterior landmark-guided approach as assessed by direct arthroscopic visualization. METHODS: A consecutive series of adult patients undergoing shoulder arthroscopy in the beach chair position were included in this study. Demographic and procedural data were collected. The time required to perform the injection, the precise location of the needle tip, and factors that affected the accuracy of the injection were also assessed. RESULTS: A standardized anterior landmark-guided glenohumeral joint injection was performed in the operating room prior to surgery, and the location of the needle tip was documented by arthroscopic visualization with a low complication profile and few barriers to implementation. A total of 81 patients were enrolled. Successful intra-articular glenohumeral needle placement by sports medicine and shoulder/elbow fellowship-trained orthopedic surgeons was confirmed in 93.8% (76/81) of patients. The average time to complete the procedure was 24.8 â€‹s. There were no patient-related variables associated with nonintra-articular injections in the cohort. CONCLUSIONS: This study demonstrated that the technique of anterior landmark-guided glenohumeral injection has an accuracy of 93.8% and requires less than 30 â€‹s to perform. This method is safe, yields similar accuracy to image-guided procedures, has improved cost and time efficiency, and requires less radiation exposure. No patient-related factors were associated with inaccurate needle placement. Anterior landmark-guided glenohumeral injections may be utilized with confidence by providers in the clinical setting. LEVEL OF EVIDENCE: Level 5. IRB: Approved under Stanford IRB-56323.

Effect of Glenoid Bone Loss and Shoulder Position on Axillary Nerve Anatomy During the Latarjet Procedure.

BACKGROUND: The Latarjet procedure is increasingly being utilized for the treatment of glenoid bone loss and has a relatively high neurological complication rate. Understanding the position-dependent anatomy of the axillary nerve (AN) is crucial to preventing injuries. PURPOSE: To quantify the effects of changes in the shoulder position and degree of glenoid bone loss during the Latarjet procedure on the position of the AN. STUDY DESIGN: Controlled laboratory study. METHODS: A total of 10 cadaveric shoulders were dissected, leaving the tendons of the rotator cuff and deltoid for muscle loading. The 3-dimensional position of the AN was quantified relative to the inferior glenoid under 3 conditions: (1) intact shoulder, (2) Latarjet procedure with 15% bone loss, and (3) Latarjet procedure with 30% bone loss. Measurements were obtained at 0°, 30°, and 60° of glenohumeral abduction (equivalent to 0°, 45°, and 90° of shoulder abduction) and at 0°, 45°, and 90° of humeral external rotation (ER). RESULTS: Abduction of the shoulder to 60° resulted in a posterior (9.5 ± 1.1 mm; P < .001), superior (3.0 ± 1.2 mm; P = .013), and lateral (19.1 ± 2.3 mm; P < .001) shift of the AN, and ER to 90° resulted in anterior translation (10.0 ± 1.2 mm; P < .001). Overall, ER increased the minimum AN-glenoid distance at 30° of abduction (14.9 ± 1.3 mm [0° of ER] vs 17.3 ± 1.5 mm [90° of ER]; P = .045). The Latarjet procedure with both 15 and 30% glenoid bone loss resulted in a superior and medial shift of the AN relative to the intact state. A decreased minimum AN-glenoid distance was seen after the Latarjet procedure with 30% bone loss at 60° abduction and 90° ER (17.7 ± 1.6 mm [intact] vs 13.9 ± 1.6 mm [30% bone loss]; P = .007), but no significant differences were seen after the Latarjet procedure with 15% bone loss. CONCLUSION: Abduction of the shoulder induced a superior, lateral, and posterior shift of the AN, and ER caused anterior translation. Interestingly, the Latarjet procedure, when performed on shoulders with extensive glenoid bone loss, significantly reduced the minimum AN-glenoid distance during shoulder abduction and ER. These novel findings imply that patients with substantial glenoid bone loss may be at a higher risk of AN injuries during critical portions of the procedure. Consequently, it is imperative that surgeons account for alterations in nerve anatomy during revision procedures. CLINICAL RELEVANCE: This study attempts to improve understanding of the position-dependent effect of shoulder position and glenoid bone loss after the Latarjet procedure on AN anatomy. Improved knowledge of AN anatomy is crucial to preventing potentially devastating AN injuries during the Latarjet procedure.

Anthropometric study of the scapula in a contemporary population from granada. Sex estimation and glenohumeral osteoarthritis prevalence.

Anthropometric studies of the scapula have been rare in Spanish populations, nevertheless they are of current interest in forensic anthropology for estimation of sex. Although the estimation of sex is usually carried out on the pelvis and skull, other measurements related to the scapula can be helpful when the skeletal remains are incomplete. Glenohumeral osteoarthritis development is influenced, among others, by the morphology of the scapula, which is one of the less studied aspects. We carried out a descriptive study of anthropometric parameters in a series of 157 scapulae (82 individuals) on bone remains dated to the 20th century from a population of Granada (Southern Spain). Seventy seven (49%) were right-side and 80 (51%) left-side; 72 (45.9%) were from males and 85 (54.1%) from females, and the mean age at death was 70.76±11.7 years. The objective was to develop a discrimination function for sex estimation based on anthropometric parameters of the scapula other than those considered to date, and to analyze the prevalence of glenohumeral osteoarthritis in relation to selected anthropometric parameters. A logistic regression model based on parameters of the upper-external segment of the scapula was done. The obtained formula: 1/1+e^ (- (-57.911 + 0.350*B + 0283*C + 0.249*b + 0.166*a +-0.100*ß) classifies male sex with 98.3% accuracy and female sex with 92.1%. Glenohumeral osteoarthritis was detected in 16.6% of individuals and was related to age (p<0.05), scapular length (p<0.05), glenoid width (p<0.05), glenopolar angle (p<0.05), and α angle (p<0.05) in bivariate analyses but showed no significant associations in multivariate analyses. This approach can be useful for anthropological-forensic identification when scapula remains are incomplete. Glenohumeral osteoarthritis is significantly associated with a smaller α angle.

Human shoulder anatomy: new ultrasound, anatomical, and microscopic perspectives.

This study aimed to describe the shoulder anatomy, together with the anatomical relationships in adults and early stages of development. The shoulder muscles were studied from ultrasound, anatomical, and microscopic perspectives in a sample of 34 human shoulders. Thickness measurements were taken of the tendons and fasciae of the subscapularis, long head tendon of the biceps brachii, supraspinatus, infraspinatus, and teres minor. Ultrasound and dissection techniques are strongly correlated. However, the measurements obtained from the dissection technique were superior to those obtained from the ultrasound in all cases, except for the thickness of the long head tendon of the biceps brachii, the teres minor tendon, and the fascia thickness of the infraspinatus. In addition, the study of shoulder anatomy revealed no differences between females and males. Relevant findings from dissection included a clear overlap between the infraspinatus and supraspinatus, which shared tendon fibers, and a similar connection between the transverse ligament of the long head tendon of the biceps brachii and the subscapularis, which created a more interconnected shoulder function. The study of the anatomical measurements shows an underestimation of the shoulder measurements in the ultrasound compared with the dissection technique, but a high correlation between the measurements made by the two techniques. We present reference values for the tendon and fascia thicknesses of the rotator cuff, with no differences observed by gender. The relationships between shoulder structures described in the anatomical study imply as well that, in the event of an injury, adjacent tissues may be affected. This extended information may facilitate future optimal clinical explorations.

Does Morphology of the Shoulder Joint Play a Role in the Etiology of Rotator Cuff Tear?

BACKGROUND: The etiology of rotator cuff tears (RCTs) have been investigated for years and many underlying causes have been identified. Shoulder joint morphology is one of the extrinsic causes of RCTs. AIM: Morphometric measurements on MRI sections determined which parameters are an important indicator of RCT in patients with shoulder pain. The aim of this study was to determine the risk factors in the etiology of RCTs by evaluating the shoulder joint morphology with the help of previously defined radiological parameters. METHOD: Between January 2019-December 2020, 408 patients (40-70 years old) who underwent shoulder MRI and met the criteria were included in the study. There were 202 patients in the RCT group and 206 patients in the control group. Acromion type, acromial index (AI), critical shoulder angle (CSA), acromiohumeral distance (AHD), lateral acromial angle (LAA), acromial angulation (AA), acromion-greater tuberosity impingement index (ATI), and glenoid version angle (GVA) were measured from the MRI images of the patients. RESULTS: AI (0.64 vs. 0.60, p = 0.003) CSA (35.3° vs. 32.4°, p = 0.004), ATI (0.91 vs. 0.83, P < 0.001), and AA (13.6° vs. 11.9°, p = 0.011) values were higher in the RCT group than in the control group and the difference was significant. AHD (8.1 mm vs. 9.9 mm, P < 0.001), LAA (77.2° vs. 80.9°, p = 0.004) and GVA (-3.9° vs. -2.5°, P < 0.001) values were lower in the RCT group than in the control group, and again the difference was significant. According to the receiver operating characteristic curve analysis, the cutoff values were 0.623 for AI and 0.860 for ATI. CONCLUSION: Acromion type, AI, CSA, AHD, LAA, AA, ATI, and GVA are suitable radiological parameters to evaluate shoulder joint morphology. High AI, CSA, AA, ATI, GVA and low AHD and LAA are risk factors for RCT.

Relationship between scapular body morphology and rotator cuff tears: a threedimensional computed tomography study.

The purpose of this study was to identify the relationship between scapula morphology and rotator cuff tears (RCT). Hundred seventeen shoulders with and 87 shoulders without RCTs were included in this retrospective study. The critical shoulder angle (CSA) and lateral acromion angle in the coronal view, and the acromial coverage angle (ACA) and coracoid and scapular spine angle (CSSA) in the sagittal view were evaluated using 3-dimensional computed tomography. The glenoid anterior tilt, anterior acromial projection angle (AAPA), coracoid process angle, scapular spine angle (SSA), and inferior angle angle (IAA) with respect to the scapular plane were measured in the sagittal view. In univariate logistic regression analysis, CSA, ACA, AAPA, SSA, and IAA were significantly greater in shoulders with RCTs, whereas CSSA was greater in shoulders without RCTs. In multivariate logistic regression analysis, CSA and IAA were greater in shoulders with RCT and were significantly associated with this condition (P=.00073, P=.0032). This study has shown us that RCTs were associated with a greater curvature of the scapular body and greater CSA and IAA.

Morphological determination of glenohumeral joint and acromioclavicular joint with computed tomography / Determinación morfológica de la articulación glenohumeral y la articulación acromioclavicular con tomografía computarizada

SUMMARY: Although acute and chronic pathologies of the glenohumeral and acromioclavicular joints are frequently encountered in the population, the anatomy and morphometry are not fully known. The aim of this study is to determine the measurements of morphometric parameters according to age groups and sex in a large series of Turkish population. Nine hundred and forty-one shoulders computed tomography (CT) images were screened and those of subjects with healthy anatomical structure were included. Humeral head diameter (HDD) was measured on CT images. Measurements were made using 3D-CT images of: width (GW) and height (GH) of the glenoid cavity; width (CW) and height (CH) of the distal clavicular joint surface; and width (AW) and height (AH) of the acromial joint surface. Data were compared, stratified by age and sex. Images of 223 patients (118 men, 105 women) were analyzed. The following mean measurements were determined: HDD, 41.77±3.77 mm; GH, 34.66±3.26 mm; GW, 25.50±2.90 mm; CW, 14.85±3.51 mm; CH, 8.49±2.27 mm; AW, 12.97±2.94 mm; AH, 7.01±1.77 mm. When startified by sex, HDD (p<0.001), GH (p<0.001), GW (p<0.001), CW (p<0.001), CH (p=0.002), AW (p<0.001) and AH (p<0.001) measurements were significantly different and mean values were greater in men. Similarly for age, significant differences were found for GH (p=0.028), CW (p<0.001), AW (p<0.001), AH (p<0.001). The parametric values we have obtained in the Turkish population we measure differ from the measurements made in different populations according to age groups and sex. Knowing these features will contribute to treatment planning, implant and prosthesis applications.

Aunque las patologías agudas y crónicas de las articulaciones glenohumeral y acromioclavicular son frecuentes en la población, la anatomía y morfometría no se conocen por completo. El objetivo de este estudio fue determinar las medidas de los parámetros morfométricos según grupos de edad y sexo en una serie de individuos de población turca. Se examinaron 941 imágenes de tomografía computarizada (TC) de hombro y se incluyeron las de sujetos con una estructura anatómica sana. El diámetro de la cabeza humeral (HDD) se midió en imágenes de TC. Las mediciones se realizaron utilizando imágenes 3D-CT de: ancho (GW) y altura (GH) de la cavidad glenoidea; anchura (CW) y altura (CH) de la superficie articular clavicular; y anchura (AW) y altura (AH) de la superficie articular acromial. Los datos fueron comparados, estratificados por edad y sexo. Se analizaron imágenes de 223 pacientes (118 hombres, 105 mujeres). Se determinaron las siguientes medidas medias: HDD, 41,77±3,77 mm; GH, 34,66 ± 3,26 mm; GW, 25,50±2,90 mm; CW, 14,85±3,51 mm; CH, 8,49±2,27 mm; AW, 12,97±2,94 mm; AH, 7,01±1,77 mm. Cuando se inicia por sexo, HDD (p<0,001), GH (p<0,001), GW (p<0,001), CW (p<0,001), CH (p=0,002), AW (p<0,001) y AH (p <0,001) las mediciones fueron significativamente diferentes y los valores medios fueron mayores en los hombres. De igual forma para la edad se encontraron diferencias significativas para GH (p=0,028), CW (p<0,001), AW (p<0,001), AH (p<0,001). Los valores paramétricos que hemos obtenido en la población turca difieren de las medidas realizadas en diferentes poblaciones según grupos de edad y sexo. El conocimiento de estas características contribuirá a la planificación del tratamiento, aplicaciones de implantes y prótesis.

Estimating glenoid fossa width for instability - related bone loss with CT scan in a Chilean sample / Estimación del ancho de la fosa glenoidea para la pérdida ósea relacionada con inestabilidad con tomografía computarizada en una muestra chilena

SUMMARY: Glenoid fossa bone loss has been associated with recurrence and failure after glenoid labrum repair for shoulder instability. Quantification of glenoid fossa bone loss is critical for the successful treatment of glenohumeral instability. The aim of this paper was to estimate a linear regression model based on glenoid height in CT scan adjusted for age and sex to calculate glenoid fossa width in a healthy Chilean sample. CT scans of 101 shoulders were reviewed. The mean age was 51.96 years (SD 19.16; range, 15-88 years) with 53 females and 48 male patients. Studies with signs of bone loss, instability, fracture, or arthritis were excluded. After 3D-CT reconstruction, the height and width of each glenoid fossa was measured using the Owens methodology. All landmarks for the 2 measurements were placed on the most lateral surface of the glenoid fossa margin. Measurements for all shoulders were recorded by 3 observers and repeated on a subset (n = 20) of shoulders, under blinded conditions, by the same observer, at least 2 weeks after the initial measurements. Descriptive statistics, intraclass correlation and regression coefficients were calculated with Stata BE 17® software. A p- value of 0.05 was considered significant. A linear regression model was estimated resulting in the formula "Width = 10.97 + 0.02 * Age + 0.41 * Height - 1.95 * Sex (1=Female, 0=Male)". This model presented all coefficients with p <0.05 and an adjusted R2 of 0.73. Furthermore, it fulfilled the assumption of linearity, normal distribution of errors, independence of errors, and homoscedasticity. Regarding the intraobserver correlation, ICC was 0.76 for height and 0.91 for width; the interobserver ICC was 0.93 for height and 0.86 for width. A 3D-CT specific formula was developed to predict glenoid fossa width based on height with sufficient accuracy to be clinically valuable.

RESUMEN: La pérdida de hueso de la fosa glenoidea se ha asociado con recurrencia y falla después de la reparación del labrum glenoideo por inestabilidad del hombro. La cuantificación de la pérdida ósea glenoidea es fundamental para el tratamiento exitoso de la inestabilidad glenohumeral. El objetivo de este trabajo fue estimar un modelo de regresión lineal basado en la altura glenoidea en una tomografía computarizada ajustada por edad y sexo para calcular el ancho de la fosa glenoidea en una muestra chilena sana. Se revisaron las tomografías computarizadas de 101 hombros. La edad media fue de 51,96 años (DE 19,16; rango, 15- 88 años) con 53 mujeres y 48 hombres. Se excluyeron los estudios con signos de pérdida ósea, inestabilidad, fractura o artritis. Después de la reconstrucción 3D-CT, se midió la altura y el ancho de cada fosa glenoidea utilizando la metodología de Owens. Todos los puntos de referencia para las 2 mediciones se colocaron en la superficie más lateral del margen glenoideo. Las mediciones de todos los hombros fueron registradas por 3 observadores y repetidas en un subconjunto (n = 20) de hombros, en condiciones ciegas, por el mismo observador, al menos 2 semanas después de las mediciones iniciales. La estadística descriptiva, la correlación intraclase y los coeficientes de regresión se calcularon con el software Stata BE 17®. Se consideró significativo un valor de p de 0,05. Se estimó un modelo de regresión lineal que resultó en la fórmula "Ancho = 10,97 + 0,02 * Edad + 0,41 * Altura - 1,95 * Sexo (1 = Mujer, 0 = Hombre)". Este modelo presentó todos los coeficientes con p <0.05 y un R2 ajustado de 0.73. Además, cumplió con los supuestos de linealidad, distribución normal de errores, independencia de errores y homocedasticidad. En cuanto a la correlación intraobservador, el CCI fue de 0,76 para la altura y 0,91 para la anchura; el ICC interobservador fue de 0,93 para la altura y 0,86 para la anchura. Se desarrolló una fórmula específica de 3D-CT para predecir el ancho glenoideo en función de la altura con suficiente precisión para ser clínicamente valiosa.