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.

Evaluation of Preoperative Magnetic Resonance Imaging Parameters with Arthroscopic Validation of Subscapularis Tendon Abnormalities in 187 Patients at a Single Center in Turkey.

BACKGROUND This study from a single center in Turkey aimed to evaluate preoperative magnetic resonance imaging (MRI) parameters with arthroscopic validation of subscapularis (SS) tendon abnormalities in 187 patients. MATERIAL AND METHODS Preoperative MRI scans of 187 patients who had undergone arthroscopic shoulder surgery by the senior author (all in lateral decubitus position) were evaluated by 3 researchers. Patients with arthroscopically proven SS tendon rupture (n=69) and without rupture (n=118) were divided into 2 groups and compared with various distances and angles. The following parameters were measured: coracohumeral distance (CHD), coracoid morphology, coraco-glenoid angle (CGA), coracoid angle (CA), coraco-humeral angle (CHA), coracoid overlap (CO), coracoid body-glenoid angle (CBGA), coracoid tip-glenoid angle (CTGA), coracoid tip-body angle (CTBA), coraco-scapular angle (CSA), lesser tuberosity angle (LTA), and lesser tuberosity height (LTH). RESULTS CHD, CHA, CA, and LTA values decreased in the SS tendon rupture group; coracoid type grade and CO increased (all P<0.001, excluding LTA [P=0.022]). The cut-off values of these measurements were CHD=7.25 mm, CHA=107.25°, CA=111.5°, LTA=31.7°, and CO=16.5 mm. The differences in CGA and CBGA values were not statistically significant (P=0.11, 0.441, respectively). CTGA, CTBA, LTH, and CSA measurements were not included in the intergroup comparisons due to insufficient inter-observer reliability (kappa=0.478, 0.239, 0.496, 0.309, respectively). Power (1- b) in post hoc analysis was calculated as 0.941. CONCLUSIONS SS tendon rupture was associated with a reduction in the parameters of CHD, CHA, CA, and LTA and an increase in CO on MRI.

A shallow morphology of the intertubercular groove is associated with medial and bilateral but not lateral pulley lesions.

PURPOSE: To investigate the influence of intertubercular groove (IG) morphology on the development of different types of biceps reflection pulley (BRP) injuries. METHODS: A consecutive cohort of 221 patients with ventral shoulder pain and a preoperative diagnosis suspecting BRP injury, who underwent arthroscopy, was retrospectively reviewed. The presence or absence as well as type of pulley injury (medial, lateral or bilateral) was confirmed arthroscopically. The intertubercular groove was evaluated on MRIs after triplanar reconstruction of the axial plane. IG depth, width, medial wall angle (MWA), lateral wall angle (LWA) and total opening angle (TOA) were measured. IG depth and width were expressed in relation to the humeral head diameter. Measurements were performed by two clinicians independently and averaged. RESULTS: Of 166 included patients 43 had bilateral, 65 medial and 38 lateral BRP lesions. 20 patients had intact BRPs and represented the control group. The intra-class correlation coefficient of measurements was 0.843-0.955. Patients with a medial or bilateral BRP injury had a flatter MWA (38.8° or 40.0° vs. 47.9°, p < 0.001), wider TOA (96.1° or 96.6° vs. 82.6°, p < 0.001), greater width (12.5 or 12.3 vs. 10.8 mm, p = 0.013) and shallower depth (5.5 or 5.4 vs. 6.2 mm, p < 0.001) than the control group. Conversely, the IG morphology of those with lateral BRP injuries did not differ significantly from the control group. The odds ratio for a medial or bilateral BRP injury when the TOA exceeded 95° was 6.8 (95% confidence interval 3.04-15.2). CONCLUSION: A dysplastic type of IG morphology with a wide TOA, flat MWA, decreased depth and increased width is associated with the presence of medial and bilateral BRP injuries. A TOA of > 95° increases the likelihood of a medial or bilateral BRP injury 6.8-fold. Lateral BRP injuries are not associated with dysplastic IG morphology. Concomitant LHBT surgery may, therefore, not always be necessary during isolated supraspinatus tendon repair. LEVEL OF EVIDENCE: Level III.

Anteroposterior and Lateral Coverage of the Acromion: Prediction of the Rotator Cuff Tear and Tear Size.

Background: The aim of this study was to assess whether the anteroposterior coverage of the acromion reflecting acromial morphology affects the rotator cuff tear (RCT) and tear size, in addition to the lateral coverage. Methods: Medical records of 356 patients with RCTs, concentric osteoarthritis, and calcific tendinitis identified using three-dimensional computed tomography between January 2016 and December 2017 were retrospectively analyzed. The patients were divided into group A (those with RCTs) and group B (those with concentric osteoarthritis or calcific tendinitis). Subsequently, group A was subdivided into three categories according to the size of RCTs: small-to-medium, large, and massive. The lateral coverage was measured through the lateral acromial angle (LAA) and critical shoulder angle (CSA), whereas the anteroposterior coverage was measured via the acromial tilt (AT), acromiohumeral interval (AHI) in the sagittal view, and anteroposterior coverage index (APCI) as a new radiologic parameter. Results: Between groups A and B, CSA (34.5° ± 3.4° and 30.8° ± 3.4°, respectively), APCI (0.83 ± 0.10 and 0.75 ± 0.08, respectively), and AHI (6.3 ± 2.0 mm and 7.8 ± 1.8 mm, respectively) were significantly different (all p < 0.001), whereas LAA and AT did not show a significant difference between the groups (p = 0.089 and p = 0.665, respectively). The independent predictive radiologic parameters of the RCT were the CSA, APCI, and AHI (p < 0.001, p < 0.001, and p = 0.043, respectively); among these, the APCI showed the highest regression coefficient (odds ratio = 2.82). The parameters associated with the size of RCTs were CSA (p = 0.022) and AHI, of which AHI, in particular, had the most significant effect on both small-to-medium and large tears (all p < 0.001). Conclusions: Large CSA, high APCI, and low AHI were predictors of RCTs, with the APCI showing the strongest correlation. In addition to the large CSA, low AHI also correlated with the size of RCTs and affected the entire size groups. We suggest that both the lateral coverage and anteroposterior coverage of the acromion should be considered essential factors for predicting the presence of RCTs and tear size.

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.

A proposal for a new classification of the long head of the biceps brachii.

INTRODUCTION: The anterior compartment of the arm consists of three muscles: the biceps brachii, brachialis and coracobrachialis. The aim of the present study was to characterize possible variations in the morphology of the proximal attachments of the long head of the biceps brachii and to propose an accurate classification of the area which can be useful for planning surgical procedures and planning rehabilitation in the region. MATERIALS AND METHODS: Eighty (40 left and 40 right, 40 female, 40 male) upper limbs fixed in 10% formalin solution were examined. RESULTS: The main tendon of the long head of the biceps brachii demonstrated three types of attachment. The most common type, Type I (53.75%), was characterized by a single attachment only for the supraglenoid tubercle. Type III (33.75%) was characterized by a single attachment to the glenoid labrum. Type II (12.5%) was characterized by a double attachment to the glenoid labrum and the supraglenoid tubercle. Additionally, two types of the accessory tendon of the long head of the biceps brachii were identified (Type A-B). Type A (14 cases) was attached to the capsule of the humeral joint, and Type B (six cases) was attached to the greater tubercle of the humerus. CONCLUSION: The long head of the biceps brachii is characterized by high morphological variability. The new classification proposes three types of proximal attachment (I-III), with two types of accessory long head of the biceps brachii (A-B) tendon. A thorough understanding of the morphological variability of the long head of the biceps brachii is necessary when planning arthroscopic procedures or even planning rehabilitation procedures.

Are critical shoulder angle and acromion index correlated to the size of a rotator cuff tear.

PURPOSE: Scapular morphology is an extrinsic factor playing role in rotator cuff tear (RCT) etiology. The objective of this study was to evaluate the relationship between critical shoulder angle (CSA) and acromion index (AI) with partial-bursal side and full thickness RCT and the size of the RCT. HYPOTHESIS: The hypothesis was that CSA and AI would be greater in partial bursal-side RCT and full-thickness RCT patients and would increase with the size of the RCT. METHODS: This retrospective study assessed 218 patients who had standard shoulder radiographs and magnetic resonance imaging. Patients were divided into three groups: intact rotator cuff (68), partial bursal-side RCT (34) and full-thickness RCT (116). In the second part, full-thickness RCT patients were divided into four groups according to RCT size; small (<1cm), medium (1-3cm), large (3-5cm) and massive (>5cm). AI and CSA measurements were evaluated from radiographs. RESULTS: The mean CSA was 32.8̊ in control group, 34.3̊ in partial group and 36.9̊ in full-thickness group. The mean AI was 0.66, 0.68 and 0.72 respectively. Significant difference was found in AI and CSA between full thickness RCT and intact RC group (p<0.01), and partial RCT and full thickness RCT group (p<0.05) in paired comparisons. In full thickness RCT size groups the mean CSA was 34.2̊, 36.4̊, 39.0̊ and 40.8̊ and mean AI was 0.70, 0.71, 0.73 and 0.79 respectively. Significant difference was found between small-large, small-massive, medium-massive groups for CSA in paired comparisons and between small-massive, medium-massive groups for AI. CONCLUSION: CSA and AI were significantly greater in full-thickness RCT patients and the size of the RCT increased with CSA and AI. The greater CSA and AI could be predictors for larger RCT. LEVEL OF EVIDENCE: III; Cross-Sectional Design; Prognosis Study.

Implication of bone morphology in degenerative rotator cuff lesions: A prospective comparative study between greater tuberosity angle and critical shoulder angle.

BACKGROUND: Degenerative rotator cuff tear is a frequent and multifactorial pathology. The role of bone morphology of the greater tuberosity and lateral acromion has been validated, and can be measured with two plain radiographic markers on true anteroposterior views: the greater tuberosity angle (GTA) and the critical shoulder angle (CSA). However, the interdependence of both markers remains unknown, as well as their relationship with the level of professional and sports activities involving the shoulder. The aim of this prospective comparative study was to describe the correlation between the GTA and CSA in patients with degenerative rotator cuff tears. HYPOTHESIS: GTA and CSA are independent factors from one another and from demographic factors, such as age, dominance, sports, or professional activities. PATIENT AND METHODS: All patients presenting to a shoulder specialized clinic were assigned to two groups. The first consisted of patients with a symptomatic degenerative rotator cuff tear visible on MRI and the control group consisted of patients with any other shoulder complaints and no history or visible imaging of any rotator cuff lesion. RESULTS: There were 51 shoulders in 49 patients in the rotator cuff tear group (RCT) and 53 shoulders in 50 patients in the control group. Patient demographics were similar in both groups. Mean GTA was 72.1°±3.7 (71.0-73.1) in the RCT group and 64.0°±3.3 (63.1-64.9) in the control group (p<0.001). Mean CSA was 36.7°±3.7 (35.7-37.8) in the RCT group, and 32.1°±3.7 (31.1-33.1) in the control group (p<0.001). A summation of GTA and CSA values over 103° increased the odds of having a rotator cuff tear by 97-fold (p<0.001). There was no correlation between GTA and CSA, nor between GTA or CSA and age, sex, tear size, or dominance. Patients with different levels of professional and sports activities did not have significantly different GTA or CSA values. CONCLUSION: GTA and CSA are independent radiologic markers that can reliably predict the presence of a degenerative rotator cuff tear. A sum of both values over 103° increases the odds of having a rotator cuff tear by 97-fold. These markers are not correlated with patient demographic or environmental factors, suggesting that the variability of the native acromion and greater tuberosity morphology may be individual risk factors for rotator cuff tear. LEVEL OF EVIDENCE: II; diagnostic study.

A prospective observational case control study investigating the coronal plane scapular morphological differences in full-thickness posterosuperior cuff tears and primary glenohumeral osteoarthritis.

INTRODUCTION: The critical shoulder angle (CSA) is a surrogate marker of the coronal plane morphology of the scapula. CSA differences between scapulae could be due to differences in glenoid inclination (GI) or the location of the most lateral part of the acromion relative to the inferior glenoid, or both. An understanding of the hierarchy of the scapular morphological changes associated with glenohumeral osteoarthritis (GHOA) and rotator cuff (RC) tears would allow accurate biomechanical modeling. METHODS: A prospective observational case control study was undertaken in which the GI, "nonglenoid"-CSA, acromial vertical offset index, acromial horizontal offset index, acromial horizontal-vertical offset index, and coronal plane angulation of the acromion (CPAA-m) were measured on high-quality radiographs to compare coronal plane scapular anatomy in: (1) patients with asymptomatic atraumatic full-thickness RC tears, (2) patients with symptomatic primary GHOA, and (3) a control group with no RC tear or GHOA treated for glenohumeral instability or symptomatic labral pathology. Intraobserver reliability of the measurements was performed. RESULTS: In the GHOA group, the GI was lower (less superiorly inclined) than the RC tear group (difference between the means: -4.8°, 95% confidence interval [CI] [-8.8°, -0.9°], P = .014) and the control group (difference between the means: -7.9°, 95% CI [-11.8°, -3.9°], P = .000); there was no difference in the acromial measurements. In the RC tear group, the nonglenoid-CSA was higher (difference between the means: 7.7°, 95% CI [3.0°, 12.3°], P = .001), the acromial vertical offset index was lower (difference between the means: -0.13, 95% CI [-0.24, -0.01], P = .026), and the acromial horizontal-vertical offset index was higher (difference between the means: 0.15, 95% CI [0.01, 0.28], P = .030) than the control group; there was no difference in the acromial horizontal offset index or the GI. The CPAA-m was lower (greater coronal plane downslope of the acromion) in both GHOA (difference between the means: -9.6°, 95% CI [-18.6°, -0.5°], P = .036) and RC tears (difference between the means: -9.9°, 95% CI [-19.0°, -0.9°], P = .029) compared with the control group. The intraclass correlation coefficients for intraobserver reliability demonstrated excellent reliability for the measurements (all >0.900). DISCUSSION: Scapulae associated with GHOA have lower GI, but no spatial differences in the location of the lateral acromion compared with a normal population. Scapulae associated with RC tears have a lower vertical offset of the lateral acromion, but no difference in horizontal offset or GI compared with a normal population. The downslope of the acromion in the coronal plane is greater (lower CPAA-m) in both RC tears and GHOA than the normal population.

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.

Acromioplasty reduces critical shoulder angle in patients with rotator cuff tear.

Critical shoulder angle (CSA) is the angle between the superior and inferior bone margins of the glenoid and the most lateral border of the acromion and is potentially affected during a rotator cuff tear (RCT). Acromioplasty is generally performed to rectify the anatomy of the acromion during RCT repair surgery. However, limited information is available regarding the changes in the CSA after anterolateral acromioplasty. We hypothesized that CSA can be decreased after anterolateral acromioplasty. Data were retrospectively collected from 712 patients with RCTs and underwent arthroscopic rotator cuff repair between January 2012 and December 2018, of which 337 patients were included in the study. The presurgical and postsurgical CSA were then determined and compared using a paired samples t test. Because previous study mentioned CSA more than 38 degrees were at risk of rotator cuff re-tear, patients were segregated into two groups: CSA < 38° and CSA ≥ 38°; these groups were compared using an independent-samples t test. These 337 participants (160 male and 177 female) presented a CSA of 38.4° ± 6.0° before anterolateral acromioplasty, which significantly decreased to 35.8° ± 5.9° after surgery (P < .05). Before surgery, 172 patients were present in the CSA ≥ 38° group and 57 were preset in the CSA < 38° group after surgery. The CSA decreased significantly in the CSA ≥ 38° group rather than in the CSA < 38° group (P < .05). In conclusion, the CSA can be effectively decreased through anterolateral acromioplasty, and this reduction in the CSA is more significant among individuals with CSA ≥ 38° than among those with CSA < 38°, indicating that acromioplasty is recommended along with RCT repair especially among individuals with a wide presurgical CSA.

Analysis of the coracoid morphology with multiplanar 2D CT and its effects on the graft size in the Latarjet procedure.

PURPOSE: In this study, we aimed to reveal the individual differences regarding the size of the coracoid and their effects on the classical and modified Latarjet procedures. METHODS: Computed tomography images of 120 patients (mean age: 41.18 ± 12.01 years) without shoulder complaints or shoulder instability were evaluated retrospectively. The glenoid width, the surgical graft length, and the coracoid total length, width, and thickness were measured using the multiplanar reconstruction method on the Sectra Picture Archiving and Communications System (PACS) system. Age, gender, side, the dominant hand, and the height of the patients were recorded and the correlations between them were investigated. On the created hypothetical model, the current size of the coracoid was evaluated to determine what size of glenoid defects it could repair by employing the classical and the modified Latarjet techniques. RESULTS: There was no significant difference between the right-hand-dominant group and the left-hand-dominant group in terms of coracoid measurement results (p > 0.05). Again, there was no statistically significant difference between the right and the left side regarding the coracoid size (p > 0.05). A positive correlation could be detected only between age and the coracoid width and thickness (p < 0.05). A positive correlation was also found between the glenoid width and the coracoid width and thickness in both shoulders (p < 0.001). Coracoid thickness could fill in the defects that amounted to 40% of the glenoid width, while the coracoid width could fill in for the defects that were 50% of the glenoid width in both genders. CONCLUSION: Our study showed that hand dominance and side were not effective on the coracoid dimensions. In addition, it has been shown that the coracoid dimensions did not have a significant effect in the choice of Latarjet technique in terms of defect repair and that repair rates of up to 40% could be achieved in glenoid defects with both techniques.

Three-dimensional geometry of the normal shoulder: a software analysis.

BACKGROUND: Three-dimensional (3D) geometry of the normal glenohumeral bone anatomy and relations is poorly documented. Our aims were (1) to determine the 3D geometry of the normal glenohumeral joint (GHJ) with reference to the scapular body plane and (2) to identify spatial correlations between the orientation and direction of the humeral head and the glenoid. METHODS: Computed tomographies (CTs) of the normal, noninjured GHJ were collected from patients who had undergone CTs in the setting of (1) polytrauma, (2) traumatic head injury, (3) chronic acromioclavicular joint dislocations, and (4) unilateral trauma with a contralateral normal shoulder. We performed 3D segmentation and measurements with a fully automatic software (Glenosys; Imascap). Measurements were made in reference to the scapular body plane and its transverse axis. Geometric measurements included version, inclination, direction, orientation, best-fit sphere radius (BFSR), humeral subluxation, critical shoulder angle, reverse shoulder angle, glenoid area, and glenohumeral distance. Statistical correlations were sought between glenoid and humeral 3D measurements (Pearson correlation). RESULTS: A total of 122 normal GHJs (64 men, 58 women, age: 52 ± 17 years) were studied. The glenoid BFSR was always larger than the humerus BFSR (constant factor of 1.5, standard deviation = 0.2). The mean glenoid version and inclination were -6° ± 4° and 7° ± 5°, respectively. Men and women were found to have significantly different values for inclination (6° vs. 9°, P = .02), but not for version. Humeral subluxation was 59% ± 7%, with a linear correlation with glenoid retroversion (r = -0.70, P < .001) regardless of age. There was a significant and linear correlation between glenoid and humeral orientation and direction (r = 0.72 and r = 0.70, P < .001). CONCLUSION: The 3D geometry of the glenoid and humeral head present distinct limits in normal shoulders that can be set as references in daily practice: version and inclination are -6° and 7°, respectively, and humeral posterior subluxation is 59%; interindividual variations, regardless of the size, are relative to the scapular plane. There exists a strong correlation between the position of the humeral head and the glenoid orientation and direction.

Glenoid size and orientation in the Chilean population / Tamaño y orientación glenoidea en la población chilena

Glenoid morphology is a key factor in determining the success of shoulder surgery. The purpose of this experimental study was to precisely determine the anatomical size and orientation of the glenoid in the Chilean population. 122 CT scans from asymptomatic Chilean patients were obtained. The mean age was 43.8 years (SD 12.3; range, 17-53 years) with 63 female and 59 male patients. For each of the scapulae, were obtained the glenoid version and inclination, maximum glenoid width and height, superior glenoid width, glenoid surface area, glenoid vault depth, and maximum scapular width. The glenoid size showed an average width of 26 ± 2.7 mm, a height of 40.3 ± 3.5 mm and a vault depth of 26.5 ± 3.7 mm. There were significant differences between men and women. The glenoid orientation showed an average of -13.9 ± 4.8° of retroversion and a superior inclination of 11.1 ± 4.7°. Significant differences between men and women were seen only for version. We conclude, that in this Chilean sample the morphological parameters of the glenoid correspond to the published literature, however, some characteristics in this cohort must be further confirmed using other methods.

La morfología glenoidea es un factor clave para determinar el éxito de la cirugía de hombro. El propósito de este estudio experimental fue determinar con precisión el tamaño anatómico y la orientación de la glenoides en la población chilena. Se obtuvieron 122 tomografías computarizadas de pacientes chilenos asintomáticos. La edad media fue de 43,8 años (DE 12,3; rango, 17-53 años) con 63 pacientes femeninos y 59 masculinos. Para cada una de las escápulas, se obtuvieron la versión glenoidea y la inclinación, el ancho y la altura glenoidea máxima, el ancho glenoideo superior, el área de superficie glenoidea, la profundidad de la bóveda glenoidea y el ancho escapular máximo. El tamaño glenoideo mostró un ancho promedio de 26 ± 2,7 mm, una altura de 40,3 ± 3,5 mm y una profundidad de bóveda de 26,5 ± 3,7 mm. Hubo diferencias significativas entre hombres y mujeres. La orientación glenoidea mostró un promedio de -13,9 ± 4,8 ° de retroversión y una inclinación superior de 11,1 ± 4,7 °. Se observaron diferencias significativas entre hombres y mujeres solo para la versión. Concluimos que en esta muestra chilena los parámetros morfológicos de la glenoides corresponden a la literatura publicada, sin embargo, algunas características de esta cohorte deben confirmarse aún más utilizando otros métodos.

Arthroscopic approaches to and anatomy of the shoulder joint of cattle: a cadaver study.

BACKGROUND: Arthroscopic surgery is described as a minimally invasive technique for diagnosis, exploration and treatment of joint disorders. It allows intraarticular structures to be assessed accurately, thereby improving the diagnostic capabilities, and it broadens the spectrum of surgical techniques feasible for treatment of articular pathologies in cattle. This study aimed to assess for cattle the described arthroscopic approaches to the shoulder joint of horses, and to describe the appearance of the corresponding intraarticular structures of the shoulder joint. Additionally, to perform histological examination where tissues were identified and assessed arthroscopically, but the tissue type was uncertain using cadaveric limbs from cattle of different age categories without any signs of orthopedic diseases of the front limbs. RESULTS: An anatomic and arthroscopic investigation with 34-cadaveric forelimbs from 20-cattle was performed. The arthroscope was inserted either immediately cranial or 1-cm caudal to the tendon of the infraspinatus muscle for the cranial and caudal approaches, respectively. The shoulder joints were examined with the limbs in either horizontal non-pulled position, abducted non-pulled position using a three-pod limb holder adjustable in height, or horizontal manually pulled position. Arthroscopy was performed using a rigid 30°arthroscope (18-cm length, 4-mm outer diameter) to view the synovial pouches with their synovial villi and the following structures: cranial rim of the glenoid, cranial portion of the humeral head, incisura-glenoidalis, caudal rim of the glenoid, caudal portion of the humeral head, and cranial and caudal cul-de-sac. Abduction of the limb allowed improved visualization of the lateral portion of the joint. Pulling the limb facilitated investigation of the medial portion of the joint. Generally, the distention range was higher in younger as compared to adult cattle, and visualization of the medial portion of the joint was, therefore, facilitated in younger animals. The main complications observed were subcutaneous fluid extravasations and partial-thickness articular cartilages wear-lines. CONCLUSION: The described arthroscopic techniques allowed good overall visualization of the most relevant anatomical structures within the healthy cadaveric joint. Further investigations are warranted to evaluate the diagnostic and therapeutic applications of these techniques and the prognosis of arthroscopic surgery as a tool for the treatment of joint lesions.

The Law of Use and Disuse: Critical Shoulder Angle and Rotator Cuff Tears-Association Does Not Imply Causation.

The critical shoulder angle has been associated with the development of rotator cuff lesions. Over time, this association has been interpreted as a cause-effect relation without scientific evidence. Beyond the controversies that exist on the reliability and relevance of this radiographic parameter, the critical shoulder angle per se may not be responsible for rotator cuff tears because patient activities throughout several decades could induce not only cuff lesions but also bone remodeling at the acromial level.

The position of the upper limb during shoulder arthroscopy does not affect the distance between axillary nerve and glenoid.

PURPOSE: The segment of the axillary nerve (AxN) near the glenoid rim is at risk of iatrogenic lesion during arthroscopic procedures. We hypothesize that the distance between the AxN and the glenoid rim is not modified by the patient's positioning. The primary objective was to compare the position of the AxN with the inferior glenoid rim in lateral decubitus or in beach chair and positions of the upper limb. METHODS: Sixteen shoulders were dissected in beach chair position with the shoulder in neutral rotation. Needle one was placed in the axillary nerve where it was the closest with the inferior glenoid rim. In lateral decubitus with traction and 70° of abduction needle two was placed in the AxN at the closest with the inferior glenoid rim. The glenoid rim was marked with a needle at 6 o'clock. In beach chair position, the distance between needle one and the glenoid needle was measured for six positions. In lateral decubitus, measures were done for two positions of abduction. In lateral decubitus with 70° of abduction, the distance between needle two and the glenoid needle was also measured. RESULTS: The mean distance between AxN and the inferior glenoid rim was 14.4 mm in reference position in beach chair. The results showed the absence of difference between the positions during surgery except for lateral decubitus with 70° of abduction. CONCLUSION: Our study showed that the position of the shoulder during arthroscopic procedures cannot take away the AxN from the inferior glenoid rim. LEVEL OF EVIDENCE: Level IV-basic science study.

Arthroscopic anatomy of the middle glenohumeral ligament. A series of 300 cases.

PURPOSE: The anatomy of the middle glenohumeral ligament (MGHL) is seldomly described during arthroscopy. The aim of this study was to determine the arthroscopic variants concerning the anatomy of the MGHL. METHODS: A prospective, observational, single-center study was conducted between June 2016 and June 2017. All patients undergoing a first-time arthroscopy of the shoulder and with no history of prior surgery or trauma of the same shoulder were consecutively enrolled. The variations of the MGHLs shape and of its glenoid and distal insertions were documented during surgery. RESULTS: A total 300 patients were included. Surgeries included rotator cuff sutures, tenotomy/tenodesis of the long head of the biceps tendon (LHBT) and subacromial decompression in respectively 31%, 32.7% and 35.5% of cases. The MGHL was absent in 12% of cases, presented a flat structure in 72% of cases, a cord-like shape in 14% and a Buford complex was observed in 1%. Its glenoid insertion was located on the labrum between the superior (SGHL) and inferior (IGHL) in 43% of cases, presented a combined insertion with the LHBT in 7%, with the SGHL in 29% and with both the SGHL and LHBT in 9%. The distal insertion was located in 67% of cases on the subscapularis tendon (SCCT) or the capsule covering it, and on the humeral bone in 21%. CONCLUSION: This study confirms and details the anatomic variants of the MGHL, notably describing the lesser-known variants of its distal insertion, yet arises the question of the exact nature and function of this so-called ligament.

Global Perspectives on Management of Shoulder Instability: Decision Making and Treatment.

The glenohumeral joint is prone to instability. Patients with instability should have a physical examination. Imaging studies can provide additional information. Classification schemes that into account soft tissue pathology, neuromuscular control, bone loss, and activity level. An arthroscopic Bankart repair is the mainstay for unidirectional instability. Bone block procedures are indicated for patients with bone loss or a failed attempt at stabilization surgery. The arthroscopic Latarjet is a promising option for these patients. For patients with multidirectional instability, prolonged rehabilitation is indicated, followed by capsular plication or inferior capsular shift if instability is unresponsive to physical therapy.