Investigation of Morphological and Biomechanical Properties of the Scapula for Shoulder Joint

Objective

The glenopolar angle is a helpful criterion for recommending operative treatment. This study aims to determine the morphometric features of the scapula and provide essential information that supplies scapular biomechanics to produce a formula.

Methods

The study was carried out on 34 dry scapulae in the laboratory of the Anatomy Department of the Faculty of Medicine, Bursa Uludag University. We used calipers for the linear measurements and the ImageJ program for the area and angle parameters. A total of 23 parameters were evaluated in the study. Statistical analyzes were performed using SPSS 22.0 software.

Results

According to the results of the correlation analysis, the highest correlation value of (R=0.957) was found to be the distance between the superior angle (angulus superior)-top of the glenoid plane and the inferior angle (angulus inferior)-the top of the glenoid plane. To estimate the glenopolar angle, we applied linear regression analysis and developed the following formula: Glenopolar angle =115.589 - (6.401 x the distance between the coracoid process and the top of the glenoid cavity) - (0.368 x angle between the glenoid plane and the lateral edge of the scapula extending towards the endpoint of the glenoid plane) (Adjusted R2=0.667).

Conclusions

Glenopolar angle can provide information about the fracture risk of the glenoid cavity and allows orthopedic surgeons to make quick decisions about the risk in the region. We believe that the study will provide a different perspective on designing different products in industrial designs for shoulder joints, especially in implantations.

Glenohumeral Cartilage Thickness: Implications in Prosthetic Design and Osteochondral Allograft Transplantation

OBJECTIVE

A complete understanding of the glenohumeral joint anatomy is crucial for osteochondral allograft (OCA) transplantation and prosthetic design. However, existing data on the cartilage thickness distribution are not consistent. This study aims to describe the cartilage thickness distribution at both the glenoid cavity and humeral head in males and females.

DESIGN

Sixteen fresh cadaveric shoulder specimens were dissected and separated to expose the glenoid and humeral head articular surfaces. The glenoid and humeral head were cut into 5-mm coronal sections. Sections were imaged and cartilage thickness was measured at 5 standardized points on each section. Measurements were analyzed based on age, sex, and regional location.

RESULTS

For the humeral head, cartilage was thickest centrally (M = 1.77 ± 0.35 mm) and thinnest superiorly and inferiorly (M = 1.42 ± 0.37 mm, 1.42 ± 0.29 mm). At the glenoid cavity, cartilage was thickest in the superior and inferior areas (M = 2.61 ± 0.47 mm, 2.53 ± 0.58 mm) and thinnest centrally (M = 1.69 ± 0.22 mm). Males were found to have thicker cartilage at both the humeral head and glenoid (P = 0.0014, P = 0.0133).

CONCLUSIONS

Articular cartilage thickness distribution of the glenoid and humeral head is nonuniform and reciprocal in nature. These results can be used to further inform prosthetic design and OCA transplantation. We noted a significant difference in cartilage thickness between males and females. This suggests that the sex of the patient should be taken into consideration when matching donors for OCA transplantation.

The morphofunctional implications of the glenoid labrum of the glenohumeral joint in hominoids

OBJECTIVES

A morphocline of the glenoid cavity has been used to infer differences in locomotor behaviors; however, the glenoid cavity is surrounded by the glenoid labrum, a fibrocartilaginous structure that could influence the functionality of the glenoid. The objectives of this study are to explore the effects of the glenoid labrum on the area, depth, and morphology of the glenoid cavity in primates.

MATERIALS AND METHODS

Photogrammetry was used to build 3D models of the glenoid, with and without the labrum, and three- (3D) and two-dimensional (2D) geometric morphometrics (GM) was applied. 2D areas were collected from zenithal images for glenoids with and without labrum to evaluate the availability of articular surface area.

RESULTS

In the 2D GM the morphocline is present in the dry-bone sample but not with the presence of the glenoid labrum. In the 3D GM there are differences between species mainly concerning the depth of the glenoid cavity. 2D areas reveal that the amount of articular area of the glenoid cavity increases with the presence of the labrum, particularly in humans.

DISCUSSION

The glenoid labrum changes the shape, increases the depth and the surface area of the glenoid cavity, particularly in humans. Therefore, the glenoid labrum might hold a functional role, increasing the stability of the glenohumeral joint of primates in general, and especially in humans.

The Correlation Between Morphologic Characteristics of Condyle and Glenoid Fossa with Different Sagittal Patterns of Jaw Assessed by Cone-Beam Computed Tomography

OBJECTIVE

This study aimed to determine the relationship between the morphologic characteristics of condyle and glenoid fossa in different sagittal skeletal patterns using cone-beam computed tomography.

METHODS

In this cross-sectional study, the lateral cephalometric and cone-beam computed tomography images of 90 patients were evaluated. The patients were categorized into three equal groups of sagittal skeletal patterns, according to the ANB angle. The greatest anteroposterior and mediolateral diameters of the mandibular condyles, as well as the angle between the long axis of the mandibular condyles and the midsagittal plane, were measured on the axial view of cone-beam computed tomography images. The anterior joint space, superior joint space, posterior joint space, articular eminence inclination, depth of the glenoid fossa, and width of the glenoid fossa were also measured on the central sagittal slices. One-way analysis of variance (ANOVA), Tukey's post hoc test and chi-square test were performed.

RESULTS

Patients with the skeletal Class III had a significantly higher articular eminence inclination, while Class II patients had a lower articular eminence inclination (P = .001). In Class III patients, the depth of the glenoid fossa was greater, and the width of the glenoid fossa was smaller than in the other groups (P < .01). The anterior and posterior joint space did not show any significant differences between the 3 groups.

CONCLUSION

There were significant differences in some morphological characteristics of the condyle and glenoid fossa in patients with different sagittal skeletal patterns; therefore, this relationship should be considered in the treatment of these patients.

Morphological classification and measurement of the glenoid cavity using three-dimensional reconstruction in a Chinese population

BACKGROUND

The purpose of this study was to examine the various shapes and record the morphometric data of the glenoid cavity in a Chinese population.

MATERIALS AND METHODS

A total of 501 scapulae, 247 left and 254 right, were analyzed. We classified the shape of the glenoid cavity as type Ⅰ (pear-shaped), type Ⅱ (oval-shaped), type Ⅲ (teardrop-shaped), type Ⅳ (calabash-shaped) or type Ⅴ (inverted comma-shaped). Four defined parameters, the superior-inferior glenoid diameter (AB), upper anterior-posterior glenoid diameter (CD), lower anterior-posterior glenoid diameter (EF) and glenoid index (GI), were measured, and five shapes were classified via three-dimensional reconstruction.

RESULTS

The mean AB, CD, EF and GI values of the glenoid were 3.51±0.41 cm, 1.95±0.28 cm, 2.60±0.34 cm, and 1.35±0.12 cm, respectively. The AB value of type Ⅱ glenoid cavities was significantly smaller than that of type Ⅰ and Ⅲ glenoid cavities (P<0.05), but the GI value of type Ⅱ glenoid cavities was larger than that of type Ⅲ cavities (P<0.05). The CD value showed a difference between type Ⅰ and type Ⅲ glenoid cavities (P<0.05). For the EF parameter, the values of type Ⅲ glenoid cavities were significantly larger than those of type Ⅰ and Ⅱ glenoid cavities (P<0.05).

CONCLUSIONS

Measuring and observing the variety of shapes and sizes of the glenoid cavity in Chinese people is conducive to for better understand its morphological features. This information can also guide surgeons in the design and selection of suitable prostheses for total shoulder arthroplasty in the Chinese population in order to reduce postoperative complications.

Evaluation of the Glenoid Track Tomographic Method in Magnetic Resonance Imaging/Arthro-MRI

Objective  To evaluate and compare the glenoid track method in 3D-reconstructed computed tomography (3D-CT) scans with magnetic resonance imaging (MRI) and/or arthro-MRI.

Methods  Forty-four shoulders with clinical and radiographic diagnosis of traumatic anterior instability were assessed using 3D-CT, MRI, and/or arthro-MRI scans. Glenoid track (GT), Hill-Sachs interval (HSI), and glenoid bone loss (GBL) were determined by a radiologist using 3D-CT images, and classified as on-track/off-track. Three surgeons, blinded to the radiologist's evaluation, performed the same determinations using MRI/arthro-MRI. Descriptive analysis, variance analysis, results disagreement analysis, and receiver operating characteristic (ROC) curves were performed.

Results  Results from the 4 examiners were fully consistent in 61.4% of the cases. Magnetic resonance imaging/arthro-MRI diagnosed off-track injuries with 35 to 65% sensitivity and on-track injuries, with 91.67 to 95.83% specificity. Accuracy ranged from 68.1 to 79.5%. The greatest data divergence occurred for off-track injuries diagnosed by MRI/arthro-MRI. The greatest data variability referred to HSI calculation. Higher HSI and GBL values were associated with greater disagreement among examiners. Hill-Sachs interval values were lower at MRI/arthro-MRI when compared to 3D-CT. Agreement between CT and MRI/arthro-MRI for the GT method was only moderate (kappa value, 0.325–0.579).

Conclusion  Magnetic resonance imaging/arthro-MRI showed low accuracy and moderate agreement for the GT method; as such, it should be used with caution by surgeons.

Cemented vs. uncemented glenoid fixation in total shoulder arthroplasty for osteoarthritis: a New Zealand Joint Registry study

BACKGROUND

Total shoulder arthroplasty (TSA) is commonly performed for shoulder osteoarthritis (OA). Uncemented metal-backed (MB) glenoid components were introduced in an attempt to avoid glenoid loosening. New Zealand and Australian Joint Registry studies have shown significantly higher revision rates when uncemented MB glenoids are used. We used the New Zealand Joint Registry (NZJR) to compare all-cause revision rates and functional scores for TSA and investigated the trends of glenoid fixation used in New Zealand.

METHODS

The NZJR was accessed for all primary TSA undertaken for OA from January 2000 to December 2017. Patient demographics were collated. All-cause revision rates were reported as rate per 100 component-years. Analysis was repeated excluding the uncemented SMR L2 glenoid (LimaCorporate), as it was a potential confounder. Kaplan-Meier survival analysis was performed. Oxford Shoulder Scores at both 6 months and 5 years were analyzed.

RESULTS

A total of 2613 TSAs were performed for OA during the study period, representing 85.0% of all TSAs in New Zealand. Overall, 62.1% of the patients were female. In addition, 69.6% of glenoids were cemented and 30.4% uncemented. The most common uncemented MB glenoid was SMR 86.6% (LimaCorporate), and cemented was Global (DePuy) 49.8%. The revision rate for TSA with uncemented glenoids was significantly higher at 2.03 compared with cemented at 0.41 per 100 component-years (P < .001). Hazard ratio 5.0 for revision of uncemented glenoids. No significant difference was found in Oxford Scores at 6 months (39.7 vs. 40.3, P = .13) or 5 years (42.1 vs. 42.8, P = .22). The most common mode of failure was glenoid loosening in cemented glenoids (44.4%), and component failure in uncemented (34.8%). Revision for rotator cuff, deep infection, and instability were comparable between groups. When excluding SMR L2, uncemented MB glenoid all-cause revision rates remained significantly higher than cemented (1.42 vs. 0.41 per 100 component-years, P < .001). SMR L1 uncemented MB glenoids had a higher revision rate than the non-SMR uncemented glenoids (1.61 vs. 0.18 per 100 component-years, P = .009). Uncemented glenoid use peaked in New Zealand in 2011 at 46.7% of TSAs but declined to 20.1% in 2017.

CONCLUSIONS

In the NZJR, primary TSAs undertaken for OA have a significantly higher all-cause revision rate when the glenoid component is uncemented. Uncemented glenoids have a 5.0 times higher revision rate. Excluding SMR L2 glenoids from the analysis, the significantly higher revision rate remained for uncemented glenoids. These data reaffirm that uncemented MB glenoids are associated with higher revision rates.

Comparative Evaluation of Coracoid Graft Dimensions in the Latarjet Surgery for Anterior Glenohumeral Instability

Objectives  The aim of the present study was to describe the dimensions of the coracoid grafts in our Latarjet surgeries and compare them with the results described in the literature. In addition, the feasibility of the 7-millimeter rule was verified. Methods  Individuals with anterior glenohumeral instability with or without bone loss participated in the present study. The dimensions of 31 coracoid process grafts of patients who were submitted to the Latarjet surgical technique were measured with an analogical caliper and recorded for posterior analysis. Results  The dimensions of the coracoid graft did not show statistically significant differences related to gender. The graft width obtained from our sample presented similarities with the dimensions reported in the literature. However, the length and thickness were smaller when compared to the reference study (Young et al, 2013). 15 The 7-millimeter rule was considered feasible regarding the graft dimensions obtained from our sample. Conclusion  The coracoid graft dimensions were similar to the dimensions described in the literature regarding width, but the same was not found for length and thickness; and the 7-millimeter rule was feasible regarding the graft dimensions obtained from our sample.

Cementless versus cemented glenoid components in conventional total shoulder joint arthroplasty: analysis from the Australian Orthopaedic Association National Joint Replacement Registry

BACKGROUND

Glenoid loosening is a common mode of failure after total shoulder arthroplasty (TSA). Newer cementless glenoid components have been introduced to promote biological fixation with the aim to decrease glenoid loosening. Limited data are available comparing revision rates between cemented and cementless glenoid fixation in TSA. The study aim was to compare the revision rates of cemented and cementless design glenoid components used in conventional TSA performed for the diagnosis of osteoarthritis. The secondary aim was to compare various subclasses of glenoid components.

METHODS

Data were obtained between April 16, 2004, and December 31, 2016, from the Australian Orthopaedic Association National Joint Replacement Registry. Within the study period, 10,805 primary conventional TSAs were identified. The analysis was undertaken for the diagnosis of osteoarthritis, which represented 95.8% of all conventional TSA procedures.

RESULTS

At 5 years, in patients with primary TSA procedures, those with cemented glenoids had a lower revision rate than those with cementless glenoids: 3.7% versus 17.9% (hazard ratio for entire period, 4.77). The most common revision diagnosis for primary conventional TSA with cementless glenoid fixation was rotator cuff insufficiency (4.4% for cementless vs 0.4% for cemented), instability and/or dislocation (3.8% for cementless vs 0.8% for cemented), and loosening and/or lysis (1.1% for cementless vs 1.1% for cemented).

CONCLUSIONS

Cementless glenoid components in conventional TSA had a significantly higher revision rate than cemented glenoid components. The loosening rates between cemented and cementless glenoid components were similar. Glenoid design and fixation are important considerations when selecting a prosthesis for TSA.

3D image-based morphometric analysis of the scapular neck length in subjects undergoing reverse shoulder arthroplasty

Scapular notching after RSA may, in part, be related to a patient's scapular morphology. The purpose of this study was to develop a novel 3 D measurement technique to describe infraglenoid tubercle morphometry. We hypothesize that the parameters describing infraglenoid tubercle would be normally distributed and would correlate with individual's demographics and glenoid morphometry. A group of 110 subjects treated with RSA were evaluated. Scapular geometry was obtained from pre-operative CT scans. The scapular neck length was defined in anterior and posterior view as the orthogonal distance between the glenoid surface and (a) the point of most significant change of curvature on lateral pillar; (b) the most lateral portion of the infraglenoid tubercle. Scapular neck angle, maximum anatomical adduction angle, glenoid width, height and version were also measured. Scapular neck length measured in the anterior and posterior view were normally distributed with mean values of 17.6 ± 2.8 mm and 7.9 ± 2.5 mm, respectively. Scapular neck angle was on average 112.4 ± 10.6° and maximal adduction angle was 17.6 ± 2.8°. No significant associations between infraglenoid tubercle morphometric parameters, demographic, glenoid size or version were identified. Improved understanding of the patient-specific risk factors for scapular notching will help surgeons with pre-surgical planning and implant selection. Parametrization of the infraglenoid tubercle presented in this study showed normal distribution in the population unrelated to gender, side or demographics. The size of the infraglenoid tubercle is a unique trait, pre-operative evaluation of the scapular neck should be always warranted to decrease the incidence of post-operative notching. Clin. Anat. 31:43-55, 2018. © 2017 Wiley Periodicals, Inc.

The Neviaser portal for superior glenoid anchor insertion: an anatomic study

PURPOSE

To measure the angular relationship between the Neviaser portal and the superior glenoid labrum in 60 cadaveric specimens to determine whether this portal can be used for reliable anchor placement.

METHODS

The Neviaser portal of 30 left and 30 right unpaired dry cadaveric scapulae with clavicles were measured by a single observer using an analogue vernier caliper. The angular relationship between the Neviaser portal and the 12 o'clock position of the glenoid labrum was calculated.

RESULTS

13 of the 60 scapulae were excluded from analysis, because the Neviaser portal was medial to the glenoid rim making safe anchor insertion unfeasible. For the remaining 47 scapulae, the mean angles α and β were 58.2º and 57.9º, respectively. Compared with the ideal angles α and β of 30º and 0º, respectively, all the 47 Neviaser portals were more posterior (relative to the 12 o'clock position) and closer to the transverse plane, making insertion of suture anchors in the optimum position unfeasible, except for one that was within 10º of the ideal angles in both planes.

CONCLUSION

Reliable insertion of suture anchors at the 12 o'clock position of the glenoid labrum through the Neviaser portal is unfeasible in most patients.

Evaluation of three-dimensional glenoid structure using MRI

The tilting angle and the shape of the glenoid cavity are considered to relate closely to shoulder stability. They are also important when planning arthroplasty and developing new designs. This study examines the glenoid cavity using 3-dimensional MRI. Forty volunteers (20 men, 20 women; average age 21.4; range 18-35 y) were enrolled in the study. The tilting angles of the glenoid bone were measured in 5 consecutive axial planes perpendicular to the glenoidal long axis. Cross sections were divided into 3 types (concave, flat, convex) according to the shape on each plane. The average tilting angles for the 5 planes from the bottom to the top were 3.3+/-4.1, 1.4+/-3.8. -0.6+/-1.9, -1.4+/-3.3, and -6.2+/-3.3 degrees anteriorly, indicating that the 3-dimensional bony structure of the glenoid was twisted anteriorly to posteriorly. Images on the bottom plane consisted of 82.5 % concave type, 15% flat type and 2.5% convex type, while only 3 cases (7.5%) showed concave at the top plane. The shape of the glenoid cavity is thought to be conducive to glenohumeral motion and stability.