Influence of coracoid anatomy on the location of glenoid rim defects in anterior shoulder instability: 3D CT-scan evaluation of 51 patients

Circumflex arterial sulcus of the scapula (sulcus arteriae circumflexae scapulae): its anatomy and clinical relevance

INTRODUCTION

The circumflex scapular artery (CSA) has been described in detail in the literature, but the groove, i.e., the circumflex sulcus (CFS), formed by the artery on the lateral pillar of the scapula has been completely neglected. The aim of the present study was to describe the variability and anatomy of the CFS.

MATERIALS AND METHODS

The study was based on the examination of 103 pairs of dry bone specimens of adult scapulae, i.e., 206 specimens, including 92 (46 pairs) male and 114 (57 pairs) female specimens. In the first step, quantitative criteria were defined for assessment of the CFS presence and type. Subsequently, statistical analysis of the obtained data was performed.

RESULTS

The study revealed considerable variability of the arterial groove, which was well developed in 33% (type A), shallow in 40% (type B), and absent in 27% (type C) of cases. The mean distance between CFS and the infraglenoid tubercle was 3.3 cm CI_0.95 (3.1-3.3), which corresponds to the proximal third of the lateral border of the scapula.

CONCLUSION

The study has confirmed variability of the arterial groove (CFS) and its localization in relation to the inferior glenoid rim. The findings are clinically important, particularly in relation to the Judet approach to scapular fractures (localization of the CSA course).

The Trillat Procedure for Anterior Glenohumeral Instability

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Anterior glenohumeral instability (AGI) is a challenging condition that requires close attention to osseous and soft-tissue abnormalities. The morphometric variance of the periarticular scapular anatomy may be involved in the pathogenesis of recurrent traumatic anterior instability.

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The Trillat procedure repositions the coracoid medially and downward by a partial wedge osteotomy, mimicking the sling effect of the Latarjet procedure by moving the conjoint tendon closer to the joint line in throwing position. The Trillat procedure decreases the coracohumeral distance without affecting the integrity of the subscapularis muscle and tendon.

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Joint preservation methods, such as the Trillat procedure, may be explored in older patients to treat AGI with simultaneous irreparable rotator cuff tears (RCTs) with a static centered head and a functional subscapularis.

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Shoulder hyperlaxity and instability can be challenging to treat with isolated soft-tissue procedures. In cases without glenoid bone loss, free bone block techniques are ineffective because of the subsequent potential graft resorption, apprehension, or recurrence. The Trillat surgery, in conjunction with an anteroinferior capsuloplasty, seems to be helpful in preventing recurrent instability and in reducing shoulder apprehension.

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Recently, several variations of the original technique have been described. In the future, anatomical, biomechanical, and clinical studies need to be conducted to further evaluate the morphometric characterization of the procedure, enhance the technical features, improve indications, and avoid coracoid impingement and other potential complications with the Trillat procedure.

Influence of coracoglenoid space on scapular neck fracture stability: biomechanical study

Background

The anatomical variation of the coracoglenoid space has the potential to influence the stability of scapular neck fractures. This paper aimed to investigate the mechanical mechanism underlying the influence of different coracoglenoid space types on scapular neck fractures by morphometric analysis and biomechanical experiments.

Methods

The morphology of 68 dried scapulae (left: 36; right: 32) was studied. Two variables, the length of the coracoglenoid distance (CGD) and the coracoglenoid notch (CGN), were measured. The distribution of CGN/CGD × 100% was used to identify the morphology of the coracoglenoid space. Each specimen was tested for failure under static axial compression loading. The average failure load, stiffness, and energy were calculated.

Results

Two coracoglenoid space types were identified. The incidence of Type I (‘‘hook’’ shape) was 53%, and that of Type II (‘‘square bracket’’ shape) was 47%. The CGD and CGN were significantly higher for type I than type II (13.81 ± 0.74 mm vs. 11.50 ± 1.03 mm, P < 0.05; 4.74 ± 0.45 mm vs. 2.61 ± 0.45 mm, P < 0.05). The average maximum failure load of the two types was 1270.82 ± 318.85 N and 1529.18 ± 467.29 N, respectively (P = 0.011). The stiffness and energy were significantly higher for type II than type I (896.75 ± 281.14 N/mm vs. 692.91 ± 217.95 N/mm, P = 0.001; 2100.38 ± 649.54 N × mm vs. 1712.71 ± 626.02 N × mm, P = 0.015).

Conclusions

There was great interindividual variation in the anatomical morphology of the coracoglenoid space. Type I (hook-like) spaces bore lower forces, were less stiff, and bore less energy, which may constitute an anatomical predisposition to scapular neck fractures.

The Glenolabral Articular Disruption Lesion Is a Biomechanical Risk Factor for Recurrent Shoulder Instability

Purpose

To investigate the biomechanical effect of a glenolabral articular disruption (GLAD) lesion on glenohumeral laxity.

Methods

Human cadaveric glenoids (n = 10) were excised of soft tissue, including the labrum to focus on the biomechanical effects of osteochondral surfaces. Glenohumeral dislocations were performed in a robotic test setup, while displacement forces and three-dimensional morphometric properties were measured. The stability ratio (SR), a biomechanical characteristic for glenohumeral stability, was used as an outcome parameter, as well as the path of least resistance, determined by a hybrid robot displacement. The impacts of chondral and bony defects were analyzed related to the intact glenoid. Statistical comparison of the defect states on SR and the path of least resistance was performed using repeated-measures ANOVA and Tukey’s post hoc test for multiple comparisons (P < .05). The relationship between concavity depth and SR was approximated in a nonlinear regression.

Results

The initial SR of the intact glenoid (28.3 ± 7.8%) decreased significantly by 4.7 ± 3% in case of a chondral defect (P = .002). An additional loss of 3.2 ± 2.3% was provoked by a 20% bony defect (P = .004). The path of least resistance was deflected significantly more inferiorly by a GLAD lesion (2.9 ± 1.8°, P = .002) and even more by a bony defect (2.5 ± 2.9°, P = .002). The nonlinear regression with concavity depth as predictor for the SR resulted in a high correlation coefficient (r = .81).

Conclusions

Chondral integrity is an important contributor to the SR. Chondral defects as present in GLAD lesions may cause increased laxity, influence the humeral track on the glenoid during dislocation, and represent a biomechanical risk factor for a recurrent instability.

Clinical Relevance

Cartilage deficiency corresponding to GLAD lesions may be a risk factor for impaired surgical outcomes.

The coracoglenoid notch: anatomy and clinical significance

INTRODUCTION

The superior surface of the anatomical neck is presented in the classification of scapular fractures as a 2-cm-long structure, which does not correspond to reality. This issue has not yet been adequately addressed in the literature. The aim of the study was to assess the variability of a notch between the upper rim of the glenoid and the coracoid base, the so-called coracoglenoid notch (CGN), and its clinical significance.

MATERIALS AND METHODS

The study was based on the examination of 204 dry bone specimens of adult scapulae (92 male and 112 female). We have determined quantitative criteria for the evaluation of the CGN type, measuring the offset of anatomical neck using a digital caliper. The findings were compared with 3D CT reconstructions of fractures of the scapular anatomical neck.

RESULTS

Three basic types of CGN have been identified: type A-a well-developed notch in 31%, type B-a shallow notch in 53% and type C-an absent notch in 16%. No significant difference in CGN was found between the sexes, or between the right and left sides. When compared with our six cases of the anatomical neck fracture of the scapula, two patients displayed CGN type A and type B, respectively; but in four patients, it was impossible to distinguish between types A and B.

CONCLUSION

The study has documented a high variability of CGN. Its presentation in the classification schemes does not correspond to anatomical reality. The presence of a deep, or shallow, notch may constitute an anatomical predisposition to a fracture of the anatomical neck.