Relationship between the Thickness of the Coracoid Process and Latarjet Graft Positioning-An Anatomical Study on 70 Embalmed Scapulae

High resorption rates following glenoid augmentation procedures do not seem to lead to higher recurrence rates or worse clinical outcomes: a systematic review and meta-analysis

PURPOSE

Bone augmentation techniques show a relatively high complication rate, which might be due to graft non-union and resorption. It is unclear which augmentation techniques demonstrate the highest amount of non-union and resorption and whether this leads to worse clinical or functional outcomes. Therefore, the aim of this review was (i) to compare non-union and resorption rates between surgical approaches, procedures, graft types, donor sites and fixation methods regarding clinical and functional outcomes and (ii) determine whether high non-union or resorption rates lead to less favorable clinical or functional outcomes.

METHODS

The Preferred Reporting Items for Systematic Reviews and Meta-Analyses statements were followed. PubMed, EMBASE (Ovid) and Cochrane Library were searched on December 15th 2021 for studies examining bone graft non-union or resorption using radiograph or CT following glenoid augmentation to treat anterior shoulder dislocation.

RESULTS

The search resulted in 103 inclusions, comprising 5,128 glenoid augmentations. When comparing pooled proportions of bony union, graft fracture rate, hardware failure rate, recurrence rate, return to sports and Rowe score, most results were similar between approaches, procedures, graft types, donor sites and fixation methods. High resorption rates were seen for allograft augmentation (74.3; 95% CI: 39.8-92.7) compared to autograft augmentation (15.5; 95% CI 10.1-23.2), but this was not associated with higher recurrence rates or worse clinical outcomes. Meta-analyses (8 studies; 494 patients) demonstrated no difference in incomplete and complete non-union rates between arthroscopic and open procedures; however, both analyses showed substantial heterogeneity. Higher partial resorption rates were observed on CT (48.0; 95% CI 43.3-52.7) compared to radiograph (14.1; 95% CI 10.9-18.1). Three studies comprising 267 shoulders demonstrated a higher rate of non-union and recurrence in smokers, whereas one study comprising 38 shoulders did not.

CONCLUSION

Non-union and resorption rates were similar among procedures, grafts and fixation methods. Higher resorption rates were observed in allografts, but this was not associated with higher recurrence rates or worse clinical outcomes. Pooling data demonstrated substantial heterogeneity and definitions varied among studies, warranting more standardized measuring.

LEVEL OF EVIDENCE

IV.

Comparison of two coracoid process transfer techniques on stress shielding using three-dimensional finite-element model

Background

We created patient-based 3D finite-element (FE) models that simulate the congruent-arc Latarjet (CAL) and traditional Latarjet (TL) procedures and then compared their stress distribution patterns with different arm positions and glenoid defects.

Methods

The computed tomography data of 10 adult patients (9 men and 1 woman, ages: 18–50 years) were used to develop the 3D FE glenohumeral joint models. Twenty-five and 35% bony defects were created on the anterior glenoid rim, and the coracoid process was transferred flush with the glenoid by the traditional and congruent-arc techniques using two half-threaded screws. A load was applied to the greater tuberosity toward the center of the glenoid, and a tensile force (20 N) was applied to the coracoid tip along the direction of the conjoint tendon. The distribution patterns of the von Mises stress in the traditional and congruent-arc Latarjet techniques were compared.

Results

The mean von Mises on the graft was significantly greater for the TL technique than for the CAL. While the von Mises stress was greater in the distal medial part of the graft in the TL models, a higher stress concentration was observed in the distal lateral edge of the coracoid graft in the CAL models. The proximal medial part of the graft exhibited significantly lower von Mises stress than the distal medial part when compared according to technique, defect size, and arm position. Increasing the glenoid defect from 25 to 35% resulted in a significant increase in stress on the lateral side of the graft in both models.

Conclusion

The stress distribution patterns and stress magnitude of the coracoid grafts differed according to the procedure. Due to placing less stress on the proximal–medial part of the graft, the CAL technique may lead to insufficient stimulation for bone formation at the graft–glenoid interface, resulting in a higher incidence of graft osteolysis.

Clinical relevance The CAL technique may lead to a higher incidence of graft osteolysis.

Level of evidence

Basic Science Study; Computer Modeling.

A cadaveric morphometric analysis of coracoid process with reference to the Latarjet procedure using the "congruent arc technique"

INTRODUCTION

Congruent arc Latarjet procedure involves rotating the coracoid process so that its inferior surface is flush with the glenoid face, owing to their matching radius of curvature (ROC). However, there has been no cadaveric study to actually measure and compare the ROC of coracoid with glenoid, especially in Indian population.

MATERIALS AND METHODS

44 shoulders were dissected in 24 cadavers to measure usable length of coracoid process, width, height, ROC of coracoid and glenoid as well as ulnar length (as proxy of cadaver height). Critical coracoid height and length were estimated based on screw sizes of 2.7 mm, 3.5 mm, 4 mm and 4.5 mm, and pair concordance between height and length calculated. ROC of coracoid and glenoid were compared to measure extent of congruency.

RESULTS

The mean usable length of coracoid process, width and height at mid-point were 21.8 mm, 13.7 mm and 8.6 mm, respectively. Out of the different screw sizes, 2.7 mm screws were found safe in 82% shoulders. 24 coracoid-glenoid pairs fulfilled the operational definition (≤ 5 mm) of congruency while rest 20 were seemingly incongruent chiefly due to coracoid variations, with mean ROC difference 4.13 mm (95% CI 1.51-6.74 mm). The ulnar length was significantly smaller in the incongruent ROC group (p = 0.0002).

CONCLUSIONS

The available length as well as height of the transferred coracoid must be considered when deciding optimum diameter fixation screws in Latarjet procedure. Owing to smaller anatomic dimensions of coracoid in Indian population, 2.7-mm screws provide the safest fixation option. Also, the ROC of coracoid and glenoid does not match in substantial proportion of the cadavers. Pre-operative planning should include a CT-based assessment of glenoid and coracoid dimensions to decide the technique of Latarjet procedure and the optimum diameter fixation screws required.

The co-occurrence of a four-headed coracobrachialis muscle, split coracoid process and tunnel for the median and musculocutaneous nerves: the potential clinical relevance of a very rare variation

The coracobrachialis muscle (CBM) originates from the apex of the coracoid process, in common with the short head of the biceps brachii muscle, and from the intermuscular septum. Both the proximal and distal attachment of the CBM, as well as its relationship with the musculocutaneus nerve demonstrate morphological variability, some of which can lead to many diseases. The present case study presents a new description of a complex origin type (four-headed CBM), as well as the fusion of both the short biceps brachii head, brachialis muscle and medial head of the triceps brachii. In addition, the first and second heads formed a tunnel for the musculocutaneus and median nerves. This case report has clear clinical value due to the split mature of the coracoid process, and is a significant indicator of the development of interest in this overlooked muscle.