Arthroscopic glenoid reconstruction for glenoid bone loss in recurrent anterior glenohumeral instability, using osteochondral autograft from the contralateral lateral femoral condyle: a new technique and case report

Acromion and Distal Clavicle Grafts for Arthroscopic Glenoid Reconstruction

BACKGROUND

We intended to determine if an acromion or distal clavicle bone graft could restore large glenoid defects using two novel, screw-free graft fixation techniques.

METHODS

Twenty-four sawbone shoulder models were divided into four groups (n = 6 per group) according to fixation technique and bone graft: (1) modified buckle-down technique with clavicle graft, (2) modified buckle-down technique with acromion graft, (3) cross-link technique with acromion graft, (4) cross-link technique with clavicle graft. Testing was performed sequentially in (1) intact models, (2) after creation of a 30% by-width glenoid defect and (3) after repair. The shoulder joint was translated anteriorly, and glenohumeral contact pressures and load were measured to quantify the biomechanical stability.

RESULTS

Maximum contact pressures were restored to 42-56% of intact glenoid using acromion and clavicle grafts with novel fixation techniques. Acromion grafts attained higher maximum contact pressures than clavicle grafts in all groups. Peak translational forces increased by 171-368% after all repairs.

CONCLUSIONS

This controlled laboratory study on sawbone models found that both the acromion and distal clavicle are suitable autologous bone graft options for treating large anterior glenoid defects, having appropriate dimensions and contours for reconstructing the glenoid arc. The modified buckle-down and cross-link techniques are two graft fixation techniques that restore stability to the shoulder joint upon repairing a large glenoid defect and are advantageous in being screw-free and simple to execute.

Influence of Graft Positioning during the Latarjet Procedure on Shoulder Stability and Articular Contact Pressure: Computational Analysis of the Bone Block Effect

The Latarjet procedure is the most popular surgical procedure to treat anterior glenohumeral (GH) instability in the presence of large anterior glenoid bone defects. Even though the placement of the bone graft has a considerable influence on its efficacy, no clear indications exist for the best graft position. The aim of this study was to investigate the influence of the medial-lateral positioning of the bone graft on the contact mechanics and GH stability due to the bone block effect. Four finite element (FE) models of a GH joint, with a 20% glenoid bone defect, treated by the Latarjet procedure were developed. The FE models differed in the medial-lateral positioning of the bone graft, ranging from a flush position to a 4.5 mm lateral position with respect to the flush position. All graft placement options were evaluated for two separate shoulder positions. Anterior GH instability was simulated by translating the humeral head in the anterior direction, under a permanent compressive force, until the peak translation force was reached. Joint stability was computed as the ratio between the shear and the compressive components of the force. The lateralization of the bone graft increased GH stability due to the bone block effect after a 3 mm lateralization with respect to the flush position. The increase in GH stability was associated with a concerning increase in peak contact pressure due to the incongruous contact between the articulating surfaces. The sensitivity of the contact pressures to the medial-lateral positioning of the bone graft suggests a trade-off between GH stability due to the bone block effect and the risk of osteoarthritis, especially considering that an accurate and consistent placement of the bone graft is difficult in vivo.

A review of bone grafting techniques for glenoid reconstruction

BACKGROUND

Traumatic anterior shoulder dislocations can cause bony defects of the anterior glenoid rim and are often associated with recurrent shoulder instability. For large glenoid defects of 20-30% without a mobile bony fragment, glenoid reconstruction with bone grafts is often recommended. This review describes two broad categories of glenoid reconstruction procedures found in literature: coracoid transfers involving the Bristow and Latarjet procedures, and free bone grafting techniques.

METHODS

An electronic search of MEDLINE and PubMed was conducted to find original articles that described glenoid reconstruction techniques or modifications to existing techniques.

RESULTS

Coracoid transfers involve the Bristow and Latarjet procedures. Modifications to these procedures such as arthroscopic execution, method of graft attachment and orientation have been described. Free bone grafts have been obtained from the iliac crest, distal tibia, acromion, distal clavicle and femoral condyle.

CONCLUSION

Both coracoid transfers and free bone grafting procedures are options for reconstructing large bony defects of the anterior glenoid rim and have had similar clinical outcomes. Free bone grafts may offer greater flexibility in graft shaping and choice of graft size depending on the bone stock chosen. Novel developments tend towards minimising invasiveness using arthroscopic approaches and examining alternative non-rigid graft fixation techniques.