Use of posteroanterior reference guides for bone block or coracoid process transfer in anterior glenohumeral instability: a cadaveric study of the relationship to the suprascapular nerve.

Background: Iatrogenic suprascapular nerve injury secondary to posterior drilling or screw penetration is a recognized complication of bone block or coracoid process transfers for anterior glenohumeral instability. We present the first cadaveric study that assesses the safety of posteroanterior reference guides and quantifies the relationship of the suprascapular nerve to posterior glenoid fixation with suture buttons.

Methods: Anterior glenoid bone block reconstruction with suture buttons utilizing a posteroanterior reference guide was performed in 10 fresh frozen cadavers via a posterior portal. Bullets were inserted in predefined superior and inferior guide holes via percutaneous incisions to facilitate posteroanterior drilling. Looped guide wires were used to deliver suture buttons from anterior to posterior positions. The shoulder joint was disarticulated and the infraspinatus sharply elevated until the suprascapular nerve was visualized. Four independent static measures of the shortest distance from the superior drill sleeve to the lateral aspect of the suprascapular nerve were recorded.

Results: The suprascapular nerve was not compromised utilizing the posteroanterior guide and suture button fixation technique in any specimen. The mean distance from superior sleeve tunnel to the suprascapular nerve was 5.00 mm (range, 3.25-8.00 mm) in females and 6.80 mm (range, 5.50-8.75 mm) in males. The shortest distance was 3.25 mm and the longest was 8.75 mm.

Conclusion: The use of posteroanterior reference guides for suture button fixation was not associated with iatrogenic suprascapular nerve injury in the specimens examined. However, the proximity of the suprascapular nerve underscores the need for caution. Comparative analysis with anteroposterior bone block techniques is required to establish the potential benefits of this procedure. Level of evidence: V.