Anatomic study of the coracoid process: safety margin and practical implications.

PURPOSE

The aim of this study was to define a safety margin for coracoid process osteotomy that does not compromise the coracoclavicular ligaments and that can be used in the coracoid transfer procedures.

METHODS

Thirty shoulders from 15 cadavers were dissected, exposing the coracoid process and attached anatomic structures. The distance of the insertion of these structures to the coracoid process apex was measured.

RESULTS

The average length of the coracoid process was 4.26 ± 0.26 cm. The average width and height at the tip were 2.11 ± 0.2 and 1.49 ± 0.12 cm, respectively. The average distance from the tip to the anterior and posterior margin of the pectoralis minor was 0.1 ± 1.17 and 1.59 ± 0.27 cm, respectively. The average distance from the tip to the posterior margin of the coracoacromial ligament was 2.79 ± 0.33 cm. The average distance from the apex to the most anterior part of the trapezoid ligament was 3.33 ± 0.38 cm. We obtained a constant value of 0.85 cm for this measure, and the value increased with each 1.0-cm increase in the distance from the tip to the posterior margin of the pectoralis minor. The safety margin for osteotomy (i.e., available bone distance for the coracoid process transfer) was 2.64 cm.

CONCLUSIONS

This study established a safety margin of 2.64 cm for the osteotomy of the coracoid process and its relation with the posterior margin of the pectoralis minor. The anatomic descriptions of bone and soft tissue, as well as a measure of correlation for the safety margin of the coracoid, provide tools for surgeons performing anatomic surgical procedures to correct glenohumeral instability with significant bone loss.

CLINICAL RELEVANCE

Knowing the safety margin allows the surgeon to perform a safe osteotomy without direct visualization of the coracoclavicular ligaments attachments, thereby making procedures more anatomic.