Concomitant injury of the annular ligament in fractures of the coronoid process and the supinator crest.

BACKGROUND

Fractures of the coronoid process or the supinator crest, as well as arthroscopic resection of osteophytes around the coronoid process, can endanger the attachment of the annular ligament (AL) to the proximal ulna. The purpose of this study was to investigate the corresponding insertional areas of the AL within this context.

METHODS

In 30 embalmed human cadaveric elbow specimens, the insertional area of the AL at the anterior and posterior margin of the sigmoid notch was characterized. The distances and relations of the AL insertion anteriorly to the coronoid surface, the coronoid tip, and the depth of the coronoid process, as well as posteriorly to the supinator crest, were evaluated macroscopically.

RESULTS

The mean distance of the anterior insertion area was 1.9 ± 0.6 mm (range, 1.0-3.1 mm) to the coronoid articular surface and 6.2 ± 1.7 mm (range, 2.9-10.2 mm) to the tip of the coronoid. The distance of the anterior insertion in relation to the depth of the coronoid process was 44% ± 11% (range, 30%-69%). The distance of the posterior insertion area to the level of the sigmoid notch measured from 3.5 ± 1.5 mm (range, 0.5-6.5 mm) to 17.7 ± 2.9 mm (range, 13.1-25.4 mm).

CONCLUSIONS

Coronoid fractures involving 44% or more of the coronoid process and anterolaterally oriented fractures where one-third of the anterolateral facet is affected are accompanied by a complete anterior bony disruption of the AL. Arthroscopic resection of the coronoid tip should be limited to 1 mm distal to the coronoid articular surface to avoid injury to the AL. Fractures of the upper half of the supinator crest place the AL at risk at its posterior insertion.