PAPER 064: AN ANTHROPOMETRIC STUDY OF THE DISTAL HUMERUS WITH IMPLICATIONS TOWARDS CONTRALATERAL REGISTRATION

Abstract

Purpose: The successful placement of elbow prostheses, external fixators and ligament reconstructions is dependent on the accurate identification of the elbow’s flexion-extension (FE) axis. In the case of periarticular bone loss, the FE axis must be visually estimated, as the necessary anatomical landmarks may not be available. Hence, referencing the uninjured elbow anatomy may prove beneficial in accurately defining this axis. However, this is contingent on the morphological features being similar between the two sides. Our objective was to compare distal humeral morphology between paired specimens. Our hypothesis was that anthropometric measurements from the distal humerus would be similar to the contralateral side.

Method: CT Images of 25 paired distal humeri were obtained. A right-to-left surface registration was then performed on each pair using the iterative closest point (icp) least-squares algorithm, thus placing each specimen in the same coordinate system.. Anthropometric characteristics measured (and compared between the left and right sides) included the angles of the FE and epicondylar axes in both the coronal and transverse planes, the anterior offset of the FE axis with respect to the humeral shaft axis, the length of the FE axis and the radius of curvature of the capitellum and trochlea.

Results: There was no statistically significant difference between the left and right humeri for the eight anthropometric characteristics studied (p > 0.05). The mean difference in magnitude for the FE axis angle was approximately 1.0° in both the coronal and transverse planes and the difference in magnitude for 80% of the paired specimens was less than 1.5°.

Conclusion: The anthropometric features of the distal humerus that are typically employed during elbow surgery are similar from side to side. Preoperative imaging of the contralateral normal elbow should be considered in patients with periarticular bone loss where referencing anatomical landmarks of the injured side is not possible. This information can be used as part of a preoperative plan to determine the ideal position of the implant, ligament reconstruction or external fixator during surgery. Contralateral imaging should be particularly useful when combined with computer-assisted elbow surgery.