Morphologic analysis of the sublime tubercle: considerations in the approach to ulnar collateral ligament reconstruction.

Background: Given the increased incidence of ulnar collateral ligament (UCL) injuries and the projected increase in reconstruction procedures, a robust understanding of the morphologic location of the sublime tubercle is paramount to anatomic reconstruction. There is limited research evaluating the morphology of the sublime tubercle of the proximal ulna in an anterior-to-posterior plane. Methods: Twenty-five computed tomography (CT) scans of intact proximal elbow joints for patients were selected using a de-identified database. Cases with history of fracture or surgical intervention to the elbow joint were excluded. These CT scans were then imported into the Mimics Innovation Suite 24.0 software to analyze the sublime tubercle angle from the midpoint of the trochlear notch. All left elbow angle and clock-face values were converted to right elbow values for analysis. Results: The average sublime tubercle angle from the midpoint of the trochlear notch was 282.53 degrees. The angle was converted to a clock face descriptor which located the sublime tubercle at 9.42. Our findings demonstrate that, in the non-throwing population, the morphology of the sublime tubercle can be expected to have a consistent medial location between 9 and 10 o'clock or 2 and 3 o'clock on the contralateral elbow. Conclusions: In relation to the proximal ulnar landmarks, the sublime tubercle, in the non-throwing population, has a consistent relative location.