Accuracy of medial-to-lateral transcondylar screw placement using an aiming device and preoperative computer tomography planning for the treatment of humeral intracondylar fissure

OBJECTIVE To determine the accuracy of transcondylar screws placed from medial-to-lateral using preoperative planning on computed tomography (CT) and an aiming device in elbows with humeral intracondylar fissures (HIFs). STUDY DESIGN Retrospective case series. ANIMALS Twenty-five client-owned dogs with HIF. METHODS A 4.5-mm transcondylar screw was placed in 34 elbows with HIF. humeral condylar diameter (HCD) was measured at the humeral condylar isthmus on CT. Entry and exit points were planned at 0.3 × HCD cranial and 0.2 × HCD distal to the medial epicondyle and 0.3 × HCD cranial and 0.3 × HCD distal to the lateral epicondyle. An aiming device was used to guide drilling from the medial entry point to the lateral exit point. The difference between planned and actual screw entry and exit points, and the angular deviation of the actual screw axis from the planned screw axis, was assessed on the postoperative CT scans. RESULTS Thirty-three out of 34 screws were completely within the humeral condyle. Thirteen out of 34 screws were placed less than 2 mm from planned entry and exit points in both the transverse and the frontal plane. The axis of the screw deviated by a mean of 3.2° (transverse plane) and 3.5° (frontal plane) from the planned axis. CONCLUSION Humeral transcondylar screws placed with the technique tested here were entirely within the humeral condyle in 33 out of 34 elbows. CLINICAL SIGNIFICANCE Use of CT planning and an aiming device allows accurate placement of transcondylar screws from medial-to-lateral in dogs with HIF.