Introduction: Fractures of the capitellum are uncommon and difficult to treat surgically. Capitellar open reduction internal fixation (ORIF) utilizes a lateral open approach with posterior to anterior or anterior to posterior screw fixation. We inves- tigated the use of an anterior portal for placement of anterior to posterior screw fixation through cadaveric measurement of the anatomical relationships from an anterior to posterior placed Kirshner wire (K-wire) to anterior elbow structures and calculated the percentage of articular surface accessed from the anterior portal.
Methods: Eight fresh frozen cadaveric elbows without radiographic or cutaneous evidence of prior trauma or surgery were mounted with arthroscopic setup with the antecubital fossa facing the surgeon. An arthroscopic proximal anteromedial portal was cannulized and the radiocapitellar joint was evaluated. A single 1 centimeter (cm) portal was placed 1 cm distal to the elbow flexion crease and based lateral to the biceps tendon. Portal was confirmed with spinal needle and blunt dissection with hemostat was performed down to capsular tissue and for arthrotomy. A spinal needle sheath was threaded over a blunt switching stick and served as cannula for 0.062 K-wire placement. Articular mapping was performed with cartilage scrap- ing by the K-wire and then the K-wire was placed at the perceived center along the proximal to distal and radial to ulnar axis of the capitellum. Fluoroscopic confirmation of the wire was performed. Under loupe magnification, anatomical dissection and shortest distance measurements were recorded with digital calipers from the K-wire to dissected structures. Capitellar articular measurements were recorded and the articular area defined by the K-wire was also recorded. Data analysis was calculated with average distance in millimeters (mm) and standard deviation. Structures that were pierced or touching the K-wire were recorded as 0.1 mm.
Results: The average distance from the K-wire to the radial, lateral antebrachial cutaneous, and median nerve was 1.8 mm, 11.5 mm, and 28.0 mm, respectively. The average distance from the median cubital vein and biceps tendon was 3.7 mm and 13.4 mm. The pin track pierced the brachioradialis and supinator muscles in all but one specimen. The average capitellar articular surface marked was 39.1% of the calculated articular footprint of the capitellum.
Conclusions: The anterior portal to the capitellum is directly adjacent to the radial nerve and lateral antebrachial cutaneous nerve where each is susceptible to injury. We recommend blunt dissection and insertion of a cannula to allow drilling and placement of internal fixation in a relatively safe manner with respect to neurovascular structures. Additionally, we believe the anterior portal allows access to articular capitellum fracture fragments and may be a useful adjunct fixation strategy for capitellar ORIF.
