Vascular Compromising Effect of Drilling for Osteochondral Lesions of the Talus: A Three-Dimensional Micro-Computed Tomography Study.

PURPOSE: To explore an optimal drilling depth and direction for osteochondral lesions of the talus based on a 3-dimensional vascular microarchitecture model constructed with micro-computed tomography (microCT).

METHODS: Twelve tali were perfused with the contrast agent and then scanned with microCT. The talar dome was divided into 9 zones, and the vessel densities were measured at the subchondral depths of 0 to 5 mm, 5 to 10 mm and 10 to 15 mm in each zone. The anterolateral (AL) and posterolateral (PL) approaches of retrograde drilling were simulated and the vascular compromising effect was evaluated.

RESULTS: The vessel density of the 0- to 5-mm depth was lower than that of the 5- to 10-mm (P = .001) and 10- to 15-mm (P = .007) depths, but no significant difference was found between the 5- to 10-mm and 10- to 15-mm depths (P > .9999). The vessel density in the 5- to 10-mm depth of medial talar dome was similar to that of the adjacent zones (P = .05). Vessel density in the 5- to 10-mm depth around the lateral talar dome was higher in the anterior and medial side. The anterolateral approach disturbed the main intraosseous vessels from the tarsal canal-tarsal sinus, causing extensive vascular compromise in the talus neck and body, whereas the posterolateral approach disturbed only the vessels near the tunnel.

CONCLUSIONS: The vessel density changed greatly from the subchondral 0- to 5-mm to the 5- to 10-mm depth. The vessel densities of the 5- to 10-mm depth around the medial talar dome were similar, whereas the anterior and medial side of the lateral talar dome was better vascularized. The posterolateral approach caused less vascular damage than the anterolateral approach.

CLINICAL RELEVANCE: The anterograde drilling depth was preferable to the subchondral 5- to 10-mm depth. There was no preferred drilling direction for the osteochondral lesion in the medial talar dome, whereas it is preferable to drill anteriorly or medially in the lateral dome. The posterolateral approach might be a safer alternative for retrograde drilling.