Is the Anterior Tibial Artery Safe During Ankle Arthroscopy? Anatomic Analysis of the Anterior Tibial Artery at the Ankle Joint by Magnetic Resonance Imaging

Background: Pseudoaneurysm of the anterior tibial artery (ATA) after ankle arthroscopy is an uncommon complication but can cause unexpected consequences. However, its contributing factor is not fully understood. Hypothesis: Anatomic factors, such as ATA variations and the distance between the ATA and joint capsule, may contribute to the occurrence of pseudoaneurysm. Study Design: Case series; Level of evidence, 4. Methods: The magnetic resonance images and medical records of 358 ankle cases were analyzed. According to locations of the ATA in relation to the peroneus tertius (PT) and the extensor digitorum longus (EDL) tendon on axial magnetic resonance imaging, patients were classified as type 1 (safe type), type 2 (increased risk type), or type 3 (high-risk type). In addition, distances between the anterior joint capsule and the ATA were measured to evaluate the thickness of the anterior fat pad, which contains the ATA and anterior compartment tendons. Results: In 336 cases (93.8%), the ATA was located medial to the EDL (type 1, safe). In 7 cases (2.0%), the ATA was located lateral to the EDL and PT tendon (type 2, increased risk); and in 15 cases (4.2%), the branching artery was observed lateral to the EDL and PT tendon and the ATA was in the normal position (type 3, high risk). The mean distance between the anterior joint capsule and the ATA was 2.3 +/- 1.1 mm. Conclusion: In 22 (6.2%) of the 358 cases, the ATA and its branches were located near the anterolateral ankle portal, which introduces the risk of vascular damage during arthroscopic surgery. Furthermore, the mean distance between the ATA and the joint capsule was only 2.3 +/- 1.1 mm, and thus the ATA is very close to the anterior working space of the ankle joint. Careful preoperative evaluation and an intra-articular procedure may reduce the risk of vascular complications attributable to ankle arthroscopy.