All-Inside Lateral Meniscal Repair via Anterolateral Portal Increases Risk of Vascular Injury: A Cadaveric Study David Weijia Mao, M.B.B.S., B.Med.Sci., M.R.C.S., Upasana Upadhyay, M.B.B.S., Srikiran Thalanki, M.B.B.S., M.S.(Orthopaedics), and Dave Lee Yee Han, M.B.B.S., F.R.C.S. Purpose: To compare the distance from the device tip to the neurovascular structures during an all-inside medial and lateral meniscal repair using anteromedial and anterolateral portals in a fresh-frozen cadaveric study. Methods: Ten fresh-frozen cadaveric knees were studied. The popliteal artery, popliteal vein, and tibial nerve were identified after dissection via a posterior approach. An all-inside meniscal repair device was set to a 20-mm depth limit and inserted into a fixed point in the posterior horn at the meniscocapsular junction. This was performed for medial and lateral menisci via anteromedial and anterolateral arthroscopic portals. The distances between the device tip and the neurovascular structures were measured. We performed t tests to determine statistical significance. Results: The distance between the device and popliteal artery was significantly closer when aimed at the posterior horn of the lateral meniscus via the anterolateral portal (4.7  2.3 mm) versus the anteromedial portal (13.0  8.0 mm, P ¼ .010). The distance to the popliteal vein was closer via the anterolateral portal (6.7  2.9 mm) versus the anteromedial portal (13.9  5.8 mm, P ¼ .004). For medial meniscal repair, the distance to the popliteal artery was significantly closer via the anteromedial portal (12.8  11.3 mm) versus the anterolateral portal (23.8  7.7 mm, P ¼ .022). The distance to the popliteal vein was closer via the ante- romedial portal (16.5  11.3 mm) versus the anterolateral portal (28.3  8.2 mm, P ¼ .017). No significant difference was found in the distance to the tibial nerve when aimed at either meniscus via either portal. Conclusion: For all-inside meniscal repair, the popliteal vein is at risk and the popliteal artery is at high risk of injury when the posterior horn of the lateral meniscus is repaired via an anterolateral working portal. Clinical Relevance: The popliteal artery and vein are at risk of injury when the posterior horn of the lateral meniscus undergoes all-inside repair via the anterolateral portal. Surgeons need to be aware of the risks when performing this repair. T here is a higher risk of complications in arthro- scopic knee surgery with more complex procedures such as meniscal repair, synovectomy, and anterior and posterior cruciate ligament reconstruction. 1 For arthroscopic meniscal surgery, the incidence of nerve injury is reported to be up to 0.6% and that of arterial injury, up to 0.03%. 2-5 Popliteal artery injury and sequelae such as pseudoaneurysms and arteriovenous fistulas from arthroscopic meniscal repair are rare, with few reports published in the literature. 6,7 Severe neu- rovascular complications can occur, including irrevers- ible ischemia, compartment syndrome, permanent neurologic deficit, limb loss, and even death. 8 The popliteal artery is in close proximity to the lateral meniscus in the posterior knee. In a magnetic resonance imaging study, de Araujo Goes et al. 9 reported that the mean distance from the popliteal artery to the tibial plateau was 9.54 mm. Keser et al. 10 found the popliteal artery to lay lateral to the midline in 94% of cases. There are limited studies on the effect of the choice of working portal for meniscal repair on the risk of neu- rovascular injury. This is important as the use of all- inside devices becomes more common. As surgeons introduce these devices from either the anteromedial or anterolateral portal, they must be aware of any increased risks when doing so. The purpose of this study was to compare the distance from the device tip to the neurovascular structures From the Department of Orthopaedic Surgery, Changi General Hospital, Singapore. The authors report that they have no conflicts of interest in the authorship and publication of this article. Full ICMJE author disclosure forms are available for this article online, as supplementary material. Received February 26, 2019; accepted July 15, 2019. Address correspondence to David Weijia Mao, M.B.B.S., B.Med.Sci., M.R.C.S., Department of Orthopaedic Surgery, Changi General Hospital, 2 Simei St 3, Singapore 529889. E-mail: dave.w.mao@gmail.com Ó 2019 by the Arthroscopy Association of North America 0749-8063/19249/$36.00 https://doi.org/10.1016/j.arthro.2019.07.023 Arthroscopy: The Journal of Arthroscopic and Related Surgery, Vol 36, No 1 (January), 2020: pp 225-232 225