Posterior “Double Cannular Sliding Technique” for Resection of Posterior Septum of the Knee Joint  Nam Yong Choi, M.D., Ph.D., Hyung Kook Cheong, M.D., Hyun Seok Song, M.D., Ph.D., Chan Woong Moon, M.D., Ph.D.  Arthroscopy Techniques  Volume 6, Issue 5, Pages e1515-e1521 (October 2017) DOI: 10.1016/j.eats.2017.06.028 Copyright © 2017 Arthroscopy Association of North America Terms and Conditions

Fig 1 Creation of portals. The patient is placed in the supine position under general endotracheal anesthesia. The right lower limb is prepared in the routine manner, and the tourniquet is inflated. The standard anterolateral and anteromedial portals are made, and the arthroscope is placed between the posterior cruciate ligament and the medial femoral condyle after a routine arthroscopic examination. Then, after exchanging the arthroscope with the obturator, the arthroscope is inserted in the posteromedial compartment. After confirming the location of the posteromedial portal under the arthroscope by pressing fingers on the posteromedial soft spot, an 18-gauge needle is inserted while the knee is flexed in 90°. The 18-gauge spinal needle is placed 5 mm posteriorly and parallel to the posterior aspect of the medial femoral condyle (A). After skin incision, capsular enlargement is performed with a straight hemostat (B). A 5.75-mm cannula (Arthrex) is inserted in the same direction (C). After placing the arthroscope in the posterolateral compartment with the transnotch approach, a posterolateral portal is made in the same manner (D-F). (ALP, anterolateral portal; AMP, anteromedial portal; LFC, lateral femoral condyle; MFC, medial femoral condyle; PLC, posterolateral compartment; PMC, posteromedial compartment; V, viewing portal; W, working compartment.) Arthroscopy Techniques 2017 6, e1515-e1521DOI: (10.1016/j.eats.2017.06.028) Copyright © 2017 Arthroscopy Association of North America Terms and Conditions

Fig 2 Resection of the lateral side of the posterior septum. Using a transnotch approach, the arthroscope reaches the posteromedial compartment through the anterolateral portal (A) of the right knee. The switching stick is inserted through the cannula in the posteromedial portal (B) with maintaining 90° flexion of the knee. The arthroscope is rotated in the 9 o'clock position without going beyond the posterior condyle (C). Then, the septum is gently perforated through in the direction parallel to the posterior wall using the switching stick (D, E). After the arthroscope is placed in the posterolateral compartment, the switching stick is passed through the cannula positioned in the posterolateral portal (F-H) with 90° flexion of the knee. The instrument (shaver or RF) is inserted into the posterolateral portal, whereas the switching stick is withdrawn in the posteromedial direction (I, J). Here, the assistant pushes both cannulas in the direction of the septum and fixes the position of the cannula (K), and then the switching stick is withdrawn up to the septum (L). The posterior septum of the posterolateral compartment is resected with a shaver (or RF), but an abrupt procedure may be limited due to the fixed cannulas (M-O). All of these procedures are controlled under direct visualization (P) with 90° flexion of the knee. Red arrow, direction of the sliding switching stick; blue arrow, direction of cannular movement; arrow head, medial side of the posterior septum; square, lateral side of the posterior septum; asterisk, intervening fatty layer of the posterior septum. (ALP, anterolateral portal; AMP, anteromedial portal; LAT, lateral; MED, medial; MFC, medial femoral condyle; PLC, posterolateral compartment; PLP, posterolateral portal; PMC, posteromedial compartment; PMP, posteromedial portal; RF, radiofrequency; V, viewing portal; W, working compartment.) Arthroscopy Techniques 2017 6, e1515-e1521DOI: (10.1016/j.eats.2017.06.028) Copyright © 2017 Arthroscopy Association of North America Terms and Conditions

Fig 3 Resection of the medial side of the posterior septum. The switching stick is passed through again (A-C). After positioning the arthroscope in the posteromedial compartment via anterolateral portal again, the switching stick is withdrawn to the posterolateral compartment and the instrument (shaver or RF) approaches the posteromedial portal (D) with 90° flexion of the right knee. After the assistant fixes the position of the cannula, the switching stick is withdrawn up to the septum and the posterior septum of the posteromedial compartment is resected with the instrument (shaver or RF) (E-G). All of these procedures are controlled under direct visualization (H) with 90° flexion of the knee. red arrow, direction of the sliding switching stick; blue arrow, direction of cannular movement; arrow head, medial side of the posterior septum; square, lateral side of the posterior septum; asterisk, intervening fatty layer of the posterior septum. (ALP, anterolateral portal; AMP, anteromedial portal; LAT, lateral; MED, medial; MFC, medial femoral condyle; PLC, posterolateral compartment; PLP, posterolateral portal; PMC, posteromedial compartment; PMP, posteromedial portal; RF, radiofrequency; V, viewing portal; W, working compartment.) Arthroscopy Techniques 2017 6, e1515-e1521DOI: (10.1016/j.eats.2017.06.028) Copyright © 2017 Arthroscopy Association of North America Terms and Conditions

Fig 4 Establishment of direct posterior-posterior triangulation. The arthroscope and instrument are inserted separately through the posteromedial and posterolateral portals, respectively, to form a direct posterior-posterior triangulation with 90° flexion of the right knee (A-C). Arrow head, medial side of the posterior septum; square, lateral side of the posterior septum; asterisk, intervening fatty layer of the posterior septum. (PLC, posterolateral compartment; PLP, posterolateral portal; PMC, posteromedial compartment; PMP, posteromedial portal; V, viewing portal; W, working compartment.) Arthroscopy Techniques 2017 6, e1515-e1521DOI: (10.1016/j.eats.2017.06.028) Copyright © 2017 Arthroscopy Association of North America Terms and Conditions