Endoscopic Resection of Medial Extra-articular Cysts of the Knee Tun Hing Lui, M.B.B.S.(HK), F.R.C.S.(Edin), F.H.K.A.M., F.H.K.C.O.S.  Arthroscopy Techniques  Volume 6, Issue 2, Pages e461-e466 (April 2017) DOI: 10.1016/j.eats.2016.11.001 Copyright © 2016 Arthroscopy Association of North America Terms and Conditions

Fig 1 Endoscopic resection of a medial extra-articular cyst of the right knee. Magnetic resonance imaging of the illustrated case. (A) Coronal view shows a multiloculated cyst at the medial side of the knee. (B, C) Sagittal views show posterior extension of the cyst. (D) Axial view shows the posteromedial location of the cyst. (Arrowhead, the multiloculated cyst; M, medial femoral condyle.) Arthroscopy Techniques 2017 6, e461-e466DOI: (10.1016/j.eats.2016.11.001) Copyright © 2016 Arthroscopy Association of North America Terms and Conditions

Fig 2 Endoscopic resection of a medial extra-articular cyst of the right knee. The patient is in the supine position with the legs spread. (A) The cyst and the medial boundary of the popliteal fossa including the medial hamstring tendons and the medial head of the gastrocnemius are outlined. The proximal border of the medial femoral condyle is also marked. The posterior distal portal is located between the medial hamstring tendons and the medial head of the gastrocnemius and just distal to the medial knee joint line. (B) The anterior proximal portal is located at the anterior corner of the upper border of the medial femoral condyle. It is established by an inside-out technique. The trocar cannula passes through both portals. (APP, anterior proximal portal; C, cyst; FC, upper border of the femoral condyle; H, lateral border of the medial hamstring tendons; MG, lateral border of the medial head of the gastrocnemius; PDP, posterior distal portal.) Arthroscopy Techniques 2017 6, e461-e466DOI: (10.1016/j.eats.2016.11.001) Copyright © 2016 Arthroscopy Association of North America Terms and Conditions

Fig 3 Endoscopic resection of a medial extra-articular cyst of the right knee. The patient is in the supine position with the legs spread. (A) The posterior distal portal (PDP) is the viewing portal and the anterior proximal portal (APP) is the working portal. (B) The proximal part of the cyst (C) is resected with an arthroscopic shaver (AS) and the surrounding normal structures are exposed. (MHm, medial hamstring muscle.) Arthroscopy Techniques 2017 6, e461-e466DOI: (10.1016/j.eats.2016.11.001) Copyright © 2016 Arthroscopy Association of North America Terms and Conditions

Fig 4 Endoscopic resection of a medial extra-articular cyst of the right knee. The patient is in the supine position with the legs spread. After completion of resection of the proximal part of the cyst (C), the arthroscope is advanced and exits the anterior proximal portal (APP). The arthroscope is removed leaving the cannula (AC) in situ. (A) A 4.0-mm Wissinger rod (WR) is inserted into the cannula, passing through the anterior proximal and posterior distal (PDP) portals. (B) The cannula is removed and reinserted along the rod via the anterior proximal portal. (C) The cannula passes through both portals and the rod is removed. The arthroscopic shaver (AS) is inserted half-way into the cannula via the posterior distal portal. Arthroscopy Techniques 2017 6, e461-e466DOI: (10.1016/j.eats.2016.11.001) Copyright © 2016 Arthroscopy Association of North America Terms and Conditions

Fig 5 Endoscopic resection of a medial extra-articular cyst of the right knee. The patient is in the supine position with the legs spread. (A) The anterior proximal portal (APP) is the viewing portal. The distal part of the cyst (C) is resected with the arthroscopic shaver via the posterior distal portal (PDP). (B) The cyst wall close to the posterior distal portal is resected to expose the medial head of the gastrocnemius (MG), the semimembranosus tendon (SMT), and the semitendinosus tendon (STT). Arthroscopy Techniques 2017 6, e461-e466DOI: (10.1016/j.eats.2016.11.001) Copyright © 2016 Arthroscopy Association of North America Terms and Conditions

Fig 6 Endoscopic resection of a medial extra-articular cyst of the right knee. The patient is in the supine position with the legs spread. The posterior distal portal is the viewing portal. Completeness of resection of the cyst is confirmed by no more cyst wall in the operated site and the surrounding normal structures are exposed. (MFC, medial femoral condyle; MHm, medial hamstring muscle.) Arthroscopy Techniques 2017 6, e461-e466DOI: (10.1016/j.eats.2016.11.001) Copyright © 2016 Arthroscopy Association of North America Terms and Conditions