Arthroscopic anatomy of the posterolateral corner of the knee: anatomic relations and arthroscopic approaches

Abstract

Introduction: Although open-surgical techniques for the reconstruction of the posterolateral corner (PLC) are well established, the use of arthroscopic procedures has recently increased. When compared with open surgical preparation, arthroscopic orientation in the PLC is challenging and anatomic relations may not be familiar. Nevertheless, a profound knowledge of anatomic key structures and possible structures at risk as well as technical variations of arthroscopic approaches are mandatory to allow a precise and safe surgical intervention.

Materials and methods: In a cadaveric video demonstration, an anterolateral (AL), anteromedial (AM), posteromedial (PM) and posterolateral (PL) portal, as well as a transseptal approach (TSA) were developed. Key structures of the PLC were defined and sequentially exposed during posterolateral arthroscopy. Finally, anatomic relations of all key structures were demonstrated.

Results: All key structures of the PLC can be visualized during arthroscopy. Thereby, careful portal placement is crucial in order to allow an effective exposure. Two alternatives of the TSA were described, depending on the region of interest. The peroneal nerve can be visualized dorsal to the biceps femoris tendon (BT), lateral to the soleus muscle (SM) and about 3 cm distal to the fibular styloid (FS). The distal attachment of the fibular collateral ligament (FCL) can be exposed on the lateral side of the fibular head (FH). The fibular attachment of the popliteofibular ligament (PFL) is exposed at the tip of the FS.

Conclusion: Arthroscopy of the posterolateral recessus allows full visualization of all key structures of the posterolateral corner, which provides the basis for anatomic and safe drill channel placement in PLC reconstruction. A sufficient exposure of relevant anatomic landmarks and precise portal preparation reduce the risk of iatrogenic vascular and peroneal nerve injury.

Keywords: Anatomy; Arthroscopy; Footprint; Posterolateral corner; Preparation; Reconstruction.

Fig. 1

Transcondylar approach and implementation of the posteromedial portal in a left knee After preparation of the intercondylar notch, the arthroscope is passed underneath the posterior cruciate ligament into the posteromedial recessus (a), to visualize the posteromedial joint capsule (b). A needle is introduced for proper placement of the PM portal (c). Using a cannula (Twist-In®, Arthrex, Naples, FL, USA) can be helpful to secure the portal and facilitate management of instruments (d). PCL posterior cruciate ligament, ACL anterior cruciate ligament, MFC medial femoral condyle, PMJC posteromedial joint capsule

Fig. 2

Transseptal approach and posterolateral portal. After implementing the posteromedial portal, the camera is retracted and passed underneath the anterior cruciate ligament and into the PL recessus visualizing the dorsal septum from the lateral side (a). A shaver (Excalibur®, Arthrex, Naples, FL, USA) is introduced through the posteromedial portal to create a transseptal approach under indirect visualization (b). Through the transcondylar view, size and position of the transseptal portal can be validated (c). To access the PL recessus, the arthroscope is placed into the PM portal and passed through the transseptal approach (d). Under direct visualization a PL portal is created, analogously to the PM portal (e, f). In case of revision surgery with extensive scarring or decreased opening of the medial joint space, primary visualization of the dorsal septum from the medial side may be required. Therefore, the arthroscope is first passed through the AL portal, underneath the PCL and into the posteromedial recessus, in order to observe resection of the septum. DS dorsal septum, LFC lateral femoral condyle, PHLM posterior horn of the lateral meniscus, MFC medial femoral condyle, PMJC posteromedial joint capsule, PLJC posterolateral joint capsule, PMF popliteomeniscal fibers

Fig. 3

Preparation of the popliteus muscle–tendon unit. With a shaver, the popliteomeniscal fibers are carefully resected, in order to expose the popliteus tendon (PLT) while preserving the lateral meniscus (a). The PLT is located closely underneath the fibers, inside the popliteal sulcus (black asterisk) (b, c). In case of a popliteus bypass, this view is essential for tibial tunnel placement. Further preparation is performed closely to the popliteus muscle, to avoid injury of neurovascular structures. Thus, a radiofrequency electrode (CoolCut®, Arthrex, Naples, FL, USA) can be utilized, to prevent excessive bleeding (d, e). The lateral inferior genicular artery (LIGA) (white hash) is a frequent cause of bleeding (f). It is located at the dorsolateral side of the popliteus tendon, behind the soleus muscle and should be spared or coagulated to prevent bleeding. PLJC posterolateral joint capsule, LFC lateral femoral condyle, PHLM posterior horn of the lateral meniscus, PLT popliteus tendon

Fig. 4

Exposure of the fibula head and the peroneal nerve. For preparation of the fibula head, a less traumatic shaver blade is advantageous (Torpedo®, Arthrex, Naples, FL, USA) (a). The fibula head can be palpated through the skin, to generate observable intraarticular movement. After careful preparation, the popliteofibular ligament (blue triangles) appears as a broad and fan-like shiny structure, which originates distally and dorsally of the styloid process and inserts at the musculotendinous junction of the PLT (b). Fat tissue (black cross), which is located dorsally of the soleus muscle indicates the course of the peroneal nerve (c). After careful resection, the nerve (yellow asterisks) can be visualized (d). In relation to the fibula head, the nerve is located lateral and distal to the hypothetical direction of a fibular drill channel for PLC reconstruction (e). From the tip of the styloid process to the peroneal nerve, a distance of 2.5 cm is measured (f). FH fibula head, SM soleus muscle, SM soleus muscle, FS fibular styloid

Fig. 5

Preparation of the lateral collateral ligament (FCL). The fibular FCL attachment is partially covered by the posterior parts of the popliteofibular ligament (PFL) (a). Therefore, the most dorsal fibers need to be removed, in order to gain access to the FCL (b). The FCL appears as a shiny vertical structure, at the lateral side of the fibula head (green dot). Inferior and posterior to the FCL, the horizontal course of the biceps femoris tendon (BT) is visible (c). Although neither the FCL, nor the peroneal nerve (yellow asterisk) should be arthroscopically exposed in patients, the anatomic locations of both structures in relation to the fibula head are important to know when performing arthroscopic PLC reconstruction (d). FS fibular styloid, PFL popliteofibular ligament, BT biceps femoris tendon

Fig. 6

Annotated illustration of the key structures in the PLC (a). Location of the peroneal nerve in the PLC (b). PLT popliteus tendon, PFL popliteofibular ligament, BFT biceps femoris tendon, SM soleus muscle, FCL fibular collateral ligament