Arthroscopy

Arthroscopy is Endoscopy of joints. The joints covered by Arthroscopy are Knee, Shoulder, Wrist, Ankle, Elbow, Hip, etc. Of these, the joint that is most commonly treated using Arthroscopy is Knee. Relatively a simple joint, Knee is also one of the most prone for injuries. Because of high incidence of injuries and its relative simplicity, Knee joint has assumed the position of default joint for Arthroscopy.

Knee Arthroscopy for diagnostic purposes involves minimum two holes. These holes are called Portals in medical terminology. The primary portal is the Anterolateral portal. This portal is made not more than 1cm lateral to the Patellar Tendon and 1cm superior to the lateral joint line. This portal is taken without any direct visual aid. For making the portal, surgeons use surgical blade and make a small incision at the desired position. This small incision is later made deeper to penetrate the capsule and to reach inside the joint proper. This is called the principal portal because it allows visualisation of the entire joint through one portal only. This portal is made before any other portals. All the other portals are then made under direct visualisation using the telescope through this portal. The position for the anterolateral portal is decided as mentioned above so as to protect the fat pad and the anterior part (horn) of the lateral meniscus from getting penetrated and thus damaged. Also, the portal is made with the joint in 90deg flexion.

Besides the Anterolateral portal, there are other standard portals such as Anteromedial, Superolateral and Posteromedial. While performing the procedure, the second in line is the Anteromedial portal that is made after making the Anterolateral portal. Note that the Anterolateral portal carries the Arthroscope. With the joint visualised from within, the Anteromedial portal is made. To ensure the protection of fat pad and anterior horn of the medial meniscus, a 18 gauge needle is used that is penetrated from a point that is 1cm medial to the edge of Patellar Tendon and 1cm superior to the medial joint line. This needle is advanced in the anterior-posterior direction untill it is confirmed visually (on the monitor) that it is in the right position. On ensuring the correct placement, Anteromedial portal is made. This portal is used primarily for inserting the instruments used in Arthroscopic surgeries. All the other portals are made subsequently. During diagnostic Arthroscopy, this portal is used to insert the probe that is used to clear the line of vision for the scope and palpate/feel soft tissues like menisci.

Generally only one more portal is made and that is the Superolateral portal that is useful for drainage of the irrigation fluid. An outflow cannula is inserted through this portal for allowing complete drainage of the fluid. Many of our Indian surgeons do not even make this portal. It should be noted that the Arthroscope is inserted in the primary portal after starting the infusion of fluid and the outflow is through the cannula itself, thus eliminating the need of Superolateral portal.

Typically, the diagnosis of knee involves a circular route consisting of seven points. This route is called the Seven Point Tour of the Knee. The seven points of the tour are as follows:
Patellofemoral joint or the posterior aspect of Patella or Patellar tracking
Lateral Gutter
Overall view of the lateral meniscus
Medial Gutter
Overall view of the medial meniscus
Detailed view of the lateral meniscus
Detailed view of the medial meniscus

Though not followed religiously, this is a rough pattern of the way a surgeon assesses the knee. While demonstrating our scope or any equipment on a leg model, we have to adhere to this tour. Repeated following of this tour also aids in remembering and understanding the orientation during Arthroscopy. It is very easy for a novice to lose the orientation inside the joint because of the 30deg direction of view (the most commonly used scope in Arthroscopy is 4mm in diameter and 30deg direction of view). More about the use of direction of view will be discussed in the unit dealing with Arthroscope and its accessories.

While crossing over to the medial compartment from the lateral compartment of the knee, Anterior Cruciate Ligament (ACL) and Posterior Cruciate Ligament (PCL) are assessed in the Intercondylar Notch. Also, during the tour, the condyles are assessed for osteochondral or purely chondral defects. While performing the diagnosis, it is essential to have a hook probe as many a times, the tears in menisci and tension of the ACL are examined using the probe. Some of these defects may not be visible without palpating the fore-mentioned tissues. To palpate these soft tissues while performing Arthroscopy is afforded by the probe.