Arthroscopic Knee Examination

Abstract

Arthroscopic knee examination seems to be a primary technique in knee arthroscopy. In fact, completing a full-scale examination of the knee joint is challenging. The main purpose of this section is to describe how, technically, a standard knee examination can be completed without omissions in examination space and some special injuries. The intra-articular space of the knee joint includes the suprapatellar pouch, the lateral gutter, the medial gutter, the patellofemoral joint, the anterior compartment, the femoral notch, the medial, lateral, posteromedial, and posterolateral compartments. From the aspect of completing the examination, there is no need to follow a certain sequence of procedures, if each space can be reached, and every part of the intraarticular structure can be checked.

Arthroscopic knee examination seems to be a primary technique in knee arthroscopy. In fact, completing a full-scale examination of the knee joint is challenging. The main purpose of this section is to describe how, technically, a standard knee examination can be completed without omissions in examination space and some special injuries. The intra-articular space of the knee joint includes the suprapatellar pouch, the lateral gutter, the medial gutter, the patellofemoral joint, the anterior compartment, the femoral notch, the medial, lateral, posteromedial, and posterolateral compartments. From the aspect of completing the examination, there is no need to follow a certain sequence of procedures, if each space can be reached, and every part of the intraarticular structure can be checked.

The Diagnostic Value of Arthroscopic Knee Examination

At present, knee imaging examination technology has been quite mature. The diagnosis of knee injury mainly depends on medical history, physical examination, and imaging examination. In overall, knee examination operation for the diagnosis of disease is of little significance. However, despite this, there are still some diseases that rely on arthroscopic knee examination for accurate diagnosis. The overall indication of arthroscopic knee exploration is those who cannot be clearly diagnosed through medical history, physical examination, and auxiliary imaging examinations (Table 1.1).

Table 1.1 The indication of arthroscopic knee examination

The first specific indication of arthroscopic knee examination is a suspected meniscus tear at the conjunction with the capsule. Some special types of meniscus injury, such as injury at the junction of the meniscus and the capsule, non-displaced root tear of the posterior horn of the meniscus, and some kinds of radius tear, are relatively difficult to detect through MRI examination and rely on arthroscopic examination as the final diagnose method. [1].

The second specific indication of arthroscopic knee examination is unexplained knee hematoma without cause of trauma. The etiologies mainly involve intra-articular hemangioma and hemorrhagic synovitis. [2].

The third specific indication of arthroscopic knee examination refers to insidious gout. Arthroscopy is the only way to diagnose insidious gout when the patient has gout-related signs and symptoms, but the result of serum uric acid test is within the normal range. Uric acid crystallization can be found on the synovium, and other types of uric acid deposition can even be found on other structures.

MRI examination is sensitive and reliable for the diagnosis of cartilage lesions, and arthroscopic examination is only used as a supplementary measure.

Another indication of arthroscopic examination is to detect the cartilage status to define the suitability of knee alignment correction operation. Compared with MRI examination, arthroscopic examination is the most accurate and can avoid unnecessary osteotomy.

Procedures of Arthroscopic Knee Examination

There is no standard procedure for knee arthroscopic examination. The following is my personal recommendation of the order of examination, in which the convergence of the checked part is often along the swing movement of the scope. In addition, the examination of the knee joint and the basic joint debridement are combined. There is no pure observation without any operation (Table 1.2).

Table 1.2 Step-by-step procedure of arthroscopic knee examination

Patient Position

The patient is placed in supine position. A tourniquet is placed at the proximal thigh. The knee is flexed at 90 degrees, and a supporting post is placed at the lateral side of the thigh in the position corresponding to the tourniquet. The knee is extended. Another supporting post is placed just at the proximal side of the joint line.

Portal Establishment

The knee is flexed at 90 degrees. The soft area among the patella tendon, the lateral femoral, and tibial condyles are palpated. At the top edge of the soft area, close to the lateral edge of the patella tendon, the high anterolateral portal is established. The anteromedial portal is created at a position close to the medial edge of the patella tendon, at a level parallel to the high anterolateral portal.

The Suprapatellar Pouch

At full knee extension, the arthroscope is placed into the suprapatellar pouch. The suprapatellar plica is examined [3]. (Fig. 1.1) In case of closed suprapatellar plica or plica with a small hole, the plica is opened to explore the proximal side of it [4]. The suprapatellar pouch is checked for free bodies and synovium disorders such as inflammation, hypertrophy, or fibrosis. In case of knee arthrofibrosis, reduction of the suprapatellar pouch can be revealed.

Fig. 1.1

Examination of the suprapatellar pouch (arthroscopic view of the left knee through the anterolateral portal.)

The Lateral Gutter

With lateral swing and retrieving movement, the scope is placed to the lateral gutter of the knee. Lateral synovial plica usually exists but is seldom symptomatic (Fig. 1.2).

Fig. 1.2

Examination of the lateral gutter (arthroscopic view of the left knee through the anterolateral portal. LSP, lateral synovial plica)

In patients with patella dislocation, bone fragment may be detected adhering to the lateral side of the lateral femoral condyle. At the bottom of the lateral gutter, the popliteal tendon hiatus can be detected (Fig. 1.3). Peripheral meniscus tear manifesting as hiatus extension and free body in the hiatus are detected.

Fig. 1.3

Examination of the popliteal hiatus (arthroscopic view of the left knee through the anterolateral portal). PH popliteal hiatus, PT popliteal tendon, LFC lateral femoral condyle, LM lateral meniscus

The Patellofemoral Joint Viewed from the Lateral Side

The arthroscope is lifted from the bottom of the lateral gutter to the anterolateral edge of the lateral femoral condyle. The patellofemoral joint is checked from the lateral side (Fig. 1.4). The patella height related to the femoral trochlea, osteophyte at the proximal femoral trochlea, and the proximal patella should be checked. In case of large infrapatellar fat pad, the shaver is placed in through the anteromedial portal to partially remove it till the patellofemoral joint is clear.

Fig. 1.4

Arthroscopic lateral view of the patellofemoral joint through the anterolateral portal. P patella. TG trochlea groove. IPFP infrapatellar fat pad

The Medial Synovial Plica and the Medial Gutter

The arthroscope is placed into the patellofemoral joint. The medial synovial plica is checked. (Fig. 1.5) In case of type II or type III medial synovial plica, it is removed.

Fig. 1.5

Examination of the medial synovial plica (arthroscopic view of the anteromedial side of the left knee through the anterolateral portal). MSP medial synovial plica, MFC medial femoral condyle

The scope is placed through the patellofemoral joint to face the medial gutter downward. The medial gutter is checked (Fig. 1.6).

Fig. 1.6

Examination of the medial gutter (arthroscopic view of the medial gutter of the left knee through the anterolateral portal). MG medial gutter, MFC medial femoral condyle

Anterior Compartment

The arthroscope is retrieved back to the anterior knee compartment. The knee is flexed at 30 degrees. The anterior compartment is checked. The infrapatellar plica is removed to expose the anterior outlet of the femoral notch (Fig. 1.7).

Fig. 1.7

Examination of the anterior knee compartment revealing the infrapatellar plica (arrow) (arthroscopic view of the anterior compartment through the anterolateral portal)

The transverse knee ligament is checked to detect hypertrophy. The anterior cruciate ligament insertion is checked at the inferior side of the transverse knee ligament, especially when ACL tibial avulsion fracture is to be detected. The tertial tibial eminence is detected. When there is an anterior meniscofemoral ligament, which connects the anterior horn of the medial meniscus and the lateral wall of the intercondylar notch, a fibrous structure is present at the anterior side of the anterior cruciate ligament. The anterior meniscofemoral ligament may cause symptoms at knee extension and is recommended to be removed. [5].

The Patellofemoral Joint Viewed from the Distal Side

The patellofemoral joint is checked from the distal side. Lateral displacement of the patella and cartilage degeneration or injury of the patella and the femoral groove are checked. In case of acute patella dislocation, the medial patellofemoral ligament is checked to detect the status of injury (Fig. 1.8).

Fig. 1.8

Arthroscopic distal view of the patellofemoral joint through the anterolateral portal. P patella, TG trochlea groove

The Femoral Notch

The knee is flexed at 30 degrees. The femoral notch is examined to detect osteophytes and femoral notch stenosis (Fig. 1.9) and whether there is impingement to the anterior cruciate ligament. The knee is flexed at 90 degrees. The deep site of the femoral notch is examined to detect free bodies and the integrity of the cruciate ligaments.

Fig. 1.9

Examination of the femoral notch (arthroscopic view of the left knee through the anterolateral portal). ACL anterior cruciate ligament (torn in this case). PCL posterior cruciate ligament. MFC medial femoral condyle. LFC Lateral femoral condyle

Medial Compartment

The knee is flexed at 30 degrees. The anterior horn and the body of the medial meniscus is checked. Normally, the anterior horn of the medial meniscus is attached to the lower site of the medial tibial plateau. Cartilage status of the medial compartment is checked.

The knee is placed close to full extension. Pulling, medial opening and external rotating maneuver on the leg is performed to open the medial joint space by an assistant. The posterior horn of the medial meniscus is checked (Fig. 1.10). If there is a high suspicion of injures of the posterior horn of the medial meniscus, and the medial joint space cannot be opened for exact evaluation. The medial collateral ligament is released first to open the medial joint space, and the posterior horn of the medial meniscus is checked [6].

Fig. 1.10

Examination of the posterior horn of the medial meniscus (arthroscopic view of the medial compartment of the left knee through the anterolateral portal). MM posterior horn of the medial meniscus, MFC medial femoral condyle, MTC medial tibial condyle

Posteromedial Compartment

The knee is flexed at 30 degrees, and the arthroscope faces the intercondylar notch. Forceps are inserted through the interspace of the medial femoral condyle and posterior cruciate ligament into the posteromedial compartment. If the posteromedial compartment cannot be inserted because of the osteogenic hyperplasia on the medial wall of the intercondylar notch and the medial tibial eminence, the osteophytes on the medial wall of the intercondylar notch are removed with forceps, and the top of the medial tibial eminence is removed with a burr until the passage to the posteromedial compartment is opened. With the arthroscope placed into the femoral notch, the attachment of the posterior horn of the medial meniscus is checked to rule out the root tear of the medial meniscus (Fig. 1.11).

Fig. 1.11

Examination of the posterior root of the medial meniscus (arthroscopic femoral notch view of the left knee through the anterolateral portal). MM posterior root of the medial meniscus, MFC medial femoral condyle, MTC medial tibial condyle, PCL posterior cruciate ligament

The arthroscope is inserted into the posteromedial compartment along the space between the medial wall of the intercondylar notch and posterior cruciate ligament. The knee is then flexed at 90° and the posteromedial compartment is examined thoroughly (Fig. 1.12). The main purpose is to detect whether there is damage at the junction of the meniscus and the joint capsule (ramp lesion), synovial lesions, and free body.

Fig. 1.12

Examination of the posteromedial compartment (arthroscopic view of the posteromedial compartment of the left knee through the anterolateral portal and the femoral notch). MFC medial femoral condyle, PMC posteromedial compartment

Lateral Compartment

The arthroscope is pulled out of the joint. The lower leg is placed in a figure-of-4 position. The arthroscope is placed into the joint through the anteromedial portal. A shaver is placed in to remove the synovial tissue near the anterolateral portal to expose the anterior edge of the lateral meniscus. The anterior horn of the lateral meniscus is observed (Fig. 1.13). The hook is used to check the stability of the lateral meniscus, and check whether there are free bodies at the inferior site of the lateral meniscus. Then the body and the posterior horn of the lateral meniscus is checked.

Fig. 1.13

Examination of the lateral compartment (arthroscopic view of the lateral compartment of the left knee through the anteromedial portal). LFC lateral femoral condyle, LTC lateral tibial condyle, LM lateral meniscus

The Posterolateral Compartment

The arthroscope was inserted through the space between the anterior cruciate ligament and the lateral femoral condyle into the posterolateral compartment (Fig. 1.14). Free bodies are found out. Any synovium lesions are checked.

Fig. 1.14

Examination of the posterolateral compartment (Arthroscopic view of the posterolateral compartment of the left knee through the anteromedial portal). LFC lateral femoral condyle, PLC posterolateral compartment

Comments on Current Procedures

The pearls and pitfall of the current procedure are listed in Table 1.3. The most difficult part of this procedure is getting access to the posteromedial compartment in case of femoral notch stenosis. As for a thorough examination of the posterior septum, posteromedial and posterolateral portals should be used.

Table 1.3 Pearls and pitfalls of arthroscopic knee examination