Physical Examination for Meniscus Tears

Fig. 2.1

Palpation of the meniscus. (a) Palpation of medial meniscus. (b) Palpation of lateral meniscus

The lateral knee must also be evaluated carefully with palpation. Analogous to the medial aspect of the knee, the lateral meniscus can be palpated at the upper edge of the lateral tibial plateau (Fig. 2.1b) and the LCL can be palpated as it extends from the lateral femoral epicondyle to the fibular head. Tenderness to palpation along the lateral joint line can indicate a lateral meniscus tear, LCL injury, or lateral compartment osteoarthritis. The biceps femoris and iliotibial tract can also be palpated as they cross the knee joint to insert on the fibular head and lateral tibial tubercle, respectively. Palpation of the lateral joint line can be facilitated by placing the knee in a crossed position, or the “figure of four” position. This places a varus moment on the knee, opening up the lateral compartment. The LCL can easily be palpated running from the lateral epicondyle to the fibular head, and posterior to this structure on the joint line is the lateral meniscus body and posterior horn segment. Care must be taken to differentiate joint-line tenderness from popliteus tendonitis (more proximal) or iliotibial friction band syndrome (more proximal).

The final step in the palpation of the knee joint is the assessment for intra-articular effusions. While the absence of indentations adjacent to the infrapatellar tendon implies the presence of a large intra-articular effusion, specific physical examination maneuvers can assist with the detection of more subtle effusions. The first maneuver involves the creation of a fluid wave to detect an effusion. With the knee extended, intra-articular fluid can be milked into the suprapatellar pouch by sliding the hand proximally along the medial aspect of the patella. Next, this fluid can be compressed out of the suprapatellar pouch by sliding the hand distally along the lateral aspect of the patella. A fluid bulge can be seen medial to the patella with this lateral compression in the presence of an intra-articular effusion. Another maneuver to detect an effusion involves the ballottement of the patella in the presence of an effusion. One hand is used to compress fluid from the suprapatellar pouch to beneath the patella while the second hand squeezes fluid from the inferior aspect of the joint to beneath the patella. A finger can then be used to depress the patella, which will feel as if it is bouncing on the underlying effusion [8].

Range of Motion

The physician should evaluate both active and passive range of motion of the knee joint. Normal knee extension ranges from 0° to -10°, and normal knee flexion ranges from 130° to 150°. The patella should be observed for appropriate tracking with active and passive knee range of motion. Patellofemoral crepitus can often be observed with range of motion in the presence of patellofemoral osteoarthritis. Crepitus and/or pain in early flexion indicates more distal patella disease. Joint pain that is present during both active and passive range of motion is often associated with intra-articular pathology while pain that is present only with active range of motion has a higher likelihood of being related to an extra-articular soft tissue disorder [8].

Joint Stability

The assessment of joint stability is an essential part of every orthopedic knee examination. When evaluating joint stability, the physician should perform a series of maneuvers to both the affected and unaffected knee to test the collateral and cruciate ligaments for laxity. The MCL is best evaluated with the patient supine by applying a valgus stress to the knee joint both with the knee in 30° of flexion and in full extension. The LCL can be assessed in a similar manner by applying a varus stress to the knee joint in 30° of flexion and full extension. By stressing the knee in flexion and extension, the clinician can test the collateral ligaments both in isolation and in combination with the secondary stabilizers of the knee. Laxity to valgus or varus stress with the knee in 30° of flexion indicates an isolated injury to the MCL or LCL, respectively. When laxity is also noted to varus or valgus stress with the knee in full extension, one or both cruciate ligaments are likely injured in addition to a collateral ligament [9]. The physical examination maneuvers utilized for the evaluation of the collateral ligaments are summarized in Table 2.1.

Table 2.1

Physical examination of the collateral ligaments

Physical exam test	Technique	Significance
Valgus stress	Valgus stress applied to knee in 30° flexion and full extension	Laxity in 30° flexion indicates isolated MCL injury. Laxity in full extension indicates MCL injury with associated cruciate ligament injury
Varus stress	Varus stress applied to knee in 30° flexion and full extension	Laxity in 30° flexion indicates isolated LCL injury. Laxity in full extension indicates LCL injury with associated cruciate ligament injury

The examiner should also consider meniscal pathology when evaluating the stability of the collateral ligaments. When performing isolated varus or valgus stress, pain on the side of compression suggests meniscal injury while pain on the side of distraction implicates ligamentous pathology. As a result, medial knee pain with varus stress and lateral knee pain with valgus stress are concerning for medial and lateral meniscus tears, respectively [10].

The posteromedial and posterolateral complexes of the knee are also important collateral stabilizers of the knee joint. The posterior oblique ligament and posteromedial joint capsule of the posteromedial complex prevent excessive anteromedial rotation, while the posterolateral complex (popliteus, fibular collateral ligament, popliteofibular ligament, fabellofibular ligament, arcuate complex, and lateral head of the gastrocnemius) prevents excessive posterolateral rotation. The anterior rotation drawer test and dial test are important maneuvers to determine whether pathology in these structures may exist.

The anterior rotation drawer test can be used to assess for both posteromedial and posterolateral instability. This maneuver is performed by applying an anterior drawer force to the tibia with the knee flexed at 90°. The anterior force is first applied in the neutral position, then with 15° of tibial internal rotation, and finally with 30° of tibial external rotation. Increased subluxation of the tibial plateau in reference to the femoral condyles in neutral position that is accentuated by external rotation and decreased by internal rotation is indicative of anteromedial instability. Anterior tibial subluxation in neutral position that is increased with internal rotation and decreased by external rotation is indicative of posterolateral instability [11].

The dial test can also be used to assess for posterolateral instability. This maneuver can be performed both with the patient supine and prone. With either position, the examiner should use one hand to grasp each of the patient’s feet and externally rotate the lower legs simultaneously first at 30° of knee flexion and then at 90° of knee flexion. A positive dial test is indicated by asymmetric external rotation (>15°) of the symptomatic extremity when compared to the asymptomatic extremity. A positive dial test performed at 30° of knee flexion is concerning for an isolated PLC injury. A positive dial test both at 30 and 90° of knee flexion is concerning for a PCL injury in addition to a PLC injury [6]. The prone position may be more favorable since it safeguards against excessive anteromedial tibial subluxation.

After the collateral ligaments are evaluated, attention should then be turned to examination of the cruciate ligaments. The physical examination tests used during the evaluation for ACL injury, including the Lachman test, anterior drawer, and pivot shift test, are summarized in Table 2.2. The Lachman test is the most sensitive and specific physical examination maneuver for the detection of an ACL injury with reported sensitivity ranging from 80 % to 99 % [12–17] and a specificity of 95 % [14]. This test is performed with the patient placed in the supine position with the knee flexed at approximately 20–30°. With one hand stabilizing the femur, the examiner’s second hand is used to briskly anteriorly translate the proximal tibia with respect to the femur. A soft end point to anterior translation or greater translation when compared to the unaffected knee is considered a positive Lachman test and is concerning for a possible ACL injury [17].

Table 2.2

Physical examination of the anterior cruciate ligament

Physical exam test	Technique	Significance	Reliability
Lachman test	Anterior proximal tibial translation with knee in 30° flexion	Soft end point or increased translation compared to contralateral knee is concerning for ACL injury	Sensitivity: 80–99 % [12–17]
Lachman test			Specificity: 95 % [14]
Anterior drawer	Anterior proximal tibial translation with knee in 90° flexion	Soft end point or increased translation compared to contralateral knee is concerning for ACL injury	Sensitivity: 22.2–95.24 % [12–14, 16, 17]
Anterior drawer			Specificity: >97 % [14]
Pivot shift	Knee passively flexed with lower extremity in slight internal rotation (IR) while valgus stress applied	An appreciable “clunk” at 30° knee flexion from spontaneous reduction of displaced tibial plateau is suggestive of ACL injury	Sensitivity: 35–98.4 % [13, 14]
Pivot shift			Specificity: >98 % [13, 14]

The anterior drawer test may also be used to assist with the identification of an ACL injury. In this test, the patient is positioned supine with the hip flexed at 45° and the knee flexed at 90°. The examiner places both hands on the proximal tibia with thumbs on the anterior tibial plateau and remaining fingers wrapped posteriorly. The lower extremity can be stabilized by sitting on the patient’s foot. An anterior translational force is then applied to the proximal tibia in relation to the femur. Analogous to the Lachman test, the anterior drawer test is positive for injury to the ACL injury when it results in a soft end point or increased anterior translation of the proximal tibia when compared to the unaffected side [9]. Reported sensitivity of this test is much more variable, ranging from 22.2 % to 95.24 % [12–17]. The specificity of the anterior drawer has been reported as greater than 97 % [14].

The pivot shift test is another effective maneuver for the detection of an ACL tear. This test is based on the anterior subluxation of the lateral tibial plateau relative to the femoral condyle that occurs with full knee extension in the presence of an ACL injury. A positive pivot shift test detects the spontaneous reduction of the tibial plateau with flexion of an ACL deficient knee. To perform the pivot shift test, the examiner uses one hand on the patient’s ankle to raise the lower extremity with the knee in full extension and slight internal rotation. The examiner then applies a valgus stress to the knee joint while passively flexing the knee. A positive test will result in a profound clunk at approximately 30° of flexion when the displaced tibial plateau spontaneously reduces beneath the femoral condyle [18]. The sensitivity of the pivot shift test has also been reported to have variable results (35 % to 98.4 %) [13, 14]. The specificity of this test has been reported as 98 % or greater [13, 14].

The PCL can also be evaluated by a variety of clinical examination maneuvers, which are summarized in Table 2.3. The knee should first be inspected for a posterior sag sign, which is indicative of a PCL tear. To test for this sign, the patient is positioned supine with 45° of hip flexion and 90° of knee flexion. In this position, the medial tibial plateau should sit approximately 1 cm anterior to the medial femoral condyle in a knee with an intact PCL. In the presence of a torn PCL, the tibial plateau will sag posteriorly resulting in a loss of this visible step-off and a positive posterior sag sign [7]. The posterior sag sign has been reported to have a sensitivity of 79 % and specificity of 100 % [19].

Table 2.3

Physical examination of the posterior cruciate ligament