Anterior Drawer Test of the Knee

Anterior Drawer Test of the Knee is used to determine the integrity of the Anterior Cruciate Ligament (ACL), full or partial ACL tear.

See Also:  Anterior Cruciate Ligament Injury

How is Knee Anterior Drawer Test done?

• The patient lies in the supine position with the clinician standing to the side of the patient,s involved knee.
• The clinician grasps the lower leg of the patient just distal to the joint space of the knee and the patient’s knee is flexed to 90 degrees so that the foot is flat and the lower leg is not rotated.
• The clinician fixates the patient’s leg by sitting on the foot. The clinician can place the thumbs either in the joint space or just distal to it to assess mobility.
• The clinician tests the tension in the musculature. It is important that all muscles around the knee be relaxed to allow any translatory movement to occur.
• With both hands, the clinician now abruptly pulls the lower leg forward.

Ensure the tibia’s neutral rotation to avoid action by secondary stabilizers [e.g., medial collateral ligament (MCL)] and that it is not posteriorly subluxated prior to initiation of the physical test (as occurs in a PCL deficient knee).

See Also: Lachman's Test

What does a positive Anterior Drawer Test of the Knee mean?

This test is positive for an ACL tear when an abnormal anterior movement of the tibia occurs compared with the other extremity.

It is graded by severity:

1. Grade 1: 5 mm
2. Grade II: 5-10 mm
3. Grade III: > 10 mm.

Sensitivity & Specificity

There is wide variation in the reported sensitivities of the anterior drawer test. The anterior drawer test in 80 degrees of flexion without rotation has been found to have ¹:

• Sensitivity: 40.9%
• Specificity: 96.8%

Anterior drawer test variations:

There are a number of variations to the anterior drawer test, all of which involve positioning the patient supine ²:

Anterior drawer test and maximal external rotation:

• The initial positions of the patient and clinician are the same as in the anterior drawer test in 80 degrees of flexion without rotation, except that the lower leg is positioned in maximum external rotation.
• The ACL and the medial and posteromedial capsuloligamentous structures are tested in this position.
• If this test is positive, there is likely to be an anteromedial rotatory instability.
• The specific medial and posteromedial structures that are affected can be further differentiated by the abduction (valgus) stress tests previously described.
• No diagnostic accuracy studies have been performed to determine the sensitivity and specificity of this test.

Anterior drawer test and maximal internal rotation:

• The initial positions of the patient and clinician are the same as in the anterior drawer test in 80 degrees of flexion without rotation, except that the lower leg is now maximally internally rotated.
• When in maximal internal rotation, the PCL can completely restrict anterior translation of the tibia. Thus, for this test to demonstrate excessive anterior translation, the PCL, ACL, and lateral or posterolateral capsuloligamentous structures have to be affected.
• No diagnostic accuracy studies have been performed to determine the sensitivity and specificity of this test.

As a rule, the anterior drawer is best assessed in neutral rotation. This allows one to demonstrate the greatest degree of displacement.

Rotation forces the tibia into a position where the twisting of the peripheral ligaments and capsular structures increases tension in the joint, impairing the mobility of the drawer.

Assessment of rotational stability together with assessment of lateral stability in flexion and extension provides information about the complexity of the ligament injury and the stability of the secondary stabilizers.

Jakob Maximum Drawer Test:

• The patient is supine with the knee flexed 50 to 60°.
• The examiner pushes the tibial head into maximum anterior subluxation with his or her forearm while grasping the patient’s contralateral knee with the hand of the same arm.
• With the other hand, the examiner grasps the tibial head and palpates how far anteriorly the medial or lateral joint cavity is displaced.
• The patient’s lower leg is not immobilized in this test so that rotation is not restricted. This allows maximum tibial displacement.

Weatherwax described a modified anterior drawer test in which the lower leg is supported in the examiner’s axilla. It is relatively difficult to establish a specific position of tibial rotation with this technique, but anterior displacement is easily recognized.

Feagin recommends performing 90° drawer tests with the patient in the sitting position. Gravity pulls the tibia downward and helps to relax the muscles. The advantages claimed are that anterior displacement of the tibia can be more easily perceived and confirmed and that the rotational response of the proximal tibia (medial and lateral compartmental translation) also can be evaluated using this technique.

Notes

Factors limiting the anterior drawer test include:

1. The need to overcome the effects of gravity while moving the tibia anteriorly.
2. Guarding by the hamstring group, masking anterior displacement of the tibia on the femur,
3. Effusion within the capsule, providing resistance to movement or the inability to flex the knee to 90 degrees .
4. The geometry of the articular condyles, causing the triangular shape of the menisci to form a block against anterior movement of the tibia, similar to a doorstop’s wedging against the bottom of a door.
5. Flexing the knee to 90 degrees, causing anterior displacement of the tibia, masking the amount of further displacement during the drawer test.
6. Reduced sensitivity to lesions located in the posterolateral bundle.

False-negatives may occur with this test for the same reasons as those in the Lachman test:

1. Significant hemarthrosis,
2. Protective hamstring spasm,
3. Tear of the posterior horn of the medial meniscus and lateral menisci.

The menisci, especially the lateral menisci, can give a false-negative anterior drawer test when they engage in the joint space under the femoral condyles in a “doorstop manner” during the anterior dislocation movement.

A marked displacement is usually indicative of combined injuries of ACL and MCL ± posterolateral corner (PLC) ligament complex.

The anterior drawer test in 90° of flexion is often negative in acute injuries because pain often prevents the patient from achieving this degree of flexion and causes reflexive muscle contraction.

The situation is different in chronic ligament injuries, where the primary symptom is the sensation of instability. In these cases, the test can usually be performed painlessly in 90° of flexion and still provide useful diagnostic information.

Given the low sensitivity of this test, the clinician should not rule out an acute ACL injury solely on the basis of a negative anterior drawer.

An anterior drawer should not automatically be interpreted as an anterior cruciate ligament tear. On the other hand, a negative drawer test does not necessarily confirm that the anterior cruciate is intact. The proximal portion of the tibia is pulled anteriorly or pushed posteriorly. It can be difficult to determine the exact starting position (the neutral position) from which an anteriorly directed force will produce an anterior drawer.

For example, where the examiner exerts an anterior drawer stress in the presence of a posterior cruciate ligament injury in which the tibial head is posteriorly depressed (a spontaneous posterior drawer), it will seem as if an isolated anterior drawer is present. What has actually happened in this case is that the tibia has merely been draw n anteriorly out of its posterior displacement (due to the posterior cruciate tear) and into a neutral position. The anterior cruciate then tenses and limits further anterior displacement of the tibia.

Door Stopper effect of meniscus and its role in diagnosis of ACL tear

With knee flexed to 90° for classic anterior drawer sign, medial meniscus, being attached to tibia, abuts against acutely convex surface of medial femoral condyle and has “door-stopper” effect, hindering anterior translation of tibia. With knee extended however, the relatively flat weight-bearing surface of femur does not obstruct forward motion of meniscus and tibia when anterior stress is applied.

Significance of “end point” in stress testing

There are two discernable end-points in stress testing for disruptions of ligaments about the knee:

1. “Hard” implying a firm, definite stop
2. “Soft or mushy” a less distinct and less sudden stop.

Following are the types of end points and their interpretations:

• Firm end point with haemarthrosis: Implies an acute partial rupture.
• Firm end point without haemarthrosis: implies an old partial rupture or elongation.
• Soft end point with haemarthrosis: Complete rupture.
• Soft end point without haemarthrosis: Old complete rupture, acute complex ligamentous injury.

Reference

1. Katz JW, Fingeroth RJ. The diagnostic accuracy of ruptures of the anterior cruciate ligament comparing the Lachman test, the anterior drawer sign, and the pivot shift test in acute and chronic knee injuries. Am J Sports Med. 1986 Jan-Feb;14(1):88-91. doi: 10.1177/036354658601400115. PMID: 3752353.
2. Winkel D, Matthijs O, Phelps V: Examination of the Knee. Gaithersburg, MD: Aspen, 1997.
3. Amis, AA: The functions of the fibre bundles of the anterior cruciate ligament in anterior drawer, rotational laxity and the pivot shift. Knee Surg Sports Traumatol Arthrosc, 20:613, 2012.
4. More, RC, et al: Hamstrings-an anterior cruciate ligament protagonist. Am J Sports Med, 21:231, 1993.
5. Christel, PS, et al: The contribution of each anterior cruciate ligament bundle to the Lachman test: a cadaver investigation. J Bone Joint Surg, 94B:68, 2012.
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