MusculoSkeletal Exam

Figure 12.59 The medial and lateral rotators of the knee.

Position of patient: Sitting upright with the knees bent over the edge of the table (Figure 12.60).

Resisted test: Take the tibia with both hands and ask the patient to attempt to rotate it. Have the patient

Neurological Examination

Motor

The innervation and spinal levels of the muscles that function across the knee joint are listed in Table 12.1.

The Knee Chapter 12

Figure 12.61 The patient is positioned for the patellar reflex. The reflex can also be obtained with the patient seated, by tapping on the patellar tendon with the knee flexed.

Reflexes

Knee Jerk

The knee jerk is performed to test the L3 and L4 nerve roots (Figure 12.61). To test the knee jerk, place the patient in the supine position. Elevate the leg behind the knee with one hand so that it is flexed approximately 20–30 degrees. Take the reflex hammer and tap the patellar tendon below the patella to observe the response. Look for contraction of the quadriceps muscle with or without elevation of the foot from the table. Perform the test bilaterally for comparison. Loss of this reflex may be due to a radiculopathy of the L3 or L4 nerve roots, or damage to the femoral nerve or quadriceps muscle.

Hamstring Jerk

The medial and lateral hamstring reflexes are performed to test the L5–S1 (medial hamstring) and S1–S2 (lateral hamstring) root levels (Figure 12.62). The patient is prone with the knee flexed and the leg supported. Place your thumb over the medial or lateral hamstring tendon and tap your thumb with

the reflex hammer. Look for contraction of the hamstring muscle exhibited by knee flexion. Compare both sides.

Sensation

Light touch and pinprick sensation should be examined after the motor examination. The dermatomes for the anterior aspect of the knee are L2 and L3. Please refer to Figure 12.63 for the exact locations of the key sensory areas of these dermatomes. We have included dermatome drawings from more than one anatomy text to emphasize the variability that exists among patients and anatomists. The peripheral nerves providing sensation in the knee region are shown in Figure 12.64.

Infrapatellar Nerve Injury

The infrapatellar branch of the saphenous nerve may be cut during surgery of the knee. Tinel’s sign may be obtained by tapping on the medial aspect of the tibial tubercle (Figure 12.65). A positive response would be tingling or tenderness.

Obturator

nerve

Medial intermediate cutaneous nerve of the thigh

Lateral cutaneous nerve of the thigh

Medial cutaneous nerve of the thigh (femoral)

Posterior cutaneous nerve of the thigh

Saphenous nerve (femoral)

Lateral cutaneous nerve of the calf (peroneal)

Superficial peroneal nerve

Figure 12.64 The nerve distributions to the skin of the anterior and posterior aspects of the thigh and leg.

The Knee Chapter 12

Infrapatellar branch of saphenous nerve

Figure 12.65 The infrapatellar branch of the saphenous nerve can be injured during surgery. This will cause numbness or tingling in the distribution of this nerve medial to the patella. Tapping the region of the nerve with a reflex hammer will cause a tingling sensation, known as Tinel’s sign.

Referred Pain Patterns

Pain in the region of the knee may be referred from the ankle and hip. Pain in the knee that is referred from the hip is usually felt medially. An L3, L4, or L5 radiculopathy can also be perceived as pain in the knee (Figure 12.66).

Special Tests

Flexibility Tests

An estimation of quadriceps flexibility can be performed by asking the patient to take the lower leg with one hand and bend the knee and foot behind him or her so as to bring the heel toward the buttocks (Figure 12.67). The patient may compensate for a tight rectus femoris

Figure 12.66 Pain may be referred to and from the knee.

by rotating the pelvis anteriorly and flexing the hip. Hamstring flexibility is described in the chapter on hip examination.

Tests for Stability and Structural Integrity

Without support from the soft tissues, the tibiofemoral joint is inherently unstable. Figure 12.68 shows the structures that provide stability for the knee.

There is an abundance of testing procedures with associated eponyms that have been developed in an effort to test the stability of the anterior and posterior cruciate ligaments in various planes. Some of the more commonly used tests are described in this section. A clear understanding of the functional anatomy of the cruciate ligaments is necessary in order to appreciate the purpose of the various tests. Many of the tests reveal subtle responses and require a great deal of experience to interpret.

In testing the anterior and posterior cruciate ligaments, you should first examine the patient for anterior and posterior instability of the tibia. This can be accomplished with the anterior drawer and posterior drawer

tests, which are performed with the knee in 90 degrees of flexion. These tests were described earlier on p. 357.

Lachman Test and “Reverse” Lachman Test

These tests are used to elicit excessive anterior or posterior movement of the tibia that results from damage to the anterior or posterior cruciate ligament. The tests are performed with the patient in the supine position and the knee flexed to about 30 degrees. Use one hand to stabilize the thigh while trying to displace the tibia anteriorly for the Lachman test, or posteriorly for the reverse Lachman test. A positive test result implies damage to the anterior or posterior cruciate ligament (Figures 12.69 and 12.70). As with all tests of stability, you must examine the opposite side for comparison.

In testing anteromedial and anterolateral instability, the goal is to reproduce the “giving way” phenomenon that the patient recognizes after injury to the anterior cruciate ligament. The test may be performed beginning with the patient’s knee extended or beginning with the patient’s knee flexed. A sudden jerk, which is the giving way phenomenon, is noted by the patient and the examiner as the knee is moved from

Figure 12.69 The position of the examiner and patient for the Lachman test. It is very important that the patient be relaxed for this test.

the extended to a flexed position, or from the flexed to an extended position.

Pivot Shift Test (MacIntosh)

The patient is placed in the supine position with the hip extended. Take the affected foot in one hand and

medially rotate the tibia on the femur. The other hand is placed behind the patient’s knee so that a valgus stress and flexion maneuver can be performed simultaneously. At about 25–30 degrees of flexion, there is a sudden jerk and you will feel and see the lateral femoral condyle jump anteriorly on the lateral tibial plateau. This is a positive test result and signifies a rupture of the anterior cruciate ligament. As the knee is flexed further, the tibia suddenly reduces (Figure 12.71).

Hughston (Jerk) Test

This test is performed similarly to the pivot shift test. However, the starting position is with the patient’s knee flexed to 90 degrees. Again, take one hand and rotate the tibia medially while using the other hand behind the knee to apply a valgus and extension stress. Here, the lateral femoral condyle starts out in a forward subluxed position relative to the tibia. As the knee is extended, the lateral femoral condyle will jerk posteriorly at about 25–30 degrees of flexion. This is a positive test result and indicates a rupture of the anterior cruciate ligament (Figure 12.72).

Slocum Test

This test can be used to define damage in the anterior cruciate and medial collateral ligaments (Figure 12.73). The patient is in the supine position and the hip is flexed to 80–90 degrees. The knee is flexed to 45 degrees. Place the leg and foot in 15 degrees of lateral rotation and sit on the foot to stabilize it in this position. Take the lower leg with both of your hands and attempt to pull the tibia anteriorly. The test result will be positive when anterior movement occurs primarily on the medial side of the knee. This test can also be performed with the leg and foot in 30 degrees of medial rotation. When excessive movement of the lateral part of the tibia is noted, the test result is positive and indicates anterior cruciate ligament and posterolateral capsular damage.

Additional tests for anteromedial and anterolateral instability include the Losee test, the crossover test, the Noyes test, and the Nakajima test.

Tests for Meniscal Damage

The goal of these tests is to assess the presence of meniscal injury. The tests are performed by applying a stress to the knee that reproduces pain or a click as the torn meniscus is impinged by the tibia and femur.

Chapter 12 The Knee

A

B

C

Figure 12.72 The Hughston jerk test. (A) Note the initial starting position with the knee in 90 degrees of flexion and the leg internally rotated as a valgus stress is applied. (B), (C). Note

that the patient’s knee is extended while maintaining internal rotation of the leg and valgus stress at the knee.

McMurray’s Test

This test can be performed to examine the lateral and medial menisci. The patient is placed in a supine

position with the test knee completely flexed, so that the heel approaches the buttock. Put your hand on the knee so that the thumb and index fingers are along the joint line of the knee. Take the other hand and rotate the tibia internally (medially), while applying a varus stress. A painful click on rotation is significant for damage to the lateral meniscus (Figure 12.74A).

If the tibia is rotated externally (laterally) while applying a valgus stress, the medial meniscus can be examined (Figure 12.74B).

The test can be performed in a position of less than full flexion. With more extension, the further anterior portions of the meniscus can be examined. The result of McMurray’s test can also be positive in the presence of osteochondritis dissecans of the medial femoral condyle.

Bounce Home Test

The purpose of this test is to examine for a blockage to extension that may result from a torn meniscus. The patient is placed in a supine position. Take the heel of the patient’s foot and cup it in your hand and then flex the patient’s knee fully. Allow the patient’s knee to extend passively. If the patient’s leg does not extend fully, or if the end feel is rubbery, there is a blockage to extension and the test result is positive (Figure 12.75).

Apley (Grinding, Distraction) Test

This test is performed to assess whether medial or lateral joint line pain is due to meniscus or collateral ligament damage. The test is performed with the patient in the prone position. The knee is flexed to 90 degrees, and the patient’s thigh is stabilized by the weight of your knee. Grab the patient’s ankle with your hand and rotate the tibia internally and externally while applying a downward force on the foot. Pain during compression with rotation is significant for meniscal damage. Perform the same rotation medially and laterally, but this time pulling upward on the foot and ankle so as to distract the tibia from the femur. If rotation with distraction is painful, the patient is more likely to have a ligamentous injury (Figure 12.76).

Modified Helfet Test

This test is used to confirm that the “screw home” mechanism of the knee is intact. Normally, the tibia laterally rotates when the knee is extended. Figure 12.77(A) shows that the tibial tuberosity is in

Chapter 12 The Knee

line with the midline of the patella when the knee is flexed to 90 degrees. When the knee is extended, as in Figure 12.77(B), the tibial tuberosity should line up with the lateral border of the patella. If this does not happen, there is an injury to the meniscus, cruciate ligament or quadriceps mechanism.

Childress’ Sign (Duck Walk Test)

This test is used to confirm a tear of the posterior horn of the meniscus. The patient squats and walks “like a duck”. If there is a click, pain or snapping sensation, the test is positive.

Patellofemoral Joint Tests

Apprehension (Fairbanks) Test

This test is used to diagnose prior dislocation of the patella. The patient is placed in a supine position with the quadriceps muscles as relaxed as possible. The knee is flexed to approximately 30 degrees while you carefully and gently push the patella laterally. The test result is positive if the patient feels that the patella is going to dislocate and abruptly contracts the quadriceps (Figure 12.78).

Test for Plica

Medial and lateral plicae are synovial thickenings that connect from the femur to the patella. In some individuals, these synovial thickenings are overdeveloped and may be pinched in the patellofemoral joint or may be painful. The plicae can be examined by having the patient lie in the supine position with the thigh relaxed. Test for the medial plica by pushing the patella medially with one hand. Then attempt to pluck the plica like a guitar string on the medial aspect of the patella. Check for lateral patellar plica by pushing the patella laterally with one hand and attempting to pluck the plica on the lateral aspect of the patella.

Patellofemoral Arthritis (Waldron) Test

This test is used to detect the presence of patellofemoral arthritis. The patient is asked to perform several deep knee bends slowly. Place your hand over the patella so that you can palpate the patella as the patient bends and straightens. Tell the patient to inform you if there is pain during the bending or straightening. The presence of crepitus during a complaint of pain is positive for patellofemoral joint disease.