The examination is performed initially with the patient sitting and then with the patient in lying position. During the active movements, the examiner should observe 1) the excursion of the patella to ensure that it tracks freely and smoothly; 2) the range of motion (ROM) available; 3) whether pain occurs during the movement, and if so, where; and 4) what appears to be limiting the movement. The active movements may be done in the sitting or supine position, and, as always, the most painful movements should be done last (Figure 12-27).

Full knee flexion is 135° (0° being straight knee). As the patient moves the knee through flexion and extension, the examiner should watch the movement of the patella as it “tracks” along the femoral trochlea. The examiner should note whether the movement is smooth from beginning to end or whether there is a lag or abrupt jump of the patella as it attempts to center in the groove.⁵⁶ The patella does not follow a straight path as the knee moves from extension to flexion. Normally, it follows a curved pattern moving medially in early flexion and then laterally (Figure 12-28).⁵⁷ In the presence of pathological patellar tracking and patellar instability, an inverted “J” sign may be noted.^58,59 During the initiation of flexion (e.g., going in to a squat), the laterally located patella moves suddenly medially to enter the trochlea. The key to the J sign is the sudden movement medially instead of the normal smooth movement pattern. As in the observation phase, the examiner should note whether dynamic movement causes lateral tilt, anteroposterior tilt, or rotation of the patella during movement.^48,57

Active knee extension is approximately 0° but may be −15°, especially in women, who are more likely to have hyperextended knees (genu recurvatum). The knee extensor muscles develop the greatest force near 60°, and the knee flexor muscles develop their greatest force at 45° to 10°. To complete the last 15° of knee extension, a 60% increase in force of the quadriceps muscles is required. The examiner should also watch for evidence of quadriceps lag, which means the quadriceps muscles are not strong enough to fully extend the knee. The lag results from loss of mechanical advantage, muscle atrophy, decreasing power of the muscle as it shortens, adhesion formation, effusion, or reflex inhibition (Table 12-3). In non–weight-bearing, active medial rotation of the tibia on the femur should be 20° to 30°, whereas active lateral rotation should be 30° to 40° at 90° flexion in non–weight-bearing (Figure 12-29, A). In weight bearing (closed kinetic chain), the femur rotates on the tibia (Figure 12-29, B).

If, during the history, the patient has complained that repetitive or combined movements or sustained postures have resulted in symptoms, these movements should also be tested.

If, on active movements, the ROM is full, overpressure may gently be applied to test the end feel of the various movements in the tibiofemoral joint. This action would preclude the need to do passive movements to the tibiofemoral joint. However, the examiner must do movements of the patella passively (Figure 12-30).

At the tibiofemoral joint, the end feel of flexion is tissue approximation; the end feel of extension and of medial and lateral rotation of the tibia on the femur is tissue stretch. During passive movement, the examiner is also looking for a capsular pattern of the tibiofemoral joint.⁶⁰ This pattern is more limitation of flexion than of extension. Passive medial rotation of the tibia on the femur should be approximately 30° when the knee is flexed to 90°. Passive lateral rotation of the tibia on the femur at 90° of knee flexion should be 40°.

Although full knee extension is usually preferable for everyday activities (e.g., standing, walking), full flexion (135°) is often not necessary except where people kneel back on their heels. However, approximately 117° of flexion is necessary for activities, such as squatting to tie a shoelace or to pull on a sock. Sitting in a chair requires approximately 90° of flexion, and climbing stairs (average height) requires approximately 80° of flexion.

Lancaster, et al.⁶¹ advocated doing a motion palpation test when assessing the knee for articular damage when the damage is severe. The patient sits on the edge of the examining table with the knees flexed to about 90°. The examiner passively moves the patient’s knee between 100° and 0° flexion three to four times at about 30°/sec. While doing this movement with one hand, the examiner applies about 2.3 kg (5 lbs) compression over the patellofemoral joint while the index finger of the same hand palpates immediately distal to the inferior pole of the patella (Figure 12-31). The examiner is palpating for joint crepitus and location, and severity of any discomfort that would indicate positive signs or possible articular damage.

Passive medial and lateral movement of the patella is also carried out to determine its mobility and to compare it with the unaffected side. Normally, the patella should move up to half its width medially and laterally in extension (Figure 12-32). When the patella is pushed medially or laterally, the examiner should note whether it stays parallel to the femoral condyles or whether it tilts or rotates.⁴⁰ For example, if pushed medially when the medial structures are tight, the lateral border of the patella tilts up. Likewise, tight lateral structures cause the medial border to tilt up. If the lateral structures are tight superiorly, the inferior pole of the patella medially rotates. These are examples of dynamic tilt and rotation problems of the patella. The side-to-side passive motion of the patella should also be tested in 45° of flexion, which is a more functional position and gives a better indication of functional instability of the patella.⁶² The end feel of these movements is tissue stretch. Lateral displacement must be performed with care, especially in patients who have experienced a dislocated patella.

The examiner must also ensure full and normal flexibility of the quadriceps, hamstring, iliotibial band, and abductor and adductor muscles of the thigh, as well as the gastrocnemius muscles (Figure 12-33). Tightness of any of these structures or of the lateral retinaculum can alter gait and postural mechanics, which may lead to pathology. For example, tight hamstrings can contribute to patellofemoral pathology because of increased knee flexion at heel strike and during stance phase.⁴⁸ Limitation of hip rotation in extension can lead to patellofemoral pathology as well.³⁰ If the rectus femoris is tight, full excursion of the patella in the trochlea is not possible, especially if the hip is extended. A tight iliotibial band can lead to lateral tracking of the patella.^48,63 Tests for the hamstring, abductor, adductor, and rectus femoris muscles have been described in Chapter 11. A functional test for the quadriceps (described under the “Special Tests” section in this chapter) is also a passive movement test (heel to buttock) for the femoral nerve. To test the gastrocnemius muscle, the examiner extends the patient’s knee and, while holding it straight, dorsiflexes the patient’s ankle. The examiner should be able to reach at least 90° (plantigrade), although 10° to 15° of dorsiflexion is more common.

For a proper test of the muscles, resisted isometric movements must be performed. In some cases (e.g., patellofemoral pain syndrome [PFPS]), hip strength should also be tested as hip abductors and lateral rotators have been found to be weak in PFPS patients.64 The patient should be tested in the supine position (Figure 12-34).

Ideally, these resisted isometric movements are performed with the joint in its resting position. Segal and Jacob⁶⁵ suggest testing the quadriceps muscle at 0°, 30°, 60°, and 90° while observing any abnormal tibial movement (e.g., ligament instability) or excessive pain from patellar compression (e.g., patellofemoral syndrome). Figure 12-35 shows the quadriceps complex components and their angle of pull. Table 12-4 lists the muscles acting at the knee.

Although these movements are tested with the patient in the supine-lying position, the hamstrings are often tested with the patient prone. If the knee is flexed to 90° and the heel is turned out, the greatest stretch is placed on the lateral hamstring muscle (biceps femoris). If the heel is turned in, the greatest stretch is placed on the medial hamstring (semimembranosus and semitendinosus) muscles.

Ankle movements are tested because the gastrocnemius muscle crosses the posterior knee and both plantar and dorsiflexion movements cause movement of the fibula. Dorsiflexion causes the fibula to move up and increases the stress being applied to the ligaments supporting the superior tibiofibular joint. Plantar flexion decreases the stress on these ligaments and also brings the gastrocnemius into play, supporting the posterior knee and assisting knee flexion.

If the history has indicated concentric, eccentric, or econcentric movements have caused symptoms, these types of contractions should be tested as well, but only after isometric testing has been performed.

Kannus and colleagues⁶⁶ developed a scoring scale for measuring isokinetic and isometric strength (Figure 12-36). The scale can be used to show improvement in strength over time. When using isokinetic values, different test parameters may be used. It is important to realize, however, that most knee isokinetic tests are not done with the knee in a functional position.

Depending on the speed, the hamstring/quadriceps ratio is normally between 50% and 60%.⁶⁷ As the speed of isokinetic testing increases, however, the ratio approaches 1 : 1, or 100%.^68,69

Instabilities produced on the examining table are easily produced functionally, especially in athletes who participate in activities, such as vigorous cutting and jumping or rapid deceleration, which produce high physiological joint loads. Functional tests and numerous numerical knee rating systems have been developed for the knee, many of them for specific populations (e.g., athletes) or to assess outcomes after surgery or for specific conditions. The examiner must pick the appropriate test or scale, realizing that each has advantages and disadvantages.70–73

If the active, passive, and resisted isometric movements are performed with little difficulty, the examiner may put the patient through a series of functional tests to see whether these sequential activities produce pain or other symptoms. These tests may be scored by the time taken to do the test or by the distance or height attained when doing the test. If the results are so measured, three measurements should be taken and averaged. In some cases, the results of different tests may be combined. Fonseca and coworkers⁷⁴ found that the time ratio of figure-eight running to straight running was one of the most effective ways of differentiating patients with anterior cruciate ligament deficiencies from normal patients (Figure 12-37). Some of these tests may involve walking (e.g., Timed “Up and Go” test [TUG test], sit-to-stand test). These walking tests may be used when any lower limb joint is affected but are primarily designed for elderly people.⁷⁵ Boonstra et al.⁷⁵ felt the TUG test could be used as a global functional test following total knee arthroplasty while the sit-to-stand was a more biomechanical function test.

These functional activities, which are provided as examples, must be geared to the individual patient, and in some cases, to specific pathology.⁷⁶ Paxton et al.⁷⁷ recommended doing knee-specific, activity-specific, and general health questionnaires to provide a more accurate assessment of outcomes. Squatting reveals limitations of flexion and may cause impingement with meniscal lesions. Duck waddle, if attempted, can demonstrate increased symptoms in meniscal and ligamentous lesions. Older patients should not be expected to accomplish the last five or six (see earlier) movements unless they have been doing these or similar activities in the recent past. Daniel and coworkers⁷⁸ outlined different functional and intensity levels that are useful especially for getting an indication of functional activities from a patient’s perspective (Table 12-5). Functional strength tests for sedentary individuals are shown in Table 12-6.

Strobel and Stedtfeld⁷⁹ put forward the one-leg hop test. The patient stands and does a “long jump” hop on one leg while landing on the same leg. This is a single-leg hop for distance (Figure 12-38, A).^80–83 Noyes and associates⁸⁰ considered symmetry of less than 85% between the legs to be abnormal. The test is repeated three times alternately with each leg. If instability is evident, the distance for the affected leg is less than that for the normal leg. Any functional deficit between the two limbs has been called the limb symmetry index (LSI).⁸⁴ Juris et al.⁸⁵ advocated doing a maximal controlled leap in addition to the one-leg hop test. For this test, which is said to test force absorption, the patient stands on one foot and “leaps forward” to land on the opposite foot. Patients should be instructed to maintain the flexed hip/knee position during takeoff and extend the leg for landing. Patients must “stick” on landing with no movement of the landing foot and must be upright with hands on hips within 1 second. The distance is measured and the test repeated with the opposite start leg.

Since the advent of the single-leg hop, modifications have been developed.⁸⁶ Each test is usually repeated three times, and the average of the three scores is used as the measured value. These modifications include the following:

These functional tests are for active persons and can be quite demanding; however, they have been shown to have high test-retest reliability.⁸⁴ Losee⁸⁹ mentioned several additional tests. For example, in the deceleration test, the patient is asked to run at full speed and to stop suddenly on command.²⁸ The test is positive for rotary instability if the patient stops without using the quadriceps or decelerates in a crouched position (more than 30° flexion of the knee). The effect of the test can be accentuated by having the patient turn away from the affected leg just as he or she is about to stop.⁹⁰ As the patient does the test, the examiner should watch to ensure that the patient uses the affected leg to help stop. With instability problems, the patient uses only the good leg to stop, “hopping through” with the injured leg.

For the “disco test,” the patient stands on one leg with the knee flexed 10° to 20°. The patient is asked to rotate or twist left and right while holding the flexed position (Figure 12-40).²⁸ Apprehension during the test or refusal to do the test is a positive sign for rotary instability. If pain is felt on the joint line, it may indicate meniscus pathology, in which case it is called Merke’s sign.⁷⁹ Pain on medial rotation along the joint line implies medial meniscus pathology, and pain on lateral rotation implies lateral meniscus pathology.

Larson⁹¹ advocated the leaning hop test. For this test, the patient hops up and down on one leg while abducting the opposite leg. A positive test is apprehension during the test or refusal to do the test and is a positive sign for rotary instability.

Numerical rating systems are commonly done to determine the state of the knee. Most of these measures combine clinical (e.g., ROM) and functional (e.g., stair climbing) measures. Many of these scoring systems have not been tested on normal subjects and show possible interviewer bias, nor are the values given to each measure explained. In addition, there may be male and female differences.^92,93

Noyes and colleagues^94–97 developed the Cincinnati Knee Rating System (Figure 12-41), which deals with pain, swelling, stability, and activity level and is a good functional rating system for active persons. Irrgang and associates⁹⁸ use two scales, an Activities of Daily Living Scale⁹⁹ and a Sports Activity Scale (Figures 12-42 and 12-43), to detect clinically significant changes over time. The Knee Society¹⁰⁰ also has a rating scale (Figure 12-44). The Knee Society advocates keeping knee rating and functional assessment separate. This knee-rating scale deals first with pain, ROM, and stability, giving positive points up to 100 and grouping deductions that can take away from the overall value. Function is dealt with separately on the scale.

Lysholm and Gillquist¹⁰¹ developed a frequently used scale primarily designed to score clinical instability that may also be used for chondral lesions of the knee (Table 12-7).^102–106 The International Knee Documentation Committee has also developed a number of assessment forms, three of which are included here (Figures 12-45 to 12-47).^97,107–112 The Tegner Activity Scale^102,106,113 (Figure 12-48) is useful in determining the patient’s current level of activity relative to his or her previous level and can also be used as a guide for rehabilitation and the level of activity the patient hopes to achieve. Table 12-8 and the Kajula Score Questionnaire (Figure 12-49) show examples of a patellofemoral joint evaluation scale that can be used to assess functional levels in patients with patellofemoral syndrome after surgery or nonsurgery.^114,115 Similar scales used to measure patellofemoral dysfunction also exist.^116–119 Other scales, such as the Western Ontario and McMaster University Osteoarthritis Index (WOMAC), Knee Injury and Osteoarthritis Outcome Score (KOOS),^103,112,120 and Lequesne Index, have been developed to determine the outcome of arthroplasties in osteoarthritis (see Chapter 11).^121–131 Each of these knee-rating scales is slightly different. The scale that works best for the examiner and the examiner’s clientele should be used. Other knee-rating scales are also available.^{101,132–137}

Because the knee, more than any other joint in the body, depends on its ligaments to maintain its integrity, it is imperative that the ligaments be tested. The ligaments of the knee joint act as primary stabilizers and guide the movement of the bones in proper relation to one another. Depending on the motion being tested, the ligaments act as primary or secondary restraints (Table 12-9). For example, the anterior cruciate ligament is the primary restraint to anterior tibial displacement and a secondary restraint to varus-valgus motion in full extension and rotation.^98,138 If the primary restraint is injured, pathological motion occurs. If the secondary restraint is injured but the primary restraint is not, pathological motion in that direction does not occur. If both primary and secondary restraints are injured, the pathological motion is greater.⁹⁸ There are several ligaments around the knee, but four deserve special mention (Figure 12-50).

Collateral and Cruciate Ligaments

Collateral Ligaments.

The medial (tibial) collateral ligament lies more posteriorly than anteriorly on the medial aspect of the tibiofemoral joint. It is made up of two layers, one superficial and one deep. The deep layer is a thickening of the joint capsule that blends with the medial meniscus; it is sometimes called the medial capsular ligament. The superficial layer is a strong, broad triangular strap. It starts distal to the adductor tubercle and extends to the medial surface of the tibia, approximately 6 cm (2.4 inches) below the joint line. It blends with the posterior capsule and is separated from the capsule and the medial meniscus by a bursa.

The entire medial collateral ligament is tight throughout the full ROM, although there is varying stress placed on different parts of the ligament as it moves through the full range because of the shape of the femoral condyles. All of its fibers are taut on full extension. In flexion, the anterior fibers are the most taut; in mid range, the posterior fibers are the most taut.139

The lateral (fibular) collateral ligament is round and lies under the tendon of the biceps femoris muscle. It runs from the lateral epicondyle of the femur to the fibular head. It also lies more posteriorly than anteriorly. This ligament is tight in extension and loosens in flexion, especially after 30° flexion. As the knee flexes, it provides protection to the lateral aspect of the knee. It is not attached to the lateral meniscus but rather is separated from it by a small fat pad.¹³⁹

Cruciate Ligaments.

The cruciate ligaments cross each other and are the primary rotary stabilizers of the knee.140 These strong ligaments are named in relation to their attachment to the tibia and are intracapsular but extrasynovial. Each ligament has an anteromedial and a posterolateral portion. The anterior cruciate ligament has, in addition, an intermediate portion.

The anterior cruciate ligament extends superiorly, posteriorly, and laterally, twisting on itself as it extends from the tibia to the femur. Its main functions are to prevent anterior movement of the tibia on the femur, to check lateral rotation of the tibia in flexion, and, to a lesser extent, to check extension and hyperextension at the knee. It also helps to control the normal rolling and gliding movement of the knee. The anteromedial bundle is tight in both flexion and extension, limits anterior translation and helps stabilize medial and lateral rotation,^141,142 whereas the posterolateral bundle is tight in low flexion angles (closer to extension) and medial rotation. It limits anterior translation, hyperextension, and rotation.¹⁴¹ As a whole, the ligament has the least amount of stress on it between 30° and 60° flexion.^{139,140,143,144}

The posterior cruciate ligament extends superiorly, anteriorly, and medially from the tibia to the femur. This strong, fan-shaped ligament, the stoutest ligament in the knee, is a primary stabilizer of the knee against posterior movement of the tibia on the femur, and it checks extension and hyperextension. In addition, the ligament helps to maintain rotary stability and functions as the knee’s central axis of rotation. Along with the anterior cruciate ligament, it acts as a rotary guide to the “screwing home” mechanism of the knee.^139,144 For the posterior cruciate ligament, the bulk of the fibers are tight at 30° flexion, but the posterolateral fibers are loose in early flexion.

With lateral rotation of the tibia, both collateral ligaments become more taut, and the cruciate ligaments become relaxed (Figure 12-51). With medial rotation of the tibia, the reverse action occurs: the collateral ligaments become more relaxed, and the cruciate ligaments become tighter.^139,145

LaPrade et al.¹⁴⁶ have stressed the importance of the popliteus in controlling rotation of the tibia on the femur by contributing to lateral rotation stability. They felt the muscle, in fact, acts like a dynamic ligament to help stabilize the knee (see Figure 12-50). Morgan et al.¹⁴⁷ reported that the oblique popliteal ligament, which is an expansion of the semimembranosus tendon (see Figure 12-50), was the primary structure preventing hyperextension of the knee.

Testing of Ligaments

When testing the ligaments of the knee, the examiner must watch for four one-plane instabilities and four rotational instabilities (Table 12-10 and Figure 12-52).

TABLE 12-10

Tests for Ligamentous Instability around the Knee

Instability	Tests Used to Determine Instability	Structures Injured to Some Degree If Test Positive*	Notes
One-plane medial (straight medial)	1. Abduction (valgus) stress with knee in full extension	1. Medial collateral ligament (superficial and deep fibers) 2. Posterior oblique ligament 3. Posteromedial capsule 4. Anterior cruciate ligament 5. Posterior cruciate ligament 6. Medial quadriceps expansion 7. Semimembranosus muscle	1. If either cruciate ligament is torn (third-degree sprain) or stretched, rotary instability will also be evident 2. Order of injury is usually medial collateral ligament, then posteromedial corner, posterior capsule, anterior cruciate ligament, and finally posterior cruciate ligament
	2. Abduction (valgus) stress with knee slightly flexed (20° to 30°)	1. Medial collateral ligament (superficial and deep fibers) 2. Posterior oblique ligament 3. Posterior cruciate ligament	1. Depending on degree of pain, opening and end feel, primarily signifies medial collateral ligament sprain (first, second, or third degree) 2. If posterior cruciate ligament is torn (third-degree sprain), rotary instability will also be evident 3. Opening of 12° to 15° signifies injury to posterior cruciate ligament 4. If tibia is laterally rotated, stress is taken off posterior cruciate ligament 5. If tibia is medially rotated, stress is increased on cruciate ligaments while medial collateral ligament relaxes
One-plane lateral (straight lateral)	1. Adduction (varus) stress with knee in full extension	1. Lateral collateral ligament 2. Posterolateral capsule 3. Arcuate-popliteus complex 4. Biceps femoris tendon 5. Anterior cruciate ligament 6. Posterior cruciate ligament 7. Lateral gastrocnemius muscle	1. If either cruciate ligament is torn (third-degree sprain) or stretched, rotary instability will also be evident 2. Order of injury is lateral collateral ligament, arcuate-popliteus complex, anterior cruciate ligament, posterior cruciate ligament 3. With severe injury (third degree), common peroneal nerve and circulation may be affected
	2. Adduction (varus) stress with knee slightly flexed (20° to 30°) and tibia laterally rotated	1. Lateral collateral ligament 2. Posterolateral capsule 3. Arcuate-popliteus complex 4. Iliotibial band 5. Biceps femoris tendon	1. Depending on degree of pain, opening and end feel, primarily signifies lateral collateral ligament sprain (first, second, or third degree) 2. If tibia is not laterally rotated, maximum stress will not be placed on lateral collateral ligament 3. Lateral rotation of tibia results in relaxation of both cruciate ligaments 4. With flexion, the iliotibial band lies over the center of the lateral joint line 5. If tibia is medially rotated, stress is increased on both cruciate ligaments while lateral collateral ligament relaxes 6. Order of injury is lateral collateral ligament, arcuate-popliteus complex, and iliotibial band and/or biceps femoris
One-plane anterior	1. Lachman test (20° to 30° knee flexion) or its modifications	1. Anterior cruciate ligament 2. Posterior oblique ligament 3. Arcuate-popliteus complex	1. Medial collateral ligament and iliotibial band lax in this position 2. Tests primarily posterolateral bundle of anterior cruciate ligament 3. Primarily tests anterior cruciate ligament but with severe injury (third-degree), structures in posteromedial and posterolateral corners may also be injured
	2. Anterior drawer sign (90° knee flexion) 3. Active drawer test (90° knee flexion)	1. Anterior cruciate ligament 2. Posterolateral capsule 3. Posteromedial capsule 4. Medial collateral ligament 5. Iliotibial band 6. Posterior oblique ligament 7. Arcuate-popliteus complex	1. Tests primarily anteromedial bundle of anterior cruciate ligament 2. If anterior cruciate ligament and medial or lateral structures are torn (third-degree sprain) or stretched, rotary instability will also be evident 3. Be sure posterior cruciate has not been injured, giving possible false-positive test
One-plane posterior	1. Posterior drawer sign (90° knee flexion) 2. Posterior sag sign 3. Active drawer test 4. Godfrey test 5. Reverse Lachman test (20° to 30° knee flexion)	1. Posterior cruciate ligament 2. Arcuate-popliteus complex 3. Posterior oblique ligament 4. Anterior cruciate ligament	1. If posterior cruciate ligament and medial or lateral structures are torn (third-degree sprain) or stretched, rotary instability will also be evident 2. With severe injury (third-degree), collateral ligaments may also be injured
Anteromedial rotary	1. Slocum test (foot laterally rotated 15°) 2. Lemaire’s anteromedial jolt test 3. Dejour test	1. Medial collateral ligament (superficial and deep fibers) 2. Posterior oblique ligament 3. Posteromedial capsule 4. Anterior cruciate ligament	1. Test must not be done in extreme lateral rotation of tibia because passive stabilizing will result from “coiling” to maximum rotation
Anterolateral rotary	1. Slocum test (foot medially rotated 30°) 2. Losee test 3. Jerk test of Hughston 4. Active pivot shift 5. Nakajima test	1. Anterior cruciate ligament 2. Posterolateral capsule 3. Arcuate-popliteus complex 4. Lateral collateral ligament 5. Iliotibial band	1. Tests go from flexion to extension 2. Tests bring about anterior subluxation of the tibia on femur, causing patient to experience “giving way” sensation 3. Slocum test must not be done in extreme medial rotation of tibia because passive stabilization will result from “coiling” to maximum rotation 4. Shift may be “slip” (second degree) or “jerk” (third degree), depending on degree of sprain or injury
	1. Lateral pivot shift test of Macintosh 2. Slocum ALRI test 3. Crossover test 4. Flexion-rotation drawer test 5. Flexion-extension valgus test 6. Martens test	1. Anterior cruciate ligament 2. Posterolateral capsule 3. Arcuate-popliteus complex 4. Iliotibial band	1. Tests go from extension to flexion 2. Tests cause reduction of anterior subluxed tibia on femur 3. Shift may be “slip” (second degree) or “jerk” (third degree), depending on degree of sprain or injury
Posteromedial rotary	1. Hughston’s posteromedial drawer sign 2. Posteromedial pivot shift test	1. Posterior cruciate ligament 2. Posterior oblique ligament 3. Medial collateral ligament (superficial and deep fibers) 4. Semimembranosus muscle 5. Posteromedial capsule 6. Anterior cruciate ligament	1. Watch for changing position of tibial tubercle relative to femoral condyles
Posterolateral rotary	1. Hughston’s posterolateral drawer sign 2. Jakob test (reverse pivot shift maneuver) 3. External rotational recurvatum test 4. Dynamic posterior shift test 5. Loomer’s test 6. Active posterolateral drawer sign	1. Posterior cruciate ligament 2. Arcuate-popliteus ligament 3. Lateral collateral ligament 4. Biceps femoris tendon 5. Posterolateral capsule 6. Anterior cruciate ligament	1. Watch for changing position of tibial tubercle relative to femoral condyles

ALRI, Anterolateral rotary instability.

*The amount of displacement gives an indication of how badly and how much of the structures are injured (i.e., first-, second-, or third-degree sprain).

There are a number of tests for each type of instability. The examiner should use the one or two tests that he or she believes gives the best results. It is not essential to do all of the tests discussed. The techniques chosen must be practiced diligently so that the examiner becomes proficient at doing them; only with practice will the examiner be able to determine which structures are injured. It is also important to understand that the direction of instability does not imply that only structures in that direction are injured. For example, with anterolateral rotary instability (ALRI), it is not necessarily structures on the anterolateral side of the knee that are injured. In fact, posterior structures are often commonly injured as well. With ALRI, the posterolateral capsule and the arcuate-popliteus complex may also be injured.²⁸

Instabilities About the Knee

• One-plane medial instability

• One-plane lateral instability

• One-plane anterior instability

• One-plane posterior instability

• Anteromedial rotary instability

• Anterolateral rotary instability

• Posteromedial rotary instability

• Posterolateral rotary instability

When testing for ligament stability of the knee, the examiner should keep the following points in mind:

1. The normal knee is tested first to establish a baseline and to show the patient what to expect. This action helps to gain the patient’s confidence by showing what the test involves.

2. When one is comparing the normal and injured limbs, the test must be the same for both limbs. The examiner must use the same initial starting position and the same amount of force, apply the same force at the same point or throughout the range, and note the position at which the displacement occurs.148

3. The muscles must be relaxed if the tests are to be valid. Maximum laxity would be demonstrated with the patient under anesthesia.

4. The appropriate stress should be applied gently.

5. The stress is repeated several times and increased to the point of pain to demonstrate maximum laxity without causing muscle spasm.

6. It is not only the degree of opening but also the quality of the opening (i.e., the end feel) that is of concern. Left-right differences of 3 mm or more are classified as pathological.148

7. If the ligament is intact, there should be an abrupt stop or end feel when the ligament is stressed. A soft or indistinct end feel usually signifies ligamentous injury.149

8. Ligaments of the knee tend to act in concert to maintain stability, and individual ligaments are difficult to isolate in terms of their function. Therefore more than one test may be found to be positive when assessing for the different instabilities. For example, a patient may exhibit a one-plane medial and one-plane anterior instability as well as an anteromedial rotary instability and/or ALRI, depending on the severity of the injury to the various ligamentous structures.

9. Tests for ligament instability are more accurate for assessment of a chronic injury than for assessment of an acute injury in the unanesthetized knee because of the presence of muscle spasm and swelling in the acutely injured knee.

10. For the tests involving rotary instability in which the tibia is moved in relation to the femur, if the movement is into extension, subluxation of the tibia relative to the femur occurs in a positive test. If the movement is into flexion, reduction of the tibia relative to the femur occurs in a positive test.

11. Positive rotational tests should not be repeated too frequently because they may lead to articular cartilage damage, further meniscal tearing, or further damage to injured ligaments.

12. Because the ligamentous tests are subjective tests, the more experience the examiner has in doing them, the more accurate will be the interpretation of the test. The examiner should select only one or two from each group of tests and learn to do them well rather than learn all of the tests and risk doing them poorly.

Key Ligamentous Tests Performed on the Knee*^†150

• For one-plane medial instability:

Hughston’s valgus stress at 0° and 30°

Valgus stress at 0° and 30°

• For one-plane lateral instability:

Hughston’s varus stress at 0° and 30°

Varus stress at 0° and 30°

• For one-plane anterior instability:

Active drawer test

Drawer test

Lachman test or its modifications

• For one-plane posterior instability:

Active drawer test

Drawer test

Godfrey test

Posterior sag

• For anteromedial rotary instability:

Slocum test

• For anterolateral rotary instability (ALRI):

Crossover test

Jerk test of Hughston

Losee test

Noyes flexion-rotation drawer test

Pivot shift test

Slocum ARLI test

• For posteromedial rotary instability:

Hughston’s posteromedial drawer test

Posteromedial pivot shift test

• For posterolateral rotary instability:

External rotation recurvatum

Hughston’s posterolateral drawer test

Jakob test

Loomer’s posterolateral rotary instability test

Tibial external rotation (dial) test

Tests for One-Plane Medial Instability

The abduction (valgus stress) test is an assessment for one-plane (straight) medial instability, which means that the tibia moves away from the femur (i.e., gaps) on the medial side (Figure 12-53). The examiner applies a valgus stress (pushes the knee medially) at the knee while the ankle is stabilized in slight lateral rotation either with the hand or with the leg held between the examiner’s arm and trunk. The knee is first in full extension, and then it is slightly flexed (20° to 30°) so that it is “unlocked.”⁸⁶

It has been advocated that resting the test thigh on the examining table enables the patient to relax more and is easier for the examiner. The knee rests on the edge of the table; the lower leg is controlled by the examiner’s stabilizing the thigh on the table, and the lower leg is abducted, applying a valgus stress to the knee (Figure 12-54).³⁰ Similarly, a varus stress may be applied to stress the lateral structures.

Hughston³⁰ advocates a third way to do this test (Hughston’s valgus stress test ). The patient is positioned as described earlier, and the examiner faces the patient’s foot, placing his or her body against the patient’s thigh to help stabilize the upper leg in combination with one hand, which can also palpate the joint line. With the other hand, the examiner grasps the patient’s big toe and applies a valgus stress, allowing any natural rotation of the tibia (Figure 12-55). Similarly, a varus stress may be applied to test the lateral structures, but in this case, the examiner grasps the lateral aspect of the foot near the fifth and fourth toes. A varus stress is then applied to the knee. Doing the test in this fashion often allows the patient to relax more and is less likely to lead to muscle spasm limiting movement.

If the test is positive (i.e., the tibia moves away from the femur an excessive amount when a valgus stress is applied) when the knee is in extension, the following structures may have been injured to some degree:

1. Medial collateral ligament (superficial and deep fibers)

2. Posterior oblique ligament

3. Posteromedial capsule

4. Anterior cruciate ligament

5. Posterior cruciate ligament

6. Medial quadriceps expansion

7. Semimembranosus muscle

A positive finding on full extension is classified as a major disruption of the knee. The examiner usually finds that one or more of the rotary tests are also positive. If the examiner applies lateral rotation to the foot when performing the test in extension and finds excessive lateral rotation on the affected side, it is a sign of possible anteromedial rotary instability.

If the test is positive when the knee is flexed to 20° to 30°, the following structures may have been injured to some degree:

1. Medial collateral ligament

2. Posterior oblique ligament

3. Posterior cruciate ligament

4. Posteromedial capsule

This flexed part of the valgus stress test would be classified as the true test for one-plane medial instability.

Lonergan and Taylor¹⁵¹ advocated doing the Swain test for the knee. For this test, the patient is seated with the knees flexed to 90° over the edge of the examining table. The examiner then passively laterally rotates the tibia on the femur of the good leg followed by the injured leg. A positive test is indicated by pain along the medial side of the joint indicating injury to the medial collateral ligament complex, because with the knee flexed to 90° the cruciates are lax, whereas the collateral ligaments are tight. Post surgery, pain on the medial joint line may indicate inadequate healing; or, in the chronic medial side laxity, joint line pain may be medial or posteromedial (Figure 12-56).¹⁵²

If a stress radiograph is taken when the test is performed in full extension, a 5-mm opening indicates a grade 1 injury; up to 10 mm, a grade 2 injury; and more than 10 mm, a grade 3 injury.^139,153 Both limbs should be viewed for differences.¹⁵⁴

Tests for One-Plane Lateral Instability

The adduction (varus stress) test is an assessment for one-plane lateral instability (i.e., the tibia moves away from the femur an excessive amount on the lateral aspect of the leg). The examiner applies a varus stress (pushes the knee laterally) at the knee while the ankle is stabilized (Figure 12-57). The test is first done with the knee in full extension and then with the knee in 20° to 30° of flexion. If the tibia is laterally rotated in full extension before the test, the cruciate ligaments are uncoiled, and maximum stress is placed on the collateral ligaments.

As previously mentioned (see the “Tests for One-Plane Medial Instability” section), Hughston’s varus stress test may be used. In this case, the examiner grasps the fifth and fourth toes and applies a varus stress to the knee in extension and slightly (20° to 30°) flexed.

If the test is positive (i.e., the tibia moves away from the femur when a varus stress is applied) in extension, the following structures may have been injured to some degree:

1. Fibular or lateral collateral ligament

2. Posterolateral capsule

3. Arcuate-popliteus complex

4. Biceps femoris tendon

5. Posterior cruciate ligament

6. Anterior cruciate ligament

7. Lateral gastrocnemius muscle

8. Iliotibial band

The examiner usually finds that one or more rotary instability tests are also positive. A positive test indicates major instability of the knee.

If the test is positive when the knee is flexed 20° to 30° with lateral rotation of the tibia, the following structures may have been injured to some degree:

1. Lateral collateral ligament

2. Posterolateral capsule

3. Arcuate-popliteus complex

4. Iliotibial band

5. Biceps femoris tendon

This flexed part of the varus stress test is classified as the true test for one-plane lateral instability.

If a stress radiograph is taken when the test is performed in full extension, a 5-mm opening indicates a grade 1 injury; up to 8 mm, a grade 2 injury; and more than 8 mm, a grade 3 injury to the lateral ligaments of the knee.^139,153

Both varus and valgus stress testing (varus-valgus test ) can be performed at the same time while the examiner palpates the joint line. The examiner holds the ankle between the examiner’s waist and forearm while the patient lies supine with the knee extended and then flexed. At the same time, the examiner palpates the medial and lateral joint lines with the fingers. Varus and valgus stresses are applied with the heels of the examiner’s hands (Figure 12-58).⁷⁹

Tests for One-Plane Anterior Instability

Some clinicians28,30 believe that the posterior cruciate ligament should be tested (see the “Tests for One-Plane Posterior Instability” section) or observed for a posterior sag before the anterior cruciate ligament is tested to rule out false-positive tests for anterior translation. In either case, the examiner should be aware that a torn posterior cruciate can lead to a false-positive anterior translation test if the patient is tested in supine position with the knee flexed, because gravity causes the tibia to sag posteriorly.

 Active Drawer Test.

For the anterior drawer test (also called the quadriceps active test), the patient is positioned as for the normal drawer test. The examiner holds the patient’s foot down. The patient is asked to try to straighten the leg, and the examiner prevents the patient from doing so (isometric test). Muller139 advocated allowing the foot to be free and noting when the foot is lifted off the table, which occurs only after the tibia has shifted forward and stabilized. If the anterior cruciate ligament or posterior cruciate ligament is torn, the anterior contour of the knee changes as the tibia is drawn forward. If the posterior cruciate ligament is torn, a posterior sag is evident before the patient contracts the quadriceps. Contraction of the quadriceps causes the tibia to shift forward to its normal position, indicating a positive test for a torn posterior cruciate ligament.^155,156 If there is no posterior sag present and if the tibia shifts forward more on the injured side than the noninjured side, it is a positive test for anterior cruciate ligament disruption (Figure 12-59).¹⁵⁵ A second part of the test may be instituted by having the patient contract the hamstrings isometrically so that the tibial plateau moves posteriorly. This part of the test accentuates the posterior sag for posterior cruciate insufficiency, if present, and ensures maximum movement for anterior cruciate insufficiency if a quadriceps contraction is tried a second time.⁷⁹ The active drawer test is a better expression of posterior cruciate insufficiency than of anterior cruciate insufficiency.¹⁵⁷

With the drawer sign or test, if the anterior or posterior cruciate ligament is torn (third-degree sprain), some rotary instability is evident when the appropriate ligamentous tests are performed.

 Drawer Sign.

The drawer sign is a test for one-plane anterior and one-plane posterior instabilities.158 The difficulty with this test is in determining the neutral starting position if the ligaments have been injured. The patient’s knee is flexed to 90°, and the hip is flexed to 45°. In this position, the anterior cruciate ligament is almost parallel with the tibial plateau. The patient’s foot is held on the table by the examiner’s body with the examiner sitting on the patient’s forefoot and the foot in neutral rotation. The examiner’s hands are placed around the tibia to ensure that the hamstring muscles are relaxed (Figures 12-60 and 12-61). The tibia is then drawn forward on the femur (anterior drawer test). The normal amount of movement that should be present is approximately 6 mm. This part of the test assesses one-plane anterior instability. If the test is positive (i.e., the tibia moves forward more than 6 mm on the femur), the following structures may have been injured to some degree:

1. Anterior cruciate ligament (especially the anteromedial bundle)

2. Posterolateral capsule

3. Posteromedial capsule

4. Medial collateral ligament (deep fibers)

5. Iliotibial band

6. Posterior oblique ligament

7. Arcuate-popliteus complex

If only the anterior cruciate ligament is torn, the test is negative, because other structures (posterior capsule and posterolateral and posteromedial structures) limit movement. In addition, hemarthrosis, a torn medial meniscus (posterior horn) wedged against the medial femoral condyle, or hamstring spasm may result in a false-negative test. Hughston³⁰ points out that tearing of the coronary or meniscotibial ligament can allow the tibia to translate forward more than normal, even in the presence of an intact anterior cruciate ligament. In this case, when the anterior drawer test is performed, anteromedial rotation (subluxation) of the tibia occurs.

When performing this test, the examiner must ensure that the posterior cruciate ligament is not torn or injured. If it has been torn, it allows the tibia to drop or slide back on the femur, and when the examiner pulls the tibia forward, a large amount of movement occurs, giving a false-positive sign (see the “Posterior Sag Sign” section). Therefore the test should be considered positive only if it is shown that the posterior sag is not present.

Weatherwax¹⁵⁹ described a modified way of testing the anterior drawer (90–90 anterior drawer). The patient lies supine. The examiner flexes the patient’s hip and knee to 90° and supports the lower leg between the examiner’s trunk and forearm. The examiner places the hands around the tibia, as with the standard test, and applies sufficient force to slowly lift the patient’s buttock off the table (Figure 12-62).

If, when doing the anterior drawer test, there is an audible snap or palpable jerk (Finochietto jumping sign) when the tibia is pulled forward and the tibia moves forward excessively, a meniscus lesion is probably accompanying the torn anterior cruciate ligament.⁷⁹

After the anterior movement of the tibia on the femur, the posterior movement of the tibia on the femur should be completed (posterior drawer test). In this part of the test, the tibia is pushed back on the femur. This phase is a test for one-plane posterior instability. If the test is positive or a posterior sag is evident, the following structures may have been injured to some degree:

1. Posterior cruciate ligament

2. Arcuate-popliteus complex

3. Posterior oblique ligament

4. Anterior cruciate ligament

If the arcuate-popliteus complex remains intact, a positive posterior drawer sign may not be elicited.¹⁶⁰ If, when the tibia is pushed backward, the examiner forcefully rotates the tibia laterally and excessive movement occurs, the test is positive for posterolateral instability. Warren¹⁶¹ calls this maneuver the arcuate spin test.

Feagin¹⁶² advocated doing the drawer test with the patient sitting with the leg hanging relaxed over the end of the examining table (sitting anterior drawer test). The examiner places the hands as with the standardized test and slowly draws the tibia first forward and then backward to test the anterior and posterior drawer (Figure 12-63). The examiner uses the thumbs to palpate the tibial plateau movement relative to the femur. The examiner may also note any rotational deformity. The advantage of doing the test this way is that the posterior sag is eliminated because the effect of gravity is eliminated.

 Lachman Test.

The Lachman test, which may also be referred to as the Ritchie, Trillat, or Lachman-Trillat test, is the best indicator of injury to the anterior cruciate ligament, especially the posterolateral band,163–168 although this has been questioned.¹⁶⁹ It is a test for one-plane anterior instability.^86,170 The patient lies supine with the involved leg beside the examiner. The examiner holds the patient’s knee between full extension and 30° of flexion. This position is close to the functional position of the knee, in which the anterior cruciate ligament plays a major role. The patient’s femur is stabilized with one of the examiner’s hands (the “outside” hand) while the proximal aspect of the tibia is moved forward with the other (“inside”) hand (Figure 12-64). Frank¹⁷¹ reported that to achieve the best results, the tibia should be slightly laterally rotated and the anterior tibial translation force should be applied from the posteromedial aspect. Therefore the hand on the tibia should apply the translation force. A positive sign is indicated by a “mushy” or soft end feel when the tibia is moved forward on the femur (increased anterior translation with medial rotation of the tibia) and disappearance of the infrapatellar tendon slope.¹⁶⁸ A false-negative test may occur if the femur is not properly stabilized, if a meniscus lesion blocks translation, or if the tibia is medially rotated.¹⁷¹ A positive sign indicates that the following structures may have been injured to some degree:

1. Anterior cruciate ligament (especially the posterolateral bundle)

2. Posterior oblique ligament

3. Arcuate-popliteus complex