P. NEYRET, G. LE BLAY, T. AIT SI SELMI
Centre Livet, Department of Orthopaedic Surgery - F-69300 Caluire
We owe our knowledge in this field to Henri Dejour. Our grateful thanks are due to Maîtrise Orthopédique for providing us with the opportunity to translate what has so far been an oral tradition into a written record.
This review article is intended to familiarize orthopaedic surgeons with the methodology required for a systematic and logical examination of the knee joint.
° The knee needs to be examined systematically, since so much can go wrong with the knee, and so many signs and symptoms may be produced, that only a systematic technique will ensure that nothing of importance is missed.
° Equally, a logical approach is required, since the best way to remember a technique is to know why it is being applied. We will, therefore, attempt to explain what the various signs and symptoms mean in terms of knee pathology or pathophysiology.
The detailed examination of the knee will need to be preceded by taking the patient's history. This aspect of the clinical approach is vital, since it will often be found that a properly taken history will permit at least a presumptive diagnosis to be made. In fact, we might go so far as to say that good history-taking is "non-invasive arthroscopy."
This article also presents the IKDC (International Knee Documentation Committee) Knee Evaluation Form, under the various headings, in order to allow the more junior surgeons to familiarize themselves with international rating systems. The IKDC form itself was explained by P. Chistel, in the Revue de Chirurgie Orthopédique (1993, 79:473). It is used mainly in anterior cruciate ligament (ACL) surgery, to facilitate comparisons of results obtained in different studies of knee ligament trauma, in Europe and in the United States.
1 - HISTORY-TAKING
After establishing the nature of the principal complaint (or reason for consulting a doctor), a systematic history should be obtained, with questions grouped under three headings: History of present complaint; signs and symptoms; and life style (level of activity).
No. 1 HISTORY OF PRESENT COMPLAINT
As a rule, three questions should suffice to obtain all the information required under this heading. The first two concern the onset of the present complaint.
This first question allows the examiner to distinguish between two patterns - complaints with an identifiable starting point, a known accident (traumatic or post-traumatic knee disorders); and complaints that appear to have come on more insidiously, which would be more suggestive of inflammatory or degenerative disease.
The examiner should try to elicit the exact circumstances of how the disorder occurred - obtaining a description of how the accident happened or of how the problem has developed over time. Thus, in a trauma case, the examiner would seek to find out the nature of the contact (violent/non-violent; in valgus; in varus; in hyperextension) or whether the knee "went" after kicking a ball or "missing a kick." It would also be important to establish whether there was an audible "pop" in the joint, whether the knee swelled rapidly, and whether the athlete needed help to come off the pitch: - An affirmative answer to these questions would be highly suggestive of a torn ACL (Figs. 1-5).
1.3 What happened after that?
This question needs to be asked in order to obtain information on any medical or surgical treatments already applied, on rehabilitation (if any), and on the course of the condition up to the time of consultation.
No. 2 SIGNS AND SYMPTOMS
A complete picture of the patient's signs and symptoms should be obtained, since anything elicited under this heading may be of diagnostic value.
There are four categories of cardinal signs and symptoms in the knee joint:-
The examiner should establish the way in which the pain developed, its character, and its severity; the patient should be asked to point to the site of the pain.
Pain at night suggests an inflammatory cause, while pain that gets worse towards evening, or during/after exercise, would be more likely to be mechanical in origin.
Pain when going up or down stairs, or aching in positions where the knee is kept flexed for prolonged periods of time (car journeys, visits to the cinema), are indicative of patellar problems, while pain that occurs when the knee is hyperflexed is usually caused by meniscal pathology.
The patient should also be questioned about pain in other parts of the body (low back pain, hip pain).
Bar- or vice-like pain below the patella is highly suggestive of a low-riding patella.
A certain amount of confusion has occurred in the international literature, since the French use the term instabilité to denote what in English would be called laxity, and speak of laxité in the sense of the English term instability.
° "Going out": This is the term used by many lay persons to describe what will usually be found to be a torn ACL or a dislocation of the patella.
° "Giving way": This term is used to describe the sensation of the knee suddenly failing to provide proper support, especially when walking on uneven ground. The symptom may be due to three mechanisms:
- Interposition: If, during weight-bearing, a third structure (meniscus, synovial membrane, cartilage, etc.) is placed between the opposing cartilage surfaces of the joint, a protective reflex will be triggered. This reflex will make the quadriceps relax and unlock the knee, to allow the joint to clear itself.
- Cartilage damage: If one or both of the cartilage surfaces are damaged, and the surfaces come into contact, the quadriceps may also be made to relax.
- Muscle weakness: This may occur in quadriceps wasting, in polio, after surgery, etc.
A proper knowledge of this clinical feature is vital, since patients have often been misdiagnosed because of the examining physician's imperfect understanding of this symptom. There are two types of locking, which must be carefully distinguished:
° Meniscal locking (true locking): This is what a physician would consider to be locking. It is the impossibility fully to extend the knee for an appreciable period of time (more than a few minutes). This "passive flexion deformity" is brought on by a mechanical obstacle which makes the knee stop short of full extension (Fig. 6). The cause may be a bucket-handle tear of the meniscus, or a bulky flap that has dislocated forwards in the joint; a loose body or an ACL stump may also be to blame.
° Patellar catching (false locking): This is what the patient would consider to be locking. It is a momentary "sticking" of the knee, during a flexion-extension movement, with the knee incapable of flexing or extending beyond that particular point. Catching is relieved as soon as weight is transferred to the other side (Fig. 7). Usually, patellar cartilage damage will be found to have caused this fleeting episode of "locking."
The knee swells up. Swelling of the knee is always indicative of a genuine lesion of the joint. Sometimes, its character will already have been established by aspirating the joint. The features of the aspirated fluid (colour, viscosity, protein content, cellularity) make it possible to ascertain whether the condition is mechanical or inflammatory; a search for microcrystals should always be made.
° Hydroarthrosis: The accumulation of clear, straw-coloured fluid is the result of irritation of the synovial membrane, which may be primary (inflammatory disease) or secondary to cartilage damage (osteoarthritis), meniscal lesions, or the presence of a loose body (osteochondritis dissecans; osteochondral fractures). Hydroarthrosis may also be seen following ligament lesions.
° Blood in the joint (haemarthrosis) without a history of trauma could mean two things: haemophilic arthropathy, or pigmented villonodular synovitis. In the latter condition, the fluid may be amber-coloured rather than frankly bloody (Fig. 8).
2.5 Other clinical features
° Subjective sensation of internal derangement: The patient feels that there is something moving in the knee (joint mouse); something "funny"; "a lump." This feature suggests a meniscal lesion or a loose body.
° Noises in the joint: Crepitus is a faintly audible and often palpable sensation of grating during flexion-extension. Clunks and clicks are much louder, and suggestive of meniscal lesions.
For evaluation with the IKDC score, the patient will need to indicate the highest activity level that his or her knee will tolerate, even if (s)he does not practise the activities at that level. The levels are as follows:-
I - Strenuous activity
(contact sports involving pivoting and cutting)
II - Moderate activity
(pivot sports without contact; manual work)
III - Light activity
IV - Sedentary activity
Patients who report symptoms at level I but not at level II are rated B = "nearly normal."
The lowest grade within a group determines whether the patient is group-graded A, B, C, or D in the last column in Table 1.
No. 3 LEVEL OF ACTIVITY
History-taking also involves obtaining information on the patient's present and desired levels of activity. This information is important for two reasons: Firstly, it gives an idea of the degree of disability produced by the knee disorder; and, secondly, it shows what the patient would like to be able to do with his or her knee.
The questions to be asked will be a function of the patient's age:
° Young, active, or athletic patients should be questioned about the sports they practise, and about their ability to run, jump, or cut.
° Elderly or sedentary subjects should be asked about the use of walking aids, their walking distance, ability to go up and down stairs without holding on to a handrail, and whether they can get up from a sitting position without using their hands.
2 - EXAMINATION
The patient should be examined standing up, walking, and lying supine. It is essential that a comparison be made throughout with the unaffected side.
1 - In the STANDING PATIENT, a study should be made of
° Lower limb pattern: The lower limb is said to be in normal alignment if, when seen head-on, with the patellae pointing forwards, the medial malleoli and the femoral condyles touch. Genu varum describes a condition in which the femoral condyles are apart when the feet are together, while in genu valgum the ankles are separated when the knees touch. The distances should be measured; they may be expressed in centimetres (or in fingerbreadths), with the knees in extension (Figs. 9-10). With the knees in hyperextension, a varus deformity may be seen to worsen. Genu varum and genu valgum are not, in themselves, abnormal conditions. This is why "normally aligned" is not synonymous with "normal."
° Muscle wasting: With the patient standing "to attention",. the muscle bulk is checked. Quadriceps wasting shows up as wasting of the vastus medialis. Looking at the vastus medialis will give an immediate idea of whether the quadriceps is wasted. Wasting may be the result of under-use of the knee joint. It may be quantified by measuring the circumference of the thigh.
2 - In the WALKING PATIENT, the following features are checked:-
° The toeing angle is the angle between the axis of the foot and the direction in which the subject is walking. Normally, the axis will be seen to point in a slightly lateral direction, enclosing an angle of 10° to 15°. In the normal postural pattern, this angle will be the same on both sides.
° Tilting of the knee with single-leg stance: This is seen where bone wear has occurred as a result of osteoarthritis (OA). The feature does not manifest itself until several years have elapsed. Where the tilt is due to ligamentous problems, it will be seen early on.
(a) With wear in the medial compartment, the tilt will chiefly be into varus, in a position of near-extension. It is best seen from behind the patient (Fig. 11).
(b) With lateral compartment wear, on the other hand, the tilt will be into valgus and flexion; it is best appreciated from in front.
(c)A tilt into recurvatum is rare; it is not well tolerated by the patient.
3 - EXAMINATION OF THE SUPINE PATIENT
3.1 General appearance
There are two cardinal features with which the examiner has to be familiar, since they are as important in the examination of the knee joint as the temperature and pulse rate are in the general examination of a patient. They make it possible for a "spot diagnosis" of a genuine, organic knee lesion to be made by the examiner.
(a) Looking for an effusion: The examiner's hands are placed on either side of the patella, with the thumb and middle to little fingers stroking the synovial fluid towards the patella, while the index finger is used to elicit the patellar tap: The patella is at first pressed down and submerged under the synovial fluid, and will strike the trochlea, producing a tap. As the pressure is relieved, the patella will bob up like an ice cube in a drink (Fig. 12).
(b) Looking for a fixed flexion deformity: The patient is positioned supine and made to relax. The examiner grasps both the patient's heels and supports them at a height of 10 cm above the examination couch. This is the best position for screening for a flexion deformity, which is a major feature of knee pathology. This sensitive and straightforward method is ideal for screening purposes. It does not, however, lend itself to a quantification (in degrees) of the deformity. Also, since the patient's feet are braced against the examiner's abdomen, the examiner may seek to reduce the flexion deformity by pressing down on the patient's knees (Fig. 13).
- Knee pattern in the supine patient: As the patient goes from two-legged stance into the supine position, the deformity may or may not correct itself. If a lower limb malalignment was found with the patient standing on both feet, the examiner should check whether the deformity can be reduced in the supine patient, which would suggest that the deformity is articular (rather than extra-articular and bony) in origin.
Another way of checking for a flexion deformity consists in positioning the patient prone, on a firm table, with the knees supported on the table and the legs protruding beyond the table's edge. One heel is seen to be higher than the other. The distance between the two heels may be measured. It provides direct evidence of the flexion deformity. The test is reproducible, and the result is numerical (in cm). However, it requires a firm surface, and the patient must be positioned prone (Fig. 14).
In order to be able to tell whether a finding is abnormal, the affected side will have to be compared with the presumably healthy limb (the reference knee). This comparison will show whether there is a fixed flexion deformity or a genu recurvatum.
- The range of movement (ROM) is tested at this stage of the examination (which also involves screening for quadriceps wasting). Three figures are used to denote the ROM. The first indicates flexion; the second, full extension; and the third, recurvatum.
Thus, 140, 0, 5 means that flexion is 140°; the knee can be extended fully; and there is 5° of recurvatum. 120, 5, 0 would mean that flexion is 120°, there is a flexion deformity of 5°; and no recurvatum.
For evaluation with the IKDC score, the passive ROM is recorded in both knees. Values are given in 3-figure form: Extension/Flexion / Lack of extension (from 0°) / Lack of flexion (Fig. 15) (Table 2).
3.2 Extensor apparatus
- The bayonet sign: This term describes the pattern produced by the patella, the patellar tendon, and the tibial tubercle. The line resembles a bayonet fixed to a rifle.
Pathophysiology: The bayonet results from a lateral position of the tibial tubercle. It was thought for a long time that this was an organic factor contributing to patellar instability. It is now known that it is the resultant of the forces produced by the lateral position of the tibial tubercle that tends to pull the patella sideways.
Reliability: Not very good. A more reliable picture may be obtained from measuring the distance from the tibial tubercle to the inside of the trochlea on CT scans.
- Squinting of the patella
- Looking for tender points is particularly useful if the patient has also reported symptoms of pain (Fig. 16).
* Tibial tubercle: In adolescents, the tibial tubercle may be affected by apophysitis, with fragmentation of the apophysis (the accessory ossification centre). The patient will complain of pain in the tibial tubercle, and the examiner will be able to elicit tenderness over that structure (Osgood-Schlatter disease).
* Patellar tendon: This structure may be the site of repetitive strain injuries (jumper's knee); the patient will complain of pain in the patellar tendon, and extension against resistance will be painful.
* Apex of the patella: In adolescents, inflammation of the distal pole of the patella may occur as a very rare condition (Sinding-Larsen-Johansson syndrome).
* Medial facet of the patella (Fig. 17a): The medial facet of the patella may be tender to palpation, and the patient may report pain at that site. The feature is usually part of an anterior knee pain syndrome.
* Lateral facet of the patella (Fig. 17b): The examiner pushes the patella in a lateral direction, and palpates the lateral facet. Patellofemoral dysplasia will produce lateral impingement and pain and tenderness along the lateral border.
* A search should also be made for a mediopatellar plica, which appears as a tender cord that rolls under the palpating finger, on the medial femoral condyle. It sweeps along the condyle during flexion, and may give rise to pain symptoms.
* Patellar tilt: The examiner holds the edges of the patella between the thumb and index finger, thereby establishing the axis of the patella, which should differ only slightly (10° lateral tilt) from the horizontal plane of the knee seen head-on.
The patella may be said to squint (convergent or divergent squint) (Fig. 18). Broadly speaking, a convergent squint tends to occur in anterior knee pain syndrome, while a divergent squint would be more likely in recurrent dislocation.
° Patellar tests
- Apprehension sign
The patient is positioned supine, with the knee flexed between 0° and 30°. The examiner firmly pushes the patella in a lateral direction. The patient, who knows and apprehends the dislocation that will be produced by this manoeuvre, will stop the examiner. Results are recorded as + or 0.
Pathophysiology: Between 0° and 30° of flexion, the patella is at its highest point in the trochlea. Pressure from the medial side will push the patella in a lateral direction, causing it to dislocate from the trochlear groove. This will cause not only pain, but apprehension on the part of the patient (Fig. 19).
This sign may be elicited in recurrent dislocation; it is highly suggestive, and particularly useful in patella alta. As Henri Dejour puts it, "You can't get near their kneecaps." (Fig. 20)
The test must be stringently performed and analyzed.
- Patellar grind test
The examiner's hand is placed on the front of the knee. The patient performs flexion-extension. The examiner will feel a crepitus, and may even notice the patella catching. The crepitus is difficult to interpret. If there is nothing more than a positive grind test, a diagnosis of OA or of cartilage damage cannot be made.
Patellofemoral joint crepitus should be sought over the entire ROM from flexion to extension, against slight resistance. Crepitus in the tibiofemoral compartments is sought from flexion to extension, against resistance, as well as in valgus-flexion-external rotation (to test the lateral compartment) and in varus-flexion-internal rotation (to elicit medial compartment crepitus). Gradation depends on the loudness of the crepitus and on the pain produced by the manoeuvre (Table 3).
3.3 The menisci
Broadly speaking, the menisci should be examined with the knee in flexion. There must be tenderness (i.e. the patient must respond to palpation with pain). There are various ways in which the sensitivity of the tests can be enhanced. However, all the tests for meniscal lesions rely on the same principle: Stressing an injured medial or lateral meniscus will cause pain.
° Tenderness to palpation is elicited with the knee flexed 90° and the patient's foot resting on the table. The examiner's index finger probes the meniscus along the joint line. The most frequently encountered sites of tenderness are over or behind the medial collateral ligament, at the medial meniscal tender point (Fig. 21). Less often the tender point will be anterior, in which case the phenomenon may be part of a patellar disorder, a bucket-handle tear of the medial meniscus, or a lesion of the anterior horn of the lateral meniscus. The lateral meniscal tender point may be anywhere along the joint line (Fig. 22).
° Meniscal tenderness on mobilization: Compression of the different parts of the meniscus by the femoral condyle occurs as the meniscus glides backwards on the condyle during flexion, and forwards during extension.
This means that the posterior horn will be compressed when the knee is in hyperflexion (Fig. 23); while the anterior horn will be compressed in hyperextension.
The diagnostic accuracy of the tests is improved by adding a component of tibial rotation to the simple flexion-extension manoeuvres. This rotation tends to bring the posterior horns forward. Medial pain will be elicited in external rotation, and lateral pain in internal rotation.
- McMurray's test: Forced flexion and external rotation with compression of the medial joint line will elicit pain in the medial meniscus. The hand pressed over the joint line will feel a click. The test may be reversed, to examine the lateral meniscus.
- Apley's grinding test: For this test, the patient is positioned prone, with his or her knee flexed. Compression and external or internal rotation may be painful, showing that the medial or the lateral meniscus are torn. This test is always checked, by performing rotation without compression. This manoeuvre should not cause discomfort, unless the collateral ligaments are affected (Fig. 24).
- Cabot's manoeuvre: The heel is placed on the tibial crest of the opposite leg. The knee is gradually flexed, while the heel runs along the tibial crest. This movement may produce lateral pain, when the knee is in 90° of flexion with the heel resting on the other leg (Cabot's position). The lateral compartment is distracted by pressure on the medial side of the knee; this, too, may be painful.
° Cysts of the lateral meniscus will be seen in extension, and disappear in flexion. They are on or near the lateral joint line. They are best seen in semiflexion. The cysts will disappear in hyperflexion, and reappear as the knee is gradually extended; in full extension, they will once again be out of sight.
(In children, a malformation of the lateral meniscus may give rise to snapping when the knee is taken through flexion and extension. This abnormal movement is associated with a clicking noise, which may be very pronounced.)
3.4 Stability testing
3.4.1. Medial/lateral instability in extension
(a) Medial instability in extension
The examiner grasps the patient's heel (not the ankle or the leg) with one hand, while the other hand is placed against the lateral aspect of the patient's knee. A brisk valgus stress is imparted and immediately released. Medial instability is demonstrated if the medial joint line opens up (Fig. 25). Sometimes the most characteristic phenomenon is a little click as the knee reduces after the stress test. Sometimes, it is difficult to decide whether there is instability.
Several points need to be borne in mind:
° The abnormal feature is the asymmetrical pattern of the instability. The examiner may also ask the patient, "Do you think your right knee is different from your left knee?"
° The leg may be supported halfway between the knee and the ankle, by pressing it against the examiner's body. That way, a greater valgus thrust may be applied. The third point of support produces better leverage.
° The instability will be due to a lesion of the ligaments on the medial side and/or to medial tibiofemoral compartment wear.
(b) Lateral instability in extension
The examiner grasps the patient's heel with one hand, while exerting pressure against the inside of the knee with the other hand. The varus stress applied will cause lateral gaping in the laterally unstable knee. Lateral joint gaping is physiological. It is the asymmetry of the gaping that constitutes the abnormal finding.
3.4.2. Medial/lateral instability in 30° flexion
Description: The leg is held as described above, but the knee is unlocked by putting it in 20°-30° flexion.
(a) Medial instability
The movement imparted is one of valgus-flexion rather than valgus-flexion-external rotation. Instability in valgus-flexion-external rotation would be a sign of an injured medial collateral ligament.
(b) Lateral instability
Varus-flexion-internal rotation is used to investigate the lateral collateral ligaments. Once again, asymmetry would have to be demonstrated to qualify the result as abnormal (Fig. 26).
In the United States, examiners prefer to sit on the couch, between the patient's knees, for the performance of this test (Fig. 27).
The lateral collateral ligament is palpated with the knee in Cabot's position (see above), where it will be felt as a tense band. It is possible to explore both knees simultaneously, with the patient in the "frog position" described by Henri Dejour (Fig. 28).
3.4.3. Anterior instability
(a) Lachman-Trillat test
It is important to ensure that the patient is relaxed. This is all the more vital in recent trauma cases. In order to obtain relaxation, the patient is made to rest his or her head on the couch. It may be useful to roll the thigh in and out, to get the muscles to relax (Fig. 29).
For the test, the knee is unlocked in 20° flexion. The patient's heel rests on the couch. The examiner holds the patient's tibia, with the thumb on the tibial tubercle. The examiner's other hand is placed on the patient's thigh, a few centimetres above the patella. The hand on the tibia applies a brisk anteriorly directed force to the tibia (Fig. 30).
The quality of the endpoint at the end of the movement is described as either "firm" or "soft." Grading depends on the quality of the endpoint observed, and on whether there is a difference of 3-5 mm between the affected and the unaffected knee. A soft endpoint will make the grading "abnormal" rather than "nearly normal."
If the movement of the tibia on the femur comes to a sudden stop, this is described as a firm endpoint. If it does not, the endpoint is described as soft. A soft endpoint is pathognomonic of a torn ACL. It is easier to demonstrate a firm endpoint, which is also recognized by the patient. If the ACL is torn in one knee, the patient will be perfectly aware of the difference between the firm endpoint in the healthy, and the soft endpoint in the cruciate-deficient knee. Sometimes, the endpoint will be firm, but translation will be seen to be asymmetrical. This is known as a "delayed firm endpoint" (increased excursion and a good endpoint). It is indicative of a torn and partially healed ACL (ACL adherent to PCL), of a stretched ACL graft, or a torn PCL (changing the "starting point" of the test). A firm endpoint results from the sudden tensioning of the ACL (Fig. 31). The test is of lesser value in knees affected by OA, with a large number of osteophytes.
Lachman used to perform the test with the thumb of the distal hand on the medial joint line, so as to feel the displacement of the tibia on the femur.
In Trillat's modification of the test, the thumb is placed on the tibial tubercle, so as to get visual evidence of the translation. In our practice, we prefer Trillat's method.
The Lachman-Trillat test, the drawer test in 70° flexion, and the medial and lateral joint opening tests may be performed manually or using an arthrometer (KT-1000, KT-2000) or stress radiography. If an arthrometer is used, a force of 134 N (30 lbs.) will need to be applied. Measurements are performed on both sides. The difference between the affected side and the opposite side is recorded. Usually, only one value is recorded. The absolute value is also of interest, and should be recorded for prospective study purposes.
If, after ACL surgery, the operated side is found to be tighter than the healthy side, the graft will be at increased risk of failure.
Active resisted extension
In obese patients or subjects with bulky muscles, it may be difficult for the examiner to encircle the patient's thigh with his or her hand. In such cases, the examiner may place a fist under the knee, hold the ankle against the couch with the other hand, and ask the patient to lift the leg against resistance (Fig. 31b). This resisted quad setting will move the tibial tubercle forward. This is a useful screening test, which will not, however, be positive unless there is major instability. It would be preferable to obtain stress radiographs (134 N stress) on which to base the diagnosis.
(c) Pivot shifts
Tests screening for pivot shift were first described by M. Lemaire, in 1968. Since then, many such tests have been devised, of which we shall only list the main ones. According to Noyes, the phenomenon is potentiated when the hip is abducted. At present, attempts are being made to substantiate the diagnostic value of these tests. However, they should not be expected to provide more than they can: A shift means that the ACL has gone. Sometimes, though, the ACL may be deficient without a pivot shift occurring during the relevant tests.
Screening for pivot shift must be done systematically, using the customary techniques. The IKDC form records only the greatest shift found. The scoring system is conventional: + = glide; ++ = clunk; +++ = gross.
- Pivot shift in extension (Dejour's test) (1978)
(1) The patient's foot is wedged between the body and the elbow of the examiner. The examiner places one hand flat under the patient's tibia, pushing it forwards (force applied in an anterior direction), with the knee in extension. The other hand is placed against the patient's thigh, pushing the other way (force applied in a posterior direction) (Fig. 32).
(2) The lower limb is taken into slight abduction, by the examiner's elbow, with the examiner's body acting as a fulcrum to produce the valgus.
(3) The examiner maintains the anterior tibial translation and the valgus, and imparts flexion.
At 20°-30° flexion, pivot shifting will occur, with a clunk as the lateral tibial plateau suddenly reduces (Fig. 33).
Significance: The valgus stress associated with the anterior tibial drawer makes the lateral tibial plateau sublux on the lateral femoral condyle and compresses the structures. The sudden reduction of the convex lateral tibial plateau compressed under the lateral condyle is responsible for the clunk. Sometimes, a clunk may be elicited with compression, rather than any major valgus stress. The pivot shift is easy to produce, and causes no discomfort. It is a mixture of shift and Lachman, and provides evidence of ACL tears and damage to posteromedial structures.
- The glide pivot shift test described by Henri Dejour is the equivalent of Noyes' test. It produces a glide (a minor form of shift) rather than a proper clunk. The patient is unaware of the slip of the plateaus on the femoral condyles. The valgus component is less pronounced than are the compression and anterior drawer applied by the examiner. It produces joint play rather than a pivot shift. It can be seen in patients with a torn and partially healed ACL, as well as after ACL grafts or other ACL surgery (Fig. 34).
- The pivot shift test of MacIntosh
"When I pivot, my knee shifts." This is how a hockey player described his symptoms - hence the name of the test.
MacIntosh realized that the sensation of shifting or slipping was related to rupture of the ACL.
He devised a test to reproduce the sensation reported by patients, involving stress applied to the knee in valgus and flexion, with or without internal rotation (Fig. 35).
Description of the test: The patient is positioned supine, with the examiner standing on the affected side. The examiner uses one hand to hold the patient's foot in very slight internal rotation. With the other hand, (s)he applies a valgus stress to the posterolateral aspect of the proximal calf. At this point, flexion is started. The lateral tibial plateau will be seen to sublux forwards during the first degrees of flexion. As flexion progresses, the anterolaterally subluxed tibia will suddenly reduce, at 30° of flexion. This reduction is associated with a characteristic clunk, which the patient will readily recognize.
- Hughston's jerk test
The patient is positioned supine, with the examiner holding the lower limb in such a way as to have the hip flexed 45°, the knee flexed 90°, and the leg in internal rotation. The distal hand grasps the foot and places it in internal rotation, while the left hand applies valgus stress to the upper end of the leg.
A jerk is defined as a sudden change in the relationship between the joint surfaces. The phenomenon occurs as the subluxation reduces near full extension.
Hughston thought that rotational phenomena were more important (hence his defence of the concept of rotary instability).
- Slocum's ALRI test (1976)
The patient is placed in a semilateral position, with the knee unsupported, and the lower limb resting only on its heel. This allows internal rotation of the foot, to produce translation of the lateral tibial plateau. The examiner stands behind the patient's back, with the distal hand holding the upper end of the leg, and the proximal hand around the lower end of the thigh. The test is started in extension, using vertical pressure. Next, flexion is commenced. Translation occurs at 20°, and the pivot shifts at 40° (Fig. 36).
- Losee's test (1969)
Over the years, Losee has described five tests: The first is identical with the MacIntosh test; the second uses external rotation of the tibia to elicit the pivot shift; the third (deceleration test) uses the quadriceps slingshot effect; while the fourth and the fifth test the anti-pivot shift effect of extra-articular ligament reconstructions.
(c) Anterior drawer in 90° flexion, or direct anterior drawer
The examiner sits on the patient's foot, which has been placed in neutral position. The knee is in 90° flexion. The index fingers are used to check that the hamstrings are relaxed, while the other fingers encircle the upper end of the tibia and push the tibia forwards (Fig. 37).
If a direct anterior drawer is obtained, the ACL will be torn. However, for this sign to be elicited, peripheral structures such as the medial meniscus or the meniscotibial ligament must also be damaged. This ligament forms a wedge, in 90° flexion, preventing anterior tibial translation. The finding of an anterior drawer is conclusive evidence of an ACL tear. However, not every ACL tear will be associated with a positive anterior drawer test.
° Drawer in external rotation (foot in external rotation). This test examines the posteromedial structures (posteromedial corner, posterior horn of medial meniscus). The results are recorded as +++/0.
° Drawer in internal rotation (foot in internal rotation). The diagnostic value of this test is less well established.
° One-leg hop functional test (Dale Daniel)
This test investigates the greatest distance the patient can hop on one leg.
The test is performed three times, and the mean value achieved is recorded. It is a comparative test, the result of which is expressed as a percentage of the value achieved on the healthy side.
3.4.4. Posterior instability
- Posterior tibial sag in 90° flexion
In the IKDC form, the posterior tibial sag is recorded in 70° flexion; a comparison is made with the opposite side, looking sideways at the knees to establish the amount by which the tibial tubercle has dropped backwards. Posterior tibial translation may be confirmed if it is seen that quadriceps contraction pulls the tibia forward.
- Straight posterior drawer
With the patient supine, the test is performed with the knee in 70°-90° flexion and the foot in neutral rotation. The examiner sits on the patient's foot, placing both thumbs on the tibial tubercle, and pushing the tibia backwards. A positive test (i.e. one in which the tibial plateau moves in a posterior direction) means that the PCL is torn.
Oddly enough, this is a difficult test to perform, since the patient's tibia may often sag spontaneously, requiring this posterior translation to be reduced before the test is started, since otherwise the result may be erroneously given as an anterior drawer. The quality of the endpoint (firm or soft) is of no significance in the posterior drawer test.
To check the knee pattern, the knees should be inspected side-on, to see whether the tibial tubercle has sagged backwards. The knees should be in 90° flexion, with the patient's feet resting on the couch. It is preferable to use Godfrey's drop back test.
There are three tests that can be used to demonstrate a posterior drawer, and which may be resorted to in case of doubt:
- Godfrey's drop back test: The patient is supine, with the thighs and knees flexed 90°, legs horizontal, and heels held by the examiner in such a way as to have the legs parallel to the table. The test is positive if the upper end of the tibia on the affected side is seen to drop backwards (Fig. 38).
- Muller's test: Patient positioning is identical to that for the posterior drawer test in 90° flexion. Tibial sag is observed. The patient is asked to set his or her quadriceps: Before the heel will have had time to lift off the couch, the posterior displacement of the tibia will have reduced.
- Active extension against resistance: This is the same as Muller's test, but in 20° of flexion. This test is of lesser practical value.
- Posterior drawer in external rotation
The foot is placed in external rotation. This test is equivalent to the straight posterior drawer test in patients with PCL deficiency. The result is more pronounced in cases of posterolateral lesions.
- Posterior drawer in internal rotation
The foot is placed in internal rotation. Translation is usually 4 mm less than in the straight posterior drawer test. If the same value is obtained, this would be indicative of a lesion of the medial meniscofemoral or even the medial collateral ligament.
- Whipple's test: In order to rule out tibial translation as a result of gravitational sag, the patient should preferably be examined prone. "This test is difficult. It has not yet gained wide acceptance." (B. Moyen). The information provided is the same as that obtained with the conventional posterior drawer test performed with the patient supine, feet resting on the couch. Apart from the fact that sag is eliminated, this test is completely unconstrained.
- Posterior translation in 20° flexion: Posterior displacement may be observed with the knee in 20° of flexion. If the result is the same as that of the straight posterior drawer test, there will be associated posterolateral lesions.
3.4.5. Posterolateral instability
(a) External rotation recurvatum test
Description: The patient is supine. The examiner stands at the foot of the couch, and grasps the patient's big toes, lifting the feet off the couch. The affected knee will go into varum-plus-recurvatum (Fig. 39).
According to Hughston, this test provides information on major disabling peripheral instabilities; it cannot be positive unless the PCL is also torn: A positive recurvatum test shows that at least one cruciate is torn and that there is a posterolateral lesion. Of the cruciates, the ACL is more often involved than the PCL.
(b) Jakob test (reverse pivot shift test)
The patient lies supine. The examiner stands at the patient's feet, and places his or her distal hand on the patient's ankle, with the patient's leg braced against the examiner's pelvis. The proximal hand supports the upper third of the calf on the lateral side, and imparts a valgus force so as to compress the lateral compartment. The lateral tibial plateau will drop back under its own weight, with the foot in external rotation.
This test starts with the knee in flexion. The joint is gradually taken into extension by its own weight.
At a given point, the subluxation will reduce with a snap, and the foot will go into neutral rotation. The test involves a pivot shift manoeuvre, but since it starts from a subluxed position of the lateral tibial plateau, with reduction in extension, it is known as a reverse test.
The jolt is produced by the reduction of the posterior subluxation through the action of the lateral head of the gastrocnemius, the capsule, and the pull of the iliotibial band, which, past 40° of flexion, moves from a flexor to an extensor function. All these factors will tend to pull the tibial plateau forward, out of its posteriorly subluxed position. Since there cannot be any rolling-sliding, the plateau will snap back into reduction.
Significance: This test provides evidence of a posterolateral instability which may or may not be associated with a lesion of the PCL. The test is not very specific.
Posterior subluxation of the lateral tibial plateau may occur without any PCL deficiency, since, in external rotation, the PCL is relaxed and will allow a certain amount of posterior displacement of the tibial plateau. However, where the PCL is torn, the pivot shift will be very much more pronounced.
(c) Increased external rotation
It is indicative of lateral lesions. The test is performed as a side-to-side comparison:-
° External rotation in 20° flexion: The examiner stands at the foot of the couch, and looks for unequal rotation. The difference found may be expressed in degrees (Fig. 40).
° External rotation in 90° flexion.
(d) Lateral hypermobility
This test has been described by Gilles Bousquet. It is performed with the knee flexed at 90°, with the examiner's hands around the top of the tibia (tibial tubercle), applying external rotation (Fig. 41). A positive test shows that the posterolateral structures have been injured.
To complete the test, the examiner should
° Look for stiffness of the hamstrings,. With the hip flexed at 90°, the popliteal angle is measured (Fig. 42). The examiner tries to take the knee into extension, maintaining the foot in dorsiflexion.
° Look for stiffness of the rectus femoris. For this, the patient is positioned prone. The heel is brought towards the buttock, with the hip in extension. The heel-to-buttock distance is measured (Fig. 43). While the patient is supine, a check should also be made for popliteal (Baker's) cysts. This test should always form part of the general examination of a knee patient; in particular, it must always be borne in mind that knee pain may be due to problems in the hip or the spine.
3 - FURTHER INVESTIGATIONS
The following techniques are available for the further workup of knee patients:
1 - Scout radiographs
A.p. single-leg stance; lateral in 30° of flexion; axial views in 30° of flexion.
Instability should be investigated using the radiological Lachman test. For the instrumented test, a Telos device may be used (varus, medial/lateral instability, a.p. instability).
Long films may be used to measure limb length and study the axes of the lower limb.
Rosenberg views (p.a. weight-bearing views in flexion) may be used to detect incipient OA or to screen for osteochondritis dissecans of the medial femoral condyle.
2 - Other imaging techniques
° Arthrography: This is a useful technique in peripheral meniscal detachment, or when there is a suspicion of recurrent meniscal lesions.
° CT is essential in cases of patellar instability and of bone disease (tumour, trauma).
° MRI shows meniscal lesions, injuries of the cruciates, villonodular synovitis, and necrosis of the femoral condyles.
° Radionuclide bone scans should be requested if it is thought that the patient may be suffering from a tumour, from incipient avascular necrosis of a femoral condyle, or from reflex sympathetic dystrophy; or if an infection is suspected.
3 - Blood tests
Sed rate, blood count, CRP, and rheumatological tests (latex fixation, Rose-Waaler, complement, ANA, antimitochondrial antibodies, Lyme serology, etc.) should be ordered in inflammatory knee conditions.
5 - Arthroscopy and biopsy
These modalities are rarely indicated in the diagnostic workup of knee patients. They may occasionally be used in inflammatory conditions.
The various signs observed may be grouped together to distinguish a number of knee disorder patterns:-
- Complete isolated anterior instability = Lachman-Trillat +; pivot shift +
- Incomplete isolated anterior instability = Lachman-Trillat: Delayed firm endpoint +; glide pivot shift +
- Advanced anterior instability = Lachman-Trillat +; pivot shift +, straight anterior drawer +
- Posterior instability = Lachman-Trillat: Delayed firm endpoint +; posterior drawer +, tibial sag +, pivot shift 0
- Organic patellar instability = Apprehension +
- Anterior knee pain syndrome = Medial facet tenderness + (quad/hamstring stiffness ±)
- Medial meniscus lesions = Effusion +, medial joint line tenderness +, McMurray +, Grinding +
- Lateral meniscus lesions = Effusion +, lateral joint line tenderness +, Grinding +, Cabot +
- Isolated peripheral lesions:
Medial collateral ligament = Instability in valgus-flexion-external rotation
- Associated peripheral lesions:
Medial triad (ACL + MCL + IM ±)
Lachman-Trillat +, direct anterior drawer +, valgus-flexion-external rotation +,
instability in extension-valgus +
- Posterolateral lesions: Posterior drawer +, reverse pivot shift +
Posterior drawer +, straight anterior drawer +, Lachman-Trillat +, pivot shift +, external rotation recurvatum +
(in lateral pentad);
Medial instability in extension, valgus-flexion-external rotation, varus-flexion-internal rotation +
(in medial pentad)
PS: The authors would appreciate hearing from other colleagues, in order to expand and augment the present list of tests. Please send your suggestions, descriptions of tests, etc. to
Prof. Philippe Neyret
8, rue de Margnolles