History

Despite improvements in advanced imaging techniques, clinical examination of the knee remains an essential step in evaluating the knee patient. Evaluation of every patient should begin with a complete history of the symptoms and/or a full description of the mechanism of injury. Often, the history will direct the examiner to the area of knee involvement. This will sharpen the physical examination, result in a more accurate diagnosis, and allow the clinician to be more proficient.

Observation and Inspection

The examination should begin with observation. Observation of the patient’s gait provides critical information. The examiner should note the patient’s ability to ambulate, the use of gait aids, the speed of ambulation, and the amount of discomfort present with attempted ambulation. Evaluation of the gait pattern and the stance position of the lower limb is performed while the patient ambulates. A shortened stance phase of gait (antalgic gait) will confirm the side of involvement. A short leg gait requires confirmation of limb length. This may be accompanied by a significant varus or valgus deformity at the knee or may represent an extra-articular deformity requiring further evaluation. Varus or valgus alignment should be noted, as well as any medial or lateral thrust in the stance phase of gait (Fig. 3-1). The clinical alignment of the lower part of the leg (anatomic axis) measures the femorotibial angle (Fig. 3-2) and is different from the mechanical axis of the limb (Fig. 3-3), as measured from the femoral head through the knee to the center of the ankle on a standing roentgenogram. With a goniometer applied to the anterior aspect of the thigh and the lower part of the leg and centered on the patella, the examiner can report the clinical varus or valgus alignment. This measurement should be used along with the roentgenographic measurements.

Figure 3-1 Medial thrust of the femur indicates shift of the femur medially on the tibia through the stance phase of gait in the coronal plane (A). Lateral thrust indicates lateral shift of the femur in the coronal plane (B).

(From Tria AJ Jr, Klein KS: An illustrated guide to the knee, New York, 1992, Churchill Livingstone.)

Figure 3-2 The anatomic axis is measured by drawing lines parallel to the long axis of the femur and the tibia and measuring the intercepting angle.

(From Tria AJ Jr, Klein KS: An illustrated guide to the knee, New York, 1992, Churchill Livingstone.)

Figure 3-3 The mechanical axis of the leg is measured in the standing position with an imaginary “plumb line” dropped from the femoral head to the ground. This angular measurement gives the best functional evaluation of lower extremity alignment.

(From Tria AJ Jr, Klein KS: An illustrated guide to the knee, New York, 1992, Churchill Livingstone.)

Patellar alignment must also be observed. It is influenced by femoral neck anteversion, tibial torsion, the anatomy of the individual patellar facets, and the depth and angle of the femoral sulcus (Fig. 3-4). The Q angle is drawn from the middle of the tibial tubercle to the middle of the patella and then to the anterior superior iliac spine of the pelvis. The normal angle is 10 to 20 degrees.

Figure 3-4 High femoral neck retroversion rotates the distal end of the femur externally. In combination with internal tibial torsion, the Q angle is decreased. Patellar tracking is improved, and patellofemoral sulcus alignment is normal. High femoral neck anteversion rotates the distal end of the femur internally. In combination with external tibial torsion, the Q angle is increased. Patellar tracking is compromised, and the patella tends to track laterally.

(From Tria AJ Jr, Klein KS: An illustrated guide to the knee, New York, 1992, Churchill Livingstone.)

Clinical effusion may be apparent visually. Active range of motion should be recorded, along with any limitations to full extension or flexion. Active range of motion will be further evaluated with palpation and should be compared with passive range of motion of the knee (Fig. 3-5). It is customary that full extension should be considered 0 degrees, and flexion is recorded as an increasing number or as the distance of the heel of the foot from the buttocks. An inability to fully extend may represent lag, a locked knee, or a flexion contracture. An inability to fully flex may be due to an effusion, pain, or extension contracture.

Figure 3-5 Full extension of the knee is the zero or neutral point.

(From Tria AJ Jr, Klein KS: An illustrated guide to the knee, New York, 1992, Churchill Livingstone.)

Quadriceps atrophy is sometimes visually apparent and can help confirm the involved side. The gross appearance of quadriceps atrophy should lead to further investigation with circumferential measurement during the palpation phase of the physical examination.

Palpation

All bony landmarks should be palpated and identified. The Q angle, Gerdy’s tubercle, the fibular head, the epicondyles of the femur, the patellar margins, and the tibiofemoral joint lines can be readily palpated in most patients.

Effusions can be graded in size by compressing the suprapatellar pouch and then noting any fluid (grade 1), slight lift-off of the patella (grade 2), a ballotable patella (grade 3), or a tense effusion with no ability to compress the patella against the femoral sulcus (grade 4) (Fig. 3-6).

Figure 3-6 Effusions of the knee are graded from 1 to 4.

(From Tria AJ Jr, Klein KS: An illustrated guide to the knee, New York, 1992, Churchill Livingstone.)

If muscle atrophy was noted on observation, thigh circumference should now be measured. The circumference of the thigh should be measured at a set distance (10 cm) above the patella with the knee in full extension, and then compared with the opposite side. The calf should be measured at its greatest circumference in the lower part of the leg.

Crepitation in and of itself may or may not represent evidence of a disorder. The location should be recorded for future reference. It may involve the medial or lateral patellofemoral articulation, the medial tibiofemoral articulation, or the lateral tibiofemoral articulation.

The Patellofemoral Joint

Examination of the patellofemoral joint includes both static and dynamic evaluation. Visual inspection should be performed to note any evidence of quadriceps atrophy or vastus medialis obliquus hypoplasia. Prepatellar swelling or erythema may be present, suggesting prepatellar bursitis. The Q angle should be measured with the patient supine and the hip and knee in full extension. If the knee is allowed to flex slightly, the Q angle will decrease with internal rotation of the tibia on the femur (Fig. 3-7). The average male Q angle is 14 ± 3 degrees, and the average female Q angle is 17 ± 3 degrees.¹ A Q angle greater than 20 degrees must be noted as excessive. Tracking of the patella from full extension into flexion should be recorded visually. In full extension, the patella begins with contact of the median ridge and the lateral facet with the lateral side of the sulcus. The patella moves more centrally and the facets increase their contact with the femoral condyles as flexion increases (Fig. 3-8). Excessive lateralization of the patella with full extensions will result in a pathologic “J-sign.” This may be seen in patients with recurrent lateral subluxations or excessive ligamentous laxity, or following a traumatic lateral patellar dislocation.

Figure 3-7 As flexion increases, the patella moves more medially, and the contact zones shift proximally and to the medial and lateral facets.

(From Tria AJ Jr, Klein KS: An illustrated guide to the knee, New York, 1992, Churchill Livingstone.)

Figure 3-8 Flexion of the knee decreases the Q angle as the result of internal tibial rotation.

(From Tria AJ Jr, Klein KS: An illustrated guide to the knee, New York, 1992, Churchill Livingstone.)

Because the patellar facets do not begin to contact the femoral sulcus until the knee is flexed 30 degrees, the medial and lateral patellofemoral articulation should be palpated at this degree of flexion. This can be accomplished by allowing the leg to bend slightly over the edge of the table or by placing a small pillow below the knee. Direct patellar compression is performed and may elicit pain over the medial or lateral facet, depending on the location of the pathology (Fig. 3-9). Direct compression can be performed at progressively increasing degrees of flexion to further isolate the location of a chondral lesion. The patellar grind test consists of quadriceps contraction while direct compression is placed on the patella. When performed in full extension, entrapped synovium can cause pain even with a normal patellofemoral joint. This is especially true in the patient with patella alta. This is an unreliable test and is not recommended. The examiner should complete the static aspect of the examination by evaluating for the presence of tenderness over the medial and lateral facets of the patella, the medial and lateral retinacula, the insertion of the quadriceps tendon, and the insertion of the patellar tendon.

Figure 3-9 The patellar compression test. With the knee flexed slightly to engage the patella in the femoral trochlea, direct compression is applied to the patella.

Dynamic evaluation should include observation of patellar tracking with active knee flexion and extension. This is performed with the patient seated on the edge of the examination table and the knees bent over the side (Fig. 3-10). The patella can be seen engaging the trochlea at 10 to 30 degrees of flexion.² Any excessive lateral displacement with full extension or any maltracking should be noted. After patellar tracking is assessed, the examiner should place one hand over the anterior aspect of the patella and provide resistance to knee extension with the opposite hand. Knee extension against resistance will elicit any patellofemoral crepitus or pain from chondral pathology. The half-squat test is a different technique to load the patellofemoral joint in a similar manner. With this test, the patient is asked to hold the position of a half-squat and report the presence of anterior knee pain.

Figure 3-10 Clinical evaluation of patellar tracking is performed with the patient seated with the knee flexed to 90 degrees. During active knee extension, the examiner can detect the presence of maltracking, excessive lateral tilt, or lateral subluxation of the patella.

Patellar tilt, mobility, and the presence of patellar apprehension are then evaluated. The patient is placed in a supine position. In full extension, neutral or slight lateral tilt of the patella is normal. The inability to tilt the patella past neutral indicates an excessively tight lateral retinaculum (Fig. 3-11). With the knee flexed 20 to 30 degrees, patellar mobility is assessed. Both medial and lateral translation should be noted. Translation should not exceed two quadrants in either direction.³ If less than one quadrant of medial translation is present, this suggests an excessively tight lateral retinaculum. Patellar apprehension should also be assessed with the knee flexed 20 to 30 degrees (Fig. 3-12).⁴ Medial apprehension may be seen but is much less frequent and often iatrogenic in nature following an excessive lateral release. Lateral apprehension is more common and may suggest recurrent subluxations, traumatic lateral patellar dislocation, or excessive ligamentous laxity.