MusculoSkeletal Exam

Chapter 12 The Knee

Patellar ligament

Tibial tubercle

	Prepatellar
	bursa
	Superficial
	infrapatellar
	bursa
Pes anserine	Deep
bursa	infrapatellar
	bursa

Figure 12.16 Location of the bursa of the knee.

Figure 12.15 Palpation of the patellar ligament.

common occurrence in the knee, you should familiarize yourself with their anatomical locations. Inflammation of any of these bursae will create localized effusions, which are easily palpable.

The prepatellar bursa is located just anterior to the patella. This bursa creates greater freedom of movement of the skin covering the anterior aspect of the patella. Inflammation of the prepatellar bursa can be caused by excessive kneeling and is referred to as housemaid’s/carpenter’s knee.

The superficial infrapatella bursa is located just anterior to the patella ligament. Inflammation can occur secondary to prolonged kneeling and is referred to as

Parson’s knee.

The deep infrapatella bursa is located directly behind the patellar ligament (Figure 12.16).

Medial Aspect

Bony Structures

Medial Femoral Condyle

Place your thumbs on either side of the infrapatellar ligament and allow them to drop into the indentation.

This places you at the joint line. Allow your fingers to move medially and superiorly first over the sharp eminence and then allow your fingers to travel over the smooth rounded surface of the medial femoral condyle. The medial femoral condyle is wider and protrudes more than the lateral femoral condyle (Figure 12.17). Localized tenderness may be secondary to osteochondritis dissecans.

Adductor Tubercle

Allow your fingers to move further cranially from the midline of the medial femoral condyle, and at the very top of the dome you will be on the adductor tubercle. You will know that you are in the correct place if the adductors are isometrically contracted and you can palpate their attachment at the tubercle (Figure 12.18). Tenderness can be secondary to an adductor magnus strain.

Medial Tibial Plateau

Allow your fingers to rest in the indentation medial to the infrapatellar ligament and press in a posterior and inferior direction. You will feel the eminence along the edge of the medial tibial plateau as your fingers move medially along the joint line (Figure 12.19). The coronary ligaments are located along the anteromedial joint line. They are more easily palpated with the tibia passively internally rotated, which allows the medial border of the tibia to move anteriorly.

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Medial condyle

Figure 12.17 Palpation of the medial femoral condyle.

Figure 12.19 Palpation of the medial tibial plateau.

Adductor tubercle

Figure 12.18 Palpation of the adductor tubercle.

Soft-Tissue Structures

Medial Meniscus

The medial meniscus is located between the medial femoral condyle and the medial tibial plateau. It is anchored by the coronary ligaments and attached to the medial collateral ligament. The meniscus is pulled anteriorly by the medial femoral condyle as the tibia is internally rotated, making it slightly more accessible to palpation (Figure 12.20). If an injury causes a tearing of the medial meniscus, tenderness to palpation will be noted along the joint line. Tears in the medial meniscus are very common. They may be coupled with injury to the medial collateral and anterior cruciate ligaments.

Medial Collateral Ligament

The medial collateral ligament is attached from the medial epicondyle of the femur to the medial condyle and shaft of the tibia. The ligament is not easily palpable since it is very flat. You can approximate its general location by following the joint line with your fingers moving in an anterior and then posterior direction. The ligament will obliterate the midjoint line (Figure 12.21). The medial collateral ligament

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Medial meniscus

Figure 12.20 Palpation of the medial meniscus.

Medial collateral ligament

Figure 12.21 Palpation of the medial collateral ligament.

Chapter 12 The Knee

is responsible for the valgus stability of the knee joint. It can be easily injured by a force directed at the lateral aspect of the knee (valgus strain). A lesion of the upper border of the ligament with subsequent periosteal damage is known as Pellegrini–Stieda disease.

Sartorius, Gracilis, and Semitendinosus Muscles (Pes Anserinus)

The pes anserinus is located on the posteromedial aspect of the knee, attaching to the inferior portion of the medial tibial plateau approximately 5–7 cm below the joint line. This common aponeurosis of the tendons of gracilis, semitendinosus, and sartorius muscles adds additional support to the medial aspect of the knee joint and protects the knee during valgus stress. Place your hand medial and slightly posterior to the tibial tubercle. You will feel a bandlike structure that becomes evident. Stabilize the patient’s leg by holding it between your knees. Resist knee flexion by using your legs as the resistance to make the tendons more evident (Figure 12.22). The semitendinosus tendon is palpated as a cordlike structure, located at the medial posterior aspect of the knee.

Anserine Bursa

The pes anserine bursa is located between the tibia and the insertion of the pes anserine aponeurosis. Like the other bursae in the knee, it is not readily palpable unless it is inflamed, in which case it will feel swollen and boggy.

Lateral Aspect

Bony Structures

Lateral Femoral Condyle

Place your fingers on either side of the infrapatellar ligament and allow them to drop into the indentation. This places you at the joint line. Allow your fingers to move in a lateral and superior direction until you reach the eminence of the lateral femoral condyle. If you continue to move laterally along the joint line with the tibia, you will feel the popliteus tendon and attachment, and then a groove. You will then palpate a flat, almost concave surface of the condyle (Figure 12.23).

Lateral Femoral Epicondyle

As you continue to move laterally past the concavity of the lateral femoral condyle, you will feel the prominence of the lateral femoral epicondyle (Figure 12.24).

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Figure 12.22 Palpation of the pes anserinus.

		Lateral
	Lateral femoral	femoral
		epicondyle
	condyle

Figure 12.23 Palpation of the lateral femoral condyle.

Figure 12.24 Palpation of the lateral femoral epicondyle.

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Lateral tibial plateau

Lateral tubercle

Figure 12.25 Palpation of the lateral tibial plateau.

Figure 12.26 Palpation of the lateral tibial tubercle.

Lateral Tibial Plateau

Allow your fingers to rest on the lateral aspect of the infrapatella ligament and press in a posterior and inferior direction. You will feel the eminence along the edge of the lateral tibial plateau as your fingers move laterally along the joint line (Figure 12.25).

Lateral Tubercle (Gerdy’s Tubercle)

Place your fingers on the lateral tibial plateau and move inferiorly. You will locate a prominence just lateral to the tibial tubercle. This is the lateral tubercle (Figure 12.26). This can be tender at the insertion of the iliotibial band.

Fibular Head

Place your middle finger over the lateral femoral epicondyle. Allow your finger to move in an inferior direction crossing the joint line and you will locate the fibular head and move your fingers in a superior direction and you will feel a bandlike structure standing away from the joint (Figure 12.27). The popliteus muscle is located underneath the lateral collateral ligament and separates the ligament from the lateral meniscus (Figure 12.28). The popliteus can be palpated, after a groove, slightly posterior to the lateral col-

Fibular head

Figure 12.27 Palpation of the fibular head.

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Lateral

collateral ligament

Figure 12.29 Palpation of the lateral collateral ligament.

Figure 12.28 Palpation of the lateral meniscus.

lateral ligament along the joint line. The lateral collateral ligament is responsible for the varus stability of the knee joint. It can be injured when the individual sustains a medial force to the knee. If a sprain has occurred, the ligament will be tender to palpation (Figure 12.29).

Iliotibial Tract

The iliotibial tract is a strong band of fascia that is attached superiorly to the iliac crest. It ensheathes the tensor fasciae latae and a large part of the gluteus maximus inserts into it. Inferiorly it attaches to the lateral condyle of the tibia (Gerdy’s tubercle) where it blends with an aponeurosis from the vastus lateralis.

Iliotibial tract

Tensor fascia latae

Gerdy’s tubercle

Figure 12.30 Palpation of the iliotibial band.

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You can locate it by placing your hand on the band, which is visible on the anterolateral aspect of the knee when the knee is extended (Figure 12.30). It is tightest when the knee is flexed between 15 and 30 degrees.

Common Peroneal Nerve

Place your fingers along the posterior aspect of the fibular head. Allow your fingers to travel behind the head, just below the insertion of the biceps femoris. The common peroneal nerve is very superficial and you can roll it under your fingers. Remember not to apply too much pressure because you can induce a neurapraxia. The nerve can normally be tender to palpation. Enlargement of the nerve is commonly noted in Charcot–Marie–Tooth disease. Damage to the common peroneal nerve will cause a foot drop, creating difficulty during the heel strike and swing phases of gait (Figure 12.31).

Posterior Aspect

Bony Structure

There are no bony structures that are best palpated on the posterior aspect.

Soft-Tissue Structures

Biceps Femoris

Have the patient lie in the prone position with the knee flexed. The biceps femoris will become a prominent

Chapter 12 The Knee

Figure 12.31 Location of the common peroneal nerve.

cordlike structure that is easily palpable proximal to its attachment to the fibular head. You can increase its prominence by providing resistance to knee flexion (Figure 12.32).

Biceps femoris

Figure 12.32 Palpation of the biceps femoris.

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Gastrocnemius

Figure 12.33 Palpation of the gastrocnemius.

Gastrocnemius

The gastrocnemius muscle is palpable on the posterior surface of the medial and lateral femoral condyles with the patient in the prone position and the knee extended. The muscle can be made more distinct by resisting either knee flexion or ankle plantar flexion. The muscle belly is located further distally over the midportion of the posterior aspect of the tibia. Tenderness can be indicative of a strain of the muscle. Localized tenderness and effusion can be indicative of a deep venous thrombosis (Figure 12.33).

Popliteal Fossa

The popliteal fossa is formed on the superior aspect by the biceps femoris on the lateral side, and the tendons of the semimembranosus and semitendinosus on the medial side. The inferior aspect is defined by the two heads of the gastrocnemius (Figure 12.34).

	Semimembranosus
	Semitendinosus
Biceps	Popliteal fossa
femoris

Figure 12.34 The popliteal fossa.

Popliteal Vein, Artery, and Nerve

The popliteal nerve is the most superficial structure passing within the popliteal fossa. This structure is not normally palpable. Deep to the nerve, the popliteal vein is located and is also not normally palpable. The popliteal artery is the deepest of the structures and can be palpated with deep, firm pressure through the superficial fascia. The popliteal pulse is much easier to palpate when the knee is flexed between 60 and 90 degrees, relaxing the muscle and connective tissue.

A comparison should be made between the dorsalis pedis and tibialis posterior pulses to rule out vascular compression. If you palpate an irregular lump on the artery, it may be an aneurysm.

Semimembranosus muscle

The major insertion of the semimembranosus tendon is at the posteromedial aspect of the tibia, 1 cm distal to the joint line of the knee. The tendon is about 6 mm in diameter and is surrounded by a large synovial sleeve. Because of its proximity to the medial joint line, inflammation of the tendon and/or its sheath can be misinterpreted as medial joint line pain. Semimembranosus inflammation may be the result of repetitive or excessive stretching of the muscle.

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Gastrocnemius-Semimembranosus Bursa

The gastrocnemius-semimembranosus bursa is located in the popliteal fossa. It is not normally palpable unless it becomes inflamed. It is then known as a Baker’s cyst. It is more easily visible and palpable if the patient’s knee is in extension. The cyst is easily moveable and is normally painless (Figure 12.35). Any type of knee effusion can cause a Baker’s cyst to develop.

Trigger Points

Trigger points of the quadriceps and hamstring muscles can refer pain distally to the knee. Common trigger point locations for these muscles are illustrated in Figures 12.36 and 12.37.

Baker's cyst
	Figure 12.36 (below) Trigger points in the right hamstring
	muscle are represented by the X’s. Referred pain pattern
	distributions are represented by the stippled regions. Adapted
	with permission from Travell J, Rinzler SI. The myofascial genesis
Figure 12.35 Baker’s cyst.	of pain. Postgrad Med 1952; 31: 425–431.

Semitendinosus

Biceps femoris (both heads)

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Vastus medialis

Figure 12.37 Trigger points in the quadriceps muscle are depicted above. The stippled regions are areas of referred pain from the trigger points, noted by the X’s. Adapted with permission from Travell J, Rinzler SI. The myofascial genesis of pain. Postgrad Med 1952; 31: 425–431.

Active Movement Testing

The two major movements of the knee joint are flexion and extension on the transverse axis. Internal and external rotation on the vertical axis can also be performed with the knee in 90 degrees of flexion. To accomplish the full range of flexion and extension, the tibia must be able to rotate. These are designed to be quick, functional tests designed to clear the joint. If the motion is pain free at the end of the range, you can add an additional overpressure to “clear” the joint. If the patient experiences pain during any of these movements, you should continue to explore whether the etiology of the pain is secondary to contractile or noncontractile structures by using passive and resistive testing.

A quick screening examination of the movements can be accomplished by asking the patient to perform a full, flat-footed squat and then to return to full extension. Flexion of the knee can also be accomplished in the prone position during which the patient is asked to bend the knee toward the buttock and

then return the leg to the table. Internal and external rotation can be observed by asking the patient to turn the tibia medially and then laterally while he or she is in the sitting position with the legs dangling off the edge of the table.

Passive Movement Testing

Passive movement testing can be divided into two categories: physiological movements (cardinal plane), which are the same as the active movements, and mobility testing of the accessory movements (joint play, component). You can determine whether the noncontractile (inert) elements are the cause of the patient’s problem by using these tests. These structures (ligaments, joint capsule, fascia, bursa, dura mater, and nerve root) (Cyriax, 1979) are stretched or stressed when the joint is taken to the end of the available range. At the end of each passive physiological movement, you should sense the end feel and determine whether

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