KNEE

CHAPTER ELEVEN KNEE

AXIOMS IN ASSESSING THE KNEE

• The knee consists of two joints: the patellofemoral and the tibiofemoral.

• Knee pain can arise from the joint itself, from periarticular tissues, or from the hip or femur.

INTRODUCTION

Pain is the most common presenting symptom of knee abnormalities. The causes of knee pain tend to be age related. A convenient way to classify knee pain complaints is by age group and by whether the pain is intraarticular, periarticular, or referred (Table 11-3).

TABLE 11-3 INTRAARTICULAR KNEE PAIN DIFFERENTIATED BY AGE

Age	Intraarticular
Juvenile (2-10 yrs)	Juvenile chronic arthritis Osteochondritis dissecans Septic arthritis Torn discoid lateral meniscus
Adolescent (10-18 years)	Osteochondritis dissecans Torn meniscus Anterior knee pain syndrome Patellar malalignment
Early adult (18-30 yrs)	Torn meniscus Instability Anterior knee pain syndrome Inflammatory conditions
Adult (30-50 yrs)	Degenerate meniscal tears Early degeneration after injury or meniscectomy Inflammatory arthropathies
Mature (>50 yrs)	Osteoarthritis Inflammatory arthropathies

Adapted from Klippel JH, Dieppe PA: Rheumatology, vol 1-2, ed 2, London, 1998, Mosby.

TABLE 11-1 KNEE JOINT CROSS-REFERENCE TABLE BY ASSESSMENT PROCEDURE

TABLE 11-2 KNEE CROSS-REFERENCE TABLE BY SUSPECTED SYNDROME OR TISSUE

Anterior cruciate ligament	Drawer test Lachman test Lateral pivot shift maneuver Slocum test
Arcuate-popliteus complex	Drawer test Lachman test Lateral pivot shift maneuver Slocum test
Anterolateral rotary syndromes	Losee test Q-angle test
Chondromalacia patella	Clarke test Fouchet sign Q-angle test
Effusion	Patella ballottement test
Iliotibial band	Drawer test Lateral pivot shift maneuver Noble compression test Slocum test
Lateral collateral ligament	Adduction stress test Lateral pivot shift maneuver Slocum test
Lateral meniscus	Apley compression/distraction test Bounce home test Clarke test McMurray sign Steinmann sign
Medial collateral ligament	Abduction stress test Drawer test Slocum test
Medial meniscus	Apley compression/distraction test Bounce home test Clarke test McMurray sign Payr sign Steinmann sign
Osteochondritis	Wilson sign
Patellar dislocation	Apprehension test for the patella Q-angle test
Patellar fracture	Dreyer sign
Patellar syndromes	Clarke test Fouchet sign Q-angle test
Posterior capsule	Drawer test Lateral pivot shift maneuver Slocum test
Posterior cruciate ligament	Drawer test Slocum test
Posterior oblique ligament	Drawer test Fouchet sign Slocum test
Quadriceps	Thigh circumference test
Valgus deformity	Q-angle test

ORTHOPEDIC GAMUT 11-1 KNEE STABILITY

Knee stability depends on four ligaments:

1. Tibial collateral

2. Fibular collateral

3. Anterior cruciate

4. Posterior cruciate

The rounded contour of the femoral condyles furnishes little stability and the flat tibial plateaus, deepened by the semilunar cartilages. The quadriceps muscle and its tendinous expansions are great contributors to the stability and function of the knee. The earliest clinical indication of internal knee derangement is atrophy of the quadriceps.

The knee is not a true hinge joint. The tibia navigates a helical course on the condyles of the femur. Most traumatic arthritis of the knee in middle-age and elderly people results from minor derangements of the soft tissues, especially the menisci.

The knee lacks the stability of the hip, which has its ball and socket, or the ankle, which has its mortise and tendon. Both the hip and the ankle have structures that give some degree of bony stability. In the knee joint, the socket of the top of the tibia is so minimal that the lateral tibial plateau may be flat or even convex. The little bit of buffering provided by the menisci gives minimal increase in stability because the menisci are unstable themselves. For stability, the knee must depend largely on the soft tissues, ligaments, capsule, and muscles.

Making an accurate diagnosis about the exact nature of the patient’s knee injury is extremely important. Examination must determine what part of the knee is injured and how bad the injury is.

ORTHOPEDIC GAMUT 11-2 KNEE

Parts of a knee vulnerable to injury:

2. Muscle tendon

8. Any combination of these

ESSENTIAL MOTION ASSESSMENT

The flexion-extension movement of the knee is not a simple hinge motion (Figs. 11-1 and 11-2). As the knee passes through its degrees of flexion and extensions, the imaginary mediolateral axis through which the movement occurs shifts up and down on the femur.

FIG. 11-1 The normal angle of knee flexion ranges from 130 to 150 degrees.

FIG. 11-2 The knee should normally extend to a straight line (0 degrees) and can occasionally be hyperextended up to 15 degrees.

ESSENTIAL MUSCLE FUNCTION ASSESSMENT

The examiner tests the muscles responsible for knee flexion and extension, the hamstrings and quadriceps, respectively (Figs. 11-3 and 11-4).

FIG. 11-3 The prime movers involved in flexion of the knee are the biceps femoris (sciatic nerve, tibial branch, S1, S2, and S3 to the long head; peroneal branch, L4, L5, S1, and S2 to the short head), semitendinosus (sciatic nerve, tibial branch, L4, L5, S1, S2, and S3), and the semimembranosus (sciatic nerve, tibial branch, L4, L5, S1, S2, and S3) muscles. The patient flexes the knee through its range of motion.

FIG. 11-4 The prime mover involved in extension of the knee is the quadriceps femoris (rectus femoris, vastus intermedius, vastus medialis, and vastus lateralis) muscle (innervated by the femoral nerve, L2, L3, and L4). Extension of the knee is tested while the patient extends the knee through its range of motion.

ORTHOPEDIC GAMUT 11-5 SCIATIC NERVE

The sciatic nerve innervates the following:

2. Biceps femoris

3. Semitendinosus

4. Semimembranosus

5. Ischial head of the adductor magnus

ESSENTIAL IMAGING

The typical knee study consists of an anteroposterior (or posteroanterior) and a lateral view. Many examiners will include tangential, tunnel, or oblique views for further evaluation. The tangential view provides an axial depiction of the patella and its relationship with the femur. The tunnel allows excellent visualization of the intercondylar region of the femoral-tibial articulation.

PROCEDURE

• While the patient is lying supine and the knee is in complete extension, the examiner, who is on the ipsilateral side, places one palm against the lateral aspect of the patient’s knee, at the joint line.

• While the other hand is gripping the ankle, the examiner laterally draws the leg to open the medial side of the joint (Fig. 11-5).

• If the patient is indifferent to this action, the examiner repeats it while the knee is in approximately 30 degrees of flexion, a position of lesser stability.

• This maneuver makes the medial joint vulnerable to torsion stress.

• The production or increase of pain, especially below, above, or at the joint line, is evidence of medial collateral ligament injury.

FIG. 11-5

The knee is an unusual joint because it contains ligaments deep within the joint. Medial and lateral collateral menisci in the joint can also be damaged. Finally, the normal motions of the knee are very complex, including two planes of rotation. Multiple and complex injuries are common.

PROCEDURE

• While the patient is lying supine and the knee is in complete extension, the examiner, who is on the ipsilateral side, places one palm against the medial aspect of the patient’s knee, at the joint line.

• While the examiner’s other hand grasps the ankle, the examiner draws the leg medially to open the lateral side of the joint (Fig. 11-6).

• If the patient is indifferent to this procedure, the examiner repeats it with the knee in approximately 30 degrees of flexion.

• An initiation or increase of pain above, below, or at the joint line is evidence of lateral collateral ligament injury.

FIG. 11-6

Little congruency exists between the articular surfaces of the tibia and the femur. As a result, the knee has a well-developed system of ligaments for stability and an arrangement of intraarticular menisci that reduce the contact loading between the femur and the tibia.

PROCEDURE

• The test involves four steps, and if any or all of these steps elicit knee pain or clicking, the test is positive.

• The patient is lying prone with the lower limbs straight and the ankles hanging over the end of the examination table.

• The examiner grasps the foot of the involved lower extremity, strongly rotates the leg internally and flexes the knee past 90 degrees.

• This maneuver is repeated with the leg strongly rotated in external rotation (Fig. 11-7).

• The examiner anchors the patient’s thigh to the examination table by placing a knee in the patient’s popliteal space.

• A small pillow or towel should be used for cushioning.

• The examiner strongly distracts the patient’s knee joint by lifting the foot.

• This move is followed by rapidly rotating the leg, both internally and externally (Fig. 11-8).

• This procedure is repeated with strong downward pressure on the patient’s foot.

• An intermediate maneuver may be performed.

• The examiner flexes the patient’s knee to 90 degrees and rapidly rotates the foot and leg both internally and externally without anchorage to rule out a rotational strain or collateral ligament tear.

• The test is significant for meniscus tear.

FIG. 11-7

FIG. 11-8

The phrase internal derangement of the knee is a common provisional diagnosis for any patient with mechanical symptoms of the knee. The initials of this phrase, IDK, also stands for “I don’t know,” and the temptation to use these initials, instead of making a complete diagnosis, must be avoided.

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Jun 5, 2016 | Posted by admin in ORTHOPEDIC | Comments Off

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