Radiography

Any knee trauma should have a complete radiographic evaluation, including anteroposterior, lateral, sunrise, and tunnel views. Avulsion injuries (of the PCL, Gerdy's tubercle, or fibular head), Segond fractures, posterior tibial sag, and lateral joint space widening should be noted (Fig. 53-9). Oblique radiographs may be necessary to evaluate for tibial plateau fractures. Flexion weight-bearing views are useful in chronic cases to assess limb alignment and medial compartment degeneration. Stress radiographs and contralateral comparison views may be useful in difficult cases; a lateral film with posterior tibial force will allow direct measure of posterior translation. A modified Laurin radiograph with or without weights (a sunrise view taken with the knee flexed 70 degrees) may demonstrate increased distance between the anterior femoral condyles and the anterior tibial edge, indicative of posterior tibial subluxation.6

With appropriate techniques and criteria, the sensitivity and specificity of magnetic resonance imaging in the diagnosis of complete PCL tears are thought to approach 100%. On magnetic resonance imaging, the normal PCL appears as a uniform band of low signal intensity. On sagittal images with the knee extended, the PCL is usually seen on one to two contiguous slices with an arcuate shape, whereas on coronal images, it appears as a vertically oblique band (Fig. 53-10). The menis-cofemoral ligaments are seen on only 60% of magnetic resonance

Figure 53-10 Sagittal magnetic resonance image of a normal posterior cruciate ligament. (From Allen CR, Rihn JA, Harner CD: Posterior cruciate ligament: Diagnosis and decision making. In Miller MD, Cole BJ [eds]: Textbook of Arthroscopy. Philadelphia, WB Saunders, 2004, pp 687-702.)

imaging studies, running in an oblique course adjacent to the anterior and posterior margins of the PCL.3

On magnetic resonance imaging, PCL injury typically appears as tearing of a portion, or the entire bulk, of PCL fibers; this is best evaluated on T2-weighted images with fat saturation (Fig. 53-11). Partial intrasubstance tears will be seen as thickening of the ligament with edema and hemorrhage causing fiber separation and associated increases in signal intensity.1,3 Isolated tears most frequently involve the midsubstance or anterior genu and

Figure 53-11 Magnetic resonance image of a complete posterior cruciate ligament tear. (From Allen CR, Rihn JA, Harner CD: Posterior cruciate ligament: Diagnosis and decision making. In Miller MD, Cole BJ [eds]: Textbook of Arthroscopy. Philadelphia, WB Saunders, 2004, pp 687-702.)

Figure 53-9 Posterior tibial subluxation in a posterior cruciate ligament-deficient knee. (From Allen CR, Rihn JA, Harner CD: Posterior cruciate ligament: Diagnosis and decision making. In Miller MD, Cole BJ [eds]: Textbook of Arthroscopy. Philadelphia, WB Saunders, 2004, pp 687-702.)

Figure 53-11 Magnetic resonance image of a complete posterior cruciate ligament tear. (From Allen CR, Rihn JA, Harner CD: Posterior cruciate ligament: Diagnosis and decision making. In Miller MD, Cole BJ [eds]: Textbook of Arthroscopy. Philadelphia, WB Saunders, 2004, pp 687-702.)

less commonly the ligament attachments, although insertions are frequently disrupted in cases of knee dislocation or combined ligament injuries. Because there is some evidence that PCL tears can heal in an elongated fashion, chronic tears (especially grades I and II) may look normal on magnetic resonance imaging. If healed with fibrosis, the ligament may demonstrate abnormal low signal along its length.1,3

Meniscal tears and bone bruises are less commonly associated with isolated PCL tears than with ACL tears. In injuries due to posterior tibial displacement in a flexed knee, any associated bone bruising typically occurs along the anterior tibial articular surfaces and posterolateral femoral condyles. In acute hyperextension injuries, bone bruising may be seen at the anterior tibia and anterior femoral condyles.3,4 Finally, posterior tibial sag may create an illusion of ACL laxity and lead to false diagnoses of ACL injury.1

Was this article helpful?

0 0
Cure Tennis Elbow Without Surgery

Cure Tennis Elbow Without Surgery

Everything you wanted to know about. How To Cure Tennis Elbow. Are you an athlete who suffers from tennis elbow? Contrary to popular opinion, most people who suffer from tennis elbow do not even play tennis. They get this condition, which is a torn tendon in the elbow, from the strain of using the same motions with the arm, repeatedly. If you have tennis elbow, you understand how the pain can disrupt your day.

Get My Free Ebook


Post a comment