the sport and labor activity . Usually , symptoms are subtle , with a feeling of discomfort or pain in the posterior face of the flexed knee and slight swelling , even in acute injury . In chronic cases , they may experience irradiation of the pain to the anterior face of the knee and when going down the stairs , walk in inclined planes or when they slowdown . 6
Physical examination must be tested for all ligament and meniscus structures . To look for the injury of the PCL , the most commonly tests are :
• Posterior sag sign
• Quadriceps activation test
• Rear drawer
• Reverse pivot shift
• Dial test at 30 ° and 90 ° of knee flexion
• External rotation recurvatum test . In cases of a chronic injury , the gait may undergo changes with the attenuation of the PCL structures , characterized by external rotation , posterolateral deviation and hyperextension ( varus thrust ). There are devices , like arthrometer , that can be used , but the evidence has shown that it underestimates the posterior
23 , 24 translation . and PCL become the main rotational stabilizers , which leads to an excessive load on these structures . On the other hand , untreated chronic PCL or ACL injuries may cause attenuation of the remaining knee stabilizers . In this way , it must be known that the normal biomechanics of the knee comes from a synergy between the static and the dynamic stabilizer structures and that the rupture of the PCL will have influence on the kinematics of the knee , causing posterior subluxation of the tibia , with increased contact forces in the medial and patellofemoral compartment , and activation of compensatory mechanisms in the march . 5 , 6 , 22
Epidemiology and pathogenesis
The rupture occurs in 5-20 % of all knee ligament injuries and there is rarely an isolated injury , being associated with 79 % of PLC injuries . 5-7 It arises by :
• Sports trauma : more common with knee-bending and footsustained or with hyperextension movement ;
• Road accidents ( 57 %): high energy and often associated with multiligamental injuries . Taking into consideration what has already been mentioned about biomechanical changes , on high energy injuries it is of capital importance to check for associate neurovascular injuries and for injuries of the other stabilizers , which , when neglected , they conduct to a failure treatment .
Semiology
The first step to evaluate the patient is the clinical history . It must be understood the circumstances , the timing and the mechanism of the injury , characterize the signs and symptoms and make an assessment of the patient ’ s profile and of
Imaging
The radiographic study in posterioranterior profile views should be performed to exclude the existence of fractures and degenerative changes . The extra-long X-ray of the lower limbs has to be performed for the identification of axial deviations .
The evidence has given more and more strength to the stress X-ray , being considered the most accurate and reproducible methods in the study of tibiofemoral translation . 5 , 24-29 These should be carried out bilaterally with the application to the knee of a force of about 89-N directed : varus / valgus at 20 ° flexion ; posterior with the knee flexed at 90 ° flexion in neutral rotation and with relaxed quadriceps . The degree of posterior translation allows the classification of the injury :
• Partial : < 8 mm ( grade I )
• Complete isolated : 8-12mm ( grade II : 8-10mm ; grade III : 10-12mm )
• Associated with the LPC : > 12mm . The MRI study is indispensable ,
28 may 2018 www . revdesportiva . pt