الفهرس 
Anatomy of Posterior Cruciate Ligament (PCL).Only 14 pages are availabe for public view
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Abstract
Posterior cruciate ligament tears have historically been underdiagnosed because they are often asymptomatic. It now appears that PCL tears occur more frequently than has been previously appreciated, accounting for one fifth or more of all knee ligament injuries (44).
The posterior cruciate ligament (PCL) is named for its insertion on the tibia. It originates from the lateral surface of the medial femoral condyle and passes posteriorly and laterally behind the ACL, The tibial attachment of PCL is to the depression behind the intra-articular upper surface of the tibia and extends for 3mm on the adjoining superior surface of the tibia (9).
Investigators have divided the PCL into various components or bundles on the basis of their tensioning patterns. The ligament consist of three main components: the anterolateral bundle, the posteromedial bundle, and the meniscofemoral ligaments (ligaments of Humphry and Wrisberg) The average length of the PCL is 38mm and average width is 13mm compared to 11mm for the ACL .PCL is approximately 1.5 as large as the ACL at femoral and midsubstance level (11, 12).
The PCL is the primary restrain to posterior tibial translation and a secondary restraint to external rotation, an important fact when dealing with concomitant posterolateral corner injuries. The posterolateral corner is the primary restraint to external rotation and aids the PCL in preventing pathologic posterior translation. Damage to posterolateral structures results in higher forces in the intact native PCL. Only small rotatory or varus-valgus laxity results from isolated loss of the PCL, unless there is a concomitant injury of the secondary extra-articular restraints (28).
Most PCL injuries occur secondarily to sports or motor vehicle trauma. A posteriorly directed force at the level of tibial tubercle is a common mechanism, e.g. fall on the flexed knee with a foot plantarflexed. Other mechanism is an external rotation of the tibia or posteromedial varus directed force. Other mechanism might be hyperextension (34).
Careful history and meticulous physical examination can stablish the diagnosis in a vast majority of cases. The appropriate use of manual testing, diagnostic imaging studies can further assist the clinician in arriving the correct diagnosis (43).
The most accurate clinical test for assessment of PCL integrity is the posterior drawer test. Magnetic resonance imaging has become the diagnostic study of choice in evaluation of the knee with a presumed PCL injury. This study is 96% to 100% sensitive in detecting tears of the PCL and can also determine the precise location of the tear, with implications for treatment. Bone scans are also a valuable tool in patients with symptomatic, chronic PCL tears. The bone scan may show early arthritic changes in the knee joint before radiographs or MRI (48).
Controversy still exists with respect to the indications for nonoperative and surgical intervention, techniques of reconstruction, and methods of rehabilitation for the PCL-injured knee. The relatively infrequent occurrence of this injury has unfortunately led to clinical studies with small sample sizes and short-term follow-up. The limited understanding of the PCL and associated injuries has additionally resulted in studies that are frequently a collection of differing patterns of PCL injury acute, chronic, isolated, combined, partial, and complete and also lack well-defined indications for surgical management (5).
Current surgical indications for PCL injuries include combined ligamentous injuries involving the PCL, symptomatic grade III laxity, and bony avulsion fractures. Many PCL reconstructive techniques are described include the single- and double-bundle reconstructions using the tibial inlay or tunnel method. Various types of graft for PCL reconstruction have been proposed and used including autograft, allograft, prosthetic, and artificial ligament reconstruction; graft with prosthetic augmentation; and extra-articular reconstruction. However, the optimum graft choice remains controversial. Patellar tendon-bone autograft is a commonly used graft because of its graft-healing potential .currently allograft is preferred as the graft of choice for PCL reconstruction. Bone-patellar tendon-bone and Achilles tendon are the most commonly used allograft tissues (46).
PCL injuries surgery, in addition to postoperative complications, may be complicated with loss of motion, instability, and failure of reconstruction, neurovascular injuries or osteonecrosis of medial femoral condyle (7).