The Posterior Cruciate Ligament (PCL) is one of the four major ligaments of the knee joint that functions to stabilize the tibia on the femur. It originates from the anterolateral aspect of the medial femoral condyle in the area of the intercondylar notch and inserts onto the posterior aspect of the tibial plateau. It functions to prevent posterior translation of the tibia on the femur. To a lesser extent, the PCL functions to resist varus, valgus, and external rotation forces. It is approximately 1.3 to 2 times as thick and about twice as strong as the anterior cruciate ligament (ACL) and, consequently, less commonly subject to injury.
Injuries to the PCL are caused by an extreme anterior force applied to the proximal tibia of the flexed knee. Common causes include dashboard injuries where the knee is forced into the dashboard during a motor vehicular collision. The PCL also can be injured secondary to falling forward onto a flexed knee. The most common sports where PCL injuries occur are football, skiing, soccer, and baseball. Less commonly, damage can occur due to a rotational hyperextension injury to the knee joint.
According to a 2003 study by Schulz et al., the mean age of PCL injuries was 27 years. The two most common causes of PCL injury were car accidents (45%) and athletic injuries (40%). Specifically, the two most common causes of injury are motorcycle accidents (28%) and soccer-related injuries (25%). The most common injury mechanism was dashboard injuries (35%) and falls on a flexed knee with the foot in plantar flexion (24%). The male to female ratio is 2:1. 
The PCL originates from the anterolateral aspect of the medial femoral condyle in the area of the intercondylar notch and inserts extra-articularly onto the posterior aspect of the tibial plateau. It is 1.3 to 2 times as thick and about two times the strength of the ACL. It can be further separated into anterolateral and posteromedial bundles. The anterolateral and posteromedial bands are respectively 65% and 35% of the body of the PCL. The anterolateral bundle is taught in knee flexion and lax in knee extension where the posteromedial bundle is tight in knee extension and lax in knee flexion. The function of the PCL is to prevent posterior translation of the tibia on the femur. Because a majority of the injuries occur in knee flexion, the anterolateral portion is more commonly injured. The PCL is the primary restraint to posterior tibial translation between 30 degrees and 90 degrees. At 90 degrees, the PCL accepts 95% of posterior translational forces. It resists posterior translation with the assistance of the posterolateral joint capsule, popliteus, medial collateral ligament, and posterior oblique ligament.
The Posterior cruciate ligament receives blood supply from the middle geniculate artery and is innervated by the tibial nerve.
Patients often will present with complaints of acute onset of posterior knee pain, swelling, and instability. A thorough history includes the mechanism of injury, such as trauma from falling onto a flexed knee or recent motor vehicle accident. There may or may not be a complaint of a “pop” with PCL tears like those frequently reported with ACL tears.
A thorough knee exam should be performed, including overall limb alignment and gait assessment. The neurovascular integrity of the lower extremity distal to the injury should also be assessed. Intimal tear to the popliteal artery should be suspected in case of weak distal pulses or Ankle-Brachial Index< 0.8 with a further investigation with arteriography. Arteriography should not delay treatment in case of an evident vascular deficit .
Initial imaging should be limited to plain X-rays. Include ipsilateral standing AP, 45-degree flexion weight-bearing, and merchant patellar views with contralateral views to assess for associated fractures, arthritis, joint effusion, and the 45-degree flexion view may show a positive sag compared to the contralateral knee.
MRI is the gold standard for the evaluation of a PCL injury. It has been reported to have accuracy in the range of 96% to 100%. It can also assess for concomitant injuries such as meniscal, Ligamentous, posterolateral joint capsule, popliteus, medial collateral ligament, and posterior oblique ligament injuries. On T1- and T2-weighted sagittal MRI images, increased signal within PCL substance or disruption in the continuity of the ligament fibers suggests acute injury. Chronic PCL injuries can be shown as posterior tibial translation. Posterior translation < 8 mm can potentially heal with the restoration of ligament continuity on MRI .
PCL injuries are graded on a scale of I-III.
The main variables to consider in managing a PCL injury is whether it is an acute or chronic injury, isolated or combined injury. Historically, nonoperative management was the first line of treatment for isolated PCL injuries regardless of how severe the injury is. This was partially due to the unreliable results of PCL reconstruction in restoring knee function and kinematics with residual laxity being commonly reported postoperatively. With advances in arthroscopy techniques, PCL reconstruction is becoming a more reliable procedure, although there is a lack of long term outcomes.
Non-operative treatments are indicated for:
PCL has an intrinsic ability to heal. This usually accomplished in a lax position . Acute treatment involves RICE (rest, ice, compression, and elevation). Initial knee bracing controls pain, posterior tibial translation, and has well managed isolated PCL injuries . Crutches could be helpful until quadriceps recovers strength. Rehabilitation is important with a focus on knee extensor strengthening. The estimated return to play is 2 to 4 weeks. Grade III injuries can be treated with knee immobilization x 4 weeks with a transition to rehabilitation focusing initially on passive range of motion followed by knee extensor strengthening.
Operative treatment is indicated for:
Operative techniques for PCL reconstruction:
The single-bundle technique (isometric point or anatomical): This is the classic PCL reconstruction technique. The anatomical technique relies on radiographic and arthroscopic references and is more preferred versus the isometric point technique which tends to result in laxity in the postoperative period as time passes due to over constraint of the joint..
The double-bundle reconstruction technique:
Theoretically, this should restore the normal knee kinematics in comparison with single-bundle reconstruction which restores kinematics only between the first 0° to 60° of flexion. This technique uses one tibial tunnel and two femoral tunnels with the anterolateral bundle tunnel being bigger than the one for the posteromedial bundle.
There are two main types of graft fixation; the transtibial tunnel versus the tibial-inlay techniques.
High Tibial Osteotomy (HTO): It is indicated in the setting of chronic PCL deficient knees and varus malalignment.it affects the mechanical weight-bearing axis of the knee by altering both the coronal and sagittal planes. Opening medial wedge osteotomy; in the coronal plane, will improve the varus malalignment and, in the sagittal plane, will increase the tibial slope which consequently increases anterior tibial translation and helps PCL deficiency by reducing posterior sagging of the tibia. In addition, HTO delays the progression of secondary osteoarthritis.
Neurovascular injury (e.g Popliteal artery injury).
Osteoarthritic progression (Patellofemoral and medial tibiofemoral).
Failure of associated ligament reconstructions or meniscal repairs.
Revision of PCL reconstruction.
Rehabilitation is fundamental in determining patients' outcomes following PCL injuries and reconstruction . There are variable rehabilitation programmes throughout the literature. But, there are main principles that should constitute the foundation for any programme. These principles include :
Pierce proposed a 5-phase post-operative programme .Patients are supported with a knee immobilizer brace for 3 days then converted to a dynamic anterior drawer brace. It has been recommended that the PCL brace be worn 24/7 for 24 weeks postoperatively.
Phase I (0- 6 weeks):
Phase II (7-12 weeks):
Phase III (13 to 18 weeks):
Phase IV (19-24 weeks):
Phase V (25-36 weeks):
PCL injuries are not uncommon and usually present to the emergency department. Mild injuries are usually managed non-operatively by the emergency department physician, nurse practitioner or the primary care provider. Acute treatment involves RICE (rest, ice, compression, and elevation). Rehabilitation is important with a focus on knee extensor strengthening. Grade III injuries can be treated with knee immobilization x 4 weeks with a transition to rehabilitation focusing initially on passive range of motion to knee extensor strengthening. Operative treatment is reserved for combined capsuloligamentous injuries, grade II or grade III injuries with bony avulsion, or chronic PCL injuries with instability.
Following injury and surgery, all patients need to enter rehabilitation to regain muscle strength and function. The time to return to activity varies from 2-8 weeks. 
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