PCL Injury in Adults
The word PCL stands for Posterior Cruciate Ligament. The essential function of the PCL is to provide resistance to posterior movement of the proximal tibia on the distal femur. The PCL is roughly 36-39 mm in length and 11-13 mm in diameter across. It has two bundles named the anterolateral bundle (ALB) and the posteromedial bundle (PMB).
The anterolateral bundle is the primary stabilizer to posterior translation of tibia when the knee is at 90° of flexion. The posteromedial bundle prevents posterior translation at full extension and works as a secondary restraint to rotatory movements of the knee.
Etiology and Mechanism of Injury
When compared to anterior cruciate ligament (ACL) injuries, the most common mode of injury to the PCL occurs due to direct contact trauma resulting in a posteriorly directed force during knee flexion.
The classic history patients present with are dashboard injury in a motor vehicle accident or due to fall directly over proximal tibia with the knee flexed.
Other mechanisms include fall onto a flexed knee with the plantar flexed foot and hyperextension injury.
PCL injury may be isolated injury and may be associated with posterolateral corner (PLC) injuries, multi ligamentous knee injuries and knee dislocation.
Types of PCL Injury:
This is the mild variety one, the PCL does not tear but undergoes a sprain. PCL fibers are stretched but not torn. This does not require surgery and can be treated conservatively by medication, physiotherapy and rehabilitation. Unless treated, the patient suffers from pain, swelling, and difficulty in movement.
In this case, the PCL is partially torn.Examination shows 1-5 mm posterior tibial translation. Tibia remains anterior to the femoral condyles. Treatment options are based on age, activity level and instability. If patient is having isolated partial tear nonsurgical treatment can be employed. When partial PCL tear is associated with other ligamentous injury then surgery has to be done.
The PCL is completely torn and the patient experiences knee instability. Examination shows 6-10 mm posterior tibial translation and because of complete injury to PCL the anterior tibia is flush with the femoral condyles. The pain is more severe and so is instability, swelling and tenderness. A surgery is usually required and is done after the swelling reduces.
This is the most severe one because in this case not only the PCL is torn but damage is caused to the other ligaments as well.
There is a combined PCL + capsuloligamentous injury, examination shows more than 10mm posterior tibial translation, tibia is posterior to the femoral condyles and often indicates an associated ACL and/or POSTEROLATERAL CORNER (PLC) injury. This is an absolute indication for surgery. Here there is no role for conservative treatment. Any delay in surgery may lead to chondral and meniscal damage due to recurrent instability will eventually results in early osteoarthritis.
Presentation and Symptoms
Patient presents with classic history of trauma such as dashboard injury, hyperflexion athletic injury with a plantar-flexed foot, hyperextension injury etc.
In acutely cases of isolated PCL injury, the patient will complain of swelling and pain. They might experience difficulty in bearing weight.
The most common complaint in patients with chronic PCL injury is pain. This is usually common with long distance walking and descending stairs. The pain is mainly located behind the patella and inner (medial) side of knee.
Some patients may complain of difficulty in walking with the knee extended particularly in mid stance, and apprehension while descending stairs because of a feeling of instability or sliding of the joint. Athletes may report a decreased capacity to suddenly change of the direction. However, the significant giving way or buckling which is very common with an ACL deficient knee is rarely observed with an isolated PCL tear. Thus, instability is most common only when PCL injury is associated with another ligamentous tear.
Posterior drawer test
The posterior drawer test is performed in supine position similar to the anterior drawer test, but in this test instead of anteriorly directed force,the proximal tibial plateau is pushed posteriorly. A positive posterior drawer test is indicated by posterior tibial translation and is due to damage to the PCL. Posterior movement of the tibia on the femur shows posterior instability compared with the normal tibia.
Quadriceps Active Test
With the patient supine, the relaxed limb is supported with the knee flexed to 90 degrees in the drawer test position. The patient makes a gentle quadriceps contraction to shift the tibia without extending the knee. Patient is asked to extend the knee against resistance provided to the foot, the tibia shifts anteriorly in PCL deficient knee.
If the posterior cruciate ligament has ruptured, the tibia sags into posterior subluxation and the patellar ligament is then directed anteriorly. Contraction of the quadriceps muscle in a knee with a posterior cruciate ligament deficiency result in an anterior shift of the tibia of 2 mm or more.
Posterior sag test of Godfrey:
An apparent posterior sag is present in the PCL deficient knee when both the knees which are placed in 90° flexion with the patient lying supine are observed from the lateral aspect.
Normally the tibial plateau is a bit anterior to femoral condyles. The normal relationship of tibial plateau to the femoral condyle gets reversed in posterior laxity.
MRI is the modality of choice to confirm clinical diagnosis of PCL rupture and evaluate for concomitant pathology.
MRI image showing complete PCL tear
With the natural history in mind, the surgeon is better judge to determine which therapy is most appropriate for a specific patient.
Isolated Grade I and II PCL injuries can be managed nonoperatively. Patient should not have any kind of instability for nonoperative management. Grade II injury with instability is indication for surgery.
Nonoperative management includes protected weight bearing and rehabilitation. Patient should mainly focus on quadriceps rehabilitation with a focus on knee extensor strengthening.
PCL repair of bony avulsion fractures or reconstruction
All Grade II with instability, Grade III above and multiligament injuries need surgery.
Open surgery is not been frequently done due to advancements in arthroscopic surgeries.
Primary PCL Repair:
This technique is used in all age groups only if the injury is fresh. If it is a case of delayed treatment, the surgeon goes for other repair options. It is done arthroscopically; torn ligament is repaired back to its foot print with the help of suture anchors.
PCL repair procedure is a promising surgical alternative for acute PCL tears. We prefer FiberTape internal bracing which works as a additional stabilizer following repair. It allows rapid rehabilitation and returning back to sports, helps patient to regain his confidence back early.
For combined injuries repair or reconstruction should be done ideally within 10–14 days to avoid development of fixed posterior tibial translation. Delay can also lead to scarring of capsular structures and atrophy of collateral ligaments.
It can be performed as open or arthroscopic surgery. Advancements in arthroscopic surgeries in recent years has made it popular.
Arthroscopic All Inside PCL Reconstruction with FiberTape Internal Brace:
This surgery is performed under regional anesthesia, which makes it a painless procedure. Patient will be awake during this procedure, sometimes patient will be allowed to watch procedure through the monitor. Surgery is performed arthroscopically with key hole which makes this procedure cosmetically more acceptable.
We use one hamstring graft for PCL reconstruction. Native PCL stump is preserved to save proprioception nerve endings. The hamstring graft with FiberTape is fixed to the bone using Tight Rope RTJ, Tight Rope loop & Conical Button made in USA (ARTHREX). We don’t use bioscrew because of weaker stability compared to Tight Rope loop & Conical Button. Dr. Prasad, Sports injury and joint replacement specialist prefers only All Inside PCL Reconstruction with Fiber Tape Internal Bracing which prevents postoperative ligament loosening and failure of graft, it also promotes painless and faster recovery.