- The PCL runs behind the Anterior Cruciate Ligament (ACL)
- It is injured less commonly than the ACL
- Frequently does not require a reconstructive procedure
- Results of surgery traditionally have not been as good as that of ACL reconstruction
- Functionally humans can survive without a PCL and still retain excellent knee function such that you can return to high level sports activities or other physical activities
- Typically 32-38mm in length.
- 11-13mm2 at its midpoint.
- Consists of two distinct fibre bundles:
- Posteromedial
- Anterolateral (The stronger of the two bundles)
- Originates from the lateral side of the medial femoral condyle
- Runs posteriorly to insert about 1-1.5cm below the posterior tibial rim
Mechanism of Injury
Typically occurs in:
- Sports
- Motor-vehicle accidents
- Other high-energy trauma
Occurs when there is a posterior (backwards) force applied to the tibia (leg bone) when the knee is flexed (bent)
In combination with a rotation moment of the knee, this may cause additional ligament injuries to the knee
A ruptured PCL can also occur when the foot is planted on the ground and the knee is flexed (less common)
What does the PCL do?
The PCL stops the tibia (leg bone) from moving backwards on the femur (thigh bone). It also plays a role in preventing excessive external rotation (outwards rotation) of the tibia in relation to the femur. Injury to other ligaments of the knee may result in an exaggerated rotation of the knee.
History
- Patients may have been able to continuing playing sport
- Been told they had “sprained” their knee
- Had minimal swelling
- Spent a period of time on the sideline
- May have been a missed diagnosis, given the innocuous nature of the injury
Examination / Signs
The signs that Nigel looks for are similar to those of an ACL rupture except the tests that are performed are in reverse.
Effusion (swelling)
- This is normally moderate to large when the injury is seen within the first couple of weeks
- The swelling is into the knee joint and always contains blood
Limp
- Patients will walk with a painful limp
- They may need crutches initially
Muscle wasting / weakness
The Quads muscles (muscles at the front of the thigh) will start to lose their bulk within 1 week of injury. This occurs because the knee joint is not being moved in its normal way
Hamstrings tightness
The Hamstrings (muscles at the back of the thigh) may feel tight as they try to protect the knee. Some patients will not be able to get their knee out straight because of this.
Tests
There are three tests that Nigel performs:
- Posterior Sag
- Posterior Drawer
- Reverse Pivot Shift
Nigel will explain each test to you and will detail each test result to you.
Imaging
- X-rays of your knee will be taken but most commonly will reveal no bony abnormality. They may reveal an effusion (swelling) present within the knee joint.
- MRI has become the mainstay for confirming the diagnosis of PCL rupture. It is also used to assess other ligaments, articular cartilage (the joint surface), and menisci (cartilage that sits in between the tibia and femur).
What should you do if you think you have injured your knee?
- Stop playing sport immediately
- ICE your knee
- Protect the knee
- Elevate the knee
- Take painkillers and anti-inflammatory medications
- If you have allergies or sensitivities, any medical conditions or you are unsure of what you can take please seek medical or pharmacy advice
Seek medical advice
- Initially - Most knees cannot be examined fully when the knee is injured because of pain and swelling therefore an appointment should be made to be seen as soon as possible after your injury
- In some cases the knee will not be able to be formally examined until about 2 weeks after the injury has occurred
- If there is any doubt ask your doctor to send you for further imaging of your knee (x-ray and MRI) or for your doctor to refer you to a sports medicine physician or a knee surgeon for a further opinion on your knee
Options for Treatment
- Most PCL injuries can be managed non-operatively even the high grade ruptures
- The non-operative treatment involves quadriceps and hamstrings strengthening along with range of movement exercises. These are done with extensive physiotherapy input and Nigel will refer you to a specialist knee physiotherapist
- Operative treatment is reserved for those people who have:
- Ongoing disability
- Functional instability
- Those who wish to return to sport but have instability with sports
- Other ligament involvement requiring an operation
