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The basics

 

  • The posterior cruciate ligament is the main ligament at the back of the middle of the knee, which prevents the tibia (shin bone) from wobbling backwards.
  • The PCL is bigger than the ACL and PCL tears are far less common than ACL tears.
  • PCL tears can occur from dashboard type injuries in car accidents, where there is impact to the front of the shin pushing the tibia directly backwards. PCL tear can also occur from hyperextension injuries (where the knee bends too far backwards, the wrong way) or from rapid forced flexion injuries (eg falling and landing on a deeply bent knee).
  • PCL tears cause pain and some swelling, but this tends to be less severe and obvious than what is normally seen with an ACL tear, and often people don’t actually fully realise that they’ve sustained what is actually a significant injury in the knee.
  • The most common thing that happens with a PCL tear is that the diagnosis is actually missed! … and often repeatedly by a succession of different (non)‘experts’!
  • PCL tears are often picked up some time later, when clinical examination shows increased laxity in the joint with an associated posterior sag (the shin bone slips too far backwards).
  • Most PCL tears can actually be managed very well conservatively, through physiotherapy rehab, without the need for a surgical reconstruction.
  • If the knee is functionally unstable despite appropriate attempts at physio rehab, then surgical reconstruction is indicated.
  • PCL tears can be associated with other concurrent damage in the knee. If there are meniscal tears then these might require a knee arthroscopy. If there is an associated tear of the posterolateral corner ligaments then it is more likely that the joint will be unstable and will require a surgical reconstruction of both the PCL and the posterolateral corner.

 


 

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The posterior cruciate ligament (PCL) is the main ligament inside the back of the knee that stops the shin bone (tibia) from wobbling too far backwards (posteriorly). The PCL is actually bigger and stronger than the ACL. Unlike the ACL, the PCL is extra-synovial, and so the fibres are not actually bathed directly in synovial fluid. Also, in many people the PCL fibres are actually splinted by either one or two adjacent smaller ligaments that pass up from the back (posterior horn) of the lateral meniscal cartilage to the femur, either side of the PCL.

PCL tears tend to occur from either dashboard-type injuries (where there is a large force hitting the front of the tibia, pushing the tibia backwards) or from falls directly onto the front of the knee, particularly with hyper-flexion of the joint. PCL tears can also occur as part of a multi-ligament injury, for example in association with ACL tears or tears of the posterolateral corner.

When the PCL tears there is pain and swelling in the knee. However, these tend to be considerably less marked than the severe pain and swelling so often seen with an ACL tear. Furthermore, the level of immobility directly after a PCL tear can often be relatively minor compared to an ACL injury, and the early recovery is often quicker.

The most common thing that so frequently seems to happen with a PCL tears is that the diagnosis is simply missed! The increased laxity that is seen in the knee after a PCL injury is less obvious than that seen with an ACL tear. Also, the patient may present with pain in their knee and slightly decreased function but with less overt symptoms than is so frequently seen with an ACL tear, and specifically there can be less of a feeling of joint instability. However, when examined properly, the knee can be demonstrated to have a posterior sag and a positive posterior tibial drawer.

The diagnosis should be confirmed with an MRI scan, which normally demonstrates the ligament injury clearly, and which also helps pick up any other additional concomitant injuries, such as tears of the meniscal cartilages, which are seen quite frequently in association with PCL tears.




Treatment

 

Early treatment consists of:-

Fortunately, the large majority of patients with an isolated PCL tear do well with conservative non-surgical management, with regular appropriate physiotherapy and rehab treatments, achieving good functional stability in the joint by building up increased strength and faster reflexes in the quads muscles, to compensate.

If there is an associated meniscal tear or other concomitant intra-articular damage, then it is likely that the patient is going to need a knee arthroscopy to sort out the inside of the joint prior to then commencing regular physiotherapy rehab treatments. Only about 10% of isolated PCL ruptures actually go on to end up needing a surgical reconstruction of the torn ligament.

If the PCL is torn as part of a multi-ligament injury then it is very likely that the PCL will need a surgical reconstruction, as part of a major multi-ligament reconstruction.

 


 

CLICK HERE for further information about surgical PCL reconstruction 

 



Written by Mr Ian McDermott
Consultant Knee Surgeon London
Last updated 24-6-15