PCL tears

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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 sagand 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:-

• rest
• anti-inflammatories
• the GAME READY system, for icing and intermittent compression
• Physiotherapy

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.