PCL reconstruction

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The posterior cruciate ligament is the main ligament at the back of the knee, connecting the femur and the tibia and preventing the tibia from wobbling too far backwards (posteriorly). The PCL is bigger than the ACL, and is not as commonly injured. The most common mechanisms of injury for a PCL tear are either a dashboard-type injury or a fall onto the front of the shin (where the shin is forced backwards) or a hyperflexion injury, which tends to happen when someone falls onto their knee and the knee is forced suddenly into deep flexion. PCL injuries can also occur with hyperextension of the knee or from major twisting injuries, and PCL tears are often found in combination with tears of other of the knee ligaments in more major injuries, such as the ACL and/or the posterolateral corner structures.

The most common thing that happens with a PCL injury is that the diagnosis is actually missed! (or at the very least delayed). After a PCL injury there is pain and swelling in the knee, but this is not as severe, overt or long-lasting as it can be with injuries of the ACL (which are far more common), and PCL deficiency tends often to cause less severe ongoing problems in a knee. There may be wobbliness and instability, especially with impact/twisting manoeuvres. Alternatively, the knee might just not feel ‘right’. Also, PCL deficiency if left untreated often ends up resulting in the patient developing further additional damage in the knee with time, such as meniscal tears.

Most patients with an isolated PCL tear actually do very well with intensive focused physiotherapy rehab, centering on building up as much strength and as fast reflexes as possible in the quads muscles, to try and compensate for the ligament deficiency. The following are indications for proceeding with surgical PCL reconstruction:-

• If a patient with no PCL has tried appropriate physiotherapy rehab, but they are still suffering significant ongoing instability of the knee.
• If the injury is a multi-ligament injury (i.e. combined with an ACL and/or posterolateral corner injury), as these rarely ever do well without surgical reconstruction of all the damaged ligaments together.
• If, as a result of the PCL deficiency and any instability in the joint the patient is developing progressive damage to the joint, such as meniscal tears.
• If the patient also needs other reconstructive procedures in the joint, such as meniscal replacement surgery (e.g. meniscal transplantation), which can only be undertaken in a solid stable joint.

Reconstruction of the PCL is a similar procedure to ACL reconstruction, but the surgery is somewhat more complex and difficult, and the early rehab somewhat slower.

When a PCL tears, the damaged ligament tissue is often frayed and tends to scar up and shrink back, and direct primary repair is very rarely ever feasible or appropriate. Instead, the ligament has to be replaced with a new ligament, called a graft. Under an anaesthetic, bone tunnels are drilled from the femur and the tibia either side of the knee, passing into the middle of the joint. The graft is passed along these tunnels, fixed at one end, tensioned, and then fixed under tension at the other end. At the same time, a knee arthroscopy is performed and any other concomitant damage in the knee is sorted out.

As with ACL reconstruction, there are various options available for where to obtain a graft from and what type of graft to use. Unlike ACLs, however, the patellar tendon graft is not a viable option, and the main choice is between a hamstring autograft or an allograft.

CLICK HERE  for further information about graft options (exactly the same applies for the PCL as for the ACL)

Recovery / rehab

Most patients are able to be discharged from hospital the morning of the following day, fully weight bearing but with crutches initially, for comfort and support. Unlike a straight forward ACL reconstruction, we normally put patients into a hinged knee brace for the first 6 weeks after a PCL reconstruction, as the graft tends to need somewhat more careful protection than an ACL graft.

The first week or so after surgery is spent pottering around at home and taking things easy. After that, patients start regular intensive physiotherapy rehab treatments, to get the movement, strength and reflexes back in the knee. Most patients are able to restart gentle slow jogging on a treadmill by 3 months post-op, with a return to sport at 9 months.

Results

The results of PCL reconstruction are good, with a success rate (based on patient symptoms, function and overall satisfaction) of about 90%, but this does very much depend on what other potential damage there might be in the joint and what other concomitant procedures might have needed to be undertaken at the same time as the PCL reconstruction (as the initial presentation of patients with a PCL tear to a knee surgeon is so often delayed, and hence by the time that a patient actually gets their PCL reconstruction there are by then already other issues with the joint that have sadly developed).