Restoring stability is an important part of biological knee replacement.
First published 2010 by Dr Kevin R Stone, and reviewed August 2023 by Dr Sheila Strover (Clinical Editor)
For the unstable knee where there has been ligament damage such as an ACL tear, a PCL tear, a posterolateral corner tear or a medial collateral ligament (MCL) tear – which are the most common injuries that we see – we want to stabilise that joint as part of any biologic knee reconstruction.
We approach that in the following way –
- If the ligament is only partially torn, such as the ACL with a partial tear, up near the femoral origin, we can do a primary repair of that partial tear with sutures into a microfractured intercondylar notch. We almost always will add a fibrin clot (made by allowing the patient's blood to clot in a tube) with or without a collagen scaffold in order to augment healing of that ligament into the intercondylar notch. It is also true for the PCL with a partial tear where we will repair it. For the MCL we will often let it heal on its own.
- For the posterolateral corner if it is completely torn and has a ‘drive-through' sign or a sign at arthroscopy where the superior and inferior aspects of the lateral meniscus can be easily seen in the same view then we will reconstruct the posterolateral corner. So for each of these reconstructions we have now moved to using allograft tissue rather than autograft tissue.
We have posted a video called ‘Knee dislocation, reconstruction of the ACL, PCL and posterolateral corner' on our website for people to see, but in general we will use a sterilised bone patellar-tendon bone allograft (photo on right) for the ACL and for the PCL, and for the posterolateral corner we will use a sterilised anterior tibialis tendon which we pass through the fibular head, underneath the skin and underneath the iliotibial band and up to a small incision through the iliotibial band to the anatomic insertion site.
For reconstruction of ruptured ligaments in the knee when we are doing a biological joint reconstruction, we don’t want to sacrifice any of the patient’s own tissue if it is not necessary. Up until about 5 years ago we felt as though allograft tissues were not as reliable as autograft tissues.
Once we were able to obtain sterilised allograft tissues whose biomechanical properties had not been damaged by the sterilisation process then we felt comfortable moving forward to use those tissues in replacement of autogenous tissues. We did not want to ‘rob Peter to pay Paul’, that is we did not want to damage one part of the knee in order to rebuild another part of the knee. Over the last 5 years our results of allograft tissue have matched our autograft tissue except that the patients have much less pain and a much faster rehabilitation.