So when a patient presents with knee pain, whether or not they have an arthritic knee, if they have a torn meniscus cartilage we are very biased towards trying to save that meniscus cartilage if at all possible.
We judge our ability to save that cartilage by the quality of the tissue of the meniscus, and so if when we look in the knee the meniscus tissue is relatively healthy then we try to repair that tissue with sutures from an inside-out technique.
Sometimes the tear has a complex pattern or a degenerative component to it and requires a stimulus in order to create additional healing, meaning sutures alone might not stabilise the meniscus enough to permit healing and there might not be enough of a healthy growth environment for it to heal.
When that is the case we then augment the healing by using a collagen ‘scaffold’ (photo on left) loaded with the patient’s own growth factors or fibrin clot (photo on right). We do that by taking a Regen biologic collagen scaffold called the Collagen Meniscus Implant, we soak it in the patient’s blood or sew a fibrin clot to it and then we sew that collagen meniscus implant into the meniscus defect and then sew the meniscus together with it. This is called a ‘meniscus reconstruction’. We believe that this will become a whole new field of meniscus treatment.
If, on the other hand, we look in the knee and the patient’s meniscus has been removed in the past or there is a substantial volume of meniscus lost, particularly at the posterior (back) aspect of the knee, then we move onto meniscus replacement – and we do that using an ‘allograft’ meniscus (photo on right - allograft lateral meniscus).
Generally we know before we go to surgery that a meniscus replacement will be required based on the patient’s history, X-rays and careful MRI. When a meniscus is required we size the meniscus by matching the donor to the recipient by sex, height and weight and then we come to the operating theatre with the meniscus prepared for implantation. The meniscus is replaced using the three-tunnel technique that we have previously published or a trough technique on the lateral side.
We do not see the degree of arthritis as a limitation to doing a meniscus replacement, nor in our study that we publish this July (2010) in the British Journal of Bone and Joint Surgery, did any particular deformity affect the outcome of a meniscus replacement, as long as the opposing articular cartilage was also treated.
Biologic knee replacement can be done in one stage most of the time except where there is relatively advanced loss of articular cartilage on either femoral condyle. When there is reasonably advanced loss of articular cartilage we prefer to do the procedure in two stages so that we can use a CPM machine and mould the paste graft on the articular cartilage surface in the first step, and then come back 8 weeks later and then place the meniscus into the repaired joint. If the articular cartilage defect is more isolated then we can do the paste graft and the meniscus replacement in one step.