If there has been a large or total previous meniscetomy the loss of protective shock absorption and load sharing in the knee can lead to pain, discomfort and swelling. This may come on only with impact or repetitive activities. In addition loss of the meniscus increases the risk of osteo-arthritis and long term joint dysfunction.
If avoiding the activities that cause problems is either impossible or not something the patient is willing to undertake long term then surgery is indicated to replace the meniscus and to improve the load sharing across the knee. This type of surgery can also be indicated to reduce the risk of developing OA in teenagers and young adults who have had a large menisectomy or as a combined procedure to reconstruct an unstable knee or cartilage surface injury. There is a belief that meniscal replacement can reduce the long term risk of OA although this has never been proven in the literature to date.
There are two types of meniscal replacement, artificial and cadeveric allograft (meniscal transplant). If there is still a portion of the old meniscus left then an artificial meniscal scaffold can be used to fill the gap of missing tissue. Mr Gallacher uses the Actifit meniscal replacement which has been shown to give good clinical results in the short and medium term. The long term results of this treatment are still unknown. The replacement acts as a scaffold to allow tissue to regrow where the meniscus has been removed. This process of new growth takes many months and it can be 12 to 18 months before the meniscal scaffold is fully integrated with your own tissue.
Cadeveric replacement involves the use of donated allograft meniscal tissue for a complete transplant. The entire meniscus is transplanted into the knee using arthroscopic surgery and fixed to the tibia and the rim of the knee capsule. This procedure is usually reserved for cases where there is no meniscus remaining at the front or back attachment to the tibia or a artificial replacement has failed. The meniscus has a very low immune presence so rejection is not normally an issue. It can be difficult to get a matching allograft meniscus as they must be size and side matched so patients often wait several months for a donor match. The surgery is technically demanding and can take several hours to perform.
Measuring meniscal defect
Actifit meniscal replacement
Cadeveric meniscus being prepared for transplant
Both artificial replacement and allograft meniscal transplant are performed as arthroscopic keyhole operations through small cuts at the front of the knee. However they are complex procedures and take around 1-3 hours to perform, usually as a daycase or overnight stay. The post operative rehabilitation is prolonged taking up to six months, initially you are in a brace partial weight bearing on crutches. It takes around six to twelve weeks to be fully weight bearing and you will not return to sports before 6-12 months.
The surgery caries all the risks of a standard keyhole operation but in addition there is a risk of the replacement failing either by tearing in the same way the native meniscus did or being absorbed by the body over time.
If there is severe arthritis in the knee already then meniscal replacement alone may not be enough to improve your symptoms and repair of the cartilage wear and/or an osteotomy may be required to offload the worn part of the knee. Occasionally the knee is so worn that only a partial or total knee replacement will suffice.