The knee meniscus is an important structure, and when it is damaged surgery attempts to restore its function. If damaged beyond repair, it is possible to perform a transplant.
Why is it important to preserve the knee meniscus?
In the not too distant past, a damaged meniscus was simply removed (meniscectomy) because doctors thought it to be only a remnant of tissue from early embryo development. Eventually they came to appreciate that removing the meniscus led to a high incidence of early knee arthritis.
Now it is appreciated that the meniscus is really important as a shock absorber and stabiliser of the joint, and surgery is focused on preserving as much of its structure and function as possible. When damaged beyond repair or reconstruction, meniscectomy may still be necessary but there still remains the possibility of a meniscus transplant for preserving function. In addition realigning the bones via osteotomy may alter the forces going through the joint to minimise pressure on the damaged side.
Why has meniscus trimming developed a bad reputation?
It has been common in the past for knee surgeons performing arthroscopy to 'trim' frayed edges of a damaged meniscus ('arthroscopic partial meniscectomy') in an attempt to prevent or slow further destruction. Studies have shown that, at least in the older population group, there is little benefit and may actually be some harm from interfering, with a slightly more rapid onset of osteoarthritis. This has prejudiced health insurance companies from paying for such procedures in patients over 65.
What are the consequences of removing a meniscus?
Injury may cause a tear in the body of the meniscus, disrupting its fibres and damaging its ability to function as a spacer, shock absorber and stabiliser of the joint. But removal of the damaged meniscus brings its own set of problems. The changed forces may damage the delicate white articular cartilage covering and protecting the ends of both femur and tibia bone, and the cartilage itself may break down and the bone put under stress. As the bone tries to repair the problem its healing systems may become disturbed and cysts and spurs may form instead. The collateral ligaments on the other side may become stretched and allow an outward thrust of the joint with each weight-bearing step. Eventually the articular cartilage and bone on the 'good' side become damaged as a consequence.
If damaged meniscus tissue needs to be removed, then today's surgeon will try to remove as little as necessary (meniscal trim), preserving where possible the very important outer rim which does most of the work protecting the vulnerable joint cartilage which it usually cushions. The younger patient may be offered a realignment osteotomy, to try and shift weight-bearing over to the good side, and if the meniscus has to be removed then a transplant may be offered.
Or the meniscus may be intact but the connections to the tibia may be damaged, such as in a meniscal root tear. Longitudinal tears through the meniscus tissue offer an opportunity for stitches (sutures) to pull the damaged edges together until fibrous healing has taken place.
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Meniscus surgery -
- Meniscus repair
- Meniscal scaffold
- Meniscus replacement
- Arthroscopic meniscectomy
Relevant material -
from the Experts -
- Expert view - 2017 - What is meniscus preservation and why does it matter? - by Prof Raju Vaishya (Knee Surgeon)
- Journal interpretation - 2021 - The future of meniscus science: international expert consensus - interpreted by Dr Sheila Strover (Clinical Editor)
Video of a meniscal trim, courtesy of Dr Ram Venkatesh