Meniscus root tears are now being recognised as a significant cause of pain, disability, and rapid joint deterioration. They can occur in younger patients as a result of high energy trauma, but are more common in patients between 45 and 60 as a result of degeneration of the meniscus with age.
The meniscus of the knee performs a very important function and protects the underlying cartilage. The articular cartilage of the knee is the smooth running surface of the joint, and is made of a substance called hyaline cartilage. There are two menisci in each knee, and they are made of a soft rubbery material called fibrocartilage. Each meniscus is C-shaped, and attached only to the bone of the tibia by the meniscus roots.
The roots and the outer rim of the meniscus prevent the meniscus from being pushed sideways out of the joint when the knee bears load. Meniscus root tears can be either disruption of the meniscus attachment direct from the bone (true meniscus root tear) or a tear which disconnects the root region completely from the body of the meniscus (complete radial tear) can cause the entire meniscus to lose its ability to protect the underlying cartilage. The effect of the tear is comparable to removal of the entire meniscus, and exposes the cartilage to very large stresses.
Once the meniscus is pushed out, or extruded, the underlying cartilage can start to rapidly deteriorate. The bone nearby can frequently become inflamed, causing significant pain. Studies have shown that the majority of patients who suffer medial meniscus root tears which cannot be repaired undergo a rapid progression of arthritis in that region and progress to knee replacement within 5 years, and many within 1 year.
Excellent results have been obtained with surgical repair of the meniscus root. Successful repair can remove the pain, and restore the function of the meniscus. However, as previously discussed, the main reason for tears in an older age group is due to degeneration of the meniscus substance. The quality of the remaining meniscus tissue needs to be carefully assessed prior to attempting a repair, as well as the ability of the patient to use crutches for around 6 weeks, and avoid pressure on the repaired knee.
Repairs are performed via arthroscopy (keyhole surgery). Repair of the meniscus root involves passing stitches into the meniscus remnant, and re-anchoring it to the bone.
Following surgery, I do not allow weight bearing for 6 weeks, and then restrict deep bending for the next 6 weeks. After 3 months I allow full activity with no restrictions.
Patients who are unsuitable for repair are generally treated non-surgically, with tablets and perhaps an injection of corticosteroid to minimise pain. If this is insufficient, surgical procedures such as unicompartmental knee replacement or high tibial osteotomy are very successful in removing the pain.