Why is a parrot-beak tear problematical?
Often the 'beak' of a parrot-beak tear may flip underneath the rest of the meniscus and be missed on arthroscopy unless the surgeon is diligent in probing and pulling at the undersurface of the body of the meniscus.
Over time this protruding bit may nourish itself from the joint fluid and get bigger, rounding itself off, and occasionally causing catching in the joint.
If the loose bit flips over and gets trapped in the recess (arrow) between meniscus and tibia, it may reveal itself on MRI scan as a 'comma sign'. The loose end is usually trimmed off with a partial meniscectomy under arthroscopy.
Can a parrot beak tear heal on its own?
A parrot-beak tear is not likely to heal on its own because it is in the 'white-white' inner part of the meniscus where there is no, or very little, blood supply.
Attempts at healing merely round off the loose end of the tear, while further stress on the meniscus may catch on the rounded bit and cause the oblique tear to extend. If it is symptomatic then the 'beak' is generally removed via an arthroscope in a partial meniscectomy procedure. In some cases, especially if the tear is in the lateral meniscus, where its special anatomy makes it more vulnerable to meniscus incompetence, a surgeon may attempt a repair.
"....Unstable meniscus flap tears with entrapped recess fragments tend to be complex tears located in the nonvascular region of the meniscus, have poor quality of the flap tissue after reduction, have the potential to revert back to the displaced configuration, and occur in older patients with less healing potential for repair....."
How is a parrot-beak tear managed?
The surgeon will usually choose to trim off the problematic bit under arthroscopy.
"Partial meniscectomy for parrot beak tears is often recommended, owing to the avascular zone; however, partial meniscectomy, especially with the lateral meniscus, has a high failure rate for return to sports, leading to residual meniscus extrusion and lateral compartment osteoarthritis."
Relevant links on KNEEguru
A-Z Keywords
Radial tear, Lateral meniscus, Partial meniscectomy, Avascular zone, Meniscal tear
Forum discussions
- "2 days post arthroscopy" - A patient has a parrot-beak tear debrided during arthroscopy.