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.
Peer-reviewed paper
Peer-reviewed paper Quote from peer-reviewed paper:
"Displacement of the flap inferiorly to the meniscotibial recess is more common than superior displacement to the meniscofemoral recess....Appropriate diagnosis and management of symptomatic displaced flap tears of the meniscus may be further complicated by the presence of associated articular cartilage loss."
Citation: Hashimoto Y, Takigami J, Tomihara T, Salimi H, Katsuda H, Shimada N, Nakamura H. Arthroscopic Repair for Parrot Beak Tear of Lateral Meniscus with Reduction Suture and Inside-Out Technique. Arthrosc Tech. 2021 Nov 2;10(12):e2633-e2637. doi: 10.1016/j.eats.2021.08.005. PMID: 35004142; PMCID: PMC8719056.
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.
Peer-reviewed paperQuote from peer-reviewed paper:
"....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....."
Citation: Bassett AJ, Hadley CJ, Tjoumakaris F, Freedman KB. The Meniscal Grammar Signs: Comma and Apostrophe Signs for Characterization of a Displaced Fragment in the Meniscal Recess. Arthrosc Tech. 2019 Jul 4;8(7):e727-e732. doi: 10.1016/j.eats.2019.03.008. PMID: 31485399; PMCID: PMC6713919.
How is a parrot-beak tear managed?
The surgeon will usually choose to trim off the problematic bit under arthroscopy.
Peer-reviewed paperQuote from peer-reviewed paper:
"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."
Citation: Bassett AJ, Hadley CJ, Tjoumakaris F, Freedman KB. The Meniscal Grammar Signs: Comma and Apostrophe Signs for Characterization of a Displaced Fragment in the Meniscal Recess. Arthrosc Tech. 2019 Jul 4;8(7):e727-e732. doi: 10.1016/j.eats.2019.03.008. PMID: 31485399; PMCID: PMC6713919.
Forum discussions
- "2 days post arthroscopy"
A patient has a parrot-beak tear debrided during arthroscopy.