Hi Xue,
Good questions.
In the case you have uploaded I feel this is from old trauma.
It can come about in 2 ways.
1: An avulsion from the talus or fibula leaving a small chip of bone in the area of the ligament.
2: A tear of the ATFL where there is no avulsion, however during the healing phase some dystrophic calcification is deposited.
I think you can usually tell the difference between this and a calcific tendinosis.
Calcific tendinosis is hydroxyapatite deposition. This is a bone salt and it must migrate via the enthesis to the tendon , usually as a result of tendinosis. So this occurs in tendons, not capsular ligaments like ATFL. The hydroxyapatite is less dense than an avulsion and more “cloud like”.
If you have an old deposit of hydroxyapatite it may become dense and then I can’t tell the difference between it and dystrophic calcification, however this does not matter as both are likely to be asymptomatic.
So with a ligament I think of avulsion fracture and dystrophic calcification (CPPD is also a possibility)
In tendons I think of calcific tendinosis (hydroxyapatite) and if it is chronic I am happy to call it dystrophic calcification when it is densely shadowing.
As for the second part of the question:
When you tear an ATFL is usually heals up nicely with a neat amount of granulation tissue. Sometimes the granulation is excessive and it can lead to anteroom-lateral gutter impingement symptoms some months after the initial injury. This may be accompanied by an avulsion fracture or dystrophic calcification as discussed. Sometimes you will see vascularity as synovitis is present due to the impingement.
I would describe it as ab “excessive granulation response and synovitis leading to anterolateral gutter impingement”
The patient will be complaining about stiffness / tightness/ lack of flexibility in the anteroom-lateral gutter of the ankle following an inversion injury event.
You can also see post traumatic synovitis in the tibia-talar part of the deltoid ligament which we call a POMI lesion (poster-medial impingement)
Steve