Hi Linh,
You raise many points in this question.
I will list the appearances I am looking for in this spectrum.
A normal ATFL will have densely packed parallel lines of collagen and will prevent the talus from moving anterior when challenged by the Quanson modified anterior draw test. A trace of fluid beneath it is normal.
An acute strain looks like a swollen, hypo echoic ligament but without any focal defect and maintains stability when challenged by the Quanson modified anterior draw test. There must be an acute trauma history.
A partial tear is the same as the acute strain appearance, however there will be a partial thickness defect in the ligament. Again an acute history is essential.
A complete tear presents with complete disruption in the ATFL with ankle joint synovial fluid passing through the defect into the subcutaneous space causing swelling and bruising. There may or may not be a bony avulsion at the point of failure. When challenged by the Quanson modified anterior draw test the talus migrates anteriorly away from the lateral malleolus.
An old tear looks similar to an acute strain with an “intact” ligament in situ, however in this case the ligament is not native collagen but rather granulation tissue. When challenged by the Quanson modified anterior draw test it usually provides reasonable stability but this is variable and those patients that still feel “unstable” may have more movement and laxity. In this case a prior history of trauma but no immediate injury is essential.
In cases of anterolateral gutter impingement it is exactly the same as an old tear, however rather than the scar tissue being similar in thickness to the native ligament it is more than twice as thick and causes impingement. It may also be vascular and the patient will be experiencing ankle tightness.
As for vascularity, in all acute injuries you will see hyperaemia as part of the injury / heal response.
In an old granulated ligament there should be no flow,
In anterolateral gutter impinegement there is often some flow due to the synovitis caused by the impingement.
Steve