Clinical features of ACL tear

clinical features

Typically ACL injury is seen in noncontact deceleration or change of direction e.g - in instances where the athlete lands from a jump awkwardly or pivots in the opposite direction (1).

• patient may hear a 'pop' sound or may feel tearing sensation and may collapse to the ground due to the knee giving away (1)
• there is sever pain which decreases within minutes and the patient may be able to weight bear, albeit gingerly (2)

A rapid onset of swelling within 3 hours of injury is seen in around 80% of the patients.

• swelling is caused by haemarthrosis due to torn ACL
• intra articular fracture (seen in high energy injuries) may also cause haemartrosis
• gradual swelling (over 24 hours) does not rule out ACL tears (1)

Attempts to continue activity following injury often causes instability and difficulty in bearing weight (1)

Reference:

• (1) Alford JW, Bach BR. Examination through familiarity with basics and a systemic approach. Managing ACL tears:Evaluation and diagnosis. The journal of musculoskeletal medicine 2004
• (2) Scotney B. Sports knee injuries - assessment and management. Aust Fam Physician. 2010;39(1-2):30-4