What is an ACL (Anterior Cruciate Ligament) Tear?

Functional Biomechanics of the ACL

The anterior cruciate ligament (ACL) resides at the core of the knee joint, functioning as the primary restraint against anterior tibial translation and secondary restraint to internal tibial rotation. Acute tears predominantly stem from non-contact deceleration and pivoting mechanisms during athletic sports.

Injury Presentation and Hemarthrosis

Rupture classically triggers a loud auditory 'pop' accompanied by immediate joint collapse. Disruption of the middle genicular artery vessels causes rapid gross hemarthrosis (tense joint swelling) within 1 to 4 hours of trauma.

Cardinal Symptoms

• Audible intra-articular pop followed by immediate inability to continue activity
• Rapid hemorrhagic effusion filling the suprapatellar pouch
• Instability and episodes of the knee giving way during rotational movements
• Marked restriction in terminal extension and flexion due to guarding

Frequently Asked Questions

Can an ACL heal spontaneously?

Because the intra-articular synovial environment lyses the protective fibrin clot, complete ACL tears possess negligible spontaneous healing capacity, necessitating surgical reconstruction in pivoting athletes.

What graft choices are utilized in ACL reconstruction?

Autologous hamstring, bone-patellar tendon-bone (BPTB), or quadriceps tendon grafts represent established options implanted via anatomical arthroscopic technique.