Overview
An ACL injury is a tear of the anterior cruciate ligament, commonly from pivoting or landing movements.

Symptoms
A popping sensation, rapid swelling, instability, and difficulty bearing weight.

Diagnosis
Physical exam and MRI.

Treatment
Rehabilitation is essential. Surgical reconstruction is considered for active individuals with instability or high‑demand activities.

When to seek care
Immediate evaluation is recommended after acute knee injury with instability or swelling.