Ligaments are strong, fibrous bands of connective tissue (extracellular matrix and fibroblasts) that connect one bone to another and play a key role in musculoskeletal stability and function. Ligaments help stabilize joints by keeping bones in proper alignment and supporting them during motion. Some ligaments, such as those in the spine, have an increased degree of flexibility to enable some limited motion. Although they’re strong, ligaments can be strained and torn when subjected to certain types of forces including torsion or twisting.
Any ligament can be torn, but the ligaments of the knee are among the most commonly injured, largely due to continual exposure to stress and torsion when in motion. The knee includes the anterior and posterior cruciate ligaments (ACL and PCL) that crisscross in the front and back of the knee respectively, and the collateral ligaments that support the sides of the knees. Among these ligaments, the ACL is the one injured most often, with roughly 100,000 ACL repairs being performed in the U.S. each year. Most ACL injuries occur from non-contact activities, usually as a result of severe or sudden twisting. Women are about nine times more likely to experience an ACL tear compared to men. 
WHAT ARE THE SYMPTOMS?
The symptoms of a torn ligament can vary slightly depending on where the ligament is located. For instance, while a torn ligament generally results in some instability in a joint, the degree of instability can vary depending on the joint that’s affected and even depending on which ligament is involved. Symptoms can also vary depending on whether the ligament is torn completely through or only partially torn.
In most cases, symptoms of a torn ligament include :
- pain in an affected joint
- pain or tenderness near the ligament
- difficulty moving a joint or loss of range of motion in the joint
- swelling or bruising near the ligament
- instability in a joint, especially the knee
- a “popping” noise when the injury occurs
Treatment for most torn ligaments may begin with conservative approaches like ice and rest, but to return to function, most injuries involving tears require surgery to stabilize the ligament and help it regain strength.  Even partial tears may require surgery to ensure the edges line up properly and knit together for optimal strength. Surgical approaches include minimally invasive arthroscopy that uses small incisions and special surgical instruments to facilitate faster healing and recovery, and open approaches that enable the surgeon to have greater access to the ligament, bones and surrounding tissues.
Once repair has been made or healing is under way, rehabilitation using physical, occupational or sports therapy (or a combination) can help ensure the ligament returns to health and function and an affected joint regains mobility, strength and range of motion.