They study of ligaments are known as Desmology. Ligaments are a strong band of white fibrous connective tissue composed mainly of long, stringy collagen fibres joins bones to other bones or to cartilage in the joints. They played the main role in the stability of the joint (because the main characteristic of ligaments is like elastic, it will gradually lengthen when under tension- muscle contraction & relaxation or joint distraction & compression) and the freedom of movement within a certain range.

A sprain is damage to or tearing of ligaments or the capsules, when excessive forces like joint twist or abnormal joint mobility leads to torn or damage the ligaments that hold the bones together, results in ligament sprain. The common sites are the ankle and knee joints in the lower limb, wrist and finger joints are in the upper lime. When excessive force is applied to a joint, the ligaments that hold the bones together may be torn or damaged. This action results in a sprain, and its seriousness depends on how badly the ligaments are torn. Any joint can be sprained, but the most frequently injured joints are the ankle, knee, and finger. The knee joint (major weight bearing joint in the body) is a vulnerable joint in the body gets injured very easily and frequently. Ligament injuries are usually graded depends on their severity. Grade I, Grade II and Grade III.

Symptoms of a ligament injury are:
severe pain at the time of the injury
feel or hear a pop or tear inside the joint
immediate swelling and bruising at the joint and
instability and giving way of the joint after injury.
In the current medical field, a wide variety of Physiotherapy modalities are available in management of ligament injuries. Treatment includes:
*Pain and swelling relieve techniques *Hands on techniques like manipulation, mobilization and therapeutic massage, Therapeutic exercise and training in ADL.