Generally, there are three categories of sprains and strains. The key to differentiating the grades has to do with joint instability and overall strength of the affected area.

A grade I strain/sprain involves little to no tearing of the muscle, tendon or ligament with no joint instability. There is little to no bruising and the joint remains strong and fully functional. A grade I injury involves little pain and generally the joint is able to tolerate weight. These mild injuries require about 3-6 weeks rehab.

A grade II injury involves a tear of the muscle, tendon or ligament and is usually painful. There is moderate joint instability, there is localized swelling and the person is not able to bear weight. Hence, there is considerable weakness associated with the tear as well as bruising. These injuries may require casting and generally take about 2-3 months to for healing.

A grade III injury involves a complete rupture/tear of the ligament, muscle or tendon. There is obvious joint instability, pain, swelling and bruising. Surgery is generally required to repair the damage. Complete return to function can take up to 8-12 months.