Grade 3 being the most severe, where the muscle has been torn. The treatment for a grade 3 strain is normally an operation to repair the muscle, and 3 or 4 months rehabilitation. In very severe cases a graph may be needed or even reconstruction which may need 2or 3 operations.
Grade 2 this is where most of the damage is done to the muscle fibers. The rehabilitation for a grade 2 is 1 or 2 months.
Grade 1 is where there is light damage to the muscle fibers. The rehabilitation is usually around 2 or 3 weeks.